refacto: refacto repo layer code while adding new usecase methods

A lot of work is still to be done ...

.air.toml

@@ -7,7 +7,7 @@ tmp_dir = "tmp"
   bin = "./_output/howmuch"
   cmd = "make build"
   delay = 1000
-  exclude_dir = ["assets", "tmp", "vendor", "testdata", "_output"]
+  exclude_dir = ["assets", "tmp", "vendor", "testdata", "_output", "internal/howmuch/adapter/repo/sqlc"]
   exclude_file = []
   exclude_regex = ["_test.go"]
   exclude_unchanged = false

.gitea/workflows/demo.yaml

@@ -0,0 +1,63 @@
+# MIT License
+#
+# Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+name: Build and test
+run-name: ${{ gitea.actor }} is building and testing the project!
+on: [push]
+
+jobs:
+  Build:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "🎉 The job was automatically triggered by a ${{ gitea.event_name }} event."
+      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by Gitea!"
+      - run: echo "🔎 The name of your branch is ${{ gitea.ref }} and your repository is ${{ gitea.repository }}."
+      - name: Check out repository code
+        uses: actions/checkout@v4
+      - run: echo "💡 The ${{ gitea.repository }} repository has been cloned to the runner."
+      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
+      - name: List files in the repository
+        run: |
+          ls ${{ gitea.workspace }}
+      - name: Setup Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: '1.23.1'
+      - run: go version
+      - name: Setup sqlc
+        uses: sqlc-dev/setup-sqlc@v4
+        with:
+          sqlc-version: '1.25.0'
+      - run: sqlc version
+      - name: Build backend
+        run: make build
+      - name: Test backend
+        run: make test
+      - name: Setup node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+      - name: Build frontend
+        run: make web-build
+      - name: Test frontend
+        run: make web-test
+      - run: echo "🍏 This job's status is ${{ job.status }}."

.gitignore

@@ -24,4 +24,38 @@ go.work.sum
 
 # Custom
 /_output
-/deployment/db_data
+/deployment/tmp
+/tmp/**
+
+# Vue
+#
+# Logs
+web/logs
+web/*.log
+web/npm-debug.log*
+web/yarn-debug.log*
+web/yarn-error.log*
+web/pnpm-debug.log*
+web/lerna-debug.log*
+
+web/node_modules
+web/.DS_Store
+web/dist
+web/dist-ssr
+web/coverage
+web/*.local
+
+web/cypress/videos/
+web/cypress/screenshots/
+
+# Editor directories and files
+web/.vscode/*
+web/!.vscode/extensions.json
+web/.idea
+web/*.suo
+web/*.ntvs*
+web/*.njsproj
+web/*.sln
+web/*.sw?
+
+web/*.tsbuildinfo

Makefile

@@ -29,12 +29,16 @@ GO_LDFLAGS += \
 # ==============================================================================
 .PHONY: all
 all: add-copyright format build
-
+web: web-all
 # ==============================================================================
 
 .PHONY: build
-build: tidy # build.
-	@go build -v -ldflags "$(GO_LDFLAGS)" -o $(OUTPUT_DIR)/howmuch $(ROOT_DIR)/cmd/howmuch/main.go 2>/dev/null
+build: tidy sqlc # build.
+	@go build -v -ldflags "$(GO_LDFLAGS)" -o $(OUTPUT_DIR)/howmuch $(ROOT_DIR)/cmd/howmuch/main.go
+
+.PHONY: sqlc
+sqlc:
+	@sqlc generate
 
 .PHONY: format
 format: # format code.
@@ -42,7 +46,7 @@ format: # format code.
 
 .PHONY: add-copyright
 add-copyright: # add license to file headers.
-	@addlicense -v -f $(ROOT_DIR)/LICENSE $(ROOT_DIR) --skip-files=database.yml --skip-dirs=$(OUTPUT_DIR),deployment,migrations,configs,sqlc
+	@addlicense -v -f $(ROOT_DIR)/LICENSE $(ROOT_DIR) --skip-files=database.yml --skip-dirs=$(OUTPUT_DIR),deployment,migrations,configs,sqlc,web,mock
 
 .PHONY: swagger
 swagger: # Run swagger.
@@ -52,6 +56,22 @@ swagger: # Run swagger.
 tidy: # Handle packkages.
 	@go mod tidy
 
+.PHONY: test
+test:
+	@go test ./...
+
 .PHONY: clean
 clean: # Clean up.
 	@-rm -vrf $(OUTPUT_DIR)
+
+.PHONY: web-build
+web-build:
+	$(MAKE) -C web build
+
+.PHONY: web-test
+web-test:
+	$(MAKE) -C web test
+
+.PHONY: web-all
+web-all:
+	$(MAKE) -C web all

README.md

@@ -13,6 +13,19 @@
       - [Version](#version)
     - [2024/10/03](#20241003)
     - [2024/10/04](#20241004)
+    - [2024/10/06](#20241006)
+      - [Workflow](#workflow)
+    - [2024/10/07](#20241007)
+      - [The choice of the front end framework](#the-choice-of-the-front-end-framework)
+    - [2024/10/08](#20241008)
+    - [2024/10/09](#20241009)
+    - [2024/10/11](#20241011)
+    - [2024/10/13](#20241013)
+    - [2024/10/15](#20241015)
+    - [2024/10/16](#20241016)
+    - [2024/10/17](#20241017)
+    - [2024/10/18](#20241018)
+    - [2024/10/19](#20241019)
 <!--toc:end-->
 
 A tricount like expense-sharing system written in Go
@@ -23,6 +36,8 @@ It is a personal project to learn go and relative technologies.
 
 ---
 
+![Gitea action](https://git.vinchent.xyz/vinchent/howmuch/actions/workflows/demo.yaml/badge.svg)
+
 ## Project Diary
 
 ### 2024/09/30
@@ -46,11 +61,11 @@ Next I need to design the API.
   - add other users to that event
   - A user can only view their own events, but not the events of other users'
   - A user can add an expense to the event (reason, date, who payed how much,
-  who benefited how much)
+    who benefited how much)
   - Users in the event can edit or delete one entry
   - changes are sent to friends in the event
   - User can get the money they spent themselves and the money they must pay
-  to each other
+    to each other
   - User can also get the total amount or the histories.
 
 That is what I thought of for now.
@@ -94,10 +109,10 @@ The execution of the program is then just a command like `howmuch run`.
 Moreover, in a distributed system, configs can be stored on `etcd`.
 
 > [Kubernetes stores configuration data into etcd for service discovery and
-cluster management; etcd’s consistency is crucial for correctly scheduling
-and operating services. The Kubernetes API server persists cluster state
-into etcd. It uses etcd’s watch API to monitor the cluster and roll out
-critical configuration changes.](https://etcd.io/docs/v3.5/learning/why/)
+> cluster management; etcd’s consistency is crucial for correctly scheduling
+> and operating services. The Kubernetes API server persists cluster state
+> into etcd. It uses etcd’s watch API to monitor the cluster and roll out
+> critical configuration changes.](https://etcd.io/docs/v3.5/learning/why/)
 
 #### Business logic
 
@@ -105,8 +120,8 @@ critical configuration changes.](https://etcd.io/docs/v3.5/learning/why/)
 - init DBs (Redis, SQL, Kafka, etc.)
 - init web service (http, https, gRPC, etc.)
 - start async tasks like `watch kube-apiserver`; pull data from third-party
-services; store, register `/metrics` and listen on some port; start kafka
-consumer queue, etc.
+  services; store, register `/metrics` and listen on some port; start kafka
+  consumer queue, etc.
 - Run specific business logic
 - Stop the program
 - others...
@@ -158,26 +173,26 @@ that has several layers:
 - Entities: the models of the product
 - Use cases: the core business rule
 - Interface Adapters: convert data-in to entities and convert data-out to
-output ports.
+  output ports.
 - Frameworks and drivers: Web server, DB.
 
 Based on this logic, we create the following directories:
 
 - `model`: entities
 - `infra`: Provides the necessary functions to setup the infrastructure,
-especially the DB (output-port), but also the router (input-port). Once
-setup, we don't touch them anymore.
+  especially the DB (output-port), but also the router (input-port). Once
+  setup, we don't touch them anymore.
 - `registry`: Provides a register function for the main to register a service.
-It takes the pass to the output-port (ex.DBs) and gives back a pass
-(controller) to the input-port
+  It takes the pass to the output-port (ex.DBs) and gives back a pass
+  (controller) to the input-port
 - `adapter`: Controllers are one of the adapters, when they are called,
-they parse the user input and parse them into models and run the usecase
-rules. Then they send back the response(input-port). For the output-port
-part, the `repo` is the implementation of interfaces defined in `usecase/repo`.
+  they parse the user input and parse them into models and run the usecase
+  rules. Then they send back the response(input-port). For the output-port
+  part, the `repo` is the implementation of interfaces defined in `usecase/repo`.
 - `usecase`: with the input of adapter, do what have to be done, and answer
-with the result. In the meantime, we may have to store things into DBs.
-Here we use the Repository model to decouple the implementation of the repo
-with the interface. Thus in `usecase/repo` we only define interfaces.
+  with the result. In the meantime, we may have to store things into DBs.
+  Here we use the Repository model to decouple the implementation of the repo
+  with the interface. Thus in `usecase/repo` we only define interfaces.
 
 Then it comes the real design for the app.
 
@@ -198,9 +213,372 @@ type User struct {
 
 Use Buffalo pop `Soda CLI` to create database migrations.
 
-### 2024/10/07
+### 2024/10/06
 
 Implement the architecture design for User entity.
 
 Checked out OpenAPI, and found that it was not that simple at all. It needs
 a whole package of knowledge about the web development!
+
+For the test-driven part,
+
+- model layer: just model designs, **nothing to test**
+- infra: routes and db connections, it works when it works. Nothing to test.
+- registry: Just return some structs, no logic. **Not worth testing**
+- adapter:
+  - input-port (controller) test: it is about testing parsing the input
+    value, and the output results writing. The unit test of controller is to
+    **make sure that they behave as defined in the API documentation**. To
+    test, we have to mock the **business service**.
+  - output-port (repo) test: it is about testing converting business model
+    to database model and the interaction with the database. If we are going
+    to test them, it's about simulating different type of database behaviour
+    (success, timeout, etc.). To test, we have to mock the
+    **database connection**.
+- usecase: This is the core part to test, it's about the core business.
+  We provide the data input and we check the data output in a fake repository.
+
+With this design, although it may seem overkill for this little project, fits
+perfectly well with the TDD method.
+
+Concretely, I will do the TDD for my usecase level development, and for the
+rest, I just put unit tests aside for later.
+
+#### Workflow
+
+1. OAS Definition
+2. (Integration/Validation test)
+3. Usecase unit test cases
+4. Usecase development
+5. Refactor (2-3-4)
+6. Input-port/Output-port
+
+That should be the correct workflow. But to save time, I will cut off the
+integration test part (the 2nd point).
+
+### 2024/10/07
+
+I rethought about the whole API design (even though I have only one yet). I
+have created `/signup` and `/login` without thinking too much, but in fact
+it is not quite _RESTful_.
+
+**REST** is all about resources. While `/signup` and `/login` is quite
+comprehensible, thus service-oriented, they don't follow the REST philosophy,
+that is to say, **resource-oriented**.
+
+If we rethink about `/signup`, what it does is to create a resource of `User`.
+Thus, for a backend API, it'd better be named as `User.Create`. But what
+about `/login`, it doesn't do anything about `User`. It would be strange to
+declare it as a User-relevant method.
+
+Instead, what `/login` really does, is to **create a session**.
+In consequence, we have to create a new struct `Session` that can be created,
+deleted, or updated.
+
+It might seem overkill, and in real life, even in the official Pet store
+example of OpenAPI, signup and login are under /user. But it just opened my
+mind and forces me to **think and design RESTfully**!
+
+That being said, for the user side, we shall still have `/signup` and `/login`,
+because on the Front-end, we must be user-centered. We can even make this
+2 functions on the same page with the same endpoint `/login`. The user enter
+the email and the password, then clicks on `Login or Signup`. If the login
+is successful, then he is logged in. Otherwise, if the user doesn't exist
+yet, we open up 2 more inputs (first name and last name) for signup. They
+can just provide the extra information and click again on `Signup`.
+
+That, again, being said, I am thinking about doing some Front-end stuff just
+to make the validation tests of the product simpler.
+
+#### The choice of the front end framework
+
+I have considered several choices.
+
+If I didn't purposely make the backend code to provide a REST API, I might
+choose server-side-rendering with `templ + htmx`, or even `template+vanilla
+javascript`.
+
+I can still write a rather static Go-frontend-server to serve HTMLs and call
+my Go backend. _And it might be a good idea if they communicate on Go native
+rpc._ It worth a try.
+
+And I have moved on to `Svelte` which seems very simple by design and the
+whole compile thing makes it really charm. But this is mainly a Go project,
+to learn something new with a rather small community means potentially more
+investment. I can learn it later.
+
+Among `Angular`, `React` and `Vue`, I prefer `Vue`, for several reasons.
+First, `Angular` is clearly overkill for this small demo project. Second,
+`React` is good but I personally like the way of Vue doing things. And I
+work with Vue at work, so I might have more technical help from my colleagues.
+
+So the plan for this week is to have both the Front end part and Backend part
+working, just for user signup and login.
+
+I would like to directly put this stuff on a CI-pipeline for tests and
+deployment, even I have barely nothing yet. It is always good to do this
+preparation stuff at the early stage of the project. So we can benefit from
+them all the way along.
+
+Moreover, even I am not really finishing the project, it can still be
+something representable that I can show to a future interviewer.
+
+### 2024/10/08
+
+Gitea action setup ! 🎉🎉🎉
+
+Next step is to run some check and build and test!
+
+### 2024/10/09
+
+No code for today neither. But I did some design for the user story and
+the database model design.
+
+![Core user story part 1](./docs/howmuch_us1.drawio.png)
+
+![Database model](./docs/howmuch.drawio.png)
+
+### 2024/10/11
+
+I spent 2 days learning some basic of Vue. Learning Vue takes time. There
+are a lot of concepts and it needs a lot of practice. Even though I may not
+need a professional level web page, I don't want to copy one module from this
+blog and another one from another tutorial. I might just put aside the
+front-end for now and concentrate on my backend Go app.
+
+For now, I will just test my backend with `curl`.
+
+And today's job is to get the login part done!
+
+### 2024/10/13
+
+Finally it took more than just one night for me to figure out the JWT.
+
+The JWT token is simple because it doesn't need to be stored to and fetched
+from a database. But there is no way to revoke it instead of waiting for the
+expiry date.
+
+To do so, we still have to use a database. We can store a logged out user's
+jti into Redis, and each time we log in, look up the cache to find if the
+user is logged out. And set the cache's timeout to the expiry time of the
+token, so that it is removed automatically.
+
+It'd better to inject the dependency of Redis connection into the `Authn`
+middleware so that it's simpler to test.
+
+### 2024/10/15
+
+Redis is integrated to keep a blacklist of logged out users. BTW `memcached`
+is also interesting. In case later I want to switch to another key-value
+storage, I have made an interface. It also helps for the test. I can even
+just drop the redis and use a bare-hand native hashmap.
+
+Quite a lot benefits. And then I realised that I have done "wrong" about
+`sqlc`. I shouldn't have used the pgx driver, instead the `database/sql`
+driver is more universal, if I want to switch to sqlite or mysql later.
+
+Well it's not about changing the technical solution every 3 days, but a
+system than can survive those changes elegantly must be a robust system, with
+functionalities well decoupled and interfaces well defined.
+
+I will add some tests for existing code and then it's time to move on to
+my core business logic.
+
+### 2024/10/16
+
+I am facing a design problem. My way to implement the business logic is to
+first write the core logic code in the domain service level. It will help me
+to identify if there are any missing part in my model design. Thus, when
+some of the business logic is done, I can create database migrations and then
+implement the adapter level's code.
+
+The problem is that my design depends heavily on the database. Taking the
+example of adding an expense to en event.
+
+Input is a valid `ExpenseDTO` which has the `event`, `paiements` and
+`receptions`. What I must do is to open a database transaction where I:
+
+1. Get the Event. (Most importantly the `TotalAmount`)
+2. For each `paiemnt` and `reception` create a transaction related to the
+`User`. And insert them into the database.
+3. Update the `TotalAmount`
+4. Update the caches if any
+
+If any step fails, the transaction rolls back.
+
+This has barely no logic at all. I think it is not suitable to try to tie
+this operation to the domain model.
+
+However, there is something that worth a domain model level method, that
+is to calculate the share of each members of the event, where we will have
+the list of members and the amount of balance they have. And then we will
+do the calculate and send back a list of money one should pay for another.
+
+Finally, I think the business logic is still too simple to be put into a
+"Domain". For now, the service layer is just enough.
+
+### 2024/10/17
+
+The following basic use cases are to be implemented at the first time.
+
+- [X] A user signs up
+- [X] A user logs in
+- [ ] A user lists their events (pagination)
+- [ ] A user sees the detail of an event (description, members, amount)
+- [ ] A user sees the expenses of an event (total amount, personal expenses, pagination)
+- [ ] A user sees the detail of an expense: (time, amount, payers, recipients)
+- [ ] A user adds an expense
+- [ ] A user updates/changes an expense (may handle some extra access control)
+- [ ] A user can pay the debt to other members (just a special case of expense)
+- [ ] A user creates an event (and participate to it)
+- [ ] A user updates the event info
+- [ ] A user invites another user by sending a mail with a token.
+- [ ] A user joins an event by accepting an invitation
+- [ ] A user cannot see other user's information
+- [ ] A user cannot see the events that they didn't participated in.
+
+For the second stage:
+
+- [ ] A user can archive an event
+- [ ] A user deletes an expense (may handle some extra access control)
+- [ ] A user restore a deleted expense
+- [ ] Audit log for expense updates/deletes
+- [ ] ~A user quits an event (they cannot actually, but we can make as if they
+quitted)~ **No we can't quit!**
+
+With those functionalities, there will be an usable product. And then we can
+work on other aspects. For example:
+
+- introduce an admin to handle users.
+- user info updates
+- deleting user
+- More user related contents
+- Event related contents
+- ex. Trip journal...
+
+Stop dreaming... Just do the simple stuff first!
+
+### 2024/10/18
+
+I spent some time to figure out this one! But I don't actually need it for now.
+So I just keep it here:
+
+```SQL
+SELECT
+    e.id,
+    e.name,
+    e.description,
+    e.created_at,
+    json_build_object(
+        'id', o.id,
+        'first_name', o.first_name,
+        'last_name', o.last_name
+    ) AS owner,
+    json_agg(
+        json_build_object(
+            'id', u.id,
+            'first_name', u.first_name,
+            'last_name', u.last_name
+        )
+    ) AS users  -- Aggregation for users in the event
+FROM "event" e
+JOIN "participation" p ON p.event_id = e.id  -- participation linked with the event
+JOIN "user" u ON u.id = p.user_id            -- and the query user
+JOIN "user" o ON o.id = e.owner_id           -- get the owner info
+WHERE e.id IN (
+    SELECT pt.event_id FROM participation pt WHERE pt.user_id = $1
+    -- consider the events participated by user_id
+)
+GROUP BY
+    e.id, e.name, e.description, e.created_at,
+    o.id, o.first_name, o.last_name;
+
+```
+
+### 2024/10/19
+
+I don't plan to handle deletions at this first stage, but I note down what I
+have thought of.
+
+1. Just delete. But keep a replica at the front end of the object that we are
+deleting. And propose an option to restore (so a new record is added to the DB)
+2. Just delete, but wait. The request is sent to a queue with a timeout of
+several seconds, if the user regrets, they can cancel the request. This can be
+done on the front, but also on the back. I think it is better to do in on the
+front-end.
+3. Never deletes. But keep a state in the DB `deleted`. They will just be
+ignored when counting.
+4. Deletes when doing database cleanup. They lines deleted will be processed
+when we cleanup the DB. And they will be definitely deleted at that time.
+
+I can create a audit log table to log all the critical
+changes in my `expense` table (update or delete).
+
+Finished with the basic SQL commands. Learned a lot from SQL about `JOIN`,
+aggregation and `CTE`. SQL itself has quite amount of things to learn, this
+is on my future learning plan!
+
+_I found it quite interesting that simply with SQL, we can simulate the most
+business logic. It is a must-have competence for software design and
+development._
+
+### 2024/10/20
+
+I was thinking that I should write test for `sqlc` generated code. And then
+I found out `gomock` and see how it is done in the project of
+`techschoo/simplebank`. It's a great tutorial project. It makes me questioning
+my own project's structure. It seems overwhelmed at least at the repo level.
+
+I don't actually use the sqlc generated object, instead I do a conversion to
+my `Retrieved` objects. But with some advanced configuration we could make the
+output of sqlc object directly usable. That will save a lot of code.
+
+The problem I saw here is the dependency on `sqlc/models`, and the model
+designed there has no business logic. Everything is done in the handlers
+and the handlers query directly the DB.
+
+More concretely, `sqlc` generates `RawJSON` for some fields that are embedded
+structs. So I have to do the translation somewhere.
+
+So I will just stick to the plan and keep going with the predefined structure.
+
+I have to figure out how to use the generated mock files.
+
+The goals for the next week is to finish the basic operations for each level
+and run some integration tests with `curl`.
+
+### 2024/10/22
+
+I am facing come difficulties on testing of the `repo` functions.
+
+First, I have to keep the business logic in the service layer. That means I
+have to create the transaction at the service layer. I don't need to depend
+on the implementation detail. So I have created a Transaction interface.
+
+I don't care of the type of `tx` because I will pass it to repo layer and I
+suppose that it knows what it is doing. Considering this, my repo `Create`
+function will have to take an any and deduct the type of `tx`. So the layer
+becomes untestable, because I have to pass a *sql.Tx into it and create a
+querier.
+
+Since this repo layer is just a wrapping layer between the `sqlc.models` and
+my own models, I can extract the conversion part to functions and test them.
+I'm not testing the whole thing but I test what I can.
+
+### 2024/10/24
+
+When writing the tests. I am asking myself the differences between `[]T`,
+`[]*T` and `*[]T`.
+
+`*[]T` is simple, it is a reference to the original slice. So modifying it
+means modifying the original slice.
+
+But between `[]*T` and `[]T`, the only difference that I see (pointed out by
+`ChatGPT`) is how the memory is allocated. With `[]T` it might be better for
+the GC to deal with the memory free. I thing for my project I will stick to
+`[]T`.
+
+### 2024/10/25
+
+Read this [article](https://konradreiche.com/blog/two-common-go-interface-misuses/)
+today, maybe I am abusing the usage of interfaces?

api/openapi/openapi.yaml

@@ -37,19 +37,20 @@ servers:
   - url: https:/localhost:8000/v1
 tags:
   - name: user
+  - name: session
 
 paths:
-  /signup:
+  /user/create:
     post:
       tags:
         - user
-      description: Sign up as a new user
+      description: Create a new user
       requestBody:
-        description: Sign up
+        description: Create a new user
         content:
           application/json:
             schema:
-              $ref: '#/components/schemas/UserSignUpRequest'
+              $ref: '#/components/schemas/UserCreateRequest'
       responses:
         '200':
           description: Successful operation
@@ -58,17 +59,104 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/ErrResponse'
+                type: object
+                properties:
+                  code:
+                    type: string
+                    example: FailedOperation.UserExisted
+                  message:
+                    type: string
+                    example: "Email already existed."
         '500':
           description: Server side error
           content:
             application/json:
               schema:
                 $ref: '#/components/schemas/ErrResponse'
+  /session/create:
+    post:
+      tags:
+        - session
+      description: Create a new session for a user
+      requestBody:
+        description: Create session
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/SessionCreateRequest'
+      responses:
+        '200':
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  token:
+                    type: string
+                    example: fakjshdflauhkjhsometokenakjsdhfaksj
+        '400':
+          description: Client side error
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  code:
+                    type: string
+                    example: AuthFailure
+                  message:
+                    type: string
+                    example: "wrong email password."
+        '500':
+          description: Server side error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrResponse'
+  /session/delete:
+    post:
+      tags:
+        - session
+      description: Delete an existing session for a user
+      responses:
+        '200':
+          description: Successful operation
+          headers:
+            X-Expires-After:
+              description: date in UTC when token expires
+              schema:
+                type: string
+                format: date-time
+          content:
+            application/json:
+              schema:
+                type: string
+        '400':
+          description: Client side error
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  code:
+                    type: string
+                    example: AuthFailure
+                  message:
+                    type: string
+                    example: "user not logged in."
+        '500':
+          description: Server side error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrResponse'
+      security:
+        - jwt: []
 
 components:
   schemas:
-    UserSignUpRequest:
+    UserCreateRequest:
       type: object
       properties:
         email:
@@ -88,12 +176,30 @@ components:
         - fist_name
         - last_name
         - password
+    SessionCreateRequest:
+      type: object
+      properties:
+        email:
+          type: string
+          example: bruce@wayne.com
+        password:
+          type: string
+          example: verystrongpassword
+      required:
+        - email
+        - password
     ErrResponse:
       type: object
       properties:
         code:
           type: string
-          example: FailedOperation.UserAlreadyExists
+          example: InternalError
         message:
           type: string
-          example: "User already exists."
+          example: "Server internal error."
+  securitySchemes:
+    jwt:
+      name: Bearer authentication
+      type: http
+      bearerFormat: "JWT"
+      scheme: bearer

configs/howmuch.yml

@@ -3,6 +3,8 @@ dev-mode: true
 web:
   addr: :8000
   shutdown-timeout: 10
+  token-secret: nzMC12IJBMiiV2AAktTFpZP4BbGAf09lFPV_sATKcwI
+  token-expiry-time: 24h
 
 db:
   # DB host
@@ -14,6 +16,14 @@ db:
   # DB name
   database: howmuch
 
+  max-open-conns: 100
+  max-idle-conns: 100
+  max-lifetime: 10s
+
+cache:
+  host: 127.0.0.1:6379
+  password: ""
+
 log:
   level: debug
   disalbe-caller: false

deployment/docker-compose.yml

@@ -1,7 +1,7 @@
 services:
 
   postgres:
-    image: postgres
+    image: postgres:alpine
     restart: always
     ports:
       - "5432:5432"
@@ -20,3 +20,15 @@ services:
     restart: always
     ports:
       - 8080:8080
+
+  redis:
+    image: redis:alpine
+    restart: always
+    ports:
+      - "6379:6379"
+    deploy:
+      mode: replicated
+      replicas: 1
+    command: redis-server --save 20 1 --loglevel warning
+    volumes:
+      - ../../db_data_howmuch/redis/:/data

docs/error_code.md

@@ -0,0 +1,7 @@
+# Platform level error code design
+
+- InternalError
+- InvalidParameter
+- AuthFailure
+- ResourceNotFound
+- FailedOperation

go.mod

@@ -6,29 +6,35 @@ require (
 	github.com/fsnotify/fsnotify v1.7.0
 	github.com/gin-contrib/cors v1.7.2
 	github.com/gin-gonic/gin v1.10.0
+	github.com/golang-jwt/jwt/v5 v5.2.1
 	github.com/google/uuid v1.6.0
 	github.com/gosuri/uitable v0.0.4
 	github.com/jackc/pgx/v5 v5.7.1
+	github.com/pkg/errors v0.9.1
+	github.com/redis/go-redis/v9 v9.6.1
 	github.com/spf13/cobra v1.8.1
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.19.0
 	github.com/stretchr/testify v1.9.0
 	go.uber.org/zap v1.27.0
-	golang.org/x/net v0.25.0
+	golang.org/x/crypto v0.27.0
+	golang.org/x/net v0.26.0
 )
 
 require (
 	github.com/bytedance/sonic v1.11.6 // indirect
 	github.com/bytedance/sonic/loader v0.1.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/cloudwego/base64x v0.1.4 // indirect
 	github.com/cloudwego/iasm v0.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/fatih/color v1.14.1 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.3 // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-playground/validator/v10 v10.20.0 // indirect
+	github.com/go-playground/validator/v10 v10.22.1 // indirect
 	github.com/goccy/go-json v0.10.2 // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
@@ -59,7 +65,6 @@ require (
 	github.com/ugorji/go/codec v1.2.12 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/arch v0.8.0 // indirect
-	golang.org/x/crypto v0.27.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
 	golang.org/x/sync v0.8.0 // indirect
 	golang.org/x/sys v0.25.0 // indirect

go.sum

@@ -1,7 +1,13 @@
+github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
+github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
+github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
+github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
 github.com/bytedance/sonic v1.11.6 h1:oUp34TzMlL+OY1OUWxHqsdkgC/Zfc85zGqw9siXjrc0=
 github.com/bytedance/sonic v1.11.6/go.mod h1:LysEHSvpvDySVdC2f87zGWf6CIKJcAvqab1ZaiQtds4=
 github.com/bytedance/sonic/loader v0.1.1 h1:c+e5Pt1k/cy5wMveRDyk2X4B9hF4g7an8N3zCYjJFNM=
 github.com/bytedance/sonic/loader v0.1.1/go.mod h1:ncP89zfokxS5LZrJxl5z0UJcsk4M4yY2JpfqGeCtNLU=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cloudwego/base64x v0.1.4 h1:jwCgWpFanWmN8xoIUHa2rtzmkd5J2plF/dnLS6Xd/0Y=
 github.com/cloudwego/base64x v0.1.4/go.mod h1:0zlkT4Wn5C6NdauXdJRhSKRlJvmclQ1hhJgA0rcu/8w=
 github.com/cloudwego/iasm v0.2.0 h1:1KNIy1I1H9hNNFEEH3DVnI4UujN+1zjpuk6gwHLTssg=
@@ -11,6 +17,8 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
 github.com/fatih/color v1.14.1 h1:qfhVLaG5s+nCROl1zJsZRxFeYrHLqWroPOQ8BWiNb4w=
 github.com/fatih/color v1.14.1/go.mod h1:2oHN61fhTpgcxD3TSWCgKDiH1+x4OiDVVGH8WlgGZGg=
 github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHkI4W8=
@@ -31,10 +39,12 @@ github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/o
 github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
 github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
 github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
-github.com/go-playground/validator/v10 v10.20.0 h1:K9ISHbSaI0lyB2eWMPJo+kOS/FBExVwjEviJTixqxL8=
-github.com/go-playground/validator/v10 v10.20.0/go.mod h1:dbuPbCMFw/DrkbEynArYaCwl3amGuJotoKCe95atGMM=
+github.com/go-playground/validator/v10 v10.22.1 h1:40JcKH+bBNGFczGuoBYgX4I6m/i27HYW8P9FDk5PbgA=
+github.com/go-playground/validator/v10 v10.22.1/go.mod h1:dbuPbCMFw/DrkbEynArYaCwl3amGuJotoKCe95atGMM=
 github.com/goccy/go-json v0.10.2 h1:CrxCmQqYDkv1z7lO7Wbh2HN93uovUHgrECaO5ZrCXAU=
 github.com/goccy/go-json v0.10.2/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
+github.com/golang-jwt/jwt/v5 v5.2.1 h1:OuVbFODueb089Lh128TAcimifWaLhJwVflnrgM17wHk=
+github.com/golang-jwt/jwt/v5 v5.2.1/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
@@ -84,9 +94,13 @@ github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9G
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/pelletier/go-toml/v2 v2.2.2 h1:aYUidT7k73Pcl9nb2gScu7NSrKCSHIDE89b3+6Wq+LM=
 github.com/pelletier/go-toml/v2 v2.2.2/go.mod h1:1t835xjRzz80PqgE6HHgN2JOsmgYu/h4qDAS4n929Rs=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/redis/go-redis/v9 v9.6.1 h1:HHDteefn6ZkTtY5fGUE8tj8uy85AHk6zP7CpzIAM0y4=
+github.com/redis/go-redis/v9 v9.6.1/go.mod h1:0C0c6ycQsdpVNQpxb1njEQIqkx5UcsM8FJCQLgE9+RA=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
@@ -139,8 +153,8 @@ golang.org/x/crypto v0.27.0 h1:GXm2NjJrPaiv/h1tb2UH8QfgC/hOf/+z0p6PT8o1w7A=
 golang.org/x/crypto v0.27.0/go.mod h1:1Xngt8kV6Dvbssa53Ziq6Eqn0HqbZi5Z6R0ZpwQzt70=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9 h1:GoHiUyI/Tp2nVkLI2mCxVkOjsbSXD66ic0XW0js0R9g=
 golang.org/x/exp v0.0.0-20230905200255-921286631fa9/go.mod h1:S2oDrQGGwySpoQPVqRShND87VCbxmc6bL1Yd2oYrm6k=
-golang.org/x/net v0.25.0 h1:d/OCCoBEUq33pjydKrGQhw7IlUPI2Oylr+8qLx49kac=
-golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=
+golang.org/x/net v0.26.0 h1:soB7SVo0PWrY4vPW/+ay0jKDNScG2X9wFeYlXIvJsOQ=
+golang.org/x/net v0.26.0/go.mod h1:5YKkiSynbBIh3p6iOc/vibscux0x38BZDkn8sCUPxHE=
 golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
 golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

internal/howmuch/adapter/controller/app.go

@@ -28,4 +28,6 @@ type AppController struct {
 	User interface{ User }
 
 	Admin interface{ Admin }
+
+	Session interface{ Session }
 }

internal/howmuch/adapter/controller/session.go

@@ -0,0 +1,115 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package controller
+
+import (
+	"fmt"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/middleware/authn"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/token"
+	"github.com/gin-gonic/gin"
+)
+
+type Session interface {
+	Create(*gin.Context)
+	Delete(*gin.Context)
+}
+
+type SessionController struct {
+	userUsecase usecase.User
+	cache       core.Cache
+}
+
+func NewSessionController(u usecase.User, cache core.Cache) Session {
+	return &SessionController{u, cache}
+}
+
+type Token struct {
+	Token string `json:"token"`
+}
+
+type createParams struct {
+	Email    string `json:"email"    binding:"required,email"`
+	Password string `json:"password" binding:"required"`
+}
+
+// Create creates a session for a user and returns a token
+//
+// Since we use JWT method, this token is not stored anywhere. Thus it
+// stops at the controller level.
+func (sc *SessionController) Create(ctx *gin.Context) {
+	var user model.UserExistRequest
+
+	if err := ctx.Bind(&user); err != nil {
+		log.ErrorLog("param error", "err", err)
+		core.WriteResponse(ctx, UserParamsErr, nil)
+		return
+	}
+
+	err := sc.userUsecase.Exist(ctx, &user)
+	if err != nil {
+		core.WriteResponse(ctx, err, nil)
+		return
+	}
+
+	// user exists. Generate the token for the user
+	tokenString, err := token.Sign(user.Email)
+	if err != nil {
+		core.WriteResponse(ctx, errno.InternalServerErr, nil)
+		return
+	}
+
+	core.WriteResponse(ctx, nil, Token{
+		Token: tokenString,
+	})
+}
+
+// Delete deletes a session by putting the jwt token into the cache
+func (sc *SessionController) Delete(ctx *gin.Context) {
+	tk, err := token.ParseRequest(ctx)
+	if err != nil || tk == nil {
+		// Unlikely
+		core.WriteResponse(ctx, authn.ErrTokenInvalid, nil)
+		return
+	}
+
+	exp := time.Until(tk.Expiry)
+	key := fmt.Sprintf("jwt:%s", tk.Identity)
+
+	log.DebugLog("session delete", "key", key, "exp", exp.String())
+	err = sc.cache.Set(ctx, key, tk.Raw, exp)
+	if err != nil {
+		// unexpected
+		log.ErrorLog("error writing logged out jwt into cache", "err", err)
+		core.WriteResponse(ctx, errno.InternalServerErr, nil)
+		return
+	}
+
+	core.WriteResponse(ctx, nil, "logged out")
+}

internal/howmuch/adapter/controller/session_test.go

@@ -0,0 +1,190 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package controller
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller/usecasemock"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/middleware/authn"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/test"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/token"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+)
+
+// {{{ Test Cache
+
+type testCache struct {
+	kvMap map[string]interface{}
+}
+
+func (c *testCache) Get(ctx context.Context, key string) (string, error) {
+	val, ok := c.kvMap[key]
+	if ok {
+		return val.(string), nil
+	}
+	return "", nil
+}
+
+func (c *testCache) Set(
+	ctx context.Context,
+	key string,
+	value interface{},
+	expiration time.Duration,
+) error {
+	c.kvMap[key] = value
+	return nil
+}
+
+func (c *testCache) Close() error {
+	return nil
+}
+
+// }}}
+
+func TestSessionCreate(t *testing.T) {
+	tests := []struct {
+		Name  string
+		User  createParams
+		Errno *errno.Errno
+	}{
+		{"registered user", createParams{
+			Email:    "correct@correct.com",
+			Password: "strong password",
+		}, errno.OK},
+		{"unregistered user", createParams{
+			Email:    "unregistered@error.com",
+			Password: "strong password",
+		}, usecase.UserNotExist},
+		{"wrong email", createParams{
+			Email:    "error.com",
+			Password: "strong password",
+		}, UserParamsErr},
+		{"no passwrd", createParams{
+			Email:    "no@error.com",
+			Password: "",
+		}, UserParamsErr},
+	}
+
+	token.Init("secret", 1*time.Second)
+
+	for _, tst := range tests {
+		t.Run(tst.Name, func(t *testing.T) {
+			testUserUsecase := usecasemock.NewtestUserUsecase()
+			sessionController := NewSessionController(testUserUsecase, nil)
+			r := gin.New()
+			r.POST(
+				"/session/create",
+				func(ctx *gin.Context) { sessionController.Create(ctx) },
+			)
+			user, _ := json.Marshal(tst.User)
+			res := test.PerformRequest(t, r, "POST", "/session/create", bytes.NewReader(user),
+				test.Header{
+					Key:   "content-type",
+					Value: "application/json",
+				})
+
+			assert.Equal(t, tst.Errno.HTTP, res.Result().StatusCode, res.Body)
+
+			if tst.Errno.HTTP != http.StatusOK {
+				var got errno.Errno
+				err := json.NewDecoder(res.Result().Body).Decode(&got)
+				// XXX: the http status is not in the json. So it must be reset back the the struct
+				got.HTTP = res.Result().StatusCode
+				assert.NoError(t, err)
+				assert.Equal(t, tst.Errno, &got)
+				return
+			}
+
+			var got Token
+			err := json.NewDecoder(res.Result().Body).Decode(&got)
+			assert.NoError(t, err)
+			tkResp, err := token.Parse(got.Token)
+			assert.NoError(t, err)
+			assert.Equal(t, tst.User.Email, tkResp.Identity)
+		})
+	}
+}
+
+func TestSessionDelete(t *testing.T) {
+	testUserUsecase := usecasemock.NewtestUserUsecase()
+	kvMap := make(map[string]interface{}, 1)
+	tc := &testCache{kvMap: kvMap}
+	sessionController := NewSessionController(testUserUsecase, tc)
+	r := gin.New()
+	session := r.Group("/session")
+	{
+		session.POST("/create", func(ctx *gin.Context) { sessionController.Create(ctx) })
+		session.Use(authn.Authn(tc))
+		session.POST("/delete", func(ctx *gin.Context) { sessionController.Delete(ctx) })
+	}
+
+	params := createParams{
+		Email:    "correct@correct.com",
+		Password: "strong password",
+	}
+	user, _ := json.Marshal(params)
+	res := test.PerformRequest(t, r, "POST", "/session/create", bytes.NewReader(user),
+		test.Header{
+			Key:   "content-type",
+			Value: "application/json",
+		})
+
+	var tk Token
+	_ = json.NewDecoder(res.Result().Body).Decode(&tk)
+	tkResp, _ := token.Parse(tk.Token)
+
+	// Log out
+	res = test.PerformRequest(t, r, "POST", "/session/delete", nil,
+		test.Header{
+			Key:   "Authorization",
+			Value: fmt.Sprintf("Bearer %s", tkResp.Raw),
+		})
+
+	var loggedOut string
+	err := json.NewDecoder(res.Result().Body).Decode(&loggedOut)
+	assert.NoError(t, err)
+	assert.Equal(t, "logged out", loggedOut)
+
+	// Try to access the handler with the old token
+	res = test.PerformRequest(t, r, "POST", "/session/delete", nil,
+		test.Header{
+			Key:   "Authorization",
+			Value: fmt.Sprintf("Bearer %s", tkResp.Raw),
+		})
+
+	var unauth errno.Errno
+	err = json.NewDecoder(res.Result().Body).Decode(&unauth)
+	assert.NoError(t, err)
+	unauth.HTTP = res.Result().StatusCode
+	assert.Equal(t, *authn.ErrLoggedOut, unauth)
+}

internal/howmuch/adapter/controller/usecasemock/testuserusecase.go

@@ -1,33 +1,3 @@
-// Code generated by sqlc. DO NOT EDIT.
-// versions:
-//   sqlc v1.27.0
-// source: user.sql
-
-package sqlc
-
-import (
-	"context"
-
-	"github.com/jackc/pgx/v5/pgtype"
-)
-
-const insertUser = `-- name: InsertUser :one
-
-INSERT INTO "user" (
-    email, first_name, last_name, password, created_at, updated_at
-) VALUES ( $1, $2, $3, $4, $5, $6 )
-RETURNING id, email, first_name, last_name, password, created_at, updated_at
-`
-
-type InsertUserParams struct {
-	Email     string
-	FirstName string
-	LastName  string
-	Password  string
-	CreatedAt pgtype.Timestamp
-	UpdatedAt pgtype.Timestamp
-}
-
 // MIT License
 //
 // Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
@@ -49,24 +19,48 @@ type InsertUserParams struct {
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
-func (q *Queries) InsertUser(ctx context.Context, arg InsertUserParams) (User, error) {
-	row := q.db.QueryRow(ctx, insertUser,
-		arg.Email,
-		arg.FirstName,
-		arg.LastName,
-		arg.Password,
-		arg.CreatedAt,
-		arg.UpdatedAt,
-	)
-	var i User
-	err := row.Scan(
-		&i.ID,
-		&i.Email,
-		&i.FirstName,
-		&i.LastName,
-		&i.Password,
-		&i.CreatedAt,
-		&i.UpdatedAt,
-	)
-	return i, err
+
+package usecasemock
+
+import (
+	"context"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
+)
+
+type testUserUsecase struct{}
+
+func NewtestUserUsecase() usecase.User {
+	return &testUserUsecase{}
+}
+
+func (*testUserUsecase) Create(
+	ctx context.Context,
+	u *model.UserCreateRequest,
+) (*model.UserInfoResponse, error) {
+	return nil, nil
+}
+
+func (*testUserUsecase) Exist(ctx context.Context, u *model.UserExistRequest) error {
+	switch u.Email {
+	case "a@b.c":
+		if u.Password == "strong password" {
+			return nil
+		} else {
+			return usecase.UserWrongPassword
+		}
+	case "unregistered@error.com":
+		return usecase.UserNotExist
+	}
+	// Should never reach here
+	return nil
+}
+
+func (*testUserUsecase) GetUserBaseResponseByID(
+	ctx context.Context,
+	userID int,
+) (*model.UserBaseResponse, error) {
+	// TODO:
+	return nil, nil
 }

internal/howmuch/adapter/controller/user.go

@@ -25,33 +25,56 @@ package controller
 import (
 	"net/http"
 
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
 	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"github.com/gin-gonic/gin"
 )
 
 // User is the user controller interface, it describes all the handlers
 // that need to be implemented for the /user endpoint
 type User interface {
-	Signup(core.Context)
-	UpdateInfo(core.Context)
-	Login(core.Context)
-	Logout(core.Context)
-	ChangePassword(core.Context)
+	Create(core.Context)
+	UpdateInfo(*gin.Context)
+	ChangePassword(*gin.Context)
 }
 
-type UserController struct{}
-
-func (uc *UserController) Signup(ctx core.Context) {
-	ctx.JSON(http.StatusOK, "hello")
+type UserController struct {
+	userUsecase usecase.User
 }
 
-func (uc *UserController) UpdateInfo(ctx core.Context) {
+var UserParamsErr = &errno.Errno{
+	HTTP:    http.StatusBadRequest,
+	Code:    errno.ErrorCode(errno.InvalidParameterCode, "UserParamsErr"),
+	Message: "user info is not correct",
 }
 
-func (uc *UserController) Login(ctx core.Context) {
+func NewUserController(us usecase.User) User {
+	return &UserController{
+		userUsecase: us,
+	}
 }
 
-func (uc *UserController) Logout(ctx core.Context) {
+func (uc *UserController) Create(ctx core.Context) {
+	var userRequest model.UserCreateRequest
+
+	if err := ctx.Bind(&userRequest); err != nil {
+		core.WriteResponse(ctx, UserParamsErr, nil)
+		return
+	}
+
+	_, err := uc.userUsecase.Create(ctx, &userRequest)
+	if err != nil {
+		core.WriteResponse(ctx, err, nil)
+		return
+	}
+
+	core.WriteResponse(ctx, errno.OK, nil)
 }
 
-func (uc *UserController) ChangePassword(ctx core.Context) {
+func (uc *UserController) UpdateInfo(ctx *gin.Context) {
+}
+
+func (uc *UserController) ChangePassword(ctx *gin.Context) {
 }

internal/howmuch/adapter/repo/db.go

@@ -0,0 +1,80 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+)
+
+type dbRepository struct {
+	db *sql.DB
+}
+
+const queryTimeout = 3 * time.Second
+
+func NewDBRepository(db *sql.DB) repo.DBRepository {
+	return &dbRepository{
+		db: db,
+	}
+}
+
+// XXX: Do I need rollback? in which cases?
+
+func (dr *dbRepository) Transaction(
+	ctx context.Context,
+	txFunc func(txCtx context.Context, tx interface{}) (interface{}, error),
+) (interface{}, error) {
+	tx, err := dr.db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		if p := recover(); p != nil {
+			tx.Rollback()
+			log.PanicLog("transaction panicked!")
+		} else if err != nil {
+			tx.Rollback()
+			log.ErrorLog("transaction failed!", "err", err)
+		} else {
+			err = tx.Commit()
+		}
+	}()
+
+	data, err := txFunc(ctx, tx)
+	return data, err
+}
+
+func getQueries(queries *sqlc.Queries, tx any) *sqlc.Queries {
+	transaction, ok := tx.(*sql.Tx)
+	if ok {
+		return sqlc.New(transaction)
+	}
+	return queries
+}

internal/howmuch/adapter/repo/event.go

@@ -0,0 +1,276 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+)
+
+type eventRepository struct {
+	queries *sqlc.Queries
+}
+
+func NewEventRepository(db *sql.DB) repo.EventRepository {
+	return &eventRepository{
+		queries: sqlc.New(db),
+	}
+}
+
+// Create implements repo.EventRepository.
+func (e *eventRepository) Create(
+	ctx context.Context,
+	evEntity *model.EventEntity,
+	tx any,
+) (*model.EventEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	event, err := queries.InsertEvent(timeoutCtx, sqlc.InsertEventParams{
+		Name:            evEntity.Name,
+		Description:     sql.NullString{String: evEntity.Description, Valid: true},
+		TotalAmount:     sql.NullInt32{Int32: int32(evEntity.TotalAmount), Valid: true},
+		DefaultCurrency: evEntity.DefaultCurrency,
+		OwnerID:         int32(evEntity.OwnerID),
+		CreatedAt:       time.Now(),
+		UpdatedAt:       time.Now(),
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &model.EventEntity{
+		ID:              int(event.ID),
+		Name:            event.Name,
+		Description:     event.Description.String,
+		TotalAmount:     int(event.TotalAmount.Int32),
+		DefaultCurrency: event.DefaultCurrency,
+		OwnerID:         int(event.OwnerID),
+		CreatedAt:       event.CreatedAt,
+		UpdatedAt:       event.UpdatedAt,
+	}, nil
+}
+
+func convToEventRetrieved(eventDTO *sqlc.GetEventByIDRow) (*model.EventRetrieved, error) {
+	// marshal owner and users
+	var owner model.UserBaseRetrieved
+	err := json.Unmarshal(eventDTO.Owner, &owner)
+	if err != nil {
+		// Unexpected
+		log.ErrorLog("json unmarshal error", "err", err)
+		return nil, err
+	}
+
+	var users []model.UserBaseRetrieved
+	err = json.Unmarshal(eventDTO.Users, &users)
+	if err != nil {
+		// Unexpected
+		log.ErrorLog("json unmarshal error", "err", err)
+		return nil, err
+	}
+
+	eventRetrieved := &model.EventRetrieved{
+		ID:          int(eventDTO.ID),
+		Name:        eventDTO.Name,
+		Description: eventDTO.Description.String,
+		TotalAmount: model.MakeMoney(
+			int(eventDTO.TotalAmount.Int32),
+			model.Currency(eventDTO.DefaultCurrency),
+		),
+		DefaultCurrency: model.Currency(eventDTO.DefaultCurrency),
+		CreatedAt:       eventDTO.CreatedAt,
+		UpdatedAt:       eventDTO.UpdatedAt,
+		Owner:           &owner,
+		Users:           users,
+	}
+
+	return eventRetrieved, nil
+}
+
+// GetByID implements repo.EventRepository.
+func (e *eventRepository) GetByID(
+	ctx context.Context,
+	eventID int,
+	tx any,
+) (*model.EventRetrieved, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	eventDTO, err := queries.GetEventByID(timeoutCtx, int32(eventID))
+	if err != nil {
+		log.ErrorLog("query error", "err", err)
+		return nil, err
+	}
+
+	return convToEventRetrieved(&eventDTO)
+}
+
+func convToEventList(eventsDTO []sqlc.ListEventsByUserIDRow) ([]model.EventListRetrieved, error) {
+	events := make([]model.EventListRetrieved, len(eventsDTO))
+
+	for i, evDTO := range eventsDTO {
+		var owner model.UserBaseRetrieved
+		err := json.Unmarshal(evDTO.Owner, &owner)
+		if err != nil {
+			// Unexpected
+			log.ErrorLog("json unmarshal error", "err", err)
+			return nil, err
+		}
+		ev := model.EventListRetrieved{
+			ID:          int(evDTO.ID),
+			Name:        evDTO.Name,
+			Description: evDTO.Description.String,
+			Owner:       &owner,
+			CreatedAt:   evDTO.CreatedAt,
+		}
+
+		events[i] = ev
+	}
+
+	return events, nil
+}
+
+// ListEventsByUserID implements repo.EventRepository.
+func (e *eventRepository) ListEventsByUserID(
+	ctx context.Context,
+	userID int,
+	tx any,
+) ([]model.EventListRetrieved, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	eventsDTO, err := queries.ListEventsByUserID(timeoutCtx, int32(userID))
+	if err != nil {
+		log.ErrorLog("query error", "err", err)
+		return nil, err
+	}
+
+	return convToEventList(eventsDTO)
+}
+
+// UpdateInfo implements repo.EventRepository.
+func (e *eventRepository) UpdateEventByID(
+	ctx context.Context,
+	event *model.EventUpdateEntity,
+	tx any,
+) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	err := queries.UpdateEventByID(timeoutCtx, sqlc.UpdateEventByIDParams{
+		ID:          int32(event.ID),
+		Name:        event.Name,
+		Description: sql.NullString{String: event.Description, Valid: true},
+		UpdatedAt:   time.Now(),
+	})
+	return err
+}
+
+// GetParticipation implements repo.EventRepository.
+func (e *eventRepository) GetParticipation(
+	ctx context.Context,
+	userID, eventID int,
+	tx any,
+) (*model.ParticipationEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	partDTO, err := queries.GetParticipation(timeoutCtx, sqlc.GetParticipationParams{
+		UserID:  int32(userID),
+		EventID: int32(eventID),
+	})
+
+	if errors.Is(err, sql.ErrNoRows) {
+		// No error, but participation not found
+		return nil, nil
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &model.ParticipationEntity{
+		ID:              int(partDTO.ID),
+		UserID:          int(partDTO.UserID),
+		EventID:         int(partDTO.EventID),
+		InvitedByUserID: int(partDTO.InvitedByUserID.Int32),
+		CreatedAt:       partDTO.CreatedAt,
+		UpdatedAt:       partDTO.UpdatedAt,
+	}, nil
+}
+
+// InsertParticipation implements repo.EventRepository.
+func (e *eventRepository) InsertParticipation(
+	ctx context.Context,
+	userID int,
+	eventID int,
+	invitedByUserID int,
+	tx any,
+) (*model.ParticipationEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	var invitedBy sql.NullInt32
+	if invitedByUserID == 0 {
+		invitedBy = sql.NullInt32{Int32: 0, Valid: false}
+	} else {
+		invitedBy = sql.NullInt32{Int32: int32(invitedByUserID), Valid: true}
+	}
+	participationDTO, err := queries.InsertParticipation(timeoutCtx, sqlc.InsertParticipationParams{
+		UserID:          int32(userID),
+		EventID:         int32(eventID),
+		InvitedByUserID: invitedBy,
+		CreatedAt:       time.Now(),
+		UpdatedAt:       time.Now(),
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &model.ParticipationEntity{
+		ID:              int(participationDTO.ID),
+		UserID:          int(participationDTO.UserID),
+		EventID:         int(participationDTO.EventID),
+		InvitedByUserID: int(participationDTO.InvitedByUserID.Int32),
+		CreatedAt:       participationDTO.CreatedAt,
+		UpdatedAt:       participationDTO.UpdatedAt,
+	}, nil
+}

internal/howmuch/adapter/repo/event_test.go

@@ -0,0 +1,122 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"database/sql"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConvToEventRetrieved(t *testing.T) {
+	input := &sqlc.GetEventByIDRow{
+		ID:              123,
+		Name:            "event",
+		Description:     sql.NullString{Valid: false},
+		TotalAmount:     sql.NullInt32{Valid: false},
+		DefaultCurrency: "EUR",
+		CreatedAt:       time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		UpdatedAt:       time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		Owner:           json.RawMessage(`{"id":1, "first_name":"owner", "last_name":"owner"}`),
+		Users:           json.RawMessage(`[{"id":1, "first_name":"owner", "last_name":"owner"}]`),
+	}
+
+	want := &model.EventRetrieved{
+		ID:              123,
+		Name:            "event",
+		Description:     "",
+		TotalAmount:     model.Money{Amount: 0, Currency: "EUR"},
+		DefaultCurrency: model.Currency("EUR"),
+		CreatedAt:       time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		UpdatedAt:       time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		Owner: &model.UserBaseRetrieved{
+			ID:        1,
+			FirstName: "owner",
+			LastName:  "owner",
+		},
+		Users: []model.UserBaseRetrieved{
+			{
+				ID:        1,
+				FirstName: "owner",
+				LastName:  "owner",
+			},
+		},
+	}
+
+	got, err := convToEventRetrieved(input)
+	assert.NoError(t, err)
+	assert.Equal(t, want, got)
+}
+
+func TestConvToEventList(t *testing.T) {
+	input := []sqlc.ListEventsByUserIDRow{
+		{
+			ID:          123,
+			Name:        "event",
+			Description: sql.NullString{Valid: false},
+			CreatedAt:   time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+			Owner:       json.RawMessage(`{"id":1, "first_name":"owner", "last_name":"owner"}`),
+		},
+		{
+			ID:          456,
+			Name:        "event2",
+			Description: sql.NullString{String: "super event", Valid: true},
+			CreatedAt:   time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+			Owner:       json.RawMessage(`{"id":1, "first_name":"owner", "last_name":"owner"}`),
+		},
+	}
+
+	want := []model.EventListRetrieved{
+		{
+			ID:          123,
+			Name:        "event",
+			Description: "",
+			CreatedAt:   time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+			Owner: &model.UserBaseRetrieved{
+				ID:        1,
+				FirstName: "owner",
+				LastName:  "owner",
+			},
+		},
+		{
+			ID:          456,
+			Name:        "event2",
+			Description: "super event",
+			CreatedAt:   time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+			Owner: &model.UserBaseRetrieved{
+				ID:        1,
+				FirstName: "owner",
+				LastName:  "owner",
+			},
+		},
+	}
+
+	got, err := convToEventList(input)
+	assert.NoError(t, err)
+	assert.Equal(t, want, got)
+}

internal/howmuch/adapter/repo/expense.go

@@ -0,0 +1,267 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+)
+
+type expenseRepository struct {
+	queries *sqlc.Queries
+}
+
+func NewExpenseRepository(db *sql.DB) repo.ExpenseRepository {
+	return &expenseRepository{
+		queries: sqlc.New(db),
+	}
+}
+
+// DeleteExpense implements repo.ExpenseRepository.
+func (e *expenseRepository) DeleteExpense(ctx context.Context, expenseID int, tx any) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+	return queries.DeleteExpense(timeoutCtx, int32(expenseID))
+}
+
+// DeleteTransactionsOfExpense implements repo.ExpenseRepository.
+func (e *expenseRepository) DeleteTransactionsOfExpense(
+	ctx context.Context,
+	expenseID int,
+	tx any,
+) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+	return queries.DeleteTransactionsOfExpenseID(timeoutCtx, int32(expenseID))
+}
+
+// GetExpenseByID implements repo.ExpenseRepository.
+func (e *expenseRepository) GetExpenseByID(
+	ctx context.Context,
+	expenseID int,
+	tx any,
+) (*model.ExpenseRetrieved, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	expenseDTO, err := queries.GetExpenseByID(timeoutCtx, int32(expenseID))
+	if err != nil {
+		return nil, err
+	}
+	expense, err := convToExpenseRetrieved(&expenseDTO)
+	if err != nil {
+		return nil, err
+	}
+	return expense, nil
+}
+
+func convToPayments(raw json.RawMessage) ([]model.Payment, error) {
+	var paymentsRetrieved []model.PaymentRetrieved
+	err := json.Unmarshal(raw, &paymentsRetrieved)
+	if err != nil {
+		// Unexpected
+		log.ErrorLog("json unmarshal error", "err", err)
+		return nil, err
+	}
+
+	payments := make([]model.Payment, len(paymentsRetrieved))
+	for i, p := range paymentsRetrieved {
+		payment := model.Payment{
+			PayerID:        p.PayerID,
+			PayerFirstName: p.PayerFirstName,
+			PayerLastName:  p.PayerLastName,
+			Amount:         model.MakeMoney(p.Amount, model.Currency(p.Currency)),
+		}
+		payments[i] = payment
+	}
+
+	return payments, nil
+}
+
+func convToBenefits(raw json.RawMessage) ([]model.Benefit, error) {
+	var benefitsRetrieved []model.BenefitRetrieved
+	err := json.Unmarshal(raw, &benefitsRetrieved)
+	if err != nil {
+		// Unexpected
+		log.ErrorLog("json unmarshal error", "err", err)
+		return nil, err
+	}
+
+	benefits := make([]model.Benefit, len(benefitsRetrieved))
+	for i, b := range benefitsRetrieved {
+		benefit := model.Benefit{
+			RecipientID:        b.RecipientID,
+			RecipientFirstName: b.RecipientFirstName,
+			RecipientLastName:  b.RecipientLastName,
+			Amount:             model.MakeMoney(b.Amount, model.Currency(b.Currency)),
+		}
+		benefits[i] = benefit
+	}
+
+	return benefits, nil
+}
+
+func convToExpenseRetrieved(expenseDTO *sqlc.GetExpenseByIDRow) (*model.ExpenseRetrieved, error) {
+	payments, err := convToPayments(expenseDTO.Payments)
+	if err != nil {
+		// Unexpected
+		return nil, err
+	}
+
+	benefits, err := convToBenefits(expenseDTO.Benefits)
+	if err != nil {
+		// Unexpected
+		return nil, err
+	}
+
+	expenseRetrieved := &model.ExpenseRetrieved{
+		ID:        int(expenseDTO.ID),
+		CreatedAt: expenseDTO.CreatedAt,
+		UpdatedAt: expenseDTO.UpdatedAt,
+		Amount:    model.MakeMoney(int(expenseDTO.Amount), model.Currency(expenseDTO.Currency)),
+		EventID:   int(expenseDTO.EventID),
+		Detail: model.ExpenseDetail{
+			Name:  expenseDTO.Name.String,
+			Place: expenseDTO.Place.String,
+		},
+		Payments: payments,
+		Benefits: benefits,
+	}
+
+	return expenseRetrieved, nil
+}
+
+// InsertExpense implements repo.ExpenseRepository.
+func (e *expenseRepository) InsertExpense(
+	ctx context.Context,
+	expenseEntity *model.ExpenseEntity,
+	tx any,
+) (*model.ExpenseEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	expenseDTO, err := queries.InsertExpense(timeoutCtx, sqlc.InsertExpenseParams{
+		CreatedAt: time.Now(),
+		UpdatedAt: time.Now(),
+		Amount:    int32(expenseEntity.Amount),
+		Currency:  expenseEntity.Currency,
+		EventID:   int32(expenseEntity.EventID),
+		Name:      sql.NullString{String: expenseEntity.Name, Valid: true},
+		Place:     sql.NullString{String: expenseEntity.Place, Valid: true},
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &model.ExpenseEntity{
+		ID:        int(expenseDTO.ID),
+		CreatedAt: expenseDTO.CreatedAt,
+		UpdatedAt: expenseDTO.CreatedAt,
+		Amount:    int(expenseDTO.Amount),
+		Currency:  expenseDTO.Currency,
+		EventID:   int(expenseDTO.EventID),
+		Name:      expenseDTO.Name.String,
+		Place:     expenseDTO.Place.String,
+	}, nil
+}
+
+// ListExpensesByEventID implements repo.ExpenseRepository.
+func (e *expenseRepository) ListExpensesByEventID(
+	ctx context.Context,
+	id int,
+	tx any,
+) ([]model.ExpensesListRetrieved, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	listDTO, err := queries.ListExpensesByEventID(timeoutCtx, int32(id))
+	if err != nil {
+		return nil, err
+	}
+	res := make([]model.ExpensesListRetrieved, len(listDTO))
+	for i, dto := range listDTO {
+		elem := model.ExpensesListRetrieved{
+			ID:        int(dto.ID),
+			CreatedAt: dto.CreatedAt,
+			UpdatedAt: dto.UpdatedAt,
+			Amount:    model.MakeMoney(int(dto.Amount), model.Currency(dto.Currency)),
+			EventID:   int(dto.EventID),
+			Detail: model.ExpenseDetail{
+				Name:  dto.Name.String,
+				Place: dto.Place.String,
+			},
+		}
+		res[i] = elem
+	}
+	return res, nil
+}
+
+// UpdateExpenseByID implements repo.ExpenseRepository.
+func (e *expenseRepository) UpdateExpenseByID(
+	ctx context.Context,
+	expenseUpdate *model.ExpenseUpdateEntity,
+	tx any,
+) (*model.ExpenseEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(e.queries, tx)
+
+	expenseDTO, err := queries.UpdateExpenseByID(timeoutCtx, sqlc.UpdateExpenseByIDParams{
+		ID:        int32(expenseUpdate.ID),
+		UpdatedAt: time.Now(),
+		Amount:    int32(expenseUpdate.Amount),
+		Currency:  expenseUpdate.Currency,
+		Name:      sql.NullString{String: expenseUpdate.Name, Valid: true},
+		Place:     sql.NullString{String: expenseUpdate.Place, Valid: true},
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &model.ExpenseEntity{
+		ID:        int(expenseDTO.ID),
+		CreatedAt: expenseDTO.CreatedAt,
+		UpdatedAt: expenseDTO.CreatedAt,
+		Amount:    int(expenseDTO.Amount),
+		Currency:  expenseDTO.Currency,
+		EventID:   int(expenseDTO.EventID),
+		Name:      expenseDTO.Name.String,
+		Place:     expenseDTO.Place.String,
+	}, nil
+}

internal/howmuch/adapter/repo/expense_test.go

@@ -0,0 +1,96 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"database/sql"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConvToExpenseRetrieved(t *testing.T) {
+	input := &sqlc.GetExpenseByIDRow{
+		ID:        123,
+		CreatedAt: time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		UpdatedAt: time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		Amount:    123,
+		Currency:  "EUR",
+		EventID:   123,
+		Name:      sql.NullString{Valid: false},
+		Place:     sql.NullString{Valid: false},
+		Payments: json.RawMessage(
+			`[{"payer_id": 1, "payer_first_name": "toto", "payer_last_name": "titi", "amount": 10, "currency": "EUR"},
+            {"payer_id": 2, "payer_first_name": "tata", "payer_last_name": "titi", "amount": 10, "currency": "EUR"}]`,
+		),
+		Benefits: json.RawMessage(
+			`[{"recipient_id": 1, "recipient_first_name": "toto", "recipient_last_name": "titi", "amount": 10, "currency": "EUR"},
+            {"recipient_id": 2, "recipient_first_name": "tata", "recipient_last_name": "titi", "amount": 10, "currency": "EUR"}]`,
+		),
+	}
+
+	want := &model.ExpenseRetrieved{
+		ID:        123,
+		CreatedAt: time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		UpdatedAt: time.Date(2000, time.April, 11, 0, 0, 0, 0, time.UTC),
+		Amount:    model.Money{Amount: 123, Currency: model.Currency("EUR")},
+		EventID:   123,
+		Detail:    model.ExpenseDetail{},
+		Payments: []model.Payment{
+			{
+				PayerID:        1,
+				PayerFirstName: "toto",
+				PayerLastName:  "titi",
+				Amount:         model.Money{Amount: 10, Currency: model.Currency("EUR")},
+			},
+			{
+				PayerID:        2,
+				PayerFirstName: "tata",
+				PayerLastName:  "titi",
+				Amount:         model.Money{Amount: 10, Currency: model.Currency("EUR")},
+			},
+		},
+		Benefits: []model.Benefit{
+			{
+				RecipientID:        1,
+				RecipientFirstName: "toto",
+				RecipientLastName:  "titi",
+				Amount:             model.Money{Amount: 10, Currency: model.Currency("EUR")},
+			},
+			{
+				RecipientID:        2,
+				RecipientFirstName: "tata",
+				RecipientLastName:  "titi",
+				Amount:             model.Money{Amount: 10, Currency: model.Currency("EUR")},
+			},
+		},
+	}
+
+	got, err := convToExpenseRetrieved(input)
+	assert.NoError(t, err)
+	assert.Equal(t, want, got)
+}

internal/howmuch/adapter/repo/sqlc/db.go

@@ -0,0 +1,31 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+
+package sqlc
+
+import (
+	"context"
+	"database/sql"
+)
+
+type DBTX interface {
+	ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
+	PrepareContext(context.Context, string) (*sql.Stmt, error)
+	QueryContext(context.Context, string, ...interface{}) (*sql.Rows, error)
+	QueryRowContext(context.Context, string, ...interface{}) *sql.Row
+}
+
+func New(db DBTX) *Queries {
+	return &Queries{db: db}
+}
+
+type Queries struct {
+	db DBTX
+}
+
+func (q *Queries) WithTx(tx *sql.Tx) *Queries {
+	return &Queries{
+		db: tx,
+	}
+}

internal/howmuch/adapter/repo/sqlc/event.sql

@@ -0,0 +1,64 @@
+-- name: InsertEvent :one
+INSERT INTO "event" (
+    name, description, total_amount, default_currency, owner_id, created_at, updated_at
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING *;
+
+-- name: ListEventsByUserID :many
+SELECT
+    e.id,
+    e.name,
+    e.description,
+    e.created_at,
+    json_build_object(
+        'id', o.id,
+        'first_name', o.first_name,
+        'last_name', o.last_name
+    ) AS owner
+FROM "event" e
+JOIN "participation" p ON p.event_id = e.id  -- participation linked with the event
+JOIN "user" o ON o.id = e.owner_id           -- get the owner info
+WHERE e.id IN (
+    SELECT pt.event_id FROM participation pt WHERE pt.user_id = $1 -- consider the events participated by user_id
+)
+GROUP BY
+    e.id, e.name, e.description, e.created_at,
+    o.id, o.first_name, o.last_name;
+
+-- name: GetEventByID :one
+SELECT
+    e.id,
+    e.name,
+    e.description,
+    e.total_amount,
+    e.default_currency,
+    e.created_at,
+    e.updated_at,
+    json_build_object(
+        'id', o.id,
+        'first_name', o.first_name,
+        'last_name', o.last_name
+    ) AS owner,
+    json_agg(
+        json_build_object(
+            'id', u.id,
+            'first_name', u.first_name,
+            'last_name', u.last_name
+        )
+    ) AS users  -- Aggregation for users in the event
+FROM "event" e
+JOIN "participation" p ON p.event_id = e.id  -- participation linked with the event
+JOIN "user" u ON u.id = p.user_id            -- and the query user
+JOIN "user" o ON o.id = e.owner_id           -- get the owner info
+WHERE e.id = $1
+GROUP BY
+    e.id, e.name, e.description, e.created_at, e.updated_at,
+    e.total_amount, e.default_currency,
+    o.id, o.first_name, o.last_name;
+
+-- name: UpdateEventByID :exec
+UPDATE "event"
+SET name = $2, description = $3, updated_at = $4
+WHERE id = $1;
+
+

internal/howmuch/adapter/repo/sqlc/event.sql.go

@@ -0,0 +1,197 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+// source: event.sql
+
+package sqlc
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"time"
+)
+
+const getEventByID = `-- name: GetEventByID :one
+SELECT
+    e.id,
+    e.name,
+    e.description,
+    e.total_amount,
+    e.default_currency,
+    e.created_at,
+    e.updated_at,
+    json_build_object(
+        'id', o.id,
+        'first_name', o.first_name,
+        'last_name', o.last_name
+    ) AS owner,
+    json_agg(
+        json_build_object(
+            'id', u.id,
+            'first_name', u.first_name,
+            'last_name', u.last_name
+        )
+    ) AS users  -- Aggregation for users in the event
+FROM "event" e
+JOIN "participation" p ON p.event_id = e.id  -- participation linked with the event
+JOIN "user" u ON u.id = p.user_id            -- and the query user
+JOIN "user" o ON o.id = e.owner_id           -- get the owner info
+WHERE e.id = $1
+GROUP BY
+    e.id, e.name, e.description, e.created_at, e.updated_at,
+    e.total_amount, e.default_currency,
+    o.id, o.first_name, o.last_name
+`
+
+type GetEventByIDRow struct {
+	ID              int32
+	Name            string
+	Description     sql.NullString
+	TotalAmount     sql.NullInt32
+	DefaultCurrency string
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
+	Owner           json.RawMessage
+	Users           json.RawMessage
+}
+
+func (q *Queries) GetEventByID(ctx context.Context, id int32) (GetEventByIDRow, error) {
+	row := q.db.QueryRowContext(ctx, getEventByID, id)
+	var i GetEventByIDRow
+	err := row.Scan(
+		&i.ID,
+		&i.Name,
+		&i.Description,
+		&i.TotalAmount,
+		&i.DefaultCurrency,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.Owner,
+		&i.Users,
+	)
+	return i, err
+}
+
+const insertEvent = `-- name: InsertEvent :one
+INSERT INTO "event" (
+    name, description, total_amount, default_currency, owner_id, created_at, updated_at
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING id, name, description, default_currency, owner_id, created_at, updated_at, total_amount
+`
+
+type InsertEventParams struct {
+	Name            string
+	Description     sql.NullString
+	TotalAmount     sql.NullInt32
+	DefaultCurrency string
+	OwnerID         int32
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
+}
+
+func (q *Queries) InsertEvent(ctx context.Context, arg InsertEventParams) (Event, error) {
+	row := q.db.QueryRowContext(ctx, insertEvent,
+		arg.Name,
+		arg.Description,
+		arg.TotalAmount,
+		arg.DefaultCurrency,
+		arg.OwnerID,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	var i Event
+	err := row.Scan(
+		&i.ID,
+		&i.Name,
+		&i.Description,
+		&i.DefaultCurrency,
+		&i.OwnerID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.TotalAmount,
+	)
+	return i, err
+}
+
+const listEventsByUserID = `-- name: ListEventsByUserID :many
+SELECT
+    e.id,
+    e.name,
+    e.description,
+    e.created_at,
+    json_build_object(
+        'id', o.id,
+        'first_name', o.first_name,
+        'last_name', o.last_name
+    ) AS owner
+FROM "event" e
+JOIN "participation" p ON p.event_id = e.id  -- participation linked with the event
+JOIN "user" o ON o.id = e.owner_id           -- get the owner info
+WHERE e.id IN (
+    SELECT pt.event_id FROM participation pt WHERE pt.user_id = $1 -- consider the events participated by user_id
+)
+GROUP BY
+    e.id, e.name, e.description, e.created_at,
+    o.id, o.first_name, o.last_name
+`
+
+type ListEventsByUserIDRow struct {
+	ID          int32
+	Name        string
+	Description sql.NullString
+	CreatedAt   time.Time
+	Owner       json.RawMessage
+}
+
+func (q *Queries) ListEventsByUserID(ctx context.Context, userID int32) ([]ListEventsByUserIDRow, error) {
+	rows, err := q.db.QueryContext(ctx, listEventsByUserID, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []ListEventsByUserIDRow
+	for rows.Next() {
+		var i ListEventsByUserIDRow
+		if err := rows.Scan(
+			&i.ID,
+			&i.Name,
+			&i.Description,
+			&i.CreatedAt,
+			&i.Owner,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const updateEventByID = `-- name: UpdateEventByID :exec
+UPDATE "event"
+SET name = $2, description = $3, updated_at = $4
+WHERE id = $1
+`
+
+type UpdateEventByIDParams struct {
+	ID          int32
+	Name        string
+	Description sql.NullString
+	UpdatedAt   time.Time
+}
+
+func (q *Queries) UpdateEventByID(ctx context.Context, arg UpdateEventByIDParams) error {
+	_, err := q.db.ExecContext(ctx, updateEventByID,
+		arg.ID,
+		arg.Name,
+		arg.Description,
+		arg.UpdatedAt,
+	)
+	return err
+}

internal/howmuch/adapter/repo/sqlc/expense.sql

@@ -0,0 +1,64 @@
+-- name: InsertExpense :one
+INSERT INTO "expense" (
+    created_at, updated_at, amount, currency, event_id, name, place
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING *;
+
+-- name: DeleteExpense :exec
+DELETE FROM "expense" WHERE id = $1;
+
+-- name: DeleteTransactionsOfExpenseID :exec
+DELETE FROM "transaction" WHERE transaction.expense_id = $1;
+
+-- name: UpdateExpenseByID :one
+UPDATE "expense"
+SET updated_at = $2, amount = $3, currency = $4, name = $5, place = $6
+WHERE id = $1
+RETURNING *;
+
+-- name: ListExpensesByEventID :many
+SELECT
+    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
+    ex.name, ex.place
+FROM "expense" ex
+JOIN "event" ev ON ev.id = ex.event_id
+WHERE ev.id = $1;
+
+-- name: GetExpenseByID :one
+WITH payer_transaction as (
+    SELECT pt.expense_id,
+        json_agg(json_build_object(
+            'payer_id', p.id,
+            'payer_first_name', p.first_name,
+            'payer_last_name', p.last_name,
+            'amount', pt.amount,
+            'currency', pt.currency
+        )) AS payments
+    FROM "transaction" pt
+    JOIN "user" p ON p.id = pt.user_id
+    WHERE pt.is_income = FALSE
+    GROUP BY pt.expense_id
+), -- For each expense, aggregate payment info
+recipient_transaction as (
+    SELECT rt.expense_id,
+        json_agg(json_build_object(
+            'recipient_id', p.id,
+            'recipient_first_name', p.first_name,
+            'recipient_last_name', p.last_name,
+            'amount', rt.amount,
+            'currency', rt.currency
+        )) AS benefits
+    FROM "transaction" rt
+    JOIN "user" p ON p.id = rt.user_id
+    WHERE rt.is_income = TRUE
+    GROUP BY rt.expense_id
+) -- For each expense, aggregate benefits info
+SELECT
+    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
+    ex.name, ex.place,
+    COALESCE(pt.payments, '[]') AS payments,
+    COALESCE(rt.benefits, '[]') AS benefits
+FROM "expense" ex
+LEFT JOIN "payer_transaction" pt ON pt.expense_id = ex.id
+LEFT JOIN "recipient_transaction" rt ON rt.expense_id = ex.id
+WHERE ex.id = $1;

internal/howmuch/adapter/repo/sqlc/expense.sql.go

@@ -0,0 +1,223 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+// source: expense.sql
+
+package sqlc
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"time"
+)
+
+const deleteExpense = `-- name: DeleteExpense :exec
+DELETE FROM "expense" WHERE id = $1
+`
+
+func (q *Queries) DeleteExpense(ctx context.Context, id int32) error {
+	_, err := q.db.ExecContext(ctx, deleteExpense, id)
+	return err
+}
+
+const deleteTransactionsOfExpenseID = `-- name: DeleteTransactionsOfExpenseID :exec
+DELETE FROM "transaction" WHERE transaction.expense_id = $1
+`
+
+func (q *Queries) DeleteTransactionsOfExpenseID(ctx context.Context, expenseID int32) error {
+	_, err := q.db.ExecContext(ctx, deleteTransactionsOfExpenseID, expenseID)
+	return err
+}
+
+const getExpenseByID = `-- name: GetExpenseByID :one
+WITH payer_transaction as (
+    SELECT pt.expense_id,
+        json_agg(json_build_object(
+            'payer_id', p.id,
+            'payer_first_name', p.first_name,
+            'payer_last_name', p.last_name,
+            'amount', pt.amount,
+            'currency', pt.currency
+        )) AS payments
+    FROM "transaction" pt
+    JOIN "user" p ON p.id = pt.user_id
+    WHERE pt.is_income = FALSE
+    GROUP BY pt.expense_id
+), -- For each expense, aggregate payment info
+recipient_transaction as (
+    SELECT rt.expense_id,
+        json_agg(json_build_object(
+            'recipient_id', p.id,
+            'recipient_first_name', p.first_name,
+            'recipient_last_name', p.last_name,
+            'amount', rt.amount,
+            'currency', rt.currency
+        )) AS benefits
+    FROM "transaction" rt
+    JOIN "user" p ON p.id = rt.user_id
+    WHERE rt.is_income = TRUE
+    GROUP BY rt.expense_id
+) -- For each expense, aggregate benefits info
+SELECT
+    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
+    ex.name, ex.place,
+    COALESCE(pt.payments, '[]') AS payments,
+    COALESCE(rt.benefits, '[]') AS benefits
+FROM "expense" ex
+LEFT JOIN "payer_transaction" pt ON pt.expense_id = ex.id
+LEFT JOIN "recipient_transaction" rt ON rt.expense_id = ex.id
+WHERE ex.id = $1
+`
+
+type GetExpenseByIDRow struct {
+	ID        int32
+	CreatedAt time.Time
+	UpdatedAt time.Time
+	Amount    int32
+	Currency  string
+	EventID   int32
+	Name      sql.NullString
+	Place     sql.NullString
+	Payments  json.RawMessage
+	Benefits  json.RawMessage
+}
+
+func (q *Queries) GetExpenseByID(ctx context.Context, id int32) (GetExpenseByIDRow, error) {
+	row := q.db.QueryRowContext(ctx, getExpenseByID, id)
+	var i GetExpenseByIDRow
+	err := row.Scan(
+		&i.ID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.Amount,
+		&i.Currency,
+		&i.EventID,
+		&i.Name,
+		&i.Place,
+		&i.Payments,
+		&i.Benefits,
+	)
+	return i, err
+}
+
+const insertExpense = `-- name: InsertExpense :one
+INSERT INTO "expense" (
+    created_at, updated_at, amount, currency, event_id, name, place
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING id, created_at, updated_at, amount, currency, event_id, name, place
+`
+
+type InsertExpenseParams struct {
+	CreatedAt time.Time
+	UpdatedAt time.Time
+	Amount    int32
+	Currency  string
+	EventID   int32
+	Name      sql.NullString
+	Place     sql.NullString
+}
+
+func (q *Queries) InsertExpense(ctx context.Context, arg InsertExpenseParams) (Expense, error) {
+	row := q.db.QueryRowContext(ctx, insertExpense,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+		arg.Amount,
+		arg.Currency,
+		arg.EventID,
+		arg.Name,
+		arg.Place,
+	)
+	var i Expense
+	err := row.Scan(
+		&i.ID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.Amount,
+		&i.Currency,
+		&i.EventID,
+		&i.Name,
+		&i.Place,
+	)
+	return i, err
+}
+
+const listExpensesByEventID = `-- name: ListExpensesByEventID :many
+SELECT
+    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
+    ex.name, ex.place
+FROM "expense" ex
+JOIN "event" ev ON ev.id = ex.event_id
+WHERE ev.id = $1
+`
+
+func (q *Queries) ListExpensesByEventID(ctx context.Context, id int32) ([]Expense, error) {
+	rows, err := q.db.QueryContext(ctx, listExpensesByEventID, id)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Expense
+	for rows.Next() {
+		var i Expense
+		if err := rows.Scan(
+			&i.ID,
+			&i.CreatedAt,
+			&i.UpdatedAt,
+			&i.Amount,
+			&i.Currency,
+			&i.EventID,
+			&i.Name,
+			&i.Place,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const updateExpenseByID = `-- name: UpdateExpenseByID :one
+UPDATE "expense"
+SET updated_at = $2, amount = $3, currency = $4, name = $5, place = $6
+WHERE id = $1
+RETURNING id, created_at, updated_at, amount, currency, event_id, name, place
+`
+
+type UpdateExpenseByIDParams struct {
+	ID        int32
+	UpdatedAt time.Time
+	Amount    int32
+	Currency  string
+	Name      sql.NullString
+	Place     sql.NullString
+}
+
+func (q *Queries) UpdateExpenseByID(ctx context.Context, arg UpdateExpenseByIDParams) (Expense, error) {
+	row := q.db.QueryRowContext(ctx, updateExpenseByID,
+		arg.ID,
+		arg.UpdatedAt,
+		arg.Amount,
+		arg.Currency,
+		arg.Name,
+		arg.Place,
+	)
+	var i Expense
+	err := row.Scan(
+		&i.ID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.Amount,
+		&i.Currency,
+		&i.EventID,
+		&i.Name,
+		&i.Place,
+	)
+	return i, err
+}

internal/howmuch/adapter/repo/sqlc/models.go

@@ -0,0 +1,69 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+
+package sqlc
+
+import (
+	"database/sql"
+	"time"
+)
+
+type Admin struct {
+	ID          int32
+	Email       string
+	Password    string
+	AccessLevel int32
+}
+
+type Event struct {
+	ID              int32
+	Name            string
+	Description     sql.NullString
+	DefaultCurrency string
+	OwnerID         int32
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
+	TotalAmount     sql.NullInt32
+}
+
+type Expense struct {
+	ID        int32
+	CreatedAt time.Time
+	UpdatedAt time.Time
+	Amount    int32
+	Currency  string
+	EventID   int32
+	Name      sql.NullString
+	Place     sql.NullString
+}
+
+type Participation struct {
+	ID              int32
+	UserID          int32
+	EventID         int32
+	InvitedByUserID sql.NullInt32
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
+}
+
+type Transaction struct {
+	ID        int32
+	ExpenseID int32
+	UserID    int32
+	Amount    int32
+	Currency  string
+	IsIncome  bool
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+type User struct {
+	ID        int32
+	Email     string
+	FirstName string
+	LastName  string
+	Password  string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}

internal/howmuch/adapter/repo/sqlc/participation.sql

@@ -0,0 +1,10 @@
+-- name: InsertParticipation :one
+INSERT INTO participation (
+    user_id, event_id, invited_by_user_id, created_at, updated_at
+) VALUES ($1, $2, $3, $4, $5)
+RETURNING *;
+
+-- name: GetParticipation :one
+SELECT id, user_id, event_id, invited_by_user_id, created_at, updated_at
+FROM "participation"
+WHERE user_id = $1 AND event_id = $2;

internal/howmuch/adapter/repo/sqlc/participation.sql.go

@@ -0,0 +1,72 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+// source: participation.sql
+
+package sqlc
+
+import (
+	"context"
+	"database/sql"
+	"time"
+)
+
+const getParticipation = `-- name: GetParticipation :one
+SELECT id, user_id, event_id, invited_by_user_id, created_at, updated_at
+FROM "participation"
+WHERE user_id = $1 AND event_id = $2
+`
+
+type GetParticipationParams struct {
+	UserID  int32
+	EventID int32
+}
+
+func (q *Queries) GetParticipation(ctx context.Context, arg GetParticipationParams) (Participation, error) {
+	row := q.db.QueryRowContext(ctx, getParticipation, arg.UserID, arg.EventID)
+	var i Participation
+	err := row.Scan(
+		&i.ID,
+		&i.UserID,
+		&i.EventID,
+		&i.InvitedByUserID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const insertParticipation = `-- name: InsertParticipation :one
+INSERT INTO participation (
+    user_id, event_id, invited_by_user_id, created_at, updated_at
+) VALUES ($1, $2, $3, $4, $5)
+RETURNING id, user_id, event_id, invited_by_user_id, created_at, updated_at
+`
+
+type InsertParticipationParams struct {
+	UserID          int32
+	EventID         int32
+	InvitedByUserID sql.NullInt32
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
+}
+
+func (q *Queries) InsertParticipation(ctx context.Context, arg InsertParticipationParams) (Participation, error) {
+	row := q.db.QueryRowContext(ctx, insertParticipation,
+		arg.UserID,
+		arg.EventID,
+		arg.InvitedByUserID,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	var i Participation
+	err := row.Scan(
+		&i.ID,
+		&i.UserID,
+		&i.EventID,
+		&i.InvitedByUserID,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}

internal/howmuch/adapter/repo/sqlc/querier.go

@@ -0,0 +1,30 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+
+package sqlc
+
+import (
+	"context"
+)
+
+type Querier interface {
+	DeleteExpense(ctx context.Context, id int32) error
+	DeleteTransactionsOfExpenseID(ctx context.Context, expenseID int32) error
+	GetEventByID(ctx context.Context, id int32) (GetEventByIDRow, error)
+	GetExpenseByID(ctx context.Context, id int32) (GetExpenseByIDRow, error)
+	GetParticipation(ctx context.Context, arg GetParticipationParams) (Participation, error)
+	GetUserByEmail(ctx context.Context, email string) (User, error)
+	GetUserByID(ctx context.Context, id int32) (User, error)
+	InsertEvent(ctx context.Context, arg InsertEventParams) (Event, error)
+	InsertExpense(ctx context.Context, arg InsertExpenseParams) (Expense, error)
+	InsertParticipation(ctx context.Context, arg InsertParticipationParams) (Participation, error)
+	InsertTransaction(ctx context.Context, arg InsertTransactionParams) error
+	InsertUser(ctx context.Context, arg InsertUserParams) (User, error)
+	ListEventsByUserID(ctx context.Context, userID int32) ([]ListEventsByUserIDRow, error)
+	ListExpensesByEventID(ctx context.Context, id int32) ([]Expense, error)
+	UpdateEventByID(ctx context.Context, arg UpdateEventByIDParams) error
+	UpdateExpenseByID(ctx context.Context, arg UpdateExpenseByIDParams) (Expense, error)
+}
+
+var _ Querier = (*Queries)(nil)

internal/howmuch/adapter/repo/sqlc/transaction.sql

@@ -0,0 +1,5 @@
+-- name: InsertTransaction :exec
+INSERT INTO "transaction" (
+    created_at, updated_at, amount, currency, expense_id, user_id, is_income
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING *;

internal/howmuch/adapter/repo/sqlc/transaction.sql.go

@@ -0,0 +1,41 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+// source: transaction.sql
+
+package sqlc
+
+import (
+	"context"
+	"time"
+)
+
+const insertTransaction = `-- name: InsertTransaction :exec
+INSERT INTO "transaction" (
+    created_at, updated_at, amount, currency, expense_id, user_id, is_income
+) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
+RETURNING id, expense_id, user_id, amount, currency, is_income, created_at, updated_at
+`
+
+type InsertTransactionParams struct {
+	CreatedAt time.Time
+	UpdatedAt time.Time
+	Amount    int32
+	Currency  string
+	ExpenseID int32
+	UserID    int32
+	IsIncome  bool
+}
+
+func (q *Queries) InsertTransaction(ctx context.Context, arg InsertTransactionParams) error {
+	_, err := q.db.ExecContext(ctx, insertTransaction,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+		arg.Amount,
+		arg.Currency,
+		arg.ExpenseID,
+		arg.UserID,
+		arg.IsIncome,
+	)
+	return err
+}

internal/howmuch/adapter/repo/sqlc/user.sql

@@ -1,27 +1,15 @@
--- MIT License
---
--- Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
---
--- Permission is hereby granted, free of charge, to any person obtaining a copy
--- of this software and associated documentation files (the "Software"), to deal
--- in the Software without restriction, including without limitation the rights
--- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
--- copies of the Software, and to permit persons to whom the Software is
--- furnished to do so, subject to the following conditions:
---
--- The above copyright notice and this permission notice shall be included in all
--- copies or substantial portions of the Software.
---
--- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
--- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
--- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
--- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
--- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
--- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
--- SOFTWARE.
-
 -- name: InsertUser :one
 INSERT INTO "user" (
     email, first_name, last_name, password, created_at, updated_at
 ) VALUES ( $1, $2, $3, $4, $5, $6 )
 RETURNING *;
+
+-- name: GetUserByEmail :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE email = $1;
+
+-- name: GetUserByID :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE id = $1;

internal/howmuch/adapter/repo/sqlc/user.sql.go

@@ -0,0 +1,91 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.27.0
+// source: user.sql
+
+package sqlc
+
+import (
+	"context"
+	"time"
+)
+
+const getUserByEmail = `-- name: GetUserByEmail :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE email = $1
+`
+
+func (q *Queries) GetUserByEmail(ctx context.Context, email string) (User, error) {
+	row := q.db.QueryRowContext(ctx, getUserByEmail, email)
+	var i User
+	err := row.Scan(
+		&i.ID,
+		&i.Email,
+		&i.FirstName,
+		&i.LastName,
+		&i.Password,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const getUserByID = `-- name: GetUserByID :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE id = $1
+`
+
+func (q *Queries) GetUserByID(ctx context.Context, id int32) (User, error) {
+	row := q.db.QueryRowContext(ctx, getUserByID, id)
+	var i User
+	err := row.Scan(
+		&i.ID,
+		&i.Email,
+		&i.FirstName,
+		&i.LastName,
+		&i.Password,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
+const insertUser = `-- name: InsertUser :one
+INSERT INTO "user" (
+    email, first_name, last_name, password, created_at, updated_at
+) VALUES ( $1, $2, $3, $4, $5, $6 )
+RETURNING id, email, first_name, last_name, password, created_at, updated_at
+`
+
+type InsertUserParams struct {
+	Email     string
+	FirstName string
+	LastName  string
+	Password  string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func (q *Queries) InsertUser(ctx context.Context, arg InsertUserParams) (User, error) {
+	row := q.db.QueryRowContext(ctx, insertUser,
+		arg.Email,
+		arg.FirstName,
+		arg.LastName,
+		arg.Password,
+		arg.CreatedAt,
+		arg.UpdatedAt,
+	)
+	var i User
+	err := row.Scan(
+		&i.ID,
+		&i.Email,
+		&i.FirstName,
+		&i.LastName,
+		&i.Password,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}

internal/howmuch/adapter/repo/user.go

@@ -0,0 +1,133 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo/sqlc"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+)
+
+type userRepository struct {
+	queries *sqlc.Queries
+}
+
+func NewUserRepository(db *sql.DB) repo.UserRepository {
+	return &userRepository{
+		queries: sqlc.New(db),
+	}
+}
+
+// Create
+func (u *userRepository) Create(
+	ctx context.Context,
+	userEntity *model.UserEntity,
+	tx any,
+) (*model.UserEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(u.queries, tx)
+
+	userDB, err := queries.InsertUser(timeoutCtx, sqlc.InsertUserParams{
+		Email:     userEntity.Email,
+		FirstName: userEntity.FirstName,
+		LastName:  userEntity.LastName,
+		Password:  userEntity.Password,
+		CreatedAt: time.Now(),
+		UpdatedAt: time.Now(),
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &model.UserEntity{
+		ID:        int(userDB.ID),
+		Email:     userDB.Email,
+		FirstName: userDB.FirstName,
+		LastName:  userDB.LastName,
+		Password:  userDB.Password,
+		CreatedAt: userDB.CreatedAt,
+		UpdatedAt: userDB.CreatedAt,
+	}, nil
+}
+
+// GetByEmail if not found, return nil for user but not error.
+func (u *userRepository) GetByEmail(
+	ctx context.Context,
+	email string,
+	tx any,
+) (*model.UserEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(u.queries, tx)
+
+	userDB, err := queries.GetUserByEmail(timeoutCtx, email)
+	if errors.Is(err, sql.ErrNoRows) {
+		// No query error, but user not found
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+
+	return &model.UserEntity{
+		ID:        int(userDB.ID),
+		Email:     userDB.Email,
+		FirstName: userDB.FirstName,
+		LastName:  userDB.LastName,
+		Password:  userDB.Password,
+		CreatedAt: userDB.CreatedAt,
+		UpdatedAt: userDB.CreatedAt,
+	}, nil
+}
+
+func (u *userRepository) GetByID(ctx context.Context, id int, tx any) (*model.UserEntity, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, queryTimeout)
+	defer cancel()
+
+	queries := getQueries(u.queries, tx)
+
+	userDB, err := queries.GetUserByID(timeoutCtx, int32(id))
+	if errors.Is(err, sql.ErrNoRows) {
+		// No query error, but user not found
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+
+	return &model.UserEntity{
+		ID:        int(userDB.ID),
+		Email:     userDB.Email,
+		FirstName: userDB.FirstName,
+		LastName:  userDB.LastName,
+		Password:  userDB.Password,
+		CreatedAt: userDB.CreatedAt,
+		UpdatedAt: userDB.CreatedAt,
+	}, nil
+}

internal/howmuch/controller/repo/sqlc/db.go

@@ -1,32 +0,0 @@
-// Code generated by sqlc. DO NOT EDIT.
-// versions:
-//   sqlc v1.27.0
-
-package sqlc
-
-import (
-	"context"
-
-	"github.com/jackc/pgx/v5"
-	"github.com/jackc/pgx/v5/pgconn"
-)
-
-type DBTX interface {
-	Exec(context.Context, string, ...interface{}) (pgconn.CommandTag, error)
-	Query(context.Context, string, ...interface{}) (pgx.Rows, error)
-	QueryRow(context.Context, string, ...interface{}) pgx.Row
-}
-
-func New(db DBTX) *Queries {
-	return &Queries{db: db}
-}
-
-type Queries struct {
-	db DBTX
-}
-
-func (q *Queries) WithTx(tx pgx.Tx) *Queries {
-	return &Queries{
-		db: tx,
-	}
-}

internal/howmuch/controller/repo/sqlc/models.go

@@ -1,26 +0,0 @@
-// Code generated by sqlc. DO NOT EDIT.
-// versions:
-//   sqlc v1.27.0
-
-package sqlc
-
-import (
-	"github.com/jackc/pgx/v5/pgtype"
-)
-
-type Admin struct {
-	ID          int32
-	Email       string
-	Password    string
-	AccessLevel int32
-}
-
-type User struct {
-	ID        int32
-	Email     string
-	FirstName string
-	LastName  string
-	Password  string
-	CreatedAt pgtype.Timestamp
-	UpdatedAt pgtype.Timestamp
-}

internal/howmuch/howmuch.go

@@ -35,8 +35,10 @@ import (
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/infra/router"
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/registry"
 	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/token"
 	"git.vinchent.xyz/vinchent/howmuch/pkg/version/verflag"
 	"github.com/gin-gonic/gin"
+	"github.com/redis/go-redis/v9"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"golang.org/x/net/context"
@@ -105,28 +107,44 @@ func run() error {
 	}
 
 	// Init DB
-	dbPool, err := datastore.NewDB(
-		fmt.Sprintf(
-			"host=%s port=%d dbname=%s user=%s password=%s sslmode=%s",
-			viper.GetString("db.host"),
-			viper.GetInt("db.port"),
-			viper.GetString("db.database"),
-			viper.GetString("db.username"),
-			viper.GetString("db.password"),
-			viper.GetString("db.sslmode"),
-		),
+	dbConfString := fmt.Sprintf(
+		"host=%s port=%d dbname=%s user=%s password=%s sslmode=%s",
+		viper.GetString("db.host"),
+		viper.GetInt("db.port"),
+		viper.GetString("db.database"),
+		viper.GetString("db.username"),
+		viper.GetString("db.password"),
+		viper.GetString("db.sslmode"),
 	)
-	if err != nil {
-		log.FatalLog("DB connection failure", "err", err)
+	// TODO: viper conf should be parsed into a struct directly
+	dbExtraConf := &datastore.DbExtraConf{
+		MaxOpenConns: viper.GetInt("db.max-open-conns"),
+		MaxIdleConns: viper.GetInt("db.max-idle-conns"),
+		MaxLifetime:  viper.GetDuration("db.max-lifetime"),
 	}
-	defer dbPool.Close()
+	dbConn := datastore.NewDB(dbConfString, dbExtraConf)
+	if dbConn == nil {
+		log.FatalLog("DB connection failure")
+	}
+	defer dbConn.Close()
+
+	// Init Cache
+	cache := datastore.NewCache(&redis.Options{
+		Addr:     viper.GetString("cache.host"),
+		Password: viper.GetString("cache.password"),
+		DB:       0,
+	})
+	defer cache.Close()
+
+	// Init token
+	token.Init(viper.GetString("web.token-secret"), viper.GetDuration("web.token-expiry-time"))
 
 	// Register the core service
-	r := registry.NewRegistry(dbPool)
+	r := registry.NewRegistry(dbConn, cache)
 
 	engine := gin.Default()
 
-	engine = router.Routes(engine, r.NewAppController())
+	engine = router.Routes(engine, r.NewAppController(), cache)
 
 	server := http.Server{
 		Addr:    viper.GetString("web.addr"),

internal/howmuch/infra/datastore/cache.go

@@ -0,0 +1,66 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package datastore
+
+import (
+	"context"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"github.com/redis/go-redis/v9"
+)
+
+type RedisCache struct {
+	redis *redis.Client
+}
+
+func NewCache(opt interface{}) core.Cache {
+	redisOpt := opt.(*redis.Options)
+	return &RedisCache{redis.NewClient(redisOpt)}
+}
+
+func (c *RedisCache) Get(ctx context.Context, key string) (string, error) {
+	val, err := c.redis.Get(ctx, key).Result()
+	if err == redis.Nil {
+		log.DebugLog("redis key not found", "key", key)
+		return "", nil
+	} else if err != nil {
+		log.DebugLog("redis cache get error", "err", err)
+		return "", err
+	}
+	return val, nil
+}
+
+func (c *RedisCache) Set(
+	ctx context.Context,
+	key string,
+	value interface{},
+	expiration time.Duration,
+) error {
+	return c.redis.Set(ctx, key, value, expiration).Err()
+}
+
+func (c *RedisCache) Close() error {
+	return c.redis.Close()
+}

internal/howmuch/infra/datastore/db.go

@@ -23,22 +23,65 @@
 package datastore
 
 import (
-	"context"
+	"database/sql"
+	"time"
 
-	"github.com/jackc/pgx/v5/pgxpool"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	_ "github.com/jackc/pgx/v5"
+	_ "github.com/jackc/pgx/v5/stdlib"
 )
 
+var counts int
+
+type DbExtraConf struct {
+	MaxOpenConns int
+	MaxIdleConns int
+	MaxLifetime  time.Duration
+}
+
 // NewDB creates a new database for the application
-func NewDB(dsn string) (*pgxpool.Pool, error) {
-	conn, err := pgxpool.New(context.Background(), dsn)
+func NewDB(dsn string, opts interface{}) *sql.DB {
+	var db *sql.DB
+	var err error
+
+	for {
+		db, err = openDB(dsn)
+		if err != nil {
+			log.WarnLog("postgres not ready", "err", err)
+			counts++
+		} else {
+			log.InfoLog("connected to postgres")
+			break
+		}
+
+		if counts > 10 {
+			break
+		}
+		log.InfoLog("retry in 2 seconds")
+		time.Sleep(2 * time.Second)
+	}
+
+	if db == nil {
+		return nil
+	}
+
+	extraConf, ok := opts.(DbExtraConf)
+	if ok {
+		db.SetMaxOpenConns(extraConf.MaxOpenConns)
+		db.SetMaxIdleConns(extraConf.MaxIdleConns)
+		db.SetConnMaxLifetime(extraConf.MaxLifetime)
+	}
+	return db
+}
+
+func openDB(dsn string) (*sql.DB, error) {
+	db, err := sql.Open("pgx", dsn)
 	if err != nil {
 		return nil, err
 	}
 
-	// Ping test the conn
-	if err = conn.Ping(context.Background()); err != nil {
+	if err := db.Ping(); err != nil {
 		return nil, err
 	}
-
-	return conn, err
+	return db, nil
 }

internal/howmuch/infra/router/router.go

@@ -23,15 +23,25 @@
 package router
 
 import (
+	"net/http"
+
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller"
 	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
 	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
 	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/middleware"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/middleware/authn"
 	"github.com/gin-contrib/cors"
 	"github.com/gin-gonic/gin"
 )
 
-func Routes(engine *gin.Engine, c controller.AppController) *gin.Engine {
+// Routes can take some options to init middlewares.
+// - Cache
+func Routes(engine *gin.Engine, c controller.AppController, opt ...interface{}) *gin.Engine {
+	cache, ok := opt[0].(core.Cache)
+	if !ok {
+		panic("the first option must be a cache driver")
+	}
+
 	// Middlewares
 	// Cors
 	corsCfg := cors.DefaultConfig()
@@ -48,7 +58,27 @@ func Routes(engine *gin.Engine, c controller.AppController) *gin.Engine {
 		core.WriteResponse(ctx, errno.PageNotFoundErr, nil)
 	})
 
-	engine.POST("/signup", func(ctx *gin.Context) { c.User.Signup(ctx) })
+	v1 := engine.Group("/v1")
+	{
+		userV1 := v1.Group("/user")
+		{
+			userV1.POST("/create", func(ctx *gin.Context) { c.User.Create(ctx) })
+
+			userV1.Use(authn.Authn(cache))
+			userV1.GET(
+				":id/info",
+				func(ctx *gin.Context) { ctx.JSON(http.StatusOK, "Hello world") },
+			)
+		}
+
+		sessionV1 := v1.Group("/session")
+		{
+			sessionV1.POST("/create", func(ctx *gin.Context) { c.Session.Create(ctx) })
+			sessionV1.Use(authn.Authn(cache))
+			sessionV1.POST("/delete", func(ctx *gin.Context) { c.Session.Delete(ctx) })
+		}
+
+	}
 
 	return engine
 }

internal/howmuch/model/event.go

@@ -0,0 +1,136 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+import "time"
+
+// {{{ Request Object (from controller to service)
+
+type EventCreateRequest struct {
+	Name            string   `json:"name"        binding:"requiered"`
+	Description     string   `json:"description"`
+	OwnerID         int      `json:"owner_id"    binding:"requiered,number"`
+	DefaultCurrency Currency `json:"currency"`
+}
+
+// }}}
+// {{{ Response View Object (from service to controller)
+
+type EventListResponse struct {
+	ID          int
+	Name        string
+	Description string
+	Owner       *UserBaseResponse
+	CreatedAt   time.Time
+}
+
+type EventInfoResponse struct {
+	ID int
+
+	Name        string
+	Description string
+
+	TotalAmount Money
+
+	Owner *UserBaseResponse
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+
+	Users []UserBaseResponse
+}
+
+// }}}
+// {{{ Entity (DB In)
+
+type EventEntity struct {
+	ID int
+
+	Name            string
+	Description     string
+	TotalAmount     int
+	DefaultCurrency string
+	OwnerID         int
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+type EventUpdateEntity struct {
+	ID          int
+	Name        string
+	Description string
+	CreatedAt   time.Time
+	// TODO: maybe I can change owner too
+}
+
+// }}}
+// {{{ Retrieved (DB out)
+
+type EventRetrieved struct {
+	ID int
+
+	Name        string
+	Description string
+
+	Users []UserBaseRetrieved
+
+	TotalAmount     Money
+	DefaultCurrency Currency
+	Owner           *UserBaseRetrieved
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+type EventListRetrieved struct {
+	ID          int
+	Name        string
+	Description string
+	CreatedAt   time.Time
+	Owner       *UserBaseRetrieved
+}
+
+// }}}
+// {{{ DO Domain Object (Contains the domain service)
+
+type Event struct {
+	ID int
+
+	Name        string
+	Description string
+
+	// lazy get using participation join
+	Users []UserDO
+	// lazy get
+	Expenses []Expense
+
+	TotalAmount     Money
+	DefaultCurrency Currency
+	Owner           *UserDO
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}

internal/howmuch/model/expense.go

@@ -0,0 +1,142 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+import "time"
+
+// {{{ Requrest
+
+type ExpenseRequest struct {
+	Amount   Money         `json:"money"    binding:"required"`
+	Payments []Payment     `json:"payments" binding:"required"`
+	Benefits []Benefit     `json:"benefits" binding:"required"`
+	EventID  int           `json:"event_id" binding:"required"`
+	Detail   ExpenseDetail `json:"detail"`
+}
+
+// }}}
+// {{{ Response
+
+type (
+	ExpenseGetResponse Expense
+	ExpenseResponse    ExpenseRetrieved
+)
+
+// }}}
+// {{{ Retrieved
+
+type ExpenseRetrieved Expense
+
+type ExpensesListRetrieved struct {
+	ID        int       `json:"id"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+
+	Amount  Money `json:"money"`
+	EventID int   `json:"event_id"`
+
+	Detail ExpenseDetail `json:"detail"`
+}
+
+type PaymentRetrieved struct {
+	PayerID        int    `json:"payer_id"`
+	PayerFirstName string `json:"payer_first_name"`
+	PayerLastName  string `json:"payer_last_name"`
+	Amount         int    `json:"amount"`
+	Currency       string `json:"currency"`
+}
+
+type BenefitRetrieved struct {
+	RecipientID        int    `json:"recipient_id"`
+	RecipientFirstName string `json:"recipient_first_name"`
+	RecipientLastName  string `json:"recipient_last_name"`
+	Amount             int    `json:"amount"`
+	Currency           string `json:"currency"`
+}
+
+// }}}
+// {{{ Entity
+
+type ExpenseEntity struct {
+	ID        int
+	CreatedAt time.Time
+	UpdatedAt time.Time
+
+	Amount   int
+	Currency string
+	EventID  int
+
+	// ExpenseDetail
+	Name  string
+	Place string
+}
+
+type ExpenseUpdateEntity struct {
+	ID        int
+	UpdatedAt time.Time
+
+	Amount   int
+	Currency string
+
+	// Expense Detail
+	Name  string
+	Place string
+}
+
+// }}}
+// {{{ Domain Models
+
+type ExpenseDetail struct {
+	Name  string `json:"name"`
+	Place string `json:"place"`
+}
+
+type Payment struct {
+	PayerID        int    `json:"payer_id"         binding:"required,number"`
+	PayerFirstName string `json:"payer_first_name"`
+	PayerLastName  string `json:"payer_last_name"`
+	Amount         Money  `json:"amount"           binding:"required"`
+}
+
+type Benefit struct {
+	RecipientID        int    `json:"recipient_id"         binding:"required,number"`
+	RecipientFirstName string `json:"recipient_first_name"`
+	RecipientLastName  string `json:"recipient_last_name"`
+	Amount             Money  `json:"amount"               binding:"required"`
+}
+
+type Expense struct {
+	ID        int       `json:"id"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+
+	Amount  Money `json:"money"`
+	EventID int   `json:"event_id"`
+
+	Detail ExpenseDetail `json:"detail"`
+
+	Payments []Payment `json:"payments"`
+	Benefits []Benefit `json:"benefits"`
+}
+
+// }}}

internal/howmuch/model/money.go

@@ -0,0 +1,66 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+type Currency string
+
+// TODO: may handle a more complexe logic with the exchange rate.
+
+// XXX: Here we suppose that the currency is the same for every piece
+// of money involved in the calculate.
+
+const (
+	EUR Currency = "EUR"
+	USD Currency = "USD"
+	CNY Currency = "CNY"
+)
+
+type Money struct {
+	Amount   int      `json:"amount"   binding:"required,number"`
+	Currency Currency `json:"currency" binding:"required"`
+}
+
+func MakeMoney(amount int, currency Currency) Money {
+	return Money{amount, currency}
+}
+
+func Add(cur Currency, money ...Money) Money {
+	var sum Money
+	sum.Currency = cur
+
+	for _, m := range money {
+		sum.Amount += m.Amount
+	}
+
+	return sum
+}
+
+func Diff(cur Currency, money1 Money, money2 Money) Money {
+	var diff Money
+
+	diff.Currency = cur
+
+	diff.Amount = money1.Amount - money2.Amount
+
+	return diff
+}

internal/howmuch/model/participation.go

@@ -0,0 +1,39 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+import "time"
+
+type ParticipationEntity Participation
+
+// Participation is the association between Users and Events
+type Participation struct {
+	ID int
+
+	UserID          int
+	EventID         int
+	InvitedByUserID int
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}

internal/howmuch/model/transaction.go

@@ -0,0 +1,48 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+import "time"
+
+// {{{ Entity
+
+type TransactionEntity Transaction
+
+// }}}
+// {{{ Domain object
+
+type Transaction struct {
+	ID int
+
+	ExpenseID int
+	UserID    int
+	Amount    int
+	Currency  string
+	IsIncome  bool // To note that the direction of the money (payment or income)
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}
+// Transaction is the association between Expenses and Users

internal/howmuch/model/user.go

@@ -0,0 +1,100 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package model
+
+import "time"
+
+// {{{ Request  (from controller to service)
+
+type UserCreateRequest struct {
+	Email     string `json:"email"      binding:"required,email"`
+	FirstName string `json:"first_name" binding:"required"`
+	LastName  string `json:"last_name"  binding:"required"`
+	Password  string `json:"password"   binding:"required"`
+}
+
+type UserExistRequest struct {
+	Email    string `json:"email"    binding:"required,email"`
+	Password string `json:"password" binding:"required"`
+}
+
+// }}}
+// {{{ Response View Object (from service to controller)
+
+type UserBaseResponse UserBaseRetrieved
+
+type UserInfoResponse struct {
+	// UserBaseResponse
+	ID        int    `json:"id"`
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+
+	Email     string `json:"email"`
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}
+// {{{ Entity (DB In)
+
+type UserEntity struct {
+	ID int
+
+	Email     string
+	FirstName string
+	LastName  string
+	Password  string
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}
+// {{{ Retrieved (DB out)
+
+type UserBaseRetrieved struct {
+	ID        int    `json:"id"`
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+}
+
+// }}}
+// {{{ DO Domain Object (Contains the domain service)
+
+// TODO: For now I don't know what to do with this model
+type UserDO struct {
+	ID int
+
+	Email     string
+	FirstName string
+	LastName  string
+	Password  string
+
+	// Lazy aggregate with the Participation join
+	EventIDs []int
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}

internal/howmuch/registry/registry.go

@@ -23,8 +23,10 @@
 package registry
 
 import (
+	"database/sql"
+
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller"
-	"github.com/jackc/pgx/v5/pgxpool"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
 )
 
 // registry is an implementation of Registry interface.
@@ -32,7 +34,8 @@ import (
 // It might holds other drivers when the projects grows. For example
 // the object needed to connect to Redis or Kafka.
 type registry struct {
-	db *pgxpool.Pool
+	db    *sql.DB
+	cache core.Cache
 }
 
 // Registry returns a new app controller that will be used by main()/run()
@@ -43,15 +46,16 @@ type Registry interface {
 }
 
 // NewRegistry returns a new Registry's implementation.
-func NewRegistry(db *pgxpool.Pool) Registry {
-	return &registry{db: db}
+func NewRegistry(db *sql.DB, cache core.Cache) Registry {
+	return &registry{db: db, cache: cache}
 }
 
 // NewAppController creates a new AppController with controller struct for
 // each domain.
 func (r *registry) NewAppController() controller.AppController {
 	return controller.AppController{
-		User:  r.NewUserController(),
-		Admin: r.NewAdminController(),
+		User:    r.NewUserController(),
+		Admin:   r.NewAdminController(),
+		Session: r.NewSessionController(),
 	}
 }

internal/howmuch/registry/session.go

@@ -0,0 +1,35 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package registry
+
+import (
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
+)
+
+// NewSessionController returns a session controller's implementation
+func (r *registry) NewSessionController() controller.Session {
+	u := usecase.NewUserUsecase(repo.NewUserRepository(r.db), repo.NewDBRepository(r.db))
+	return controller.NewSessionController(u, r.cache)
+}

internal/howmuch/registry/user.go

@@ -22,9 +22,14 @@
 
 package registry
 
-import "git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller"
+import (
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/controller"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/adapter/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase"
+)
 
 // NewUserController returns a user controller's implementation
 func (r *registry) NewUserController() controller.User {
-	return &controller.UserController{}
+	u := usecase.NewUserUsecase(repo.NewUserRepository(r.db), repo.NewDBRepository(r.db))
+	return controller.NewUserController(u)
 }

internal/howmuch/usecase/repo/db.go

@@ -0,0 +1,34 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+)
+
+type DBRepository interface {
+	Transaction(
+		ctx context.Context,
+		txFunc func(txCtx context.Context, tx interface{}) (interface{}, error),
+	) (interface{}, error)
+}

internal/howmuch/usecase/repo/event.go

@@ -0,0 +1,74 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+)
+
+type EventRepository interface {
+	Create(ctx context.Context, evEntity *model.EventEntity, tx any) (*model.EventEntity, error)
+
+	// UpdateEventByID updates the event related information (name, descriptions)
+	UpdateEventByID(ctx context.Context, event *model.EventUpdateEntity, tx any) error
+
+	GetByID(ctx context.Context, eventID int, tx any) (*model.EventRetrieved, error)
+
+	// related to events of a user
+	ListEventsByUserID(ctx context.Context, userID int, tx any) ([]model.EventListRetrieved, error)
+
+	InsertParticipation(
+		ctx context.Context,
+		userID, eventID, invitedByUserID int,
+		tx any,
+	) (*model.ParticipationEntity, error)
+
+	GetParticipation(
+		ctx context.Context,
+		userID, eventID int,
+		tx any,
+	) (*model.ParticipationEntity, error)
+}
+
+type ExpenseRepository interface {
+	DeleteExpense(ctx context.Context, expenseID int, tx any) error
+	DeleteTransactionsOfExpense(ctx context.Context, expenseID int, tx any) error
+	GetExpenseByID(ctx context.Context, expenseID int, tx any) (*model.ExpenseRetrieved, error)
+	InsertExpense(
+		ctx context.Context,
+		expenseEntity *model.ExpenseEntity,
+		tx any,
+	) (*model.ExpenseEntity, error)
+	ListExpensesByEventID(
+		ctx context.Context,
+		id int,
+		tx any,
+	) ([]model.ExpensesListRetrieved, error)
+	UpdateExpenseByID(
+		ctx context.Context,
+		expenseUpdate *model.ExpenseUpdateEntity,
+		tx any,
+	) (*model.ExpenseEntity, error)
+}

internal/howmuch/usecase/repo/user.go

@@ -0,0 +1,39 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+)
+
+type UserRepository interface {
+	Create(
+		ctx context.Context,
+		u *model.UserEntity,
+		tx any,
+	) (*model.UserEntity, error)
+	GetByEmail(ctx context.Context, email string, tx any) (*model.UserEntity, error)
+	GetByID(ctx context.Context, id int, tx any) (*model.UserEntity, error)
+}

internal/howmuch/usecase/usecase/event.go

@@ -0,0 +1,190 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package usecase
+
+import (
+	"net/http"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"golang.org/x/net/context"
+)
+
+type eventUsecase struct {
+	userUC      User
+	eventRepo   repo.EventRepository
+	expenseRepo repo.ExpenseRepository
+
+	dbRepo repo.DBRepository
+}
+
+var ErrNoParticipation = &errno.Errno{
+	HTTP:    http.StatusUnauthorized,
+	Code:    errno.ErrorCode(errno.AuthFailureCode, "NoParticipation"),
+	Message: "user doesn't have access to this event",
+}
+
+// For the controller
+type Event interface{}
+
+func NewEventUsecase(
+	uuc User,
+	ev repo.EventRepository,
+	ex repo.ExpenseRepository,
+	db repo.DBRepository,
+) Event {
+	return &eventUsecase{uuc, ev, ex, db}
+}
+
+func (evuc *eventUsecase) CreateEvent(
+	ctx context.Context,
+	evRequest *model.EventCreateRequest,
+) (*model.EventInfoResponse, error) {
+	// transfer evRequest to evEntity
+
+	evEntity := &model.EventEntity{
+		Name:            evRequest.Name,
+		Description:     evRequest.Description,
+		OwnerID:         evRequest.OwnerID,
+		TotalAmount:     0,
+		DefaultCurrency: string(evRequest.DefaultCurrency),
+	}
+
+	data, err := evuc.dbRepo.Transaction(
+		ctx,
+		func(txCtx context.Context, tx any) (any, error) {
+			// Create the event
+			created, err := evuc.eventRepo.Create(ctx, evEntity, tx)
+			if err != nil {
+				return nil, err
+			}
+
+			// participate to the event
+			participation, err := evuc.eventRepo.InsertParticipation(
+				ctx,
+				created.OwnerID,
+				created.ID,
+				0,
+				tx,
+			)
+			if err != nil {
+				return nil, err
+			}
+
+			if participation == nil {
+				// Unexpected error
+				log.ErrorLog(
+					"participation existed for event-user pair",
+					"userID",
+					created.OwnerID,
+					"eventID",
+					created.ID,
+				)
+				return nil, errno.InternalServerErr
+			}
+
+			// TODO: App log, maybe can be sent to some third party service.
+			log.InfoLog(
+				"created new event",
+				"name",
+				created.Name,
+				"owner",
+				created.OwnerID,
+			)
+
+			// Construct the response
+			ownerResponse, err := evuc.userUC.GetUserBaseResponseByID(ctx, created.OwnerID)
+			if err != nil {
+				return nil, err
+			}
+
+			evResponse := &model.EventInfoResponse{
+				ID:          created.ID,
+				Name:        created.Name,
+				Description: created.Description,
+				TotalAmount: model.MakeMoney(
+					created.TotalAmount,
+					model.Currency(created.DefaultCurrency),
+				),
+				Owner:     ownerResponse,
+				CreatedAt: created.CreatedAt,
+				UpdatedAt: created.UpdatedAt,
+				Users:     []model.UserBaseResponse{*ownerResponse},
+			}
+			return evResponse, err
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	res := data.(*model.EventInfoResponse)
+
+	return res, err
+}
+
+func (evuc *eventUsecase) ListEvents(
+	ctx context.Context,
+	userID int,
+) ([]model.EventListResponse, error) {
+	eventListRetrieved, err := evuc.eventRepo.ListEventsByUserID(ctx, userID, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if the user is a member of the event
+
+	responses := make([]model.EventListResponse, len(eventListRetrieved))
+
+	for i, retrieved := range eventListRetrieved {
+		ownner := model.UserBaseResponse(*retrieved.Owner)
+		res := model.EventListResponse{
+			ID:          retrieved.ID,
+			Name:        retrieved.Name,
+			Description: retrieved.Description,
+			Owner:       &ownner,
+			CreatedAt:   retrieved.CreatedAt,
+		}
+		responses[i] = res
+	}
+	return responses, nil
+}
+
+// GetEventDetail
+func (evuc *eventUsecase) GetEventDetail(
+	ctx context.Context,
+	userID, eventID int,
+) (*model.EventInfoResponse, error) {
+	// Check if the user has the right to get this event
+	// err := evuc.participationRepo.CheckParticipation(ctx, userID, eventID)
+	// if err != nil {
+	// 	return nil, ErrNoParticipation
+	// }
+
+	// Get the eventDetail
+	// TODO: This can also be put into the cache
+
+	return nil, nil
+}

internal/howmuch/usecase/usecase/repomock/testdbrepo.go

@@ -0,0 +1,36 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repomock
+
+import (
+	"context"
+)
+
+type TestDBRepository struct{}
+
+func (tdr *TestDBRepository) Transaction(
+	ctx context.Context,
+	txFunc func(txCtx context.Context, tx interface{}) (interface{}, error),
+) (interface{}, error) {
+	return txFunc(ctx, nil)
+}

internal/howmuch/usecase/usecase/repomock/testuserrepo.go

@@ -0,0 +1,94 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repomock
+
+import (
+	"context"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"github.com/pkg/errors"
+	"golang.org/x/crypto/bcrypt"
+)
+
+var UserTestDummyErr = errors.New("dummy error")
+
+type TestUserRepository struct{}
+
+func (tur *TestUserRepository) Create(
+	ctx context.Context,
+	u *model.UserEntity,
+	tx any,
+) (*model.UserEntity, error) {
+	user := *u
+
+	user.ID = 123
+
+	if user.Email == "duplicate@error.com" {
+		return nil, errors.New("blabla (SQLSTATE 23505)")
+	}
+
+	return &user, nil
+}
+
+func (tur *TestUserRepository) GetByEmail(
+	ctx context.Context,
+	email string,
+	tx any,
+) (*model.UserEntity, error) {
+	hashedPwd, _ := bcrypt.GenerateFromPassword([]byte("strongHashed"), 12)
+	switch email {
+	case "a@b.c":
+		return &model.UserEntity{
+			ID:       123,
+			Email:    "a@b.c",
+			Password: string(hashedPwd),
+		}, nil
+	case "query@error.com":
+		return nil, UserTestDummyErr
+	case "inexist@error.com":
+		return nil, nil
+	}
+
+	return nil, UserTestDummyErr
+}
+
+func (tur *TestUserRepository) GetByID(
+	ctx context.Context,
+	id int,
+	tx any,
+) (*model.UserEntity, error) {
+	hashedPwd, _ := bcrypt.GenerateFromPassword([]byte("strongHashed"), 12)
+	switch id {
+	case 123:
+		return &model.UserEntity{
+			ID:       123,
+			Email:    "a@b.c",
+			Password: string(hashedPwd),
+		}, nil
+	case 456:
+		return nil, UserTestDummyErr
+	case 789:
+		return nil, nil
+	}
+	return nil, UserTestDummyErr
+}

internal/howmuch/usecase/usecase/user.go

@@ -0,0 +1,173 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package usecase
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"regexp"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	UserExisted = &errno.Errno{
+		HTTP:    http.StatusBadRequest,
+		Code:    errno.ErrorCode(errno.FailedOperationCode, "UserExisted"),
+		Message: "email already existed.",
+	}
+	UserNotExist = &errno.Errno{
+		HTTP:    http.StatusBadRequest,
+		Code:    errno.ErrorCode(errno.ResourceNotFoundCode, "UserNotExist"),
+		Message: "user does not exists.",
+	}
+	UserWrongPassword = &errno.Errno{
+		HTTP:    http.StatusBadRequest,
+		Code:    errno.ErrorCode(errno.AuthFailureCode, "UserWrongPassword"),
+		Message: "wrong password.",
+	}
+)
+
+type userUsecase struct {
+	userRepo repo.UserRepository
+	dbRepo   repo.DBRepository
+}
+
+type User interface {
+	Create(ctx context.Context, u *model.UserCreateRequest) (*model.UserInfoResponse, error)
+	Exist(ctx context.Context, u *model.UserExistRequest) error
+	GetUserBaseResponseByID(ctx context.Context, userID int) (*model.UserBaseResponse, error)
+}
+
+func NewUserUsecase(r repo.UserRepository, d repo.DBRepository) User {
+	return &userUsecase{
+		userRepo: r,
+		dbRepo:   d,
+	}
+}
+
+func (uuc *userUsecase) Create(
+	ctx context.Context,
+	u *model.UserCreateRequest,
+) (*model.UserInfoResponse, error) {
+	// Hash the password
+	encrypted, err := bcrypt.GenerateFromPassword([]byte(u.Password), 12)
+	if err != nil {
+		log.ErrorLog("encrypt password error", "err", err)
+		return nil, errno.InternalServerErr
+	}
+	u.Password = string(encrypted)
+	data, err := uuc.dbRepo.Transaction(
+		ctx,
+		func(txCtx context.Context, tx interface{}) (interface{}, error) {
+			created, err := uuc.userRepo.Create(txCtx, &model.UserEntity{
+				Email:     u.Email,
+				Password:  u.Password,
+				FirstName: u.FirstName,
+				LastName:  u.LastName,
+			}, tx)
+			if err != nil {
+				match, _ := regexp.MatchString("SQLSTATE 23505", err.Error())
+				if match {
+					return nil, UserExisted
+				}
+				return nil, err
+			}
+
+			// TODO: App log, maybe can be sent to some third party service.
+			log.InfoLog(
+				"created new user",
+				"email",
+				created.Email,
+				"name",
+				fmt.Sprintf("%s %s", created.FirstName, created.LastName),
+			)
+
+			return created, err
+		},
+	)
+	if err != nil {
+		// TODO: We should wrap the error at service level
+		return nil, err
+	}
+
+	userEntity := data.(*model.UserEntity)
+
+	user := &model.UserInfoResponse{
+		ID:        userEntity.ID,
+		Email:     userEntity.Email,
+		FirstName: userEntity.FirstName,
+		LastName:  userEntity.LastName,
+		CreatedAt: userEntity.CreatedAt,
+		UpdatedAt: userEntity.UpdatedAt,
+	}
+
+	return user, nil
+}
+
+func (uuc *userUsecase) Exist(ctx context.Context, u *model.UserExistRequest) error {
+	got, err := uuc.userRepo.GetByEmail(ctx, u.Email, nil)
+	// Any query error?
+	if err != nil {
+		return err
+	}
+
+	// User exists?
+	if got == nil {
+		return UserNotExist
+	}
+
+	// Password correct?
+	err = bcrypt.CompareHashAndPassword([]byte(got.Password), []byte(u.Password))
+	if errors.Is(err, bcrypt.ErrMismatchedHashAndPassword) {
+		return UserWrongPassword
+	}
+
+	return nil
+}
+
+func (uuc *userUsecase) GetUserBaseResponseByID(
+	ctx context.Context,
+	userID int,
+) (*model.UserBaseResponse, error) {
+	// TODO: should try first to get from the cache
+	// If not exists, get from the DB. And then put back
+	// into the cache with a timeout.
+	// Refresh the cache when the user data is updated (for now it cannot be updated)
+	got, err := uuc.userRepo.GetByID(ctx, userID, nil)
+	if err != nil {
+		return nil, err
+	}
+	userBaseVo := &model.UserBaseResponse{
+		ID:        got.ID,
+		FirstName: got.FirstName,
+		LastName:  got.LastName,
+	}
+	return userBaseVo, nil
+}

internal/howmuch/usecase/usecase/user_test.go

@@ -0,0 +1,99 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package usecase
+
+import (
+	"context"
+	"testing"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase/repomock"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCreateUser(t *testing.T) {
+	t.Run("normal create", func(t *testing.T) {
+		ctx := context.Background()
+		userUsecase := NewUserUsecase(&repomock.TestUserRepository{}, &repomock.TestDBRepository{})
+		input := &model.UserCreateRequest{
+			Email:     "a@b.c",
+			FirstName: "James",
+			LastName:  "Bond",
+			Password:  "verystrong",
+		}
+		want := &model.UserInfoResponse{
+			ID: 123,
+		}
+
+		got, err := userUsecase.Create(ctx, input)
+		assert.NoError(t, err)
+		assert.Equal(t, want.ID, got.ID)
+	})
+
+	t.Run("duplicate create", func(t *testing.T) {
+		ctx := context.Background()
+		userUsecase := NewUserUsecase(&repomock.TestUserRepository{}, &repomock.TestDBRepository{})
+		input := &model.UserCreateRequest{
+			Email:     "duplicate@error.com",
+			FirstName: "James",
+			LastName:  "Bond",
+			Password:  "verystrong",
+		}
+
+		_, err := userUsecase.Create(ctx, input)
+		assert.EqualError(t, err, UserExisted.Error())
+	})
+}
+
+func TestUserExist(t *testing.T) {
+	testCases := []struct {
+		Name   string
+		User   *model.UserExistRequest
+		ExpErr error
+	}{
+		{"user exists", &model.UserExistRequest{
+			Email:    "a@b.c",
+			Password: "strongHashed",
+		}, nil},
+		{"query error", &model.UserExistRequest{
+			Email:    "query@error.com",
+			Password: "strongHashed",
+		}, repomock.UserTestDummyErr},
+		{"user doesn not exist", &model.UserExistRequest{
+			Email:    "inexist@error.com",
+			Password: "strongHashed",
+		}, UserNotExist},
+		{"wrong password", &model.UserExistRequest{
+			Email:    "a@b.c",
+			Password: "wrongHashed",
+		}, UserWrongPassword},
+	}
+
+	for _, tst := range testCases {
+		ctx := context.Background()
+		userUsecase := NewUserUsecase(&repomock.TestUserRepository{}, &repomock.TestDBRepository{})
+
+		err := userUsecase.Exist(ctx, tst.User)
+		assert.ErrorIs(t, err, tst.ExpErr)
+	}
+}

internal/pkg/core/cache.go

@@ -0,0 +1,34 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package core
+
+import (
+	"context"
+	"time"
+)
+
+type Cache interface {
+	Get(ctx context.Context, key string) (string, error)
+	Set(ctx context.Context, key string, value interface{}, expiration time.Duration) error
+	Close() error
+}

internal/pkg/core/context.go

@@ -22,6 +22,19 @@
 
 package core
 
+import "time"
+
 type Context interface {
+	// Context
+	Deadline() (deadline time.Time, ok bool)
+	Done() <-chan struct{}
+	Err() error
+	Value(key any) any
+
+	// Request
+	Bind(obj any) error
+	GetHeader(key string) string
+
+	// Response
 	JSON(code int, obj any)
 }

internal/pkg/errno/code.go

@@ -24,18 +24,28 @@ package errno
 
 import "net/http"
 
+type PlatformLevelErrCode string
+
+const (
+	InternalErrorCode    = "InternalError"
+	InvalidParameterCode = "InvalidParameter"
+	AuthFailureCode      = "AuthFailure"
+	ResourceNotFoundCode = "ResourceNotFound"
+	FailedOperationCode  = "FailedOperation"
+)
+
 var (
 	OK = &Errno{HTTP: http.StatusOK, Code: "", Message: ""}
 
 	InternalServerErr = &Errno{
 		HTTP:    http.StatusInternalServerError,
-		Code:    "InternalError",
+		Code:    InternalErrorCode,
 		Message: "Internal server error",
 	}
 
 	PageNotFoundErr = &Errno{
 		HTTP:    http.StatusNotFound,
-		Code:    "ResourceNotFound.PageNotFound",
+		Code:    ErrorCode(ResourceNotFoundCode, "PageNotFound"),
 		Message: "Page not found",
 	}
 )

internal/pkg/errno/errno.go

@@ -28,6 +28,10 @@ type Errno struct {
 	Message string
 }
 
+func ErrorCode(platformErrCode string, resourceErrCode string) string {
+	return platformErrCode + "." + resourceErrCode
+}
+
 // Error implements Error() method in error interface
 func (err *Errno) Error() string {
 	return err.Message

internal/pkg/log/log.go

@@ -26,6 +26,8 @@ import (
 	"os"
 	"sync"
 
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/shared"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
@@ -100,6 +102,30 @@ func NewLogger(opts *Options) *zapLogger {
 	return &zapLogger{z: z}
 }
 
+// CtxLog writes context's information into the log
+func CtxLog(ctx core.Context) *zapLogger {
+	return std.CtxLog(ctx)
+}
+
+func (z *zapLogger) CtxLog(ctx core.Context) *zapLogger {
+	zz := z.clone()
+
+	if rid := ctx.GetHeader(shared.XRequestID); rid != "" {
+		zz.z = zz.z.With(zap.Any(shared.XRequestID, rid))
+	}
+
+	if user := ctx.GetHeader(shared.XUserName); user != "" {
+		zz.z = zz.z.With(zap.Any(shared.XUserName, user))
+	}
+
+	return zz
+}
+
+func (z *zapLogger) clone() *zapLogger {
+	zz := *z
+	return &zz
+}
+
 func (z *zapLogger) FatalLog(msg string, keyValues ...interface{}) {
 	z.z.Sugar().Fatalw(msg, keyValues...)
 }

internal/pkg/middleware/authn/authn.go

@@ -0,0 +1,77 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package authn
+
+import (
+	"fmt"
+	"net/http"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/core"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/shared"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/token"
+	"github.com/gin-gonic/gin"
+)
+
+var ErrTokenInvalid = &errno.Errno{
+	HTTP:    http.StatusUnauthorized,
+	Code:    errno.ErrorCode(errno.AuthFailureCode, "TokenInvalid"),
+	Message: "invalid token",
+}
+
+var ErrLoggedOut = &errno.Errno{
+	HTTP:    http.StatusUnauthorized,
+	Code:    errno.ErrorCode(errno.AuthFailureCode, "LoggedOut"),
+	Message: "logged out, please log in",
+}
+
+// Authn authenticates a user's access by validating their token.
+func Authn(cache core.Cache) gin.HandlerFunc {
+	return func(ctx *gin.Context) {
+		tk, err := token.ParseRequest(ctx)
+		if err != nil || tk == nil {
+			core.WriteResponse(ctx, ErrTokenInvalid, nil)
+			ctx.Abort()
+			return
+		}
+
+		key := fmt.Sprintf("jwt:%s", tk.Identity)
+
+		val, err := cache.Get(ctx, key)
+		if err != nil {
+			log.ErrorLog("cache get token", "err", err)
+			ctx.Abort()
+			return
+		}
+		if val != "" {
+			// blacklist
+			core.WriteResponse(ctx, ErrLoggedOut, nil)
+			ctx.Abort()
+			return
+		}
+
+		ctx.Header(shared.XUserName, tk.Identity)
+		ctx.Next()
+	}
+}

internal/pkg/middleware/authn/authn_test.go

@@ -0,0 +1,117 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package authn
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/errno"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/shared"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/test"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/token"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+)
+
+var loggedOutID string
+
+type testCache struct{}
+
+func (tc *testCache) Get(ctx context.Context, key string) (string, error) {
+	loggedOutKey := fmt.Sprintf("jwt:%s", loggedOutID)
+	if key == loggedOutKey {
+		return "found", nil
+	}
+	return "", nil
+}
+
+func (c *testCache) Set(
+	ctx context.Context,
+	key string,
+	value interface{},
+	expiration time.Duration,
+) error {
+	return nil
+}
+
+func (c *testCache) Close() error {
+	return nil
+}
+
+func TestAuthn(t *testing.T) {
+	token.Init("secret", 1*time.Second)
+	tk, _ := token.Sign("user")
+
+	tkParsed, _ := token.Parse(tk)
+	loggedOutID = tkParsed.Identity
+
+	cache := &testCache{}
+
+	t.Run("token found in cache", func(t *testing.T) {
+		r := gin.New()
+		r.Use(Authn(cache))
+
+		r.GET("/example", func(c *gin.Context) {
+			c.Status(http.StatusOK)
+		})
+		res := test.PerformRequest(
+			t,
+			r,
+			"GET",
+			"/example",
+			nil,
+			test.Header{Key: shared.XUserName, Value: "user"},
+			test.Header{Key: "Authorization", Value: fmt.Sprintf("Bearer %s", tk)},
+		)
+		assert.Equal(t, http.StatusUnauthorized, res.Result().StatusCode, res.Body)
+
+		var err errno.Errno
+		json.NewDecoder(res.Result().Body).Decode(&err)
+		assert.Equal(t, "AuthFailure.LoggedOut", err.Code)
+	})
+
+	t.Run("token not found in cache", func(t *testing.T) {
+		newTk, _ := token.Sign("user2")
+		r := gin.New()
+		r.Use(Authn(cache))
+
+		r.GET("/example", func(c *gin.Context) {
+			c.Status(http.StatusOK)
+		})
+		res := test.PerformRequest(
+			t,
+			r,
+			"GET",
+			"/example",
+			nil,
+			test.Header{Key: shared.XUserName, Value: "user2"},
+			test.Header{Key: "Authorization", Value: fmt.Sprintf("Bearer %s", newTk)},
+		)
+		assert.Equal(t, http.StatusOK, res.Result().StatusCode, res.Body)
+	})
+}

internal/pkg/middleware/requestid.go

@@ -23,24 +23,23 @@
 package middleware
 
 import (
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/shared"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
 )
 
-const requestID = "X-Request-Id"
-
 func RequestID() gin.HandlerFunc {
 	return func(ctx *gin.Context) {
 		var rid string
 
-		if rid = ctx.GetHeader(requestID); rid != "" {
-			ctx.Request.Header.Add(requestID, rid)
+		if rid = ctx.GetHeader(shared.XRequestID); rid != "" {
+			ctx.Request.Header.Add(shared.XRequestID, rid)
 			ctx.Next()
 		}
 
 		rid = uuid.NewString()
-		ctx.Request.Header.Add(requestID, rid)
-		ctx.Header(requestID, rid)
+		ctx.Request.Header.Add(shared.XRequestID, rid)
+		ctx.Header(shared.XRequestID, rid)
 		ctx.Next()
 	}
 }

internal/pkg/middleware/requestid_test.go

@@ -24,33 +24,15 @@ package middleware
 
 import (
 	"net/http"
-	"net/http/httptest"
 	"testing"
 
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/shared"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/test"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 )
 
-type header struct {
-	Key   string
-	Value string
-}
-
-func performRequest(
-	r http.Handler,
-	method, path string,
-	headers ...header,
-) *httptest.ResponseRecorder {
-	req := httptest.NewRequest(method, path, nil)
-	for _, h := range headers {
-		req.Header.Add(h.Key, h.Value)
-	}
-	w := httptest.NewRecorder()
-	r.ServeHTTP(w, req)
-	return w
-}
-
 func TestRequestID(t *testing.T) {
 	r := gin.New()
 	r.Use(RequestID())
@@ -58,21 +40,28 @@ func TestRequestID(t *testing.T) {
 	wanted := "123"
 
 	r.GET("/example", func(c *gin.Context) {
-		got = c.GetHeader(requestID)
+		got = c.GetHeader(shared.XRequestID)
 		c.Status(http.StatusOK)
 	})
 
 	r.POST("/example", func(c *gin.Context) {
-		got = c.GetHeader(requestID)
+		got = c.GetHeader(shared.XRequestID)
 		c.String(http.StatusAccepted, "ok")
 	})
 
 	// Test with Request ID
-	_ = performRequest(r, "GET", "/example?a=100", header{requestID, wanted})
+	_ = test.PerformRequest(
+		t,
+		r,
+		"GET",
+		"/example?a=100",
+		nil,
+		test.Header{Key: shared.XRequestID, Value: wanted},
+	)
 	assert.Equal(t, "123", got)
 
-	res := performRequest(r, "GET", "/example?a=100")
+	res := test.PerformRequest(t, r, "GET", "/example?a=100", nil)
 	assert.NotEqual(t, "", got)
 	assert.NoError(t, uuid.Validate(got))
-	assert.Equal(t, res.Header()[requestID][0], got)
+	assert.Equal(t, res.Header()[shared.XRequestID][0], got)
 }

internal/pkg/shared/const.go

@@ -0,0 +1,28 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package shared
+
+const (
+	XRequestID = "X-Request-Id"
+	XUserName  = "X-Username"
+)

internal/pkg/test/request.go

@@ -0,0 +1,52 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package test
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type Header struct {
+	Key   string
+	Value string
+}
+
+func PerformRequest(
+	t testing.TB,
+	r http.Handler,
+	method, path string,
+	body io.Reader,
+	headers ...Header,
+) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest(method, path, body)
+	for _, h := range headers {
+		req.Header.Add(h.Key, h.Value)
+	}
+	w := httptest.NewRecorder()
+	r.ServeHTTP(w, req)
+	return w
+}

internal/pkg/token/token.go

@@ -0,0 +1,117 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package token
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+type Config struct {
+	secretKey  string
+	expiryTime time.Duration
+}
+
+type Claims struct {
+	IdentityKey string `json:"identity_key"`
+	jwt.RegisteredClaims
+}
+
+type TokenResp struct {
+	Raw      string
+	Identity string
+	Expiry   time.Time
+}
+
+var (
+	once   sync.Once
+	config Config
+)
+
+var ErrMissingHeader = errors.New("Authorization is needed in the header")
+
+func Init(secretKey string, expiryTime time.Duration) {
+	once.Do(func() {
+		config.secretKey = secretKey
+		config.expiryTime = expiryTime
+	})
+}
+
+func Sign(identityKey string) (string, error) {
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, Claims{
+		identityKey,
+		jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(config.expiryTime)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			NotBefore: jwt.NewNumericDate(time.Now()),
+		},
+	})
+
+	return token.SignedString([]byte(config.secretKey))
+}
+
+func Parse(tokenString string) (*TokenResp, error) {
+	token, err := jwt.ParseWithClaims(
+		tokenString,
+		&Claims{},
+		func(t *jwt.Token) (interface{}, error) {
+			if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+				return nil, jwt.ErrSignatureInvalid
+			}
+			return []byte(config.secretKey), nil
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	if claims, ok := token.Claims.(*Claims); ok {
+		return &TokenResp{
+			tokenString,
+			claims.IdentityKey,
+			claims.ExpiresAt.Time,
+		}, nil
+	}
+
+	return nil, nil
+}
+
+func ParseRequest(c *gin.Context) (*TokenResp, error) {
+	// NOTE: Authorization: Bearer sdkfjlsfjlskdfjlsjdflk...slkdfjlka
+	header := c.GetHeader("Authorization")
+
+	if len(header) == 0 {
+		return nil, ErrMissingHeader
+	}
+
+	// get the token
+	var t string
+	fmt.Sscanf(header, "Bearer %s", &t)
+
+	return Parse(t)
+}

migrations/20241006114157_admin_table_add_constraint.postgres.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "admin"
+ADD CONSTRAINT unique_email UNIQUE ("email");

migrations/20241017215433_create_event_table.postgres.down.sql

@@ -0,0 +1 @@
+DROP TABLE "event"

migrations/20241017215433_create_event_table.postgres.up.sql

@@ -0,0 +1,10 @@
+CREATE TABLE "event" (
+  "id" serial NOT NULL,
+  PRIMARY KEY ("id"),
+  "name" character varying(255) NOT NULL,
+  "description" character varying(10000) NULL,
+  "default_currency" character varying(255) NOT NULL,
+  "owner_id" integer NOT NULL,
+  "created_at" date NOT NULL,
+  "updated_at" date NOT NULL
+);

migrations/20241017215923_create_participation_table.postgres.down.sql

@@ -0,0 +1 @@
+DROP TABLE participation;

migrations/20241017215923_create_participation_table.postgres.up.sql

@@ -0,0 +1,16 @@
+CREATE TABLE "participation" (
+  "id" serial NOT NULL,
+  PRIMARY KEY ("id"),
+  "user_id" integer NOT NULL,
+  "event_id" integer NOT NULL,
+  "invited_by_user_id" integer NULL,
+  "created_at" date NOT NULL,
+  "updated_at" date NOT NULL
+);
+
+ALTER TABLE "participation"
+ADD FOREIGN KEY ("event_id") REFERENCES "event" ("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+ALTER TABLE "participation"
+ADD FOREIGN KEY ("user_id") REFERENCES "user" ("id") ON DELETE CASCADE ON UPDATE CASCADE;
+

migrations/20241017220309_event_add_total_amount.postgres.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "event"
+ADD "total_amount" integer NULL;

migrations/20241018175610_participation_add_unique_keys.postgres.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "participation"
+ADD CONSTRAINT unique_user_event UNIQUE ("user_id", "event_id");

migrations/20241019110734_create_transaction_table.postgres.down.sql

@@ -0,0 +1 @@
+

migrations/20241019110734_create_transaction_table.postgres.up.sql

@@ -0,0 +1,14 @@
+CREATE TABLE "transaction" (
+  "id" serial NOT NULL,
+  PRIMARY KEY ("id"),
+  "expense_id" integer NOT NULL,
+  "user_id" integer NOT NULL,
+  "amount" integer NOT NULL,
+  "currency" character varying(255) NOT NULL,
+  "is_income" boolean NOT NULL DEFAULT FALSE,
+  "created_at" date NOT NULL,
+  "updated_at" date NOT NULL
+);
+
+ALTER TABLE "transaction"
+ADD FOREIGN KEY ("user_id") REFERENCES "user" ("id") ON DELETE CASCADE ON UPDATE CASCADE;

migrations/20241019112255_create_expense_table.postgres.down.sql

@@ -0,0 +1 @@
+DROP TABLE "expense";

migrations/20241019112255_create_expense_table.postgres.up.sql

@@ -0,0 +1,14 @@
+CREATE TABLE "expense" (
+  "id" serial NOT NULL,
+  PRIMARY KEY ("id"),
+  "created_at" date NOT NULL,
+  "updated_at" date NOT NULL,
+  "amount" integer NOT NULL,
+  "currency" character varying NOT NULL,
+  "event_id" integer NOT NULL,
+  "name" character varying(255) NULL,
+  "place" character varying(1000) NULL
+);
+
+ALTER TABLE "expense"
+ADD FOREIGN KEY ("event_id") REFERENCES "event" ("id") ON DELETE CASCADE ON UPDATE CASCADE

migrations/20241019112421_fk_transaction_expense.postgres.down.sql

@@ -0,0 +1 @@
+DROP TABLE transaction;

migrations/20241019112421_fk_transaction_expense.postgres.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "transaction"
+ADD FOREIGN KEY ("expense_id") REFERENCES "expense" ("id") ON DELETE CASCADE ON UPDATE CASCADE

sqlc.yml

@@ -23,9 +23,9 @@
 version: "2"
 sql:
   - engine: "postgresql"
-    queries: "internal/app/adapter/repo/sqlc"
+    queries: "internal/howmuch/adapter/repo/sqlc"
     schema: "migrations"
     gen:
       go:
-        out: "internal/app/controller/repo/sqlc"
-        sql_package: "pgx/v5"
+        out: "internal/howmuch/adapter/repo/sqlc"
+        emit_interface: true

tmp/build-errors.log

@@ -1 +0,0 @@
-exit status 2exit status 2exit status 2exit status 2exit status 2

web/.eslintrc.cjs

@@ -0,0 +1,15 @@
+/* eslint-env node */
+require('@rushstack/eslint-patch/modern-module-resolution')
+
+module.exports = {
+  root: true,
+  'extends': [
+    'plugin:vue/vue3-essential',
+    'eslint:recommended',
+    '@vue/eslint-config-typescript',
+    '@vue/eslint-config-prettier/skip-formatting'
+  ],
+  parserOptions: {
+    ecmaVersion: 'latest'
+  }
+}

web/.gitignore

@@ -0,0 +1,30 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+.DS_Store
+dist
+dist-ssr
+coverage
+*.local
+
+/cypress/videos/
+/cypress/screenshots/
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
+
+*.tsbuildinfo

web/.prettierrc.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://json.schemastore.org/prettierrc",
+  "semi": false,
+  "tabWidth": 2,
+  "singleQuote": true,
+  "printWidth": 100,
+  "trailingComma": "none"
+}

web/.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+  "recommendations": [
+    "Vue.volar",
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode"
+  ]
+}

web/Makefile

@@ -0,0 +1,22 @@
+.PHONY: all
+all: add-copyright format lint build test
+
+.PHONY: build
+build:
+	@npm install && npm run build
+
+.PHONY: format
+format: # format code.
+	@npm run format
+
+.PHONY: lint
+lint:
+	@npm run lint
+
+.PHONY: test
+test:
+	@npm run test:unit run
+
+.PHONY: add-copyright
+add-copyright: # add license to file headers.
+	@addlicense -v -f ../LICENSE ./src --skip-files=database.yml

web/README.md

@@ -0,0 +1,45 @@
+# web
+
+This template should help get you started developing with Vue 3 in Vite.
+
+## Recommended IDE Setup
+
+[VSCode](https://code.visualstudio.com/) + [Volar](https://marketplace.visualstudio.com/items?itemName=Vue.volar) (and disable Vetur).
+
+## Type Support for `.vue` Imports in TS
+
+TypeScript cannot handle type information for `.vue` imports by default, so we replace the `tsc` CLI with `vue-tsc` for type checking. In editors, we need [Volar](https://marketplace.visualstudio.com/items?itemName=Vue.volar) to make the TypeScript language service aware of `.vue` types.
+
+## Customize configuration
+
+See [Vite Configuration Reference](https://vitejs.dev/config/).
+
+## Project Setup
+
+```sh
+npm install
+```
+
+### Compile and Hot-Reload for Development
+
+```sh
+npm run dev
+```
+
+### Type-Check, Compile and Minify for Production
+
+```sh
+npm run build
+```
+
+### Run Unit Tests with [Vitest](https://vitest.dev/)
+
+```sh
+npm run test:unit
+```
+
+### Lint with [ESLint](https://eslint.org/)
+
+```sh
+npm run lint
+```

web/env.d.ts

@@ -0,0 +1 @@
+/// <reference types="vite/client" />

web/index.html

@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8">
+    <link rel="icon" href="/favicon.ico">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Vite App</title>
+  </head>
+  <body>
+    <div id="app"></div>
+    <script type="module" src="/src/main.ts"></script>
+  </body>
+</html>