From 1dd22ba8dbaf690e779150858271fe5c096a44fc Mon Sep 17 00:00:00 2001
From: Muyao CHEN <muyao.chen@intersec.com>
Date: Thu, 27 Jun 2024 14:03:43 +0200
Subject: [PATCH] Optimizing template cache by using an application config ***

---
 cmd/web/main.go          | 21 +++++++++++++++++++--
 pkg/config/config.go     |  9 +++++++++
 pkg/handlers/handlers.go | 25 +++++++++++++++++++++++--
 pkg/render/render.go     | 25 ++++++++++++++++++-------
 4 files changed, 69 insertions(+), 11 deletions(-)
 create mode 100644 pkg/config/config.go

diff --git a/cmd/web/main.go b/cmd/web/main.go
index 2ab165e..282c677 100644
--- a/cmd/web/main.go
+++ b/cmd/web/main.go
@@ -2,7 +2,10 @@ package main
 
 import (
 	"fmt"
+	"go-udemy-web-1/pkg/config"
 	"go-udemy-web-1/pkg/handlers"
+	"go-udemy-web-1/pkg/render"
+	"log"
 	"net/http"
 )
 
@@ -10,8 +13,22 @@ const portNumber = ":8080"
 
 // main is the main application function
 func main() {
-	http.HandleFunc("/", handlers.Home)
-	http.HandleFunc("/about", handlers.About)
+	var app config.AppConfig
+
+	tc, err := render.CreateTemplateCache()
+	if err != nil {
+		log.Fatal("cannot create template cache")
+	}
+	app.TemplateCahce = tc
+	app.UseCache = false
+
+	repo := handlers.NewRepo(&app)
+	handlers.NewHandlers(repo)
+
+	render.NewTemplates(&app)
+
+	http.HandleFunc("/", handlers.Repo.Home)
+	http.HandleFunc("/about", handlers.Repo.About)
 
 	fmt.Printf("Starting application on port %s\n", portNumber)
 
diff --git a/pkg/config/config.go b/pkg/config/config.go
new file mode 100644
index 0000000..1da9e87
--- /dev/null
+++ b/pkg/config/config.go
@@ -0,0 +1,9 @@
+package config
+
+import "html/template"
+
+// AppConfig holds the application config
+type AppConfig struct {
+	TemplateCahce map[string]*template.Template
+	UseCache      bool
+}
diff --git a/pkg/handlers/handlers.go b/pkg/handlers/handlers.go
index 201c327..9d8207f 100644
--- a/pkg/handlers/handlers.go
+++ b/pkg/handlers/handlers.go
@@ -1,16 +1,37 @@
 package handlers
 
 import (
+	"go-udemy-web-1/pkg/config"
 	"go-udemy-web-1/pkg/render"
 	"net/http"
 )
 
+// Repo the repository used by the handlers
+var Repo *Repository
+
+// Repository is the repository type
+type Repository struct {
+	App *config.AppConfig
+}
+
+// NewRepo creates a new repository
+func NewRepo(a *config.AppConfig) *Repository {
+	return &Repository{
+		App: a,
+	}
+}
+
+// NewHandlers sets the repository for the handlers
+func NewHandlers(r *Repository) {
+	Repo = r
+}
+
 // Home is the about page handler
-func Home(w http.ResponseWriter, r *http.Request) {
+func (m *Repository) Home(w http.ResponseWriter, r *http.Request) {
 	render.RenderTemplate(w, "home.page.tmpl")
 }
 
 // About is the about page handler
-func About(w http.ResponseWriter, r *http.Request) {
+func (m *Repository) About(w http.ResponseWriter, r *http.Request) {
 	render.RenderTemplate(w, "about.page.tmpl")
 }
diff --git a/pkg/render/render.go b/pkg/render/render.go
index 54cd584..89ea25b 100644
--- a/pkg/render/render.go
+++ b/pkg/render/render.go
@@ -2,29 +2,40 @@ package render
 
 import (
 	"bytes"
+	"go-udemy-web-1/pkg/config"
 	"html/template"
 	"log"
 	"net/http"
 	"path/filepath"
 )
 
+var app *config.AppConfig
+
+// NewTemplates sets the config for the template package
+func NewTemplates(a *config.AppConfig) {
+	app = a
+}
+
 // RenderTemplate renders a HTML template file
 func RenderTemplate(w http.ResponseWriter, tmpl string) {
-	// create a template cache
-	tc, err := createTemplateCache()
-	if err != nil {
-		log.Fatal(err)
+	var tc map[string]*template.Template
+	if app.UseCache {
+		// get the template cache from the app config
+		tc = app.TemplateCahce
+	} else {
+		tc, _ = CreateTemplateCache()
 	}
+
 	// get requested template from cache
 	t, ok := tc[tmpl]
 	if !ok {
-		log.Fatal(err)
+		log.Fatal("Could not get template from template cache")
 	}
 
 	// Write to a buffer to make sure that the template can be read and
 	// written successfully
 	buf := new(bytes.Buffer)
-	err = t.Execute(buf, nil)
+	err := t.Execute(buf, nil)
 	if err != nil {
 		log.Println(err)
 	}
@@ -36,7 +47,7 @@ func RenderTemplate(w http.ResponseWriter, tmpl string) {
 	}
 }
 
-func createTemplateCache() (map[string]*template.Template, error) {
+func CreateTemplateCache() (map[string]*template.Template, error) {
 	myCache := map[string]*template.Template{}
 
 	// get all of the files named *.page.tmpl from ./templates