use websockets to logout remote users

cmd/web/main.go

@@ -119,6 +119,8 @@ func main() {
 		Session:       session,
 	}
 
+	go app.ListenToWsChannel()
+
 	app.infoLog.Println("Connected to MariaDB")
 
 	err = app.serve()

cmd/web/routes.go

@@ -12,6 +12,8 @@ func (app *application) routes() http.Handler {
 
 	mux.Get("/", app.Home)
 
+	mux.Get("/ws", app.WsEndPoint)
+
 	mux.Route("/admin", func(mux chi.Router) {
 		mux.Use(app.Auth)
 		mux.Get("/virtual-terminal", app.VirtualTerminal)

cmd/web/templates/base.layout.gohtml

@@ -105,7 +105,12 @@
         <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js"
                 integrity="sha384-YvpcrYf0tY3lHB60NNkmXc5s9fDVZLESaAA55NDzOxhy9GkcIdslK1eN7N6jIeHz"
                 crossorigin="anonymous"></script>
-        <script src="/static/js/base.js"></script>
+        <script type="module">
+            import {wsConn, socket} from "/static/js/base.js"
+            document.addEventListener("DOMContentLoaded", function() {
+                wsConn({{.IsAuthenticated}}, {{.UserID}});
+            });
+        </script>
         {{ block "js" . }}
         {{ end }}
     </body>

cmd/web/ws-handlers.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+type WebSocketConnection struct {
+	*websocket.Conn
+}
+
+type WsPayload struct {
+	Action      string              `json:"action"`
+	Message     string              `json:"message"`
+	UserName    string              `json:"user_name"`
+	MessageType string              `json:"message_type"`
+	UserID      int                 `json:"user_id"`
+	Conn        WebSocketConnection `json:"-"`
+}
+
+type WsJSONResponse struct {
+	Action  string `json:"action"`
+	Message string `json:"message"`
+	UserID  int    `json:"user_id"`
+}
+
+var upgradeConnection = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+	// since we don't expect any communication from the client side
+	CheckOrigin: func(r *http.Request) bool { return true },
+}
+
+var clients = make(map[WebSocketConnection]string)
+
+var wsChan = make(chan WsPayload)
+
+func (app *application) WsEndPoint(w http.ResponseWriter, r *http.Request) {
+	ws, err := upgradeConnection.Upgrade(w, r, nil)
+	if err != nil {
+		app.errorLog.Println(err)
+		return
+	}
+
+	app.infoLog.Printf("Client connected from %s\n", r.RemoteAddr)
+	var response WsJSONResponse
+	response.Message = "Connected to server"
+
+	err = ws.WriteJSON(response)
+	if err != nil {
+		app.errorLog.Println(err)
+		return
+	}
+
+	conn := WebSocketConnection{Conn: ws}
+	clients[conn] = ""
+
+	go app.ListenForWS(&conn)
+}
+
+func (app *application) ListenForWS(conn *WebSocketConnection) {
+	defer func() {
+		if r := recover(); r != nil {
+			app.errorLog.Println("ERROR:", fmt.Sprintf("%v", r))
+		}
+	}()
+
+	var payload WsPayload
+
+	for {
+		err := conn.ReadJSON(&payload)
+		if err != nil {
+			// do nothing
+			app.errorLog.Println(err)
+			break
+		}
+		payload.Conn = *conn
+		wsChan <- payload
+	}
+}
+
+func (app *application) ListenToWsChannel() {
+	var response WsJSONResponse
+	for {
+		e := <-wsChan
+		switch e.Action {
+		case "deleteUser":
+			response.Action = "logout"
+			response.Message = "Your account has ben deleted"
+			response.UserID = e.UserID
+			app.broadcastToAll(response)
+		default:
+		}
+	}
+}
+
+func (app *application) broadcastToAll(response WsJSONResponse) {
+	for client := range clients {
+		// broadcast to every connected client
+		err := client.WriteJSON(response)
+		if err != nil {
+			app.errorLog.Printf("Websocket err on %s: %s", response.Action, err)
+			_ = client.Close()
+			delete(clients, client)
+		}
+	}
+}

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/go-chi/chi/v5 v5.1.0
 	github.com/go-chi/cors v1.2.1
 	github.com/go-sql-driver/mysql v1.8.1
+	github.com/gorilla/websocket v1.5.3
 	github.com/stripe/stripe-go/v79 v79.6.0
 	github.com/xhit/go-simple-mail/v2 v2.16.0
 	golang.org/x/crypto v0.26.0

go.sum

@@ -17,6 +17,8 @@ github.com/go-sql-driver/mysql v1.8.1 h1:LedoTUt/eveggdHS9qUFC1EFSa8bU2+1pZjSRpv
 github.com/go-sql-driver/mysql v1.8.1/go.mod h1:wEBSXgmK//2ZFJyE+qWnIsVGmvmEKlqwuVSjsCm7DZg=
 github.com/go-test/deep v1.1.1 h1:0r/53hagsehfO4bzD2Pgr/+RgHqhmf+k1Bpse2cTu1U=
 github.com/go-test/deep v1.1.1/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
+github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

static/js/base.js

@@ -1,3 +1,32 @@
+export let socket;
+
+export function wsConn(is_authenticated, user_id) {
+    if (is_authenticated !== 1) {
+        return;
+    }
+
+    socket = new WebSocket("ws://localhost:4000/ws")
+    socket.onopen = () => {
+        console.log("Successfully connected to websockets")
+    }
+
+    socket.onclose = event => {};
+    socket.onerror = error => {};
+
+    socket.onmessage = msg => {
+        let data = JSON.parse(msg.data);
+
+        switch (data.action) {
+            case "logout":
+                if (data.user_id === user_id) {
+                    logout()
+                }
+                break;
+            default:
+        }
+    }
+}
+
 // let loginLink = document.getElementById("login-link");
 // let vtLink = document.getElementById("vt-link");
 //
@@ -11,9 +40,9 @@
 //     loginLink.classList.remove('d-none')
 // });
 
-// function logout() {
-//     localStorage.removeItem("token");
-//     localStorage.removeItem("token_expiry");
-//     location.href = "/logout";
-// }
+function logout() {
+    localStorage.removeItem("token");
+    localStorage.removeItem("token_expiry");
+    location.href = "/logout";
+}
 

static/js/users.js

@@ -1,3 +1,5 @@
+import {socket} from "./base.js"
+
 export function showUsers(api) {
     const tbody = document.getElementById("user-table").getElementsByTagName("tbody")[0];
     const token = localStorage.getItem("token");
@@ -14,6 +16,7 @@ export function showUsers(api) {
     fetch(api + "/api/admin/all-users", requestOptions)
         .then(response => response.json())
         .then(function (data) {
+            console.log(data)
             if (data) {
                 data.forEach(i => {
                     let newRow = tbody.insertRow();
@@ -63,21 +66,6 @@ export function showUser(api, userID) {
             document.getElementById("last_name").value = data.last_name;
             document.getElementById("email").value = data.email;
         });
-
-    delBtn.addEventListener("click", function () {
-        Swal.fire({
-            title: "Are you sure?",
-            text: "You won't be able to undo this!",
-            icon: "warning",
-            showCancelButton: true,
-            confirmButtonColor: "#3085d6",
-            cancelButtonColor: "#d33",
-            confirmButtonText: 'Delete User',
-        }).then((result) => {
-            console.log("would delete user id", id);
-        });
-    })
-
 }
 
 export function saveUser(api, event) {
@@ -160,6 +148,11 @@ export function deleteUser(api) {
                     if (!data.ok) {
                         Swal.fire("Error" + data.message)
                     } else {
+                        let jsonData = {
+                            action: "deleteUser",
+                            user_id: parseInt(id),
+                        };
+                        socket.send(JSON.stringify(jsonData));
                         location.href = "/admin/all-users"
                     }
                 });