feat: implement stale client removal after timeout

- add goroutine to remove stale clients from the connection pool
- update client struct to track `LastPong` time
- set write deadline for websocket connections
- move package variables and const to `vars.go`
- log additional information when broadcasting errors

🤖

internal/websocket/handle_connection.go

@@ -2,18 +2,13 @@ package websocket
 
 import (
 	"github.com/gorilla/websocket"
-	"net"
 	"net/http"
-	"sync"
+	"time"
 
 	"git.smsvc.net/pomodoro/GoTomato/internal/helper"
 	"git.smsvc.net/pomodoro/GoTomato/pkg/models"
 )
 
-// Clients is a map of connected WebSocket clients, where each client is represented by the WebsocketClient struct
-var Clients = make(map[net.Addr]*models.WebsocketClient)
-var mu sync.Mutex // Mutex to protect access to the Clients map
-
 // Upgrade HTTP requests to WebSocket connections
 var upgrader = websocket.Upgrader{
 	CheckOrigin: func(r *http.Request) bool { return true },
@@ -31,9 +26,15 @@ func HandleConnection(w http.ResponseWriter, r *http.Request) {
 
 	// Register the new client
 	client := models.WebsocketClient{
-		Conn:   ws,
-		RealIP: r.RemoteAddr,
+		Conn:     ws,
+		LastPong: time.Now(),
+		RealIP:   r.RemoteAddr,
 	}
+	client.Conn.SetPongHandler(func(s string) error {
+		client.LastPong = time.Now()
+		return nil
+	})
+
 	mu.Lock()
 	Clients[ws.LocalAddr()] = &client
 	mu.Unlock()