add WebSocket support for real-time delivery updates with JWT authentication and automatic reconnection

backend/internal/ws/handler.go

@@ -0,0 +1,41 @@
+package ws
+
+import (
+	"net/http"
+
+	"github.com/chedius/delivery-tracker/internal/auth"
+	"github.com/gin-gonic/gin"
+	"github.com/gorilla/websocket"
+)
+
+var upgrader = websocket.Upgrader{
+	CheckOrigin: func(r *http.Request) bool { return true },
+}
+
+// HandleWS returns a Gin handler that upgrades HTTP to WebSocket
+// after validating the JWT token from the ?token= query param.
+func HandleWS(hub *Hub, jwtSecret []byte) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		token := c.Query("token")
+		if token == "" {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "missing token"})
+			return
+		}
+
+		if _, err := auth.ParseToken(token, jwtSecret); err != nil {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
+			return
+		}
+
+		conn, err := upgrader.Upgrade(c.Writer, c.Request, nil)
+		if err != nil {
+			return
+		}
+
+		client := NewClient(hub, conn)
+		hub.Register(client)
+
+		go client.WritePump()
+		go client.ReadPump()
+	}
+}