Completed stream_user.go for basic websocket streaming

Author: PythonHacker24

internal/session/stream_user.go

@@ -0,0 +1,109 @@
+package session
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/redis/go-redis/v9"
+)
+
+/* send current session of a user */
+func (m *Manager) sendCurrentSession(conn *websocket.Conn, sessionID string) error {
+	ctx := context.Background()
+
+	/* get data for current session from Redis */
+	key := fmt.Sprintf("session:%s", sessionID)
+	sessionData, err := m.redis.HGetAll(ctx, key).Result()
+	if err != nil {
+		/* user session doen't exists */
+		if err == redis.Nil {
+			message := StreamMessage{
+				Type: "session_state",
+				Data: map[string]interface{}{
+					"session_id": sessionID,
+					"exists":     false,
+				},
+				Timestamp: time.Now(),
+			}
+			return conn.WriteJSON(message)
+		}
+		/* error cannot be handed, return a error */
+		return fmt.Errorf("failed to get session data: %w", err)
+	}
+
+	/* session exists; convert Redis hash into session data */
+	session := convertRedisHashToSession(sessionData)
+	message := StreamMessage{
+		Type: "session_state",
+		Data: map[string]interface{}{
+			"session_id": sessionID,
+			"exists":     true,
+			"session":    session,
+		},
+		Timestamp: time.Now(),
+	}
+
+	return conn.WriteJSON(message)
+}
+
+/* send data regarding current session */
+func (m *Manager) listenForSessionChanges(ctx context.Context, conn *websocket.Conn, sessionID string) {
+	keyspacePattern := fmt.Sprintf("__keyspace@0__:session:%s", sessionID)
+
+	/* subscribe to Redis keyspace */
+	pubsub, err := m.redis.PSubscribe(ctx, keyspacePattern)
+	if err != nil {
+		m.errCh <- fmt.Errorf("failed to subscribe to redis events: %w", err)
+		return
+	}
+
+	defer pubsub.Close()
+
+	/* Redis update channel */
+	ch := pubsub.Channel()
+
+	/* handling session changes */
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case msg := <-ch:
+			/* changes in session stored in Redis detected; handle the event */
+			if err := m.handleSessionChangeEvent(conn, sessionID, msg); err != nil {
+				m.errCh <- fmt.Errorf("error handling session change: %w", err)
+			}
+		}
+	}
+}
+
+/* handle session change event */
+func (m *Manager) handleSessionChangeEvent(conn *websocket.Conn, sessionID string, msg *redis.Message) error {
+	ctx := context.Background()
+
+	/* get session data from Redis */
+	key := fmt.Sprintf("session:%s", sessionID)
+	sessionData, err := m.redis.HGetAll(ctx, key).Result()
+	if err != nil {
+		return fmt.Errorf("failed to get updated session data: %w", err)
+	}
+
+	/* convert session data from Redis hash to session */
+	session := convertRedisHashToSession(sessionData)
+
+	/* prepare the message payload */
+	message := StreamMessage{
+		Type: "session_update",
+		Data: map[string]interface{}{
+			"session_id":   sessionID,
+			"session":      session,
+			"event_type":   msg.Payload,
+			"event_source": "redis_keyspace",
+		},
+		Timestamp: time.Now(),
+	}
+
+	/* send the message payload via websocket */
+	return conn.WriteJSON(message)
+}