const logger = require("../utils/logger");

/**
 * Map to track typing status: { userId_receiverId: timestamp }
 * Used to prevent duplicate typing events and auto-clear stale states
 */
const typingStatus = new Map();

/**
 * Cleanup interval for stale typing indicators (every 5 seconds)
 */
setInterval(() => {
  const now = Date.now();
  const TYPING_TIMEOUT = 5000; // 5 seconds

  for (const [key, timestamp] of typingStatus.entries()) {
    if (now - timestamp > TYPING_TIMEOUT) {
      typingStatus.delete(key);
    }
  }
}, 5000);

/**
 * Generate conversation room ID from two user IDs
 * Always sorts IDs to ensure consistent room naming regardless of who initiates
 */
const getConversationRoom = (userId1, userId2) => {
  const sorted = [userId1, userId2].sort();
  return `conv_${sorted[0]}_${sorted[1]}`;
};

/**
 * Get personal user room ID
 */
const getUserRoom = (userId) => {
  return `user_${userId}`;
};

/**
 * Initialize message socket handlers
 * @param {SocketIO.Server} io - Socket.io server instance
 */
const initializeMessageSocket = (io) => {
  io.on("connection", (socket) => {
    const userId = socket.userId;
    const userRoom = getUserRoom(userId);

    logger.info("User connected to messaging", {
      socketId: socket.id,
      userId,
      userEmail: socket.user.email,
    });

    // Join user's personal room for receiving direct messages
    socket.join(userRoom);
    logger.debug("User joined personal room", {
      socketId: socket.id,
      userId,
      room: userRoom,
    });

    /**
     * Join a specific conversation room
     * Used when user opens a chat with another user
     */
    socket.on("join_conversation", (data) => {
      try {
        const { otherUserId } = data;

        if (!otherUserId) {
          logger.warn("join_conversation - missing otherUserId", {
            socketId: socket.id,
            userId,
          });
          return;
        }

        const conversationRoom = getConversationRoom(userId, otherUserId);
        socket.join(conversationRoom);

        logger.debug("User joined conversation room", {
          socketId: socket.id,
          userId,
          otherUserId,
          room: conversationRoom,
        });

        socket.emit("conversation_joined", {
          conversationRoom,
          otherUserId,
        });
      } catch (error) {
        logger.error("Error joining conversation", {
          socketId: socket.id,
          userId,
          error: error.message,
        });
      }
    });

    /**
     * Leave a specific conversation room
     * Used when user closes a chat
     */
    socket.on("leave_conversation", (data) => {
      try {
        const { otherUserId } = data;

        if (!otherUserId) {
          return;
        }

        const conversationRoom = getConversationRoom(userId, otherUserId);
        socket.leave(conversationRoom);

        logger.debug("User left conversation room", {
          socketId: socket.id,
          userId,
          otherUserId,
          room: conversationRoom,
        });
      } catch (error) {
        logger.error("Error leaving conversation", {
          socketId: socket.id,
          userId,
          error: error.message,
        });
      }
    });

    /**
     * Typing start indicator
     * Notifies the recipient that this user is typing
     */
    socket.on("typing_start", (data) => {
      try {
        const { receiverId } = data;

        if (!receiverId) {
          return;
        }

        // Throttle typing events (prevent spam)
        const typingKey = `${userId}_${receiverId}`;
        const lastTyping = typingStatus.get(typingKey);
        const now = Date.now();

        if (lastTyping && now - lastTyping < 1000) {
          // Ignore if typed within last 1 second
          return;
        }

        typingStatus.set(typingKey, now);

        // Emit to recipient's personal room
        const receiverRoom = getUserRoom(receiverId);
        io.to(receiverRoom).emit("user_typing", {
          userId,
          firstName: socket.user.firstName,
          isTyping: true,
        });

        logger.debug("Typing indicator sent", {
          socketId: socket.id,
          senderId: userId,
          receiverId,
        });
      } catch (error) {
        logger.error("Error handling typing_start", {
          socketId: socket.id,
          userId,
          error: error.message,
        });
      }
    });

    /**
     * Typing stop indicator
     * Notifies the recipient that this user stopped typing
     */
    socket.on("typing_stop", (data) => {
      try {
        const { receiverId } = data;

        if (!receiverId) {
          return;
        }

        // Clear typing status
        const typingKey = `${userId}_${receiverId}`;
        typingStatus.delete(typingKey);

        // Emit to recipient's personal room
        const receiverRoom = getUserRoom(receiverId);
        io.to(receiverRoom).emit("user_typing", {
          userId,
          firstName: socket.user.firstName,
          isTyping: false,
        });

        logger.debug("Typing stop sent", {
          socketId: socket.id,
          senderId: userId,
          receiverId,
        });
      } catch (error) {
        logger.error("Error handling typing_stop", {
          socketId: socket.id,
          userId,
          error: error.message,
        });
      }
    });

    /**
     * Mark message as read (from client)
     * This is handled by the REST API route, but we listen here for consistency
     */
    socket.on("mark_message_read", (data) => {
      try {
        const { messageId, senderId } = data;

        if (!messageId || !senderId) {
          return;
        }

        // Emit to sender's room to update their UI
        const senderRoom = getUserRoom(senderId);
        io.to(senderRoom).emit("message_read", {
          messageId,
          readAt: new Date().toISOString(),
          readBy: userId,
        });

        logger.debug("Message read notification sent", {
          socketId: socket.id,
          messageId,
          readBy: userId,
          notifiedUserId: senderId,
        });
      } catch (error) {
        logger.error("Error handling mark_message_read", {
          socketId: socket.id,
          userId,
          error: error.message,
        });
      }
    });

    /**
     * Disconnect handler
     * Clean up rooms and typing status
     */
    socket.on("disconnect", (reason) => {
      // Clean up all typing statuses for this user
      for (const [key] of typingStatus.entries()) {
        if (key.startsWith(`${userId}_`)) {
          typingStatus.delete(key);
        }
      }

      logger.info("User disconnected from messaging", {
        socketId: socket.id,
        userId,
        reason,
      });
    });

    /**
     * Error handler
     */
    socket.on("error", (error) => {
      logger.error("Socket error", {
        socketId: socket.id,
        userId,
        error: error.message,
        stack: error.stack,
      });
    });
  });

  logger.info("Message socket handlers initialized");
};

/**
 * Emit new message event to a specific user
 * Called from message routes when a message is created
 * @param {SocketIO.Server} io - Socket.io server instance
 * @param {string} receiverId - User ID to send the message to
 * @param {Object} messageData - Message object with sender info
 */
const emitNewMessage = (io, receiverId, messageData) => {
  try {
    const receiverRoom = getUserRoom(receiverId);
    io.to(receiverRoom).emit("new_message", messageData);

    logger.info("New message emitted", {
      receiverId,
      receiverRoom,
      messageId: messageData.id,
      senderId: messageData.senderId,
    });
  } catch (error) {
    logger.error("Error emitting new message", {
      receiverId,
      messageId: messageData.id,
      error: error.message,
    });
  }
};

/**
 * Emit message read event to sender
 * Called from message routes when a message is marked as read
 * @param {SocketIO.Server} io - Socket.io server instance
 * @param {string} senderId - User ID who sent the message
 * @param {Object} readData - Read status data
 */
const emitMessageRead = (io, senderId, readData) => {
  try {
    const senderRoom = getUserRoom(senderId);
    io.to(senderRoom).emit("message_read", readData);

    logger.debug("Message read status emitted", {
      senderId,
      messageId: readData.messageId,
    });
  } catch (error) {
    logger.error("Error emitting message read status", {
      senderId,
      messageId: readData.messageId,
      error: error.message,
    });
  }
};

module.exports = {
  initializeMessageSocket,
  emitNewMessage,
  emitMessageRead,
  getConversationRoom,
  getUserRoom,
};