class MessageRouter {
  /**
   * @param {ConnectionManager} connectionManager An instance of ConnectionManager.
   */
  constructor(connectionManager) {
    this.connectionManager = connectionManager;
  }

  /**
   * Routes the incoming message based on its content.
   *
   * The expected JSON structure:
   * {
   *   type: "private" | "broadcast" | "other",
   *   payload: { 
   *     u: "recipient username",   // for private messages
   *     body: "...",               // message body
   *     // additional fields for other types can be added too
   *   }
   * }
   *
   * If 'type' is omitted, it defaults to "private".
   */
  routeMessage(fromUser, data) {
    const type = data.type || 'private';
    switch (type) {
      case 'private':
        this.handlePrivateMessage(fromUser, data.payload);
        break;
      case 'broadcast':
        this.handleBroadcastMessage(fromUser, data.payload);
        break;
      default:
        this.sendError(fromUser, `Unknown message type: ${type}`);
    }
  }

  handlePrivateMessage(fromUser, payload) {
    if (!payload || !payload.u || !payload.body) {
      return this.sendError(fromUser, "Invalid payload for a private message. Required: { u, body }");
    }
    const recipientSocket = this.connectionManager.getUserSocket(payload.u);
    if (recipientSocket && recipientSocket.readyState === recipientSocket.OPEN) {
      recipientSocket.send(JSON.stringify({
        error: false,
        message: {
          from: fromUser,
          body: payload.body
        }
      }));
    } else {
      this.sendError(fromUser, `User ${payload.u} is not online`);
    }
  }

  handleBroadcastMessage(fromUser, payload) {
    if (!payload || !payload.body) {
      return this.sendError(fromUser, "Invalid payload for broadcast message. Required: { body }");
    }
    const msg = {
      error: false,
      message: {
        from: fromUser,
        body: payload.body
      }
    };
    this.connectionManager.broadcast(msg, fromUser);
  }

  sendError(toUser, errorMessage) {
    const ws = this.connectionManager.getUserSocket(toUser);
    if (ws && ws.readyState === ws.OPEN) {
      ws.send(JSON.stringify({ error: true, message: errorMessage }));
    }
  }
}

module.exports = MessageRouter;