/**
 * WebSocketTransport - WebSocket 传输层实现
 *
 * 通过 WebSocket 连接到远程 AgentBridge，使用 NDJSON 格式通信。
 * 与 ProcessTransport 共享基类的 _handleData() 实现。
 */

const WebSocket = require('ws');
const { Transport } = require('./Transport');

class WebSocketTransport extends Transport {
  constructor() {
    super();
    this.ws = null;
    this._url = null;
  }

  /**
   * 检查是否已连接
   */
  get isConnected() {
    return this.ws !== null && this.ws.readyState === WebSocket.OPEN;
  }

  /**
   * 连接到 WebSocket Server (AgentBridge)
   * @param {string} url - ws:// 地址
   * @param {string[]} _args - 忽略（兼容 Transport 接口签名）
   * @param {object} options - { timeout }
   */
  async connect(url, _args = [], options = {}) {
    this._url = url;
    const timeout = options.timeout || 10000;

    return new Promise((resolve, reject) => {
      const timer = setTimeout(() => {
        reject(new Error(`WebSocket connect timeout: ${url} (${timeout}ms)`));
      }, timeout);

      console.log(`[WebSocketTransport] 连接: ${url}`);
      this.ws = new WebSocket(url);

      this.ws.on('open', () => {
        clearTimeout(timer);
        console.log(`[WebSocketTransport] 已连接: ${url}`);
        resolve();
      });

      this.ws.on('error', (err) => {
        clearTimeout(timer);
        console.error(`[WebSocketTransport] 错误: ${err.message}`);
        this.emit('error', err);
        reject(err);
      });

      this.ws.on('message', (data) => {
        // 使用基类的 _handleData 处理 NDJSON
        this._handleData(data.toString());
      });

      this.ws.on('close', (code, reason) => {
        console.log(`[WebSocketTransport] 连接关闭: code=${code}`);
        this.emit('close', code, reason?.toString());
      });
    });
  }

  /**
   * 发送消息
   * @param {object|string} msg - 消息对象或已序列化的字符串
   */
  send(msg) {
    if (!this.isConnected) {
      throw new Error('Transport is closed');
    }
    // 支持传入 string 或 object（与 PipeTransport 行为一致）
    const str = typeof msg === 'string' ? msg : JSON.stringify(msg) + '\n';
    this.ws.send(str);
  }

  /**
   * 关闭连接
   */
  close() {
    if (this.ws) {
      try {
        this.ws.close();
      } catch {
        // ignore
      }
      this.ws = null;
    }
    this.buffer = '';
  }
}

module.exports = { WebSocketTransport };