// fresenius-serial-service.js
const { SerialPort } = require('serialport');

class FreseniusSerialService {
  constructor(options = {}) {
    this.portPath = options.portPath || 'COM5'; // 默认 Windows 串口
    this.baudRate = options.baudRate || 2400;
    this.pollInterval = options.pollInterval || 1000;

    this.port = null;
    this.isActivated = false; // 标记是否已成功激活
    this.isPolling = false;
    this.reconnectTimer = null;

    // === 严格按照你指定的命令 ===
    this.ACTIVATE_CMD = Buffer.from([0x16, 0x2F, 0x40, 0x31, 0x04, 0x03]); // . / @ 1 <EOT><ETX>
    this.CD_QUERY_CMD = Buffer.from([0x16, 0x31, 0x3F, 0x43, 0x44, 0x04, 0x03]); // . 1 ? C D <EOT><ETX>

    this.onData = options.onData || ((buf) => {});
    this.onError = options.onError || console.error;
    this.onLog = options.onLog || ((msg) => console.log(`[${new Date().toISOString()}] ${msg}`));
  }

  async open() {
    try {
      this.onLog(`🔌 正在打开串口: ${this.portPath}`);
      this.port = new SerialPort({
        path: this.portPath,
        baudRate: this.baudRate,
        dataBits: 8,
        stopBits: 1,
        parity: 'none',
        autoOpen: false,
        highWaterMark: 1024,
      });

      await new Promise((resolve, reject) => {
        this.port.open((err) => (err ? reject(err) : resolve()));
      });

      // 👇 打印所有原始输入（关键调试信息）
      this.port.on('data', (buffer) => {
        const hex = buffer.toString('hex').toUpperCase();
        this.onLog(`📥 原始输入 (${buffer.length} 字节): ${hex}`);
      });

      // 仅在底层错误或设备拔出时重连
      this.port.on('error', (err) => {
        this.onError(`🚨 串口错误: ${err.message}`);
        this.scheduleReconnect();
      });
      this.port.on('close', () => {
        this.onLog('🔌 串口连接断开，准备重连...');
        this.scheduleReconnect();
      });

      this.onLog(`✅ 串口 ${this.portPath} 已就绪`);
      this.startCommunication();
    } catch (err) {
      this.onError(`❌ 无法打开串口: ${err.message}`);
      this.scheduleReconnect(3000);
    }
  }

  scheduleReconnect(delay = 3000) {
    if (this.reconnectTimer) clearTimeout(this.reconnectTimer);
    this.reconnectTimer = setTimeout(() => {
      this.close();
      this.open();
    }, delay);
  }

  close() {
    this.isPolling = false;
    if (this.reconnectTimer) clearTimeout(this.reconnectTimer);
    if (this.port?.isOpen) this.port.close();
  }

  sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
  }

  // 发送命令并等待有效响应（自动合并分片）
  async sendCommand(cmd, validator, timeout = 2000) {
    return new Promise((resolve, reject) => {
      const timer = setTimeout(() => {
        this.port.off('data', onData);
        reject(new Error('响应超时'));
      }, timeout);

      const chunks = [];
      const onData = (data) => {
        chunks.push(data);
        const full = Buffer.concat(chunks);
        if (validator(full)) {
          clearTimeout(timer);
          this.port.off('data', onData);
          resolve(full);
        }
      };

      this.port.on('data', onData);
      this.port.write(cmd);
      this.onLog(`📤 发送命令: ${cmd.toString('hex').toUpperCase()}`);
    });
  }

  // 判断是否为有效的 CD 响应帧
  isValidCDResponse(data) {
    // 费森尤斯 CD 响应通常以 STX (0x02) 开头，长度 > 80 字节
    return data.length > 80 && data[0] === 0x02;
  }

  async startCommunication() {
    this.isPolling = true;

    while (this.isPolling && this.port?.isOpen) {
      try {
        // 第一步：如果未激活，先发送一次激活命令
        if (!this.isActivated) {
          this.onLog('🔑 发送激活命令 (仅一次)...');
          this.port.write(this.ACTIVATE_CMD);
          this.onLog(`📤 激活命令: ${this.ACTIVATE_CMD.toString('hex').toUpperCase()}`);

          // 等待设备内部服务启动（实测需 2~5 秒）
          this.onLog('⏳ 等待设备激活（3秒）...');
          await this.sleep(3000);

          // 尝试获取 CD 数据确认激活成功
          let activated = false;
          for (let i = 0; i < 3; i++) {
            try {
              const response = await this.sendCommand(
                this.CD_QUERY_CMD,
                this.isValidCDResponse.bind(this),
                2000
              );
              this.onData(response);
              this.onLog('✅ 激活成功！收到有效 CD 数据');
              this.isActivated = true;
              activated = true;
              break;
            } catch (e) {
              this.onLog(`⚠️ 激活验证第 ${i + 1}/3 次失败: ${e.message}`);
              await this.sleep(800);
            }
          }

          if (!activated) {
            this.onLog('❗ 激活未确认，将在下一轮重试');
          }
        }

        // 第二步：正常轮询 CD 数据
        if (this.isActivated) {
          try {
            const response = await this.sendCommand(
              this.CD_QUERY_CMD,
              this.isValidCDResponse.bind(this),
              2000
            );
            this.onData(response);
            this.onLog('📊 成功读取一帧治疗数据');
          } catch (err) {
            this.onLog(`⚠️ CD 查询失败: ${err.message}`);
            this.isActivated = false; // 下次重新激活
          }
        }

        await this.sleep(this.pollInterval);
      } catch (err) {
        this.onError(`⚠️ 通信循环异常: ${err.message}`);
        await this.sleep(2000);
      }
    }
  }
}


module.exports = FreseniusSerialService;