/**
 * USB Serial JS 桥接模块
 * 实现 USB 串口设备的发现、探测、连接及数据读写
 * 接口规范: docs/webview-usb-serial.md
 */
const { SerialPort } = require('serialport')
const { ipcMain } = require('electron')

class UsbSerialBridge {
  constructor(mainWindow) {
    this.mainWindow = mainWindow
    this.activeConnections = new Map()
    this.discoveredDevices = new Set()
    this.activeProbes = new Map()
    this._setupIPC()
  }

  _emit(event, data) {
    if (this.mainWindow && !this.mainWindow.isDestroyed()) {
      this.mainWindow.webContents.send(event, JSON.stringify(data))
    }
  }

  _setupIPC() {
    ipcMain.on('usb-start-discovery', () => this._startDiscovery())
    ipcMain.on('usb-stop-discovery', () => this._stopDiscovery())
    ipcMain.handle('usb-get-discovered', () => this._getDiscoveredDevices())
    ipcMain.on('usb-device-probe', (_e, p) => this._deviceProbe(p))
    ipcMain.on('usb-device-open', (_e, p) => this._deviceOpen(p))
    ipcMain.on('usb-device-close', (_e, p) => this._deviceClose(p))
    ipcMain.on('usb-device-write', (_e, p) => this._deviceWrite(p))
  }

  async _startDiscovery() {
    console.log('[usb] 开始发现串口设备...')
    try {
      const ports = await SerialPort.list()
      for (const p of ports) {
        if (!this.discoveredDevices.has(p.path)) {
          this.discoveredDevices.add(p.path)
          console.log('[usb] 发现设备:', p.path)
          this._emit('usb-callback-device-attached', {
            deviceName: p.path,
            deviceId: parseInt(p.vendorId || '0', 16) || 0,
            ports: [1]
          })
        }
      }
      console.log('[usb] 发现完成, 共', ports.length, '个设备')
    } catch (err) {
      console.error('[usb] 发现失败:', err.message)
    }
  }

  _stopDiscovery() {
    console.log('[usb] 停止发现')
  }

  _getDiscoveredDevices() {
    return JSON.stringify([])
  }

  async _deviceProbe({ deviceName, portNumber, baudRate, hexCmd, timeoutMs }) {
    const probeId = deviceName + ':' + portNumber
    console.log('[usb] 探测:', deviceName, 'port=', portNumber, 'baud=', baudRate)

    if (this.activeProbes.has(probeId)) {
      const old = this.activeProbes.get(probeId)
      clearTimeout(old.timeout)
      try { old.port.close() } catch {}
      this.activeProbes.delete(probeId)
    }

    try {
      const port = new SerialPort({
        path: deviceName,
        baudRate: baudRate || 9600,
        dataBits: 8,
        parity: 'none',
        stopBits: 1,
        autoOpen: false,
        dtr: false,
        rts: false
      })

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

      let responseHex = ''
      const timeout = setTimeout(() => {
        this.activeProbes.delete(probeId)
        try { port.close() } catch {}
        const success = responseHex.length > 0
        console.log('[usb] 探测' + (success ? '成功' : '超时') + ':', deviceName, '响应=' + (responseHex || '无'))
        this._emit('usb-callback-device-probe-result', {
          deviceName, port: portNumber, baudRate,
          success, responseHex, error: success ? '' : 'No response'
        })
      }, timeoutMs || 1000)

      port.on('data', (data) => {
        responseHex += data.toString('hex').toUpperCase()
      })

      port.on('error', (err) => {
        console.error('[usb] 探测错误:', err.message)
      })

      this.activeProbes.set(probeId, { timeout, port })

      if (hexCmd) {
        const cmdBuf = Buffer.from(hexCmd, 'hex')
        port.write(cmdBuf, (err) => {
          if (err) {
            clearTimeout(timeout)
            this.activeProbes.delete(probeId)
            try { port.close() } catch {}
            this._emit('usb-callback-device-probe-result', {
              deviceName, port: portNumber, baudRate,
              success: false, responseHex: '', error: err.message
            })
          } else {
            console.log('[usb] 已发送探测命令:', hexCmd)
          }
        })
      } else {
        console.log('[usb] 不发送探测命令, 等待自动上报...')
      }
    } catch (err) {
      console.error('[usb] 探测失败:', err.message)
      this._emit('usb-callback-device-probe-result', {
        deviceName, port: portNumber, baudRate,
        success: false, responseHex: '', error: err.message
      })
    }
  }

  async _deviceOpen({ deviceName, portNumber, baudRate }) {
    const connKey = deviceName + ':' + portNumber
    console.log('[usb] 打开:', connKey, 'baud=', baudRate)

    if (this.activeConnections.has(connKey)) {
      try { this.activeConnections.get(connKey).port.close() } catch {}
      this.activeConnections.delete(connKey)
    }

    try {
      const port = new SerialPort({
        path: deviceName,
        baudRate: baudRate || 9600,
        dataBits: 8,
        parity: 'none',
        stopBits: 1,
        autoOpen: false,
        dtr: false,
        rts: false
      })

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

      const entry = { port, deviceName, portNumber }
      this.activeConnections.set(connKey, entry)

      console.log('[usb] 打开成功:', connKey)
      this._emit('usb-callback-device-opened', {
        deviceName, port: portNumber, success: true, error: ''
      })
      this._emit('usb-callback-device-state', {
        deviceName, port: portNumber, state: 'CONNECTED'
      })

      port.on('data', (data) => {
        this._emit('usb-callback-device-data', {
          deviceName,
          port: portNumber,
          hexData: data.toString('hex').toUpperCase()
        })
      })

      port.on('error', (err) => {
        console.error('[usb] 连接错误:', err.message)
      })

      port.on('close', () => {
        console.log('[usb] 连接关闭:', connKey)
        this.activeConnections.delete(connKey)
        this._emit('usb-callback-device-state', {
          deviceName, port: portNumber, state: 'DISCONNECTED'
        })
      })
    } catch (err) {
      console.error('[usb] 打开失败:', err.message)
      this._emit('usb-callback-device-opened', {
        deviceName, port: portNumber, success: false, error: err.message
      })
    }
  }

  _deviceClose({ deviceName, portNumber }) {
    const connKey = deviceName + ':' + portNumber
    console.log('[usb] 关闭:', connKey)
    if (this.activeConnections.has(connKey)) {
      const entry = this.activeConnections.get(connKey)
      try { entry.port.close() } catch {}
      this.activeConnections.delete(connKey)
    }
  }

  _deviceWrite({ deviceName, portNumber, hexData }) {
    const connKey = deviceName + ':' + portNumber
    console.log('[usb] 写入:', connKey, 'hex=' + hexData)

    if (!this.activeConnections.has(connKey)) {
      console.error('[usb] 写入失败:', connKey, '未连接')
      return
    }

    const entry = this.activeConnections.get(connKey)
    const buf = Buffer.from(hexData, 'hex')
    entry.port.write(buf, (err) => {
      if (err) {
        console.error('[usb] 写入错误:', err.message)
      }
    })
  }

  disconnectAll() {
    for (const [key, entry] of this.activeConnections) {
      console.log('[usb] 断开:', key)
      try { entry.port.close() } catch {}
    }
    this.activeConnections.clear()
  }
}

module.exports = { UsbSerialBridge }