import {
  BLUETOOTH_ERROR_MESSAGES,
  DEFAULT_BLUETOOTH_ERROR_MESSAGE,
  TARGET_SERVICE_UUID,
  TARGET_SHORT_UUID
} from '@/constants/bluetooth'
import { showToast } from '@/utils/toast'

/**
 * 蓝牙设备搜索逻辑封装。
 * 通过回调把状态同步给页面，减少页面文件复杂度。
 */
export function createBluetoothDiscovery(options = {}) {
  const {
    onSearchingChange = () => {},
    onDeviceMapChange = () => {},
    onDeviceListChange = () => {}
  } = options

  let isSearching = false
  let deviceMap = {}
  let deviceFoundHandler = null

  function setSearching(value) {
    isSearching = Boolean(value)
    onSearchingChange(isSearching)
  }

  function setDeviceMap(nextMap) {
    deviceMap = nextMap
    onDeviceMapChange({ ...deviceMap })
    emitDeviceList()
  }

  function emitDeviceList() {
    const list = Object.values(deviceMap).sort((a, b) => {
      if (a.hasTargetService !== b.hasTargetService) {
        return a.hasTargetService ? -1 : 1
      }

      const aSignal = typeof a.RSSI === 'number' ? a.RSSI : -999
      const bSignal = typeof b.RSSI === 'number' ? b.RSSI : -999
      return bSignal - aSignal
    })

    onDeviceListChange(list)
  }

  function normalizeUuid(uuid) {
    return String(uuid || '').replace(/[^0-9a-fA-F]/g, '').toUpperCase()
  }

  function hasTargetService(device) {
    if (!Array.isArray(device.advertisServiceUUIDs)) {
      return false
    }

    const targetUuid = normalizeUuid(TARGET_SERVICE_UUID)
    return device.advertisServiceUUIDs.some((uuid) => {
      const value = normalizeUuid(uuid)
      return value === targetUuid || value.endsWith(TARGET_SHORT_UUID)
    })
  }

  function openBluetoothAdapter() {
    return new Promise((resolve, reject) => {
      uni.openBluetoothAdapter({
        success: resolve,
        fail: reject
      })
    })
  }

  function startDiscoveryWithServices(services = []) {
    return new Promise((resolve, reject) => {
      const options = {
        allowDuplicatesKey: true,
        interval: 0,
        success: resolve,
        fail: reject
      }

      if (services.length) {
        options.services = services
      }

      uni.startBluetoothDevicesDiscovery(options)
    })
  }

  function upsertDevice(rawDevice) {
    if (!rawDevice || !rawDevice.deviceId) {
      return
    }

    const existing = deviceMap[rawDevice.deviceId] || {}
    const merged = {
      ...existing,
      ...rawDevice,
      showName: rawDevice.name || rawDevice.localName || existing.showName || '未命名设备',
      hasTargetService: hasTargetService(rawDevice) || existing.hasTargetService
    }

    setDeviceMap({
      ...deviceMap,
      [rawDevice.deviceId]: merged
    })
  }

  function registerDeviceFoundHandler() {
    if (deviceFoundHandler) {
      return
    }

    deviceFoundHandler = (res) => {
      const devices = Array.isArray(res.devices) ? res.devices : [res]
      devices.forEach((device) => {
        upsertDevice(device)
      })
    }

    uni.onBluetoothDeviceFound(deviceFoundHandler)
  }

  function stopSearch(showStopToast = true) {
    return new Promise((resolve) => {
      uni.stopBluetoothDevicesDiscovery({
        complete: () => {
          setSearching(false)
          if (showStopToast) {
            showToast('已停止搜索')
          }
          resolve()
        }
      })
    })
  }

  function cleanupDiscovery() {
    if (isSearching) {
      uni.stopBluetoothDevicesDiscovery({
        complete: () => {}
      })
    }

    setSearching(false)

    if (deviceFoundHandler && uni.offBluetoothDeviceFound) {
      uni.offBluetoothDeviceFound(deviceFoundHandler)
    }

    deviceFoundHandler = null
  }

  function getBluetoothErrorText(error) {
    const errCode = error && error.errCode
    return BLUETOOTH_ERROR_MESSAGES[errCode] || DEFAULT_BLUETOOTH_ERROR_MESSAGE
  }

  async function startSearch() {
    setDeviceMap({})

    try {
      await openBluetoothAdapter()
      registerDeviceFoundHandler()

      try {
        await startDiscoveryWithServices([TARGET_SERVICE_UUID])
      } catch (error) {
        await startDiscoveryWithServices([])
      }

      setSearching(true)
    } catch (error) {
      setSearching(false)
      showToast(getBluetoothErrorText(error))
      throw error
    }
  }

  return {
    startSearch,
    stopSearch,
    cleanupDiscovery
  }
}