var SERVICE = {
  DEVICE_INFO: 'FFE0',
  DATA_COMM: 'FFE1',
  OTA: 'FFE2'
}

var CHAR = {
  DEVICE_INFO: 'FFE3',
  COMMAND: 'FFE4',
  STATUS: 'FFE5',
  BOND_INFO: 'FFE6',
  OTA_CONTROL: 'FFE7',
  OTA_DATA: 'FFE8',
  OTA_STATUS: 'FFE9'
}

var CMD = {
  SET_PARAMS: 0x01,
  START: 0x02,
  STOP: 0x03,
  QUERY_STATUS: 0x04,
  BIND: 0x05,
  UNBIND: 0x06
}

var NOTIFY = {
  STATUS_REPORT: 0x21,
  ACK: 0x22,
  TREATMENT_COMPLETE: 0x31,
  EXCEPTION: 0x32,
  BIND_SUCCESS: 0x33
}

var MODE_STATE = {
  IDLE: 0x00,
  SCANNING: 0x01,
  ACTIVE: 0x02,
  PAUSED: 0x03,
  COMPLETED: 0x04,
  ERROR: 0x05,
  OTA: 0x06
}

var WAVELENGTH = {
  IR: 1,
  R: 2,
  UV: 3,
  Y: 4
}

var TREAT_MODE = {
  NORMAL: 0,
  SMART: 1
}

var REGION = {
  LEFT_CHEEK: 0x01,
  RIGHT_CHEEK: 0x02,
  FOREHEAD: 0x04,
  CHIN: 0x08,
  NOSE: 0x10,
  LEFT_EYE: 0x20,
  RIGHT_EYE: 0x40,
  FULL_FACE: 0x7F
}

var REGION_NAMES = ['left_cheek', 'right_cheek', 'forehead', 'chin', 'nose', 'left_eye', 'right_eye']

var DEVICE_ERR = {
  0x00: 'SUCCESS',
  0x01: 'ERR_REGION_INVALID',
  0x02: 'ERR_REGION_EMPTY',
  0x03: 'ERR_BRIGHTNESS_INVALID',
  0x04: 'ERR_DURATION_INVALID',
  0x05: 'ERR_NOT_BOUND',
  0x06: 'ERR_NO_SUBSCRIPTION',
  0x07: 'ERR_TEMP_HIGH',
  0x08: 'ERR_BATTERY_LOW',
  0x09: 'ERR_ALREADY_RUNNING',
  0x0A: 'ERR_NOT_RUNNING',
  0x0B: 'ERR_OTA_FAILED',
  0x0C: 'ERR_BLE_DISCONNECTED'
}

var _deviceId = null
var _connected = false
var _chars = {}
var _cmdSeq = 0
var _pendingAcks = {}
var _listeners = {}

function nextSeq() {
  _cmdSeq = (_cmdSeq + 1) % 256
  return _cmdSeq
}

function bufferToBytes(buffer) {
  var arr = new Uint8Array(buffer)
  var bytes = []
  for (var i = 0; i < arr.length; i++) {
    bytes.push(arr[i])
  }
  return bytes
}

function bytesToBuffer(bytes) {
  var buffer = new ArrayBuffer(bytes.length)
  var view = new Uint8Array(buffer)
  for (var i = 0; i < bytes.length; i++) {
    view[i] = bytes[i]
  }
  return buffer
}

function xorChecksum(bytes) {
  var result = 0
  for (var i = 0; i < bytes.length; i++) {
    result ^= bytes[i]
  }
  return result
}

function buildFrame(type, payload) {
  var len = payload ? payload.length : 0
  var frame = [0xAA, 0x55, len, type]
  if (payload && payload.length > 0) {
    frame = frame.concat(payload)
  }
    var checkBytes = frame.slice(0)
    frame.push(xorChecksum(checkBytes))
  return bytesToBuffer(frame)
}

function parseFrame(buffer) {
  var bytes = bufferToBytes(buffer)
  if (bytes.length < 5) return null
  if (bytes[0] !== 0xAA || bytes[1] !== 0x55) return null
  var len = bytes[2]
  if (bytes.length < 5 + len) return null
  var type = bytes[3]
  var payload = bytes.slice(4, 4 + len)
  var checksum = bytes[4 + len]
  var expected = xorChecksum(bytes.slice(0, 4 + len))
  if (checksum !== expected) return null
  return { type: type, payload: payload, seq: payload.length > 0 ? payload[payload.length - 1] : 0 }
}

function uint32ToBytes(value) {
  return [
    (value >> 24) & 0xFF,
    (value >> 16) & 0xFF,
    (value >> 8) & 0xFF,
    value & 0xFF
  ]
}

function bytesToUint32(bytes, offset) {
  return (bytes[offset] << 24) | (bytes[offset + 1] << 16) | (bytes[offset + 2] << 8) | bytes[offset + 3]
}

function hexToBytes(hex) {
  var bytes = []
  for (var i = 0; i < hex.length; i += 2) {
    bytes.push(parseInt(hex.substr(i, 2), 16))
  }
  return bytes
}

function bytesToHex(bytes) {
  var hex = ''
  for (var i = 0; i < bytes.length; i++) {
    hex += ('0' + bytes[i].toString(16)).slice(-2)
  }
  return hex.toUpperCase()
}

function findCharUuid(chars, shortUuid) {
  for (var i = 0; i < chars.length; i++) {
    if (chars[i].uuid.indexOf(shortUuid) !== -1) {
      return chars[i].uuid
    }
  }
  return null
}

function on(event, callback) {
  if (!_listeners[event]) _listeners[event] = []
  _listeners[event].push(callback)
}

function off(event, callback) {
  if (!_listeners[event]) return
  if (callback) {
    _listeners[event] = _listeners[event].filter(function (cb) { return cb !== callback })
  } else {
    _listeners[event] = []
  }
}

function emit(event, data) {
  if (!_listeners[event]) return
  _listeners[event].forEach(function (cb) {
    try { cb(data) } catch (e) { console.error('ble emit error:', e) }
  })
}

function handleNotification(frame) {
  switch (frame.type) {
    case NOTIFY.STATUS_REPORT:
      emit('status', parseStatusReport(frame.payload))
      break
    case NOTIFY.ACK:
      var ack = parseAck(frame.payload)
      emit('ack', ack)
      if (_pendingAcks[ack.seq]) {
        if (ack.error_code === 0) {
          _pendingAcks[ack.seq].resolve(ack)
        } else {
          _pendingAcks[ack.seq].reject(ack)
        }
        delete _pendingAcks[ack.seq]
      }
      break
    case NOTIFY.TREATMENT_COMPLETE:
      emit('treatment_complete', parseTreatmentComplete(frame.payload))
      break
    case NOTIFY.EXCEPTION:
      emit('exception', parseException(frame.payload))
      break
    case NOTIFY.BIND_SUCCESS:
      emit('bind_result', { success: frame.payload[0] === 0x00 })
      break
  }
}

function parseStatusReport(payload) {
  if (payload.length < 14) return null
  return {
    mode_state: payload[0],
    region_mask: payload[1],
    wavelength: payload[2],
    brightness: payload[3],
    remaining_ms: bytesToUint32(payload, 4),
    error_code: payload[8],
    command_seq: payload[9],
    battery: payload[10],
    temperature: payload[11],
    bind_status: payload[12],
    subscription: payload[13]
  }
}

function parseAck(payload) {
  return {
    seq: payload[0],
    error_code: payload.length > 1 ? payload[1] : 0,
    error_msg: DEVICE_ERR[payload.length > 1 ? payload[1] : 0] || 'UNKNOWN'
  }
}

function parseTreatmentComplete(payload) {
  return {
    session_id: bytesToHex(payload.slice(0, 8)),
    regions: payload[8],
    total_duration_ms: bytesToUint32(payload, 9),
    avg_pd: payload[13]
  }
}

function parseException(payload) {
  return {
    error_code: payload[0],
    error_msg: DEVICE_ERR[payload[0]] || 'UNKNOWN',
    temperature: payload.length > 1 ? payload[1] : 0
  }
}

function isConnected() {
  return _connected && _deviceId !== null
}

function getDeviceId() {
  return _deviceId
}

function startScan(callbacks) {
  wx.openBluetoothAdapter({
    success: function () {
      wx.startBluetoothDevicesDiscovery({
        allowDuplicatesKey: false,
        success: function () {
          wx.offBluetoothDeviceFound()
          wx.onBluetoothDeviceFound(function (res) {
            var devices = res.devices || []
            for (var i = 0; i < devices.length; i++) {
              var d = devices[i]
              var name = (d.name || '').toUpperCase()
              var localName = (d.localName || '').toUpperCase()
              if (name.indexOf('HOX') !== -1 || localName.indexOf('HOX') !== -1 ||
                  name.indexOf('LIGHTMASK') !== -1 || localName.indexOf('LIGHTMASK') !== -1) {
                wx.stopBluetoothDevicesDiscovery({})
                if (callbacks.onFound) callbacks.onFound(d)
                connect(d.deviceId, callbacks)
                return
              }
            }
          })
        },
        fail: function () {
          if (callbacks.onError) callbacks.onError({ msg: '扫描失败' })
        }
      })
    },
    fail: function () {
      if (callbacks.onError) callbacks.onError({ msg: '请开启蓝牙' })
    }
  })
}

function connect(deviceId, callbacks) {
  _deviceId = deviceId
  _chars = {}

  wx.createBLEConnection({
    deviceId: deviceId,
    timeout: 10000,
    success: function () {
      _connected = true
      discoverServices(deviceId, callbacks)
    },
    fail: function () {
      _connected = false
      if (callbacks.onError) callbacks.onError({ msg: '连接失败' })
    }
  })
}

function discoverServices(deviceId, callbacks) {
  wx.getBLEDeviceServices({
    deviceId: deviceId,
    success: function (res) {
      var services = res.services
      var serviceMap = {}
      for (var i = 0; i < services.length; i++) {
        var uuid = services[i].uuid.toUpperCase()
        if (uuid.indexOf(SERVICE.DEVICE_INFO) !== -1) {
          serviceMap.deviceInfo = services[i].uuid
        } else if (uuid.indexOf(SERVICE.DATA_COMM) !== -1) {
          serviceMap.dataComm = services[i].uuid
        } else if (uuid.indexOf(SERVICE.OTA) !== -1) {
          serviceMap.ota = services[i].uuid
        }
      }

      var tasks = []
      if (serviceMap.deviceInfo) {
        tasks.push(discoverChars(deviceId, serviceMap.deviceInfo, 'deviceInfo'))
      }
      if (serviceMap.dataComm) {
        tasks.push(discoverChars(deviceId, serviceMap.dataComm, 'dataComm'))
      }

      Promise.all(tasks).then(function () {
        subscribeToNotifications(deviceId, serviceMap.dataComm).then(function () {
          if (callbacks.onConnected) callbacks.onConnected({ deviceId: deviceId })
        })
      })
    },
    fail: function () {
      if (callbacks.onError) callbacks.onError({ msg: '服务发现失败' })
    }
  })
}

function discoverChars(deviceId, serviceId, group) {
  return new Promise(function (resolve) {
    wx.getBLEDeviceCharacteristics({
      deviceId: deviceId,
      serviceId: serviceId,
      success: function (res) {
        var chars = res.characteristics || []
        for (var i = 0; i < chars.length; i++) {
          var c = chars[i]
          var uuid = c.uuid.toUpperCase()
          if (uuid.indexOf(CHAR.DEVICE_INFO) !== -1) _chars.deviceInfo = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.COMMAND) !== -1) _chars.command = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.STATUS) !== -1) _chars.status = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.BOND_INFO) !== -1) _chars.bondInfo = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.OTA_CONTROL) !== -1) _chars.otaControl = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.OTA_DATA) !== -1) _chars.otaData = { uuid: c.uuid, serviceId: serviceId }
          if (uuid.indexOf(CHAR.OTA_STATUS) !== -1) _chars.otaStatus = { uuid: c.uuid, serviceId: serviceId }
        }
        resolve()
      },
      fail: function () { resolve() }
    })
  })
}

function subscribeToNotifications(deviceId, serviceId) {
  return new Promise(function (resolve) {
    if (!_chars.status) { resolve(); return }

    wx.notifyBLECharacteristicValueChange({
      deviceId: deviceId,
      serviceId: _chars.status.serviceId,
      characteristicId: _chars.status.uuid,
      state: true,
      success: function () {
        wx.onBLECharacteristicValueChange(function (res) {
          var frame = parseFrame(res.value)
          if (frame) handleNotification(frame)
        })
        resolve()
      },
      fail: function () { resolve() }
    })
  })
}

function writeCommand(type, payload) {
  return new Promise(function (resolve, reject) {
    if (!_connected || !_deviceId) {
      reject({ error_code: 0x0C, error_msg: 'ERR_BLE_DISCONNECTED' })
      return
    }
    if (!_chars.command) {
      reject({ error_code: 0xFF, error_msg: 'command characteristic not found' })
      return
    }

    var seq = nextSeq()
    var payloadWithSeq = (payload || []).concat([seq])
    var buffer = buildFrame(type, payloadWithSeq)

    _pendingAcks[seq] = { resolve: resolve, reject: reject }

    setTimeout(function () {
      if (_pendingAcks[seq]) {
        _pendingAcks[seq].reject({ error_code: 0xFF, error_msg: 'ACK timeout' })
        delete _pendingAcks[seq]
      }
    }, 5000)

    wx.writeBLECharacteristicValue({
      deviceId: _deviceId,
      serviceId: _chars.command.serviceId,
      characteristicId: _chars.command.uuid,
      value: buffer,
      success: function () {},
      fail: function () {
        delete _pendingAcks[seq]
        reject({ error_code: 0x0C, error_msg: 'ERR_BLE_DISCONNECTED' })
      }
    })
  })
}

function readDeviceInfo() {
  return new Promise(function (resolve, reject) {
    if (!_connected || !_deviceId || !_chars.deviceInfo) {
      reject({ msg: '设备未连接或特征值未就绪' })
      return
    }
    wx.readBLECharacteristicValue({
      deviceId: _deviceId,
      serviceId: _chars.deviceInfo.serviceId,
      characteristicId: _chars.deviceInfo.uuid,
      success: function () {},
      fail: function () { reject({ msg: '读取设备信息失败' }) }
    })

    var handler = function (res) {
      if (res.characteristicId.toUpperCase().indexOf(CHAR.DEVICE_INFO) !== -1) {
        wx.offBLECharacteristicValueChange(handler)
        var bytes = bufferToBytes(res.value)
        if (bytes.length >= 14) {
          resolve({
            hw_version: (bytes[0] << 8) | bytes[1],
            fw_version: (bytes[2] << 8) | bytes[3],
            device_type: (bytes[4] << 8) | bytes[5],
            device_id: bytesToHex(bytes.slice(6, 14))
          })
        } else {
          reject({ msg: '设备信息格式错误' })
        }
      }
    }
    wx.onBLECharacteristicValueChange(handler)
  })
}

function setParams(options) {
  var regionMask = options.region_mask || REGION.FULL_FACE
  var wavelength = options.wavelength || WAVELENGTH.R
  var brightness = options.brightness || 200
  var durationMs = options.duration_ms || 600000
  var mode = options.mode !== undefined ? options.mode : TREAT_MODE.NORMAL

  var payload = [
    regionMask,
    wavelength,
    brightness,
    uint32ToBytes(durationMs),
    mode
  ].reduce(function (a, b) {
    return a.concat(Array.isArray(b) ? b : [b])
  }, [])

  return writeCommand(CMD.SET_PARAMS, payload)
}

function startTreatment(regionMask) {
  var mask = regionMask || REGION.FULL_FACE
  return writeCommand(CMD.START, [mask])
}

function stopTreatment() {
  return writeCommand(CMD.STOP, [])
}

function queryStatus() {
  return writeCommand(CMD.QUERY_STATUS, [])
}

function bindDevice(userId, bindToken) {
  var userBytes = hexToBytes(userId)
  var tokenBytes = hexToBytes(bindToken)
  var ts = Math.floor(Date.now() / 1000)
  var tsBytes = uint32ToBytes(ts)

  var payload = [0x01].concat(userBytes).concat(tokenBytes).concat(tsBytes)
  return writeCommand(CMD.BIND, payload)
}

function unbindDevice(userId) {
  var userBytes = hexToBytes(userId)
  var payload = [0x02].concat(userBytes)
  return writeCommand(CMD.UNBIND, payload)
}

function stopScan() {
  wx.stopBluetoothDevicesDiscovery({})
  wx.offBluetoothDeviceFound()
}

function disconnect() {
  if (_deviceId) {
    wx.closeBLEConnection({ deviceId: _deviceId })
    _deviceId = null
  }
  _connected = false
  _chars = {}
  _pendingAcks = {}
  _listeners = {}
  wx.closeBluetoothAdapter({})
}

wx.onBLEConnectionStateChange(function (res) {
  if (!res.connected) {
    _connected = false
    emit('disconnected', { deviceId: res.deviceId })
  }
})

function getRegionName(mask) {
  var names = []
  var bits = [
    [0x01, '左脸颊'], [0x02, '右脸颊'], [0x04, '额头'],
    [0x08, '下巴'], [0x10, '鼻部'], [0x20, '左眼周'], [0x40, '右眼周']
  ]
  for (var i = 0; i < bits.length; i++) {
    if (mask & bits[i][0]) names.push(bits[i][1])
  }
  return names
}

function getWavelengthName(code) {
  var map = { 1: '红外 850nm', 2: '红光 630nm', 3: '紫光 405nm', 4: '黄光 590nm' }
  return map[code] || '未知'
}

function getModeStateName(code) {
  var map = {
    0x00: '空闲', 0x01: '扫描中', 0x02: '护理中',
    0x03: '已暂停', 0x04: '已完成', 0x05: '异常', 0x06: 'OTA升级中'
  }
  return map[code] || '未知'
}

module.exports = {
  SERVICE: SERVICE,
  CHAR: CHAR,
  CMD: CMD,
  NOTIFY: NOTIFY,
  MODE_STATE: MODE_STATE,
  WAVELENGTH: WAVELENGTH,
  TREAT_MODE: TREAT_MODE,
  REGION: REGION,
  DEVICE_ERR: DEVICE_ERR,

  isConnected: isConnected,
  getDeviceId: getDeviceId,
  startScan: startScan,
  stopScan: stopScan,
  connect: connect,
  disconnect: disconnect,
  on: on,
  off: off,

  readDeviceInfo: readDeviceInfo,
  setParams: setParams,
  startTreatment: startTreatment,
  stopTreatment: stopTreatment,
  queryStatus: queryStatus,
  bindDevice: bindDevice,
  unbindDevice: unbindDevice,

  buildFrame: buildFrame,
  parseFrame: parseFrame,
  parseStatusReport: parseStatusReport,
  parseAck: parseAck,
  parseTreatmentComplete: parseTreatmentComplete,
  parseException: parseException,

  getRegionName: getRegionName,
  getWavelengthName: getWavelengthName,
  getModeStateName: getModeStateName,

  bufferToBytes: bufferToBytes,
  bytesToBuffer: bytesToBuffer,
  hexToBytes: hexToBytes,
  bytesToHex: bytesToHex
}