import type { DeviceAdapter, NormalizedReading } from '../types';

/**
 * 小米手环 BLE 适配器
 *
 * 支持 Mi Band 7/8 等型号，使用标准 Heart Rate Service 读取心率数据。
 * 未来可扩展步数（0xFEE1）、睡眠等 Mi Band 专有 Service。
 */

// 标准 BLE Heart Rate Service
const HRS_SERVICE = '0000180D-0000-1000-8000-00805F9B34FB';
const HRM_CHARACTERISTIC = '00002A37-0000-1000-8000-00805F9B34FB';

// 小米 Mi Band 专有 Service（步数/活动量）
// const MI_BAND_SERVICE = '0000FEE1-0000-1000-8000-8000-00805F9B34FB';

/** 解析心率测量值（Heart Rate Measurement 格式） */
function parseHeartRate(data: ArrayBuffer): number | null {
  const view = new DataView(data);
  if (view.byteLength < 2) return null;

  const flags = view.getUint8(0);
  // Bit 0: Heart Rate Format — 0 = UINT8, 1 = UINT16
  const isUINT16 = (flags & 0x01) !== 0;

  if (isUINT16) {
    if (view.byteLength < 3) return null;
    return view.getUint16(1, true); // little-endian
  }
  return view.getUint8(1);
}

export const XiaomiBandAdapter: DeviceAdapter = {
  name: 'Xiaomi Band',

  supportedModels: [
    'Mi Band',
    'Mi Smart Band',
    'Xiaomi Band',
    'Xiaomi Smart Band',
    'MI BAND',
    'MiBand',
  ],

  serviceUUIDs: [HRS_SERVICE],

  notifyCharacteristics: [
    { service: HRS_SERVICE, characteristic: HRM_CHARACTERISTIC },
  ],

  readCharacteristics: [
    { service: HRS_SERVICE, characteristic: HRM_CHARACTERISTIC },
  ],

  parseNotification(
    _serviceUUID: string,
    charUUID: string,
    data: ArrayBuffer,
  ): NormalizedReading[] {
    if (charUUID.toUpperCase().includes('2A37')) {
      const hr = parseHeartRate(data);
      if (hr !== null && hr > 0 && hr < 300) {
        return [{
          device_type: 'heart_rate',
          values: { heart_rate: hr },
          measured_at: new Date().toISOString(),
        }];
      }
    }
    return [];
  },

  parseReadResponse(
    _serviceUUID: string,
    _charUUID: string,
    _data: ArrayBuffer,
  ): NormalizedReading[] {
    // 读取模式暂不支持，使用通知模式获取数据
    return [];
  },
};

export default XiaomiBandAdapter;