import geomagnetism from 'geomagnetism';

export function useGeomagnetism() {
  const bd09toWgs84 = (bd_lat, bd_lng) => {
    const x_pi = (3.14159265358979324 * 3000.0) / 180.0;
    const x = Number(bd_lng) - 0.0065;
    const y = Number(bd_lat) - 0.006;
    const z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * x_pi);
    const theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * x_pi);
    return {
      lat: z * Math.sin(theta) - 0.002,
      lng: z * Math.cos(theta) - 0.005
    };
  };

  const calculate = (latitude, longitude, altitude = 0) => {
    try {
      // 强制转换
      const numLat = parseFloat(latitude);
      const numLng = parseFloat(longitude);

      if (isNaN(numLat) || isNaN(numLng)) {
        console.warn('磁偏角计算: 无效的经纬度', { latitude, longitude });
        return { declination: 0, success: false };
      }

      const wgs = bd09toWgs84(numLat, numLng);
      
      // 获取地磁模型 - geomagnetism.model(date) 返回模型实例
      const model = geomagnetism.model(new Date());
      
      if (!model || typeof model.point !== 'function') {
        console.error("无法加载地磁模型或模型没有point方法");
        return { declination: 0, success: false };
      }

      // point() 方法接受数组参数 [lat, lon, altitude]
      // 根据库源码，参数顺序是 [lat, lon, altitude]
      const info = model.point([wgs.lat, wgs.lng, altitude]);

      if (!info) {
        console.error('model.point() 返回 null 或 undefined');
        return { declination: 0, success: false };
      }

      // 根据 geomagnetism 库的类型定义，返回值属性名是 decl（不是 declination）
      const decl = info.decl;

      if (typeof decl !== 'number' || isNaN(decl)) {
        console.warn('磁偏角值无效:', decl, 'info对象:', info);
        return { declination: 0, success: false };
      }

      return {
        declination: decl,
        success: true
      };
    } catch (e) {
      console.error('磁偏角计算过程出错:', e);
      console.error('错误堆栈:', e.stack);
      return { declination: 0, success: false };
    }
  };

  return { calculate };
}