const isPointInPolygon =(aLat, aLon, pointList)=> {
  /* 
  :param aLon: double 经度 
  :param aLat: double 纬度 
  :param pointList: list [{latitude: 22.22, longitude: 113.113}...] 多边形点的顺序需根据顺时针或逆时针，不能乱 
  */
  var iSum = 0  
  var iCount = pointList.length
    
  if(iCount < 3) {
      return false 
  }
  for(var i = 0; i < iCount;i++) {
      var pLat1 = pointList[i][1] 
      var pLon1 = pointList[i][0]
      if(i == iCount - 1) {
          var pLat2 = pointList[0][1]
          var pLon2 = pointList[0][0]
      } else {
          var pLat2 = pointList[i + 1][1] 
          var pLon2 = pointList[i + 1][0]
      }
      if (((aLat >= pLat1) && (aLat < pLat2)) || ((aLat>=pLat2) && (aLat < pLat1))) {
          if (Math.abs(pLat1 - pLat2) > 0) {
              var pLon = pLon1 - ((pLon1 - pLon2) * (pLat1 - aLat)) / (pLat1 - pLat2);  
              if(pLon < aLon) {
                  iSum += 1 
              }
          }
      } 
  }
  if(iSum % 2 != 0) {
      return true  
  }else {
      return false 
  }  
}
module.exports = {
  isPointInPolygon,
};