export function wgs84ToGcj02(lat: number, lng: number): number[] {
  if (outOfChina(lat, lng)) return [lat, lng]
  const dLat = transformLat(lng - 105.0, lat - 35.0)
  const dLng = transformLng(lng - 105.0, lat - 35.0)
  const radLat = lat / 180.0 * Math.PI
  let magic = Math.sin(radLat)
  magic = 1 - 0.00669342162296594323 * magic * magic
  const sqrtMagic = Math.sqrt(magic)
  const dLat2 = (dLat * 180.0) / ((6335552.717000426 * magic) / (sqrtMagic) * Math.PI)
  const dLng2 = (dLng * 180.0) / ((6378245.0 / sqrtMagic * Math.cos(radLat)) * Math.PI)
  return [lat + dLat2, lng + dLng2]
}

function outOfChina(lat: number, lng: number): boolean {
  return (lng < 72.004 || lng > 137.8347 || lat < 0.8293 || lat > 55.8271)
}

function transformLat(x: number, y: number): number {
  let ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x))
  ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0
  ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0
  ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.PI / 30.0)) * 2.0 / 3.0
  return ret
}

function transformLng(x: number, y: number): number {
  let ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x))
  ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0
  ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0
  ret += (150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0
  return ret
}