const pi = 3.14159265358979324
const a = 6378245.0
const ee = 0.00669342162296594323

/**
 * WGS84坐标转换GCJ02坐标
 * @param wgLat：wgs纬度
 * @param wgLon：wgs经度
 * @return Array[lat:gcj纬度,lon:gcj经度]
 */
function wgs84togcj02(wgLat, wgLon) {
  let mgLat, mgLon
  if (outOfChina(wgLat, wgLon)) {
    console.log('out of china')
    return
  }
  let dLat = transformLat(wgLon - 105.0, wgLat - 35.0)
  let dLon = transformLon(wgLon - 105.0, wgLat - 35.0)
  let radLat = (wgLat / 180.0) * pi
  let magic = Math.sin(radLat)
  magic = 1 - ee * magic * magic
  let sqrtMagic = Math.sqrt(magic)
  dLat = (dLat * 180.0) / (((a * (1 - ee)) / (magic * sqrtMagic)) * pi)
  dLon = (dLon * 180.0) / ((a / sqrtMagic) * Math.cos(radLat) * pi)
  mgLat = wgLat + dLat
  mgLon = wgLon + dLon
  let arr = {}
  arr['lat'] = mgLat
  arr['lon'] = mgLon
  return arr
}
function outOfChina(lat, lon) {
  if (lon < 72.004 || lon > 137.8347) return true
  if (lat < 0.8293 || lat > 55.8271) return true
  return false
}
function transformLat(x, y) {
  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 * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0) / 3.0
  ret += ((20.0 * Math.sin(y * pi) + 40.0 * Math.sin((y / 3.0) * pi)) * 2.0) / 3.0
  ret += ((160.0 * Math.sin((y / 12.0) * pi) + 320 * Math.sin((y * pi) / 30.0)) * 2.0) / 3.0
  return ret
}
function transformLon(x, y) {
  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 * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0) / 3.0
  ret += ((20.0 * Math.sin(x * pi) + 40.0 * Math.sin((x / 3.0) * pi)) * 2.0) / 3.0
  ret += ((150.0 * Math.sin((x / 12.0) * pi) + 300.0 * Math.sin((x / 30.0) * pi)) * 2.0) / 3.0
  return ret
}

export default wgs84togcj02