/*
 * @Name:
 * @Descripttion:
 * @Warning:
 * @version:
 * @Author: moo
 * @Date: 2021-01-11 13:56:53
 * @LastEditors: moo
 * @LastEditTime: 2021-01-11 15:50:00
 */
package utils

import (
	"math"
)

const (
	pi   float64 = 3.1415926535897932384626
	x_pi float64 = 3.14159265358979324 * 3000.0 / 180.0
	a    float64 = 6378245.0
	ee   float64 = 0.00669342162296594323
)

type GPSMODE int

const (
	GPSMODE_WGS84 GPSMODE = 0 // 国际标准，GPS坐标（Google Earth使用、或者GPS模块）
	GPSMODE_GCJ02 GPSMODE = 1 // 中国坐标偏移标准，Google Map、高德、腾讯使用
	GPSMODE_BD09  GPSMODE = 2 // 百度坐标偏移标准
)

/**
 * GPS84、高德、百度、腾讯编码互转
 */

func transformLat(x float64, y float64) float64 {
	var ret float64
	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
}

func transformLon(x float64, y float64) float64 {
	var ret float64
	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
}
func transformGps(lat float64, lon float64) []float64 {
	if outOfChina(lat, lon) {
		return []float64{lat, lon}
	}
	dLat := transformLat(lon-105.0, lat-35.0)
	dLon := transformLon(lon-105.0, lat-35.0)
	radLat := lat / 180.0 * pi
	magic := math.Sin(radLat)
	magic = 1 - ee*magic*magic
	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 := lat + dLat
	mgLon := lon + dLon
	return []float64{mgLat, mgLon}
}

/**
 * 判断是否在中国
 * @param lat
 * @param lon
 * @return
 */
func outOfChina(lat float64, lon float64) bool {
	if lon < 72.004 || lon > 137.8347 {
		return true
	}
	if lat < 0.8293 || lat > 55.8271 {
		return true
	}
	return false
}

/**
 * 84 ==》 高德/腾讯
 * @param lat
 * @param lon
 * @return
 */
func Gps84ToGcj02(lat float64, lon float64) []float64 {
	if outOfChina(lat, lon) {
		return []float64{lat, lon}
	}
	dLat := transformLat(lon-105.0, lat-35.0)
	dLon := transformLon(lon-105.0, lat-35.0)
	radLat := lat / 180.0 * pi
	magic := math.Sin(radLat)
	magic = 1 - ee*magic*magic
	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 := lat + dLat
	mgLon := lon + dLon
	return []float64{mgLat, mgLon}
}

/**
 * 高德/腾讯 ==》 84
 * @param lon * @param lat * @return
 * */
func Gcj02ToGps84(lat float64, lon float64) []float64 {
	gps := transformGps(lat, lon)
	lontitude := lon*2 - gps[1]
	latitude := lat*2 - gps[0]
	return []float64{latitude, lontitude}
}

/**
 * 高德/腾讯 == 》 百度
 * @param lat
 * @param lon
 */
func Gcj02ToBd09(lat float64, lon float64) []float64 {
	x := lon
	y := lat
	z := math.Sqrt(x*x+y*y) + 0.00002*math.Sin(y*x_pi)
	theta := math.Atan2(y, x) + 0.000003*math.Cos(x*x_pi)
	tempLon := z*math.Cos(theta) + 0.0065
	tempLat := z*math.Sin(theta) + 0.006
	gps := []float64{tempLat, tempLon}
	return gps
}

/**
 * 百度 == 》 高德/腾讯
 * @param lat
 * @param lon
 */
func Bd09ToGcj02(lat float64, lon float64) []float64 {
	x := lon - 0.0065
	y := lat - 0.006
	z := math.Sqrt(x*x+y*y) - 0.00002*math.Sin(y*x_pi)
	theta := math.Atan2(y, x) - 0.000003*math.Cos(x*x_pi)
	tempLon := z * math.Cos(theta)
	tempLat := z * math.Sin(theta)
	gps := []float64{tempLat, tempLon}
	return gps
}

/**
 * 84 == 》 百度
 * @param lat
 * @param lon
 * @return
 */
func Gps84ToBd09(lat float64, lon float64) []float64 {
	gcj02 := Gps84ToGcj02(lat, lon)
	bd09 := Gcj02ToBd09(gcj02[0], gcj02[1])
	return bd09
}

/**
 * 百度 == 》 84
 * @param lat
 * @param lon
 * @return
 */
func Bd09ToGps84(lat float64, lon float64) []float64 {
	gcj02 := Bd09ToGcj02(lat, lon)
	gps84 := Gcj02ToGps84(gcj02[0], gcj02[1])
	//保留小数点后六位
	gps84[0] = retain6(gps84[0])
	gps84[1] = retain6(gps84[1])
	return gps84
}

/*
 * 保留小数点后六位
 * @param num
 * @return
 */
func retain6(num float64) float64 {
	// result := fmt.Sprintf("%.6f", num)
	// return Double.valueOf(result)
	result := TruncFloat(num, 0.000001)
	return result
}

/**
func main() {
	a1 := gps84_To_Gcj02(31.3055205, 121.1405001)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.3051180, 121.1404452)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.3053301, 121.1408431)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.3053266, 121.1392659)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.3039517, 121.1389722)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.2996405, 121.1384954)
	fmt.Println(a1)
	a1 = gps84_To_Gcj02(31.3065345, 121.1413582)
	fmt.Println(a1)
}
**/

func EarthDistance(lat1, lng1, lat2, lng2 float64) float64 {
	// radius := 6378.137 //return: km
	radius := float64(6378137) //return: m
	rad := math.Pi / 180.0
	lat1 = lat1 * rad
	lng1 = lng1 * rad
	lat2 = lat2 * rad
	lng2 = lng2 * rad
	theta := lng2 - lng1
	dist := math.Acos(math.Sin(lat1)*math.Sin(lat2) + math.Cos(lat1)*math.Cos(lat2)*math.Cos(theta))
	return dist * radius
}