//转换常数
const x_pi = 3.14159265358979324 * 3000.0 / 180.0
const pi = 3.14159265358979324
const a = 6378245.0
const ee = 0.00669342162296594323

function transformLon(x, y) {
    var 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 * this.pi) + 20.0 * Math.sin(2.0 * x * this.pi)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(x * this.pi) + 40.0 * Math.sin(x / 3.0 * this.pi)) * 2.0 / 3.0;
    ret += (150.0 * Math.sin(x / 12.0 * this.pi) + 300.0 * Math.sin(x / 30.0 * this.pi)) * 2.0 / 3.0;
    return ret;
}

function transformLat(x, y) {
    var 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 * this.pi) + 20.0 * Math.sin(2.0 * x * this.pi)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(y * this.pi) + 40.0 * Math.sin(y / 3.0 * this.pi)) * 2.0 / 3.0;
    ret += (160.0 * Math.sin(y / 12.0 * this.pi) + 320 * Math.sin(y * this.pi / 30.0)) * 2.0 / 3.0;
    return ret;
}
// 判断是否在国内
function outOfChina(lat, lon) {
    if (lon < 72.004 || lon > 137.8347)
        return true;
    if (lat < 0.8293 || lat > 55.8271)
        return true;
    return false;
}

/* 
 WGS-84转换GCJ-02
（即 天地图转高德、腾讯地图）
 */
export const wgs_gcj_encrypts = (latlons) => {
    var point = [];
    for (const latlon of latlons) {
        if (this.outOfChina(latlon.lat, latlon.lng)) {
            point.push({
                lat: latlon.lat,
                lng: latlon.lng
            })
            return point;
        }
        var dLat = this.transformLat(latlon.lng - 105.0, latlon.lat - 35.0);
        var dLon = this.transformLon(latlon.lng - 105.0, latlon.lat - 35.0);
        var radLat = latlon.lat / 180.0 * this.pi;
        var magic = Math.sin(radLat);
        magic = 1 - this.ee * magic * magic;
        var sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((this.a * (1 - this.ee)) / (magic * sqrtMagic) * this.pi);
        dLon = (dLon * 180.0) / (this.a / sqrtMagic * Math.cos(radLat) * this.pi);
        var lat = latlon.lat + dLat;
        var lng = latlon.lng + dLon;
        point.push({
            lat: lat,
            lng: lng
        })
    }
    return point;
}

/* 
 BD-09转换GCJ-02
 （即 百度转高德、腾讯地图）
 */
export const bd_google_encrypt = (latlons) => {
    var point = [];
    for (const latlon of latlons) {
        var x = latlon.lng - 0.0065;
        var y = latlon.lat - 0.006;
        var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi);
        var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi);
        var gg_lon = z * Math.cos(theta);
        var gg_lat = z * Math.sin(theta);
        point.push({
            lat: gg_lon,
            lng: gg_lat
        })
    }
    return point;
}

/* 
 GCJ-02转换BD-09
 （即 高德、腾讯转百度地图）
 */
export const google_bd_encrypt = (latlons) => {
    var point = [];
    for (const latlon of latlons) {
        var x = latlon.lng;
        var y = latlon.lat;
        var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi);
        var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi);
        var bd_lon = z * Math.cos(theta) + 0.0065;
        var bd_lat = z * Math.sin(theta) + 0.006;
        point.push({
            lat: bd_lat,
            lng: bd_lon
        })
    }
    return point;
}

/* 
 GCJ-02 到 WGS-84 的转换
 （即 高德、腾讯转天地图）
 */
export const gcj_wgs_encrypts = (latlons) => {
    var point = [];
    for (const latlon of latlons) {
        if (this.outOfChina(latlon.lat, latlon.lng)) {
            point.push({
                lat: latlon.lat,
                lng: latlon.lng
            })
            return point;
        }
        var dLat = this.transformLat(latlon.lng - 105.0, latlon.lat - 35.0);
        var dLon = this.transformLon(latlon.lng - 105.0, latlon.lat - 35.0);
        var radLat = latlon.lat / 180.0 * this.pi;
        var magic = Math.sin(radLat);
        magic = 1 - this.ee * magic * magic;
        var sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((this.a * (1 - this.ee)) / (magic * sqrtMagic) * this.pi);
        dLon = (dLon * 180.0) / (this.a / sqrtMagic * Math.cos(radLat) * this.pi);
        var lat = dLat;
        var lng = dLon;
        point.push({
            lat: lat,
            lng: lng
        })
    }
    return point;
}