/**
 * @desc 根据两点间的经纬度计算距离
 * @param float $lat 纬度值
 * @param float $lng 经度值
 */
const getDistance = (lat1, lon1, lat2, lon2) => {
	console.log(lat1)
	console.log(lon1)
	console.log(lat2)
	console.log(lon2)
	let ew1, ns1, ew2, ns2;
	let distance;
	// 角度转换为弧度
	ew1 = lon1 * 0.01745329252;
	ns1 = lat1 * 0.01745329252;
	ew2 = lon2 * 0.01745329252;
	ns2 = lat2 * 0.01745329252;
	distance = distance = Math.sin(ns1) * Math.sin(ns2) + Math.cos(ns1) * Math.cos(ns2) *
		Math.cos(ew1 - ew2);
	// 调整到[-1..1]范围内，避免溢出
	if (distance > 1.0)
		distance = 1.0;
	else if (distance < -1.0)
		distance = -1.0;
	// 求大圆劣弧长度
	distance = 6370693.5 * Math.acos(distance);
	let isBig = false; // 是否为大于等于1000m
	if (distance >= 1000) {
		distance /= 1000;
		isBig = true;
	}

	return distance.toFixed(2) + (isBig ? "km" : "m");

}

export default getDistance