package main

import (
	"fmt"
	"math"
)

type ProgramsInfo struct {
	Id            string
	CreatedAt     string
	UpdatedAt     string
	Name          string
	Desc          string
	Type          string
	Arch          string
	LatestVersion string
	LatestPackage string
}

var Data = `{"code":200,"data":[],"msg":"请求处理成功","success":true}`

type Point struct {
	Log float64 //经度X
	Lat float64 //维度Y
}

func main() {
	ps := []Point{{116.3325833222656, 40.04070204153866}, {116.41635407421873, 40.042804758324685}, {116.42184723828123, 39.98495642053631}, {116.3380764863281, 39.98179964655109}}
	n1 := Point{116.36966217968748, 40.01651613780475}
	//n1 := Point{116.3710354707031,39.92916527606944}
	fmt.Print(IsPointInPolygon(n1, ps))

}

func IsPointInPolygon(point Point, points []Point) bool {
	N := len(points)
	boundOrVertex := true //点在多边形顶点或者边上，算作多边形内
	intersectCount := 0
	precision := 2e-10 //浮点类型计算时候与0比较时候的容差
	var p1, p2 Point
	p := point //当前点
	p1 = points[0]
	for i := 0; i <= N; i++ {
		if p == p1 {
			return boundOrVertex
		}

		p2 = points[i%N]
		if p.Log < math.Min(p1.Log, p2.Log) || p.Log > math.Max(p1.Log, p2.Log) {
			p1 = p2
			continue
		}
		if p.Log > math.Min(p1.Log, p2.Log) && p.Log < math.Max(p1.Log, p2.Log) {
			if p.Lat <= math.Max(p1.Lat, p2.Lat) {

				if p1.Log == p2.Log && p.Lat >= math.Min(p1.Lat, p2.Lat) {
					return boundOrVertex
				}

				if p1.Lat == p2.Lat {
					if p1.Lat == p.Lat {
						return boundOrVertex
					} else {
						intersectCount++
					}
				} else {
					xinters := (p.Log-p1.Log)*(p2.Lat-p1.Lat)/(p2.Log-p1.Log) + p1.Lat
					if math.Abs(p.Lat-xinters) < precision {
						return boundOrVertex
					}

					if p.Lat < xinters {
						intersectCount++
					}
				}
			}

		} else {
			if p.Log == p2.Log && p.Lat <= p2.Lat {
				p3 := points[(i+1)%N]
				if p.Log >= math.Min(p1.Log, p3.Log) && p.Log <= math.Max(p1.Log, p3.Log) {
					intersectCount++
				} else {
					intersectCount += 2
				}
			}
		}
		p1 = p2
	}

	if intersectCount%2 == 0 { //偶数在多边形内
		return false
	} else { //奇数在多边形外
		return true
	}
}

//func IsPointInPolygon(point Point, points []Point) bool {
//	var iSum, iCount, iIndex int32
//	var dLog1, dLog2, dLat1, dLat2, dLog float64
//	if len(points) < 3 {
//		return false
//	}
//	iCount = int32(len(points))
//	for iIndex = 0; iIndex < iCount; iIndex++ {
//		dLog1 = points[iIndex].Log
//		dLat1 = points[iIndex].Lat
//		if iIndex == iCount-1 {
//			dLog2 = points[0].Log
//			dLat2 = points[0].Lat
//		} else {
//			dLog2 = points[iIndex+1].Log
//			dLat2 = points[iIndex+1].Lat
//		}
//		//判断A点是否在边的两端点的水平平行线之间，在则可能有交点，开始判断交点，开始判断交点是否在左射线上
//		if ((point.Lat >= dLat1) && (point.Lat < dLat2)) || ((point.Lat >= dLat2) && (point.Lat < dLat1)) {
//			if math.Abs(dLat1-dLat2) > 0 {
//				//得到A点向左射线与边的交点的x坐标
//				dLog = dLog - ((dLog1-dLog2)*(dLat1-point.Lat))/(dLat1-dLat2)
//				//如果交点在A点左侧（说明是左射线与边的交点），则射线与边的全部交点数加一
//				if dLog < point.Log {
//					iSum++
//				}
//			}
//		}
//	}
//	if (iSum % 2) != 0 {
//		return true
//	}
//	return false
//}