// Package timeutil
// @Author 铁憨憨[cory] 2025/6/11 20:08:00
package timeutil

import (
	"github.com/paulmach/orb"
	"github.com/paulmach/orb/geo"
	"github.com/paulmach/orb/planar"
	"github.com/tiger1103/gfast/v3/api/v1/common/shp"
	"math"
)

// 将 Polygon 结构体转换为 [][]float64 格式
func ConvertPolygonToFloatArray(polygon shp.Polygon) [][]float64 {
	// 创建结果切片，长度与 Polygon 中的 Positions 相同
	result := make([][]float64, len(polygon.Positions))

	// 遍历每个 Point 并转换为 []float64
	for i, point := range polygon.Positions {
		// 每个点转换为 [经度, 纬度, 高度, 宽度]
		result[i] = []float64{
			point.Lng,
			point.Lat,
			point.Alt,
			point.Width,
		}
	}

	return result
}

// 判断点是否在多边形内
func FanWei(mian [][]float64, dian []float64) bool {
	if len(mian) < 3 || len(dian) != 2 {
		return false
	}

	var ring orb.Ring
	for _, vertex := range mian {
		ring = append(ring, orb.Point{vertex[0], vertex[1]})
	}

	// 闭合环
	if !ring[0].Equal(ring[len(ring)-1]) {
		ring = append(ring, ring[0])
	}

	polygon := orb.Polygon{ring}
	point := orb.Point{dian[0], dian[1]}

	return planar.PolygonContains(polygon, point)
}

// 点到线段最近点（投影点）
func closestPointOnSegment(p, a, b orb.Point) orb.Point {
	ax, ay := a[0], a[1]
	bx, by := b[0], b[1]
	px, py := p[0], p[1]

	abx := bx - ax
	aby := by - ay
	apx := px - ax
	apy := py - ay

	t := (apx*abx + apy*aby) / (abx*abx + aby*aby)
	if t < 0 {
		t = 0
	} else if t > 1 {
		t = 1
	}

	return orb.Point{ax + t*abx, ay + t*aby}
}

// 点到多边形的最近距离（米）
func PointToPolygonDistance(mian [][]float64, dian []float64) float64 {
	point := orb.Point{dian[0], dian[1]}

	ring := make(orb.Ring, len(mian))
	for i, pt := range mian {
		ring[i] = orb.Point{pt[0], pt[1]}
	}

	// 闭合多边形
	if !ring[0].Equal(ring[len(ring)-1]) {
		ring = append(ring, ring[0])
	}

	polygon := orb.Polygon{ring}

	if planar.PolygonContains(polygon, point) {
		return 0
	}

	minDist := math.MaxFloat64
	for i := 0; i < len(ring)-1; i++ {
		proj := closestPointOnSegment(point, ring[i], ring[i+1])
		dist := geo.Distance(point, proj) // 单位：米
		if dist < minDist {
			minDist = dist
		}
	}
	return minDist
}

// 计算两个经纬度点之间的球面距离（单位：米）
func PointToPointDistance(p1 []float64, p2 []float64) float64 {
	point1 := orb.Point{p1[0], p1[1]}
	point2 := orb.Point{p2[0], p2[1]}
	return geo.Distance(point1, point2)
}

//func main() {
//	polygonVertices := [][]float64{
//		{106.518314, 29.627223},
//		{106.519419, 29.627223},
//		{106.518238, 29.626399},
//		{106.519491, 29.626435},
//	}
//
//	targetPoint := []float64{117.51, 40.74}
//
//	inPolygon := FanWei(polygonVertices, targetPoint)
//	fmt.Printf("点是否在多边形内：%v\n", inPolygon)
//
//	distance := pointToPolygonDistance(polygonVertices, targetPoint)
//	fmt.Printf("点到多边形的最短距离（单位米）：%.2f m\n", distance)
//}