namespace Yw.Curve
{
    public static class CurvePoint_Extensions
    {

        /// <summary>
        /// 计算总长度
        /// </summary>
        public static double CalcuTotalLength(this List<CurvePoint> ptList)
        {
            if (ptList == null || ptList.Count < 1)
            {
                return default;
            }
            double length = 0;
            for (int i = 1; i < ptList.Count; i++)
            {
                length += ptList[i].Distance(ptList[i - 1]);
            }
            return length;
        }

        /// <summary>
        /// 获取Y最小的点
        /// </summary>
        public static CurvePoint GetPointByMinY(this List<CurvePoint> ptList)
        {
            if (ptList == null || ptList.Count < 1)
            {
                return default;
            }
            return ptList.OrderBy(x => x.Y).FirstOrDefault();
        }

        /// <summary>
        /// 获取Y最大的点
        /// </summary>
        public static CurvePoint GetPointByMaxY(this List<CurvePoint> ptList)
        {
            if (ptList == null || !ptList.Any())
            {
                return default;
            }
            return ptList.OrderBy(x => x.Y).LastOrDefault();
        }

        /// <summary>
        /// 获取Y最小的点索引
        /// </summary>
        public static int GetPointIndexByMinY(this List<CurvePoint> ptList)
        {
            var pt = GetPointByMinY(ptList);
            return ptList.IndexOf(pt);
        }

        /// <summary>
        /// 获取Y最大的点索引
        /// </summary>
        public static int GetPointIndexByMaxY(this List<CurvePoint> ptList)
        {
            var pt = GetPointByMaxY(ptList);
            return ptList.IndexOf(pt);
        }

        /// <summary>
        /// 根据X 获取点索引
        /// </summary>
        public static int GetPointIndexByX(this List<CurvePoint> ptList, double x)
        {
            if (ptList == null || !ptList.Any())
            {
                return -1;
            }
            int index = 0;
            foreach (var pt in ptList)
            {
                if (Math.Abs(pt.X - x) < 0.0001)
                {
                    return index;
                }
                index++;
            }
            return -1;
        }

        /// <summary>
        /// 获取X方向距离最小的点
        /// </summary>
        public static CurvePoint GetClosestPointByX(this List<CurvePoint> ptList, double x)
        {
            if (ptList == null || ptList.Count < 1)
            {
                return default;
            }
            var pt = ptList.OrderBy(t => Math.Abs(t.X - x)).FirstOrDefault();
            return pt;
        }

        /// <summary>
        /// 获取X方向距离最小的点索引
        /// </summary>
        public static int GetClosestPointIndexByX(this List<CurvePoint> ptList, double x)
        {
            var pt = GetClosestPointByX(ptList, x);
            return ptList.IndexOf(pt);
        }

        /// <summary>
        /// 获得X值的坐标位置,可能有多个点(是线形插值,不是曲线上的点)
        /// </summary>
        public static List<double> GetInterPointY(this List<CurvePoint> ptList, double x)
        {
            if (ptList == null || ptList.Count < 1)
            {
                return default;
            }
            var list = ptList.ToList();
            var equalPoints = new List<double>();
            int num = ptList.Count;
            for (int i = 0; i < num - 1; i++)//少一个点
            {
                if ((x >= list[i].X && x <= list[i + 1].X) || (x <= list[i].X && x >= list[i + 1].X))
                {//直线插值
                    double y;
                    if (Math.Abs(list[i].X - list[i + 1].X) < 0.01)
                        y = (list[i].Y + list[i + 1].Y) * 0.5;
                    else
                        y = list[i].Y + (list[i + 1].Y - list[i].Y) * (x - list[i].X) / (list[i + 1].X - list[i].X);

                    equalPoints.Add(y);
                }
            }
            return equalPoints;
        }

        /// <summary>
        /// ptList 是一个多边形,判断点是否在多边形里
        /// 原理是 通过p做一个+X方向的射线, 偶数个交点 就是在外部,奇数个就是在内部
        /// </summary>
        public static bool IsInPolygon(this IEnumerable<CurvePoint> ptList, CurvePoint p, bool isClosed = true)
        {
            if (ptList == null || ptList.Count() < 1)
                return default;
            var list = ptList.ToList();
            int crossNum = 0;

            for (int i = 0; i < list.Count() - 1; i++)
            {
                if (p.IsIntersectLineLeft(list[i], list[i + 1]))
                {
                    crossNum++;
                }
            }

            if (isClosed)
            {
                if (p.IsIntersectLineLeft(list[list.Count - 1], list[0]))
                {
                    crossNum++;
                }
            }

            if ((crossNum % 2) == 0)
                return false;
            else
                return true;
        }



    }
}