using GummingEntity;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace GummingSupport
{
    public enum CrossingType
    {
        UnDefined, //未定义
        Parallel,//平行
        SolidCross,//实线相交
        DottedCross,//虚线相交

    }
    public class LineCheck
    {
        /// <summary>
        /// 判断两条线是否相交
        /// </summary>
        /// <param name="a">线段1起点坐标</param>
        /// <param name="b">线段1终点坐标</param>
        /// <param name="c">线段2起点坐标</param>
        /// <param name="d">线段2终点坐标</param>
        /// <param name="intersection">相交点坐标</param>
        /// <returns>是否相交 0:两线平行  -1:不平行且未相交  1:两线相交</returns>
        public static CrossingType GetCrossingType(Point a, Point b, Point c, Point d, ref Point intersection)
        {
            //判断异常
            if (Math.Abs(b.x - a.y) + Math.Abs(b.x - a.x) + Math.Abs(d.y - c.y) + Math.Abs(d.x - c.x) == 0)
            {
                if (c.x - a.x == 0)
                {
                    return CrossingType.UnDefined;// Debug.Print("ABCD是同一个点！");
                }
                else
                {
                    return CrossingType.UnDefined;//Debug.Print("AB是一个点，CD是一个点，且AC不同！");
                }
            }

            if (Math.Abs(b.y - a.y) + Math.Abs(b.x - a.x) == 0)
            {
                if ((a.x - d.x) * (c.y - d.y) - (a.y - d.y) * (c.x - d.x) == 0)
                {
                    return CrossingType.UnDefined;// Debug.Print("A、B是一个点，且在CD线段上！");
                }
                else
                {
                    return CrossingType.UnDefined;//Debug.Print("A、B是一个点，且不在CD线段上！");
                }
            }
            if (Math.Abs(d.y - c.y) + Math.Abs(d.x - c.x) == 0)
            {
                if ((d.x - b.x) * (a.y - b.y) - (d.y - b.y) * (a.x - b.x) == 0)
                {
                    return CrossingType.UnDefined;//Debug.Print("C、D是一个点，且在AB线段上！");
                }
                else
                {
                    return CrossingType.UnDefined;//Debug.Print("C、D是一个点，且不在AB线段上！");
                }
            }

            if ((b.y - a.y) * (c.x - d.x) - (b.x - a.x) * (c.y - d.y) == 0)
            {
                return CrossingType.Parallel; //Debug.Print("线段平行，无交点！");
            }

            intersection.x = ((b.x - a.x) * (c.x - d.x) * (c.y - a.y) - c.x * (b.x - a.x) * (c.y - d.y) + a.x * (b.y - a.y) * (c.x - d.x)) / ((b.y - a.y) * (c.x - d.x) - (b.x - a.x) * (c.y - d.y));
            intersection.y = ((b.y - a.y) * (c.y - d.y) * (c.x - a.x) - c.y * (b.y - a.y) * (c.x - d.x) + a.y * (b.x - a.x) * (c.y - d.y)) / ((b.x - a.x) * (c.y - d.y) - (b.y - a.y) * (c.x - d.x));

            //使用0.1 是避免浮点型数据产生极小误差
            if ((intersection.x - a.x) * (intersection.x - b.x) <= 0.1 && (intersection.x - c.x) * (intersection.x - d.x) <= 0.1 && (intersection.y - a.y) * (intersection.y - b.y) <= 0.1 && (intersection.y - c.y) * (intersection.y - d.y) <= 0.1)
            {
                return CrossingType.SolidCross; //Debug.Print("线段相交于点(" + intersection.x + "," + intersection.y + ")！");
            }
            else
            {
                return CrossingType.DottedCross; //Debug.Print("线段相交于虚交点(" + intersection.x + "," + intersection.y + ")！");
            }
        }

        public static void GetRegion(Point a, Point b, Point c, Point d, ref Point e, ref Point f)
        {
            double xMax = (a.x > b.x) ? a.x : b.x;
            double yMax = (a.y > b.y) ? a.y : b.y;
            double xMin = (a.x < b.x) ? a.x : b.x;
            double yMin = (a.y < b.y) ? a.y : b.y;

            xMax = (xMax > c.x) ? xMax : c.x;
            yMax = (yMax > c.y) ? yMax : c.y;
            xMin = (xMin < c.x) ? xMin : c.x;
            yMin = (yMin < c.y) ? yMin : c.y;

            xMax = (xMax > d.x) ? xMax : d.x;
            yMax = (yMax > d.y) ? yMax : d.y;
            xMin = (xMin < d.x) ? xMin : d.x;
            yMin = (yMin < d.y) ? yMin : d.y;

            e = new GummingEntity.Point(xMin, yMin);
            f = new GummingEntity.Point(xMax, yMax);
        }


        public static double GetDistanceP2L(double x, double y, double x1, double y1, double x2, double y2)
        {
            double cross = (x2 - x1) * (x - x1) + (y2 - y1) * (y - y1);
            if (cross <= 0) return Math.Sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1));

            double d2 = (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);
            if (cross >= d2) return Math.Sqrt((x - x2) * (x - x2) + (y - y2) * (y - y2));

            double r = cross / d2;
            double px = x1 + (x2 - x1) * r;
            double py = y1 + (y2 - y1) * r;
            return Math.Sqrt((x - px) * (x - px) + (py - y1) * (py - y1));
        }
    }
}