namespace IStation.Curve
{
    /// <summary>
    /// 曲线直线
    /// </summary>
    public class CurveLine : ICloneable
    {
        /// <summary>
        /// 
        /// </summary>
        public CurveLine() { }

        /// <summary>
        /// 
        /// </summary>
        public CurveLine(double x1, double y1, double x2, double y2)
        {
            this.Point0 = new CurvePoint(x1, y1);
            this.Point1 = new CurvePoint(x2, y2);
        }

        /// <summary>
        /// 
        /// </summary>
        public CurveLine(CurvePoint pt1, CurvePoint pt2)
        {
            this.Point0 = pt1;
            this.Point1 = pt2;
        }

        /// <summary>
        /// 
        /// </summary>
        public CurveLine(List<CurvePoint> pts)
        {
            if (pts == null || pts.Count < 2)
            {
                throw new Exception("参数错误，无法解析出直线！");
            }
            this.Point0 = pts[0];
            this.Point1 = pts[1];
        }

        /// <summary>
        /// 
        /// </summary>
        public CurveLine(CurveLine rhs)
        {
            this.Point0 = new CurvePoint(rhs.Point0);
            this.Point1 = new CurvePoint(rhs.Point1);
        }

        /// <summary>
        /// 第一个点
        /// </summary>
        public CurvePoint Point0 { get; set; }

        /// <summary>
        /// 第二个点
        /// </summary>
        public CurvePoint Point1 { get; set; }

        /// <summary>
        /// 获取插值Y
        /// </summary>
        public double GetInsertY(double x)
        {
            if (Math.Abs(this.Point1.X - this.Point0.X) < 0.000001)
            {
                return 0;
            }
            if (Math.Abs(this.Point1.Y - this.Point0.Y) < 0.000001)
            {
                return 0;
            }
            return this.Point0.Y + (this.Point1.Y - this.Point0.Y) / (this.Point1.X - this.Point0.X) * (x - this.Point0.X);
        }

        /// <summary>
        /// 是否一个点向x轴的射线穿透线段,有交点且在线的左边
        /// </summary>
        public bool IsIntersectLeft(CurvePoint pt)
        {
            double maxY = this.Point0.Y > this.Point1.Y ? this.Point0.Y : this.Point1.Y;
            double minY = this.Point0.Y > this.Point1.Y ? this.Point1.Y : this.Point0.Y;

            if (Math.Abs(this.Point1.Y - this.Point0.Y) < 0.000001)
            {
                if (Math.Abs(pt.Y - this.Point0.Y) < 0.000001)
                    return true;
                return false;
            }


            bool IsInLine = false;
            if (pt.Y < maxY && pt.Y >= minY)
            {
                if (pt.X <= (this.Point0.X + (this.Point1.X - this.Point0.X) * (pt.Y - this.Point0.Y) / (this.Point1.Y - this.Point0.Y)))
                {
                    IsInLine = true;
                }
            }
            return IsInLine;
        }

        /// <summary>
        /// 获取内部点
        /// </summary>
        public CurvePoint GetInnerPoint(double ratio)
        {
            var x = this.Point0.X + ratio * (this.Point1.X - this.Point0.X);
            var y = this.Point0.Y + ratio * (this.Point1.Y - this.Point0.Y);
            return new CurvePoint(x, y);
        }

        /// <summary>
        /// 获取内部X坐标
        /// </summary>
        public double GetInnerX(double ratio)
        {
            var x = this.Point0.X + ratio * (this.Point1.X - this.Point0.X);
            return x;
        }

        /// <summary>
        /// 获取内部Y坐标
        /// </summary>
        public double GetInnerY(double ratio)
        {
            var y = this.Point0.Y + ratio * (this.Point1.Y - this.Point0.Y);
            return y;
        }

        /// <summary>
        /// 返回直线的k和b y=kx+b
        /// </summary>
        public bool GetKandB(out double k, out double b, double ignore = 0.000001)
        {
            k = b = 0;

            if (Math.Abs(this.Point0.X - this.Point1.X) < ignore)
            {//竖直
                k = 100000000;
                b = this.Point0.X;
                return false;
            }
            if (Math.Abs(this.Point0.Y - this.Point1.Y) < ignore)
            {//平行
                k = 0;
                b = this.Point0.X;
                return true;
            }


            k = (this.Point0.Y - this.Point1.Y) / (this.Point0.X - this.Point1.X);// Math.Atan((pt1.Y - pt2.Y) / (pt1.X - pt2.X)) * 180 / Math.PI;
            b = this.Point0.Y - k * this.Point0.X;
            return true;
        }

        /// <summary>
        /// 通过 X 获取 Y
        /// </summary>
        public double GetYByX(double x)
        {
            if (!GetKandB(out double k, out double b))
            {
                return this.Point0.Y;
            }
            return k * x + b;
        }

        /// <summary>
        /// 通过 Y 获取 X
        /// </summary>
        public double GetXByY(double y)
        {
            if (!GetKandB(out double k, out double b))
            {
                return this.Point0.X;
            }
            return (y - b) / k;
        }

        /// <summary>
        /// 获取中间点
        /// </summary>
        public CurvePoint GetMiddlePoint()
        {
            return new CurvePoint((this.Point0.X + this.Point1.X) * 0.5, (this.Point0.Y + this.Point1.Y) * 0.5);
        }

        /// <summary>
        /// 通过 X 判断是否为内部点
        /// </summary>
        public bool IsInnerByX(double x)
        {
            if (x >= this.Point0.X && x <= this.Point1.X)
                return true;
            if (x >= this.Point1.X && x <= this.Point0.X)
                return true;
            return false;
        }

        /// <summary>
        /// 通过 Y 判断是否为内部点
        /// </summary>
        public bool IsInnerByY(double y)
        {
            if (y >= this.Point0.Y && y <= this.Point1.Y)
                return true;
            if (y >= this.Point1.Y && y <= this.Point0.Y)
                return true;
            return false;
        }

        /// <summary>
        /// 三个点在同一条直线上,输入(X1,Y1),(X2,Y2)以及沿(X2,Y2)侧延长Length,得到的点(X3,Y3)
        /// </summary>
        public CurvePoint GetExtendPoint(double length)
        {
            double betweenLength = this.Point0.Distance(this.Point1);
            if (betweenLength < 0.01)
                return this.Point0;

            var extPt = new CurvePoint();
            extPt.X = (this.Point1.X - this.Point0.X) * length / betweenLength + this.Point1.X;
            extPt.Y = (this.Point1.Y - this.Point0.Y) * length / betweenLength + this.Point1.Y;

            return extPt;
        }

        /// <summary>
        /// 求直线外一点到该直线的投影点
        /// </summary>
        public CurvePoint GetProjectivePoint(CurvePoint pOut)
        {
            if (!GetKandB(out double k, out double b))
                return default;
            return GetProjectivePoint(this.Point0, k, pOut);
        }

        /// <summary>
        /// 点到线的距离, 注意不一定是垂直距离,点只在(line_start和line_end之间
        /// </summary>
        public double Distance(CurvePoint pt)
        {
            var project_pt = GetProjectivePoint(pt);
            if (IsInnerByX(pt.X))
                return project_pt.Distance(pt);
            var dis1 = this.Point0.Distance(pt);
            var dis2 = this.Point1.Distance(pt);
            if (dis1 < dis2)
                return dis1;
            else
                return dis2;
        }

        /// <summary>
        /// 求直线外一点到该直线的投影点
        /// </summary>
        /// <param name="pl">线上任一点</param>
        /// <param name="k">直线斜率</param>
        /// <param name="pout">线外指定点</param>
        public static CurvePoint GetProjectivePoint(CurvePoint pl, double k, CurvePoint pout)
        {
            CurvePoint pProject = new CurvePoint();
            if (k == 0) //垂线斜率不存在情况
            {
                pProject.X = pout.X;
                pProject.Y = pout.Y;
            }
            else
            {
                pProject.X = (float)((k * pl.X + pout.X / k + pout.Y - pl.Y) / (1 / k + k));
                pProject.Y = (float)(-1 / k * (pProject.X - pout.X) + pout.Y);
            }
            return pProject;
        }


        /// <summary>
        /// 
        /// </summary>
        public CurveLine Clone()
        {
            return new CurveLine(this);
        }

        /// <summary>
        /// 
        /// </summary>
        object ICloneable.Clone()
        {
            return this.Clone();
        }

    }
}