namespace IStation.Curve
{

    /// <summary>
    /// 贝塞尔曲线类(二次)
    /// </summary>
    public class Bezier2
    {
        /// <summary>
        /// 
        /// </summary>
        public Bezier2() { }

        /// <summary>
        /// 
        /// </summary>
        public Bezier2(List<CurvePoint> points)
        {
            if (points == null || points.Count < 3)
            {
                throw new Exception("参数错误，无法解出二次贝塞尔曲线！");
            }

            this.Point0 = points[0];
            this.Point1 = points[1];
            this.Point2 = points[2];
        }


        /// <summary>
        /// 开始点
        /// </summary>
        public CurvePoint Point0 { get; set; }

        /// <summary>
        /// 开始点的控制点
        /// </summary>
        public CurvePoint Point1 { get; set; }

        /// <summary>
        /// 结束点
        /// </summary>
        public CurvePoint Point2 { get; set; }

        /// <summary>
        /// 获取 X 用于插值
        /// </summary>
        public double GetX(double uu)
        {
            return Point0.X * Math.Pow(1 - uu, 2) +
                       Point1.X * uu * (1 - uu) * 2 +
                       Point2.X * Math.Pow(uu, 2);
        }

        /// <summary>
        /// 获取 Y 用于插值
        /// </summary>
        public double GetY(double uu)
        {
            return Point0.Y * Math.Pow(1 - uu, 2) +
                       Point1.Y * uu * (1 - uu) * 2 +
                       Point2.Y * Math.Pow(uu, 2);
        }

        /// <summary>
        /// 通过 X 获取交点Y值
        /// </summary>
        public bool GetSectPointYByX(double x, out double sect_y)
        {
            sect_y = 0;
            //贝塞尔曲线与性能曲线有交点 
            if ((x <= this.Point0.X && x >= this.Point2.X) || (x >= this.Point0.X && x <= this.Point2.X))
            {
                #region 贝塞尔曲线集合循环
                //第一次循环
                for (int i = 0; i < 10; i++)
                {
                    var start0_uu = i * 0.1;
                    var end0_uu = start0_uu + 0.1;
                    var start0_p_x = this.GetX(start0_uu);
                    //var start0_p_y = this.GetY(start0_uu);
                    var end0_p_x = this.GetX(end0_uu);
                    //var end0_p_y = this.GetY(end0_uu);
                    if ((x <= start0_p_x && x >= end0_p_x) || (x >= start0_p_x && x <= end0_p_x))
                    {
                        //第二次循环
                        for (int j = 0; j < 10; j++)
                        {
                            var start1_uu = start0_uu + j * 0.01;
                            var end1_uu = start1_uu + 0.01;
                            var start1_p_x = this.GetX(start1_uu);
                            //var start1_p_y = this.GetY(start1_uu);
                            var end1_p_x = this.GetX(end1_uu);
                            //var end1_p_y = this.GetY(end1_uu);
                            if ((x <= start1_p_x && x >= end1_p_x) || (x >= start1_p_x && x <= end1_p_x))
                            {
                                //第三次循环
                                for (int k = 0; k < 10; k++)
                                {
                                    var start2_uu = start1_uu + k * 0.001;
                                    var end2_uu = start2_uu + 0.001;
                                    var start2_p_x = this.GetX(start2_uu);
                                    //var start2_p_y = this.GetY(start2_uu);
                                    var end2_p_x = this.GetX(end2_uu);
                                    //var end2_p_y = this.GetY(end2_uu);
                                    if ((x <= start2_p_x && x >= end2_p_x) || (x >= start2_p_x && x <= end2_p_x))
                                    {
                                        var set_x = (start2_p_x + end2_p_x) / 2;
                                        sect_y = this.GetX((start2_uu + end2_uu) / 2);

                                        return true;
                                    }
                                }
                                break;
                            }
                        }
                        break;
                    }

                }
                #endregion
            }

            return false;
        }

        /// <summary>
        /// 最近的点
        /// </summary>
        public CurvePoint GetClosePoint(CurvePoint ref_pt)
        {
            double boundary_min_x = Math.Min(Point0.X, Point2.X);
            double boundary_max_x = Math.Max(Point0.X, Point2.X);
            double boundary_min_y = Math.Min(Point0.Y, Point2.Y);
            double boundary_max_y = Math.Max(Point0.Y, Point2.Y);

            double ratio_x = 0;
            if (boundary_max_x == boundary_min_x)
            {
                ratio_x = 100 / (boundary_max_x);
            }
            else
            {
                ratio_x = 100 / (boundary_max_x - boundary_min_x);
            }


            double ratio_y = 0;
            if (boundary_max_y == boundary_min_y)
            {
                ratio_y = 100 / (boundary_max_y);
            }
            else
            {
                ratio_y = 100 / (boundary_max_y - boundary_min_y);
            }

            double chart_ref_x = (ref_pt.X - boundary_min_x) * ratio_x;
            double chart_ref_y = (ref_pt.Y - boundary_min_y) * ratio_y;

            CurvePoint sect = null;
            double min_dist = double.MaxValue;
            for (double uu = 0; uu <= 1; uu = uu + 0.01)
            {
                double chart_x = (GetX(uu) - boundary_min_x) * ratio_x - chart_ref_x;//由于流量扬程数量差别特别大, 所以假设他们在一个100*100的方格内,求距离
                double chart_y = (GetY(uu) - boundary_min_y) * ratio_y - chart_ref_y;
                double distance = chart_x * chart_x + chart_y * chart_y;
                if (distance < min_dist)
                {
                    min_dist = distance;
                    sect = new CurvePoint(GetX(uu), GetY(uu));
                }
            }

            return sect;
        }

        /// <summary>
        /// 求与曲线的交点 (可能有多个,但只取第一个点)
        /// </summary>
        public CurvePoint GetCrossPoint(CurveExpress curve)
        {
            if (curve == null)
                return null;

            //第一次迭代
            var index1 = GetCrossPointIndex_不迭代(curve, 0.2, 0, 5);
            if (index1 < 0)
                return null;

            //第二次迭代
            var index2 = GetCrossPointIndex_不迭代(curve, 0.02, 0.2 * index1, 10);
            if (index2 < 0)
                return null;
            double uu = 0.2 * index1 + 0.02 * index2;
            double x_bers = GetX(uu);
            double y_bers = FitHelper.GetFitPointY(curve, x_bers);

            return new CurvePoint(x_bers, y_bers);
        }

        //计算在第几个点相交(可能有多个,但只取第一个点):思路, 不断逼近,一个正数一个负数就表示有交点
        private int GetCrossPointIndex_不迭代(CurveExpress curve, double space, double start, int number)
        {
            double last_dis_y = 0;

            for (int i = 0; i <= number; i++)
            {
                double uu1 = start + space * i;
                double x_bers = GetX(uu1);
                double y_bers = GetY(uu1);
                double y_curve = FitHelper.GetFitPointY(curve, x_bers);
                double current_dis_y = y_bers - y_curve;
                if (uu1 == 0)
                {
                    last_dis_y = current_dis_y;
                    continue;
                }

                if ((current_dis_y > 0 && last_dis_y < 0) || (current_dis_y < 0 && last_dis_y > 0))
                {
                    return i - 1;
                }

                last_dis_y = current_dis_y;
            }

            return -1;
        }

        /// <summary>
        /// 变成一条一条直线端
        /// </summary>
        /// <param name="pointNumber">贝赛尔曲线中间插入的点数量</param>
        public List<CurvePoint> GetApexPoints(int pointNumber)
        {
            var points_sect_list = new List<CurvePoint>();
            for (int i = 0; i <= pointNumber; i++)
            {
                var uu = i * 1.0 / pointNumber;
                var p_x = this.GetX(uu);
                var p_y = this.GetY(uu);
                points_sect_list.Add(new CurvePoint(p_x, p_y));
            }

            return points_sect_list;
        }

        /// <summary>
        /// 获取距离
        /// </summary>
        public double Distance(CurvePoint point)
        {
            var point1 = GetClosePoint(point);
            return point.Distance(point1);
        }
    }
}