namespace Yw.Curve
{
    /// <summary>
    /// 不拟合
    /// </summary>
    public class TwinRelateCurve0 : IFitPoint
    {
        /// <summary>
        /// 
        /// </summary>
        public TwinRelateCurve0(CurveExpress express)
        {
            _express = express;
        }

        /// <summary>
        /// 
        /// </summary>
        public TwinRelateCurve0(List<CurvePoint> points)
        {
            if (points == null || points.Count < 4)
            {
                throw new Exception("出现数值计算问题, 无法解出不拟合线！");
            }
            _express = BuildCurveExpress(points);
        }

        //曲线表达式
        private CurveExpress _express = null;


        /// <summary>
        /// 获取拟合点Y
        /// </summary>
        public double GetFitPointY(double x)
        {
            if (_express == null)
            {
                return default;
            }
            //尽量用贝塞尔曲线
            if (_express.DefinePoints != null && _express.DefinePoints.Count > 4)
            {
                var b = BezierCurveHelper.CreateOpenCurves(_express.DefinePoints);
                var s = BezierCurveHelper.GetSectPointsByX(b, x);
                if (s != null && s.Count > 0)
                {
                    return s.Last().Y;
                }
            }

            if (_express.DefinePoints != null && _express.DefinePoints.Count > 1)
            {
                var sect = _express.DefinePoints.GetInterPointY(x);
                if (sect == null || sect.Count < 1)
                {
                    return default;
                }
                return sect.First();
            }
            return default;
        }

        /// <summary>
        /// 获取拟合点列表
        /// </summary>
        public List<CurvePoint> GetFitPoints(int pointNumber)
        {
            if (_express == null)
            {
                return default;
            }
            return _express.DefinePoints;
        }

        /// <summary>
        /// 通过X区间获取拟合点列表
        /// </summary>
        public List<CurvePoint> GetFitPointsByXRange(double minX, double maxX, int pointNumber)
        {
            if (_express == null)
            {
                return default;
            }
            return _express.DefinePoints;
        }

        /// <summary>
        /// 创建曲线表达式
        /// </summary>
        public static CurveExpress BuildCurveExpress(List<CurvePoint> points)
        {
            if (points == null || points.Count < 4)
            {
                return default;
            }
            points = points.OrderBy(x => x.X).ToList();
            var express = new CurveExpress
            {
                FitType = eFitType.ThroughPoint,
                DefinePoints = points.Select(x => new CurvePoint(x)).ToList()
            };
            express.Min = points.Min(x => x.X);
            express.Max = points.Max(x => x.X);

            return express;
        }

    }
}