using SharpDX;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Media.Media3D;

namespace SparkClient.Views.UserControl.ViewportData.Helper
{
    internal class LineCalculationHelper
    {
        private readonly float Y = -0.01F;
        private Vector3 point1;
        private Vector3 point2;
        /// <summary>
        /// 常数a（y=ax+b）
        /// </summary>
        private float a;
        /// <summary>
        /// 常数b（y=ax+b）
        /// </summary>
        private float b;
        public LineCalculationHelper(Vector3 point1, Vector3 point2) { 
            this.point1 = point1;
            this.point2 = point2;
            this.a = calA(point1, point2);
            this.b = calB(point1, a);
        }
        /// <summary>
        /// 常数a的计算
        /// </summary>
        /// <param name="point1"></param>
        /// <param name="point2"></param>
        /// <returns></returns>
        private float calA(Vector3 point1, Vector3 point2)
        {
            return (point1.Z - point2.Z) / (point1.X - point2.X);
        }
        /// <summary>
        /// 常数b的计算
        /// </summary>
        /// <param name="point1"></param>
        /// <param name="a"></param>
        /// <returns></returns>
        private float calB(Vector3 point1, float a)
        {
            return -(a * point1.X)+point1.Z;
        }

        public Tuple<Vector3, Vector3> calXline(float length)
        {
            var x1 = 5;
            var z1 = calZ(x1);
            var x2 = -5;
            var z2 = calZ(x2);
            return new Tuple<Vector3, Vector3>(new Vector3(x1, Y, z1), new Vector3(x2, Y, z2));
        }
        public Tuple<Vector3, Vector3> calYline(float length)
        {
            var x1 = 5;
            var z1 = calZVertical(x1);
            var x2 = -5;
            var z2 = calZVertical(x2);
            return new Tuple<Vector3, Vector3>(new Vector3(x1, Y, z1), new Vector3(x2, Y, z2));
        }

        public Tuple<Vector3, Vector3> calLineOfOffset(Tuple<Vector3, Vector3> tuple, float d)
        {
            var point1 = tuple.Item1;
            var point2 = tuple.Item2;
            var x1 = point1.X - d * (point2.Z - point1.Z)/
            (float)Math.Sqrt(Square(point2.X - point1.X) + Square(point2.Z - point1.Z));
            var z1 = point1.Z + d * (point2.X - point1.X) /
            (float)Math.Sqrt(Square(point2.X - point1.X) + Square(point2.Z - point1.Z));

            var x2 = point2.X - d * (point2.Z - point1.Z) /
            (float)Math.Sqrt(Square(point2.X - point1.X) + Square(point2.Z - point1.Z));
            var z2 = point2.Z + d * (point2.X - point1.X) /
           (float)Math.Sqrt(Square(point2.X - point1.X) + Square(point2.Z - point1.Z));
            return new Tuple<Vector3, Vector3>(new Vector3(x1, Y, z1), new Vector3(x2, Y, z2));
        }

        float Square(float number)
        {
            return number * number;
        }

        public float calZ(float x, float offset = 0)
        {
            return a * x + b + offset;
        }

        public float calZVertical(float x, float offset = 0)
        {
            return (-x / a)  + b + offset;
        }
    }
}