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

using System.Drawing;

using bbiwarg.Recognition.HandRecognition;

using Emgu.CV;
using Emgu.CV.Structure;

namespace bbiwarg.Utility
{
    class Quadrangle
    {
        public Vector2D[] Vertices { get { return new Vector2D[4] { TopLeft, TopRight, BottomRight, BottomLeft }; } }
        public Vector2D TopLeft { get; private set; }
        public Vector2D TopRight { get; private set; }
        public Vector2D BottomRight { get; private set; }
        public Vector2D BottomLeft { get; private set; }

        public Quadrangle(Vector2D topLeft, Vector2D topRight, Vector2D bottomRight, Vector2D bottomLeft)
        {
            TopLeft = topLeft;
            TopRight = topRight;
            BottomRight = bottomRight;
            BottomLeft = bottomLeft;
        }


        public Vector2D getRelativePosition(Vector2D p)
        {
            Vector2D a, b, c, d;

            a = TopLeft;
            b = TopRight;
            c = BottomRight;
            d = BottomLeft;

            float C = (a.Y - p.Y) * (d.X - p.X) - (a.X - p.X) * (d.Y - p.Y);
            float B = (a.Y - p.Y) * (c.X - d.X) + (b.Y - a.Y) * (d.X - p.X) - (a.X - p.X) * (c.Y - d.Y) - (b.X - a.X) * (d.Y - p.Y);
            float A = (b.Y - a.Y) * (c.X - d.X) - (b.X - a.X) * (c.Y - d.Y);

            float D = B * B - 4 * A * C;

            float u = (-B - (float)Math.Sqrt(D)) / (2 * A);

            float p1x = a.X + (b.X - a.X) * u;
            float p2x = d.X + (c.X - d.X) * u;
            float px = p.X;

            float v = (px - p1x) / (p2x - p1x);

            return new Vector2D(u, v);
        }

        public bool isInside(Vector2D point)
        {
            Vector2D relativePos = getRelativePosition(point);
            return (relativePos.X >= 0 && relativePos.X <= 1.0 && relativePos.Y >= 0 && relativePos.Y <= 1.0);
        }
    }
}