/*
 * Copyright (C) 2012-2020 CypherCore <http://github.com/CypherCore>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

using System;
using System.Numerics;

namespace Framework.GameMath
{
    public class Box
    {
        public Vector3[] _edgeVector = new Vector3[3];
        public Vector3 _center;
        public float _area;
        public float _volume;

        public Box(Vector3 min, Vector3 max)
        {
            Vector3 bounds = new Vector3(max.X - min.X, max.Y - min.Y, max.Z - min.Z);
            _edgeVector[0] = new Vector3(bounds.X, 0, 0);
            _edgeVector[1] = new Vector3(0, bounds.Y, 0);
            _edgeVector[2] = new Vector3(0, 0, bounds.Z);
            bool finiteExtent = true;

            for (int i = 0; i < 3; ++i)
            {
                if (!float.IsInfinity(_edgeVector[i].Length()))
                {
                    finiteExtent = false;
                    // If the extent is infinite along an axis, make the center zero to avoid NaNs
                    _center.SetAt(0.0f, i);
                }
            }


            if (finiteExtent)
            {
                _volume = bounds.X * bounds.Y * bounds.Z;
            }
            else
            {
                _volume = float.PositiveInfinity;
            }

            _area = 2 *
                (bounds.X * bounds.Y +
                 bounds.Y * bounds.Z +
                 bounds.Z * bounds.X);
        }

        public bool Contains(Vector3 point)
        {
            Vector3 u = _edgeVector[2];
            Vector3 v = _edgeVector[1];
            Vector3 w = _edgeVector[0];

            Matrix4x4 M = new(u.X, v.X, w.X, 0.0f, u.Y, v.Y, w.Y, 0.0f, u.Z, v.Z, w.Z, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f);

            // M^-1 * (point - _corner[0]) = point in unit cube's object space
            // compute the inverse of M
            Matrix4x4.Invert(M, out M);
            Vector3 osPoint = Vector3.Transform(point - Corner(0), M);

            return (osPoint.X >= 0) && (osPoint.Y >= 0) && (osPoint.Z >= 0) &&
                (osPoint.X <= 1) && (osPoint.Y <= 1) && (osPoint.Z <= 1);
        }

        Vector3 Corner(int i)
        {
            switch (i)
            {
                case 0: return _center + (0.5f * (-_edgeVector[0] - _edgeVector[1] - _edgeVector[2]));
                case 1: return _center + (0.5f * (_edgeVector[0] - _edgeVector[1] - _edgeVector[2]));
                case 2: return _center + (0.5f * (-_edgeVector[0] + _edgeVector[1] - _edgeVector[2]));
                case 3: return _center + (0.5f * (_edgeVector[0] + _edgeVector[1] - _edgeVector[2]));
                case 4: return _center + (0.5f * (-_edgeVector[0] - _edgeVector[1] + _edgeVector[2]));
                case 5: return _center + (0.5f * (_edgeVector[0] - _edgeVector[1] + _edgeVector[2]));
                case 6: return _center + (0.5f * (-_edgeVector[0] + _edgeVector[1] + _edgeVector[2]));
                default: return _center + (0.5f * (_edgeVector[0] + _edgeVector[1] + _edgeVector[2]));//case 7
            }
        }

        public bool isFinite()
        {
            return float.IsInfinity(_volume);
        }
    }
}