/*
 * C# / XNA  port of Bullet (c) 2011 Mark Neale <[email protected]>
 *
 * Bullet Continuous Collision Detection and Physics Library
 * Copyright (c) 2003-2008 Erwin Coumans  http://www.bulletphysics.com/
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from
 * the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */
// Adapted from BulletXNA 73b2e1b9: namespace isolation, no XNA rendering, one type per file.
#nullable disable
#pragma warning disable CS1591, CS0168, CS0219, CS0414, CS0660, CS0661, CS0659, CS0693, CS8981, CS0108, CS0114
using HumanoidRetargeter.Core.Formats.Mmd.Bullet.LinearMath;

namespace HumanoidRetargeter.Core.Formats.Mmd.Bullet.BulletCollision;

internal class SubSimplexConvexCast : IConvexCast
{
	// to help with pool
	public SubSimplexConvexCast()
	{
	}

	public void Initialize(ConvexShape shapeA, ConvexShape shapeB, ISimplexSolverInterface simplexSolver)
	{
		m_convexA = shapeA;
		m_convexB = shapeB;
		m_simplexSolver = simplexSolver;
	}

	public SubSimplexConvexCast(ConvexShape shapeA, ConvexShape shapeB, ISimplexSolverInterface simplexSolver)
	{
		m_convexA = shapeA;
		m_convexB = shapeB;
		m_simplexSolver = simplexSolver;
	}

	public virtual bool CalcTimeOfImpact(ref IndexedMatrix fromA, ref IndexedMatrix toA, ref IndexedMatrix fromB, ref IndexedMatrix toB, CastResult result)
	{
		m_simplexSolver.Reset();
		IndexedVector3 linVelA = toA._origin - fromA._origin;
		IndexedVector3 linVelB = toB._origin - fromB._origin;
		float lambda = 0f;
		IndexedMatrix interpolatedTransA = fromA;
		IndexedMatrix interpolatedTransB = fromB;
		IndexedVector3 r = (linVelA - linVelB);
		IndexedVector3 v;
		IndexedVector3 supVertexA = fromA * m_convexA.LocalGetSupportingVertex(-r * fromA._basis);
		IndexedVector3 supVertexB = fromB * m_convexB.LocalGetSupportingVertex(r * fromB._basis);
		v = supVertexA - supVertexB;
		int maxIter = MAX_ITERATIONS;
		IndexedVector3 n = IndexedVector3.Zero;
		bool hasResult = false;
		IndexedVector3 c;
		float lastLambda = lambda;
		float dist2 = v.LengthSquared();
		float epsilon = 0.0001f;
		IndexedVector3 w, p;
		float VdotR;
		while ((dist2 > epsilon) && (maxIter-- > 0))
		{
			supVertexA = interpolatedTransA * (m_convexA.LocalGetSupportingVertex(-v * interpolatedTransA._basis));
			supVertexB = interpolatedTransB * (m_convexB.LocalGetSupportingVertex(v * interpolatedTransB._basis));
			w = supVertexA - supVertexB;
			float VdotW = IndexedVector3.Dot(v, w);
			if (lambda > 1.0f)
			{
				return false;
			}

			if (VdotW > 0f)
			{
				VdotR = IndexedVector3.Dot(v, r);
				if (VdotR >= -(MathUtil.SIMD_EPSILON * MathUtil.SIMD_EPSILON))
				{
					return false;
				}
				else
				{
					lambda = lambda - VdotW / VdotR;
					//interpolate to next lambda
					//	x = s + lambda * r;
					interpolatedTransA._origin = MathUtil.Interpolate3(fromA._origin, toA._origin, lambda);
					interpolatedTransB._origin = MathUtil.Interpolate3(fromB._origin, toB._origin, lambda);
					//m_simplexSolver.reset();
					//check next line
					w = supVertexA - supVertexB;
					lastLambda = lambda;
					n = v;
					hasResult = true;
				}
			}

			if (!m_simplexSolver.InSimplex(ref w))
			{
				m_simplexSolver.AddVertex(ref w, ref supVertexA, ref supVertexB);
			}

			if (m_simplexSolver.Closest(out v))
			{
				dist2 = v.LengthSquared();
				hasResult = true;
			//todo: check this normal for validity
			//n=v;
			//printf("V=%f , %f, %f\n",v[0],v[1],v[2]);
			//printf("DIST2=%f\n",dist2);
			//printf("numverts = %i\n",m_simplexSolver.numVertices());
			}
			else
			{
				dist2 = 0f;
			}
		}

		//int numiter = MAX_ITERATIONS - maxIter;
		//	printf("number of iterations: %d", numiter);
		//don't report a time of impact when moving 'away' from the hitnormal
		result.m_fraction = lambda;
		if (n.LengthSquared() >= (MathUtil.SIMD_EPSILON * MathUtil.SIMD_EPSILON))
		{
			result.m_normal = IndexedVector3.Normalize(n);
		}
		else
		{
			result.m_normal = IndexedVector3.Zero;
		}

		//don't report time of impact for motion away from the contact normal (or causes minor penetration)
		if (IndexedVector3.Dot(result.m_normal, r) >= -result.m_allowedPenetration)
		{
			return false;
		}

		IndexedVector3 hitA, hitB;
		m_simplexSolver.ComputePoints(out hitA, out hitB);
		result.m_hitPoint = hitB;
		return true;
	}

	private ISimplexSolverInterface m_simplexSolver;
	private ConvexShape m_convexA;
	private ConvexShape m_convexB;
	private static readonly int MAX_ITERATIONS = 32;
}