/********************************************************************************
* ReactPhysics3D physics library, http://www.reactphysics3d.com                 *
* Copyright (c) 2010-2018 Daniel Chappuis                                       *
*********************************************************************************
*                                                                               *
* 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.                                                         *
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* 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.    *
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********************************************************************************/

// Libraries
#include "CapsuleVsConvexPolyhedronAlgorithm.h"
#include "SAT/SATAlgorithm.h"
#include "GJK/GJKAlgorithm.h"
#include "collision/shapes/CapsuleShape.h"
#include "collision/shapes/ConvexPolyhedronShape.h"
#include "collision/narrowphase/NarrowPhaseInfoBatch.h"
#include "collision/ContactPointInfo.h"
#include <cassert>

// We want to use the ReactPhysics3D namespace
using namespace reactphysics3d;

// Compute the narrow-phase collision detection between a capsule and a polyhedron
// This technique is based on the "Robust Contact Creation for Physics Simulations" presentation
// by Dirk Gregorius.
bool CapsuleVsConvexPolyhedronAlgorithm::testCollision(NarrowPhaseInfoBatch& narrowPhaseInfoBatch,
                                                       uint batchStartIndex, uint batchNbItems,
                                                       bool reportContacts, bool stopFirstContactFound,
                                                       MemoryAllocator& memoryAllocator) {

    bool isCollisionFound = false;

    // First, we run the GJK algorithm
    GJKAlgorithm gjkAlgorithm;
    SATAlgorithm satAlgorithm(memoryAllocator);

#ifdef IS_PROFILING_ACTIVE

	gjkAlgorithm.setProfiler(mProfiler);
	satAlgorithm.setProfiler(mProfiler);

#endif

    // Run the GJK algorithm
    List<GJKAlgorithm::GJKResult> gjkResults(memoryAllocator);
    gjkAlgorithm.testCollision(narrowPhaseInfoBatch, batchStartIndex, batchNbItems, gjkResults, reportContacts);
    assert(gjkResults.size() == batchNbItems);

    for (uint batchIndex = batchStartIndex; batchIndex < batchStartIndex + batchNbItems; batchIndex++) {

        // Get the last frame collision info
        LastFrameCollisionInfo* lastFrameCollisionInfo = narrowPhaseInfoBatch.lastFrameCollisionInfos[batchIndex];

        lastFrameCollisionInfo->wasUsingGJK = true;
        lastFrameCollisionInfo->wasUsingSAT = false;

        assert(narrowPhaseInfoBatch.collisionShapes1[batchIndex]->getType() == CollisionShapeType::CONVEX_POLYHEDRON ||
               narrowPhaseInfoBatch.collisionShapes2[batchIndex]->getType() == CollisionShapeType::CONVEX_POLYHEDRON);
        assert(narrowPhaseInfoBatch.collisionShapes1[batchIndex]->getType() == CollisionShapeType::CAPSULE ||
               narrowPhaseInfoBatch.collisionShapes2[batchIndex]->getType() == CollisionShapeType::CAPSULE);

        // If we have found a contact point inside the margins (shallow penetration)
        if (gjkResults[batchIndex] == GJKAlgorithm::GJKResult::COLLIDE_IN_MARGIN) {

            if (reportContacts) {

                bool noContact = false;

                // GJK has found a shallow contact. If the face of the polyhedron mesh is orthogonal to the
                // capsule inner segment and parallel to the contact point normal, we would like to create
                // two contact points instead of a single one (as in the deep contact case with SAT algorithm)

                // Get the contact point created by GJK
                assert(narrowPhaseInfoBatch.contactPoints[batchIndex].size() > 0);
                ContactPointInfo*& contactPoint = narrowPhaseInfoBatch.contactPoints[batchIndex][0];

                bool isCapsuleShape1 = narrowPhaseInfoBatch.collisionShapes1[batchIndex]->getType() == CollisionShapeType::CAPSULE;

                // Get the collision shapes
                const CapsuleShape* capsuleShape = static_cast<const CapsuleShape*>(isCapsuleShape1 ? narrowPhaseInfoBatch.collisionShapes1[batchIndex] : narrowPhaseInfoBatch.collisionShapes2[batchIndex]);
                const ConvexPolyhedronShape* polyhedron = static_cast<const ConvexPolyhedronShape*>(isCapsuleShape1 ? narrowPhaseInfoBatch.collisionShapes2[batchIndex] : narrowPhaseInfoBatch.collisionShapes1[batchIndex]);

                // For each face of the polyhedron
                for (uint f = 0; f < polyhedron->getNbFaces(); f++) {

                    const Transform polyhedronToWorld = isCapsuleShape1 ? narrowPhaseInfoBatch.shape2ToWorldTransforms[batchIndex] : narrowPhaseInfoBatch.shape1ToWorldTransforms[batchIndex];
                    const Transform capsuleToWorld = isCapsuleShape1 ? narrowPhaseInfoBatch.shape1ToWorldTransforms[batchIndex] : narrowPhaseInfoBatch.shape2ToWorldTransforms[batchIndex];

                    // Get the face normal
                    const Vector3 faceNormal = polyhedron->getFaceNormal(f);
                    Vector3 faceNormalWorld = polyhedronToWorld.getOrientation() * faceNormal;

                    const Vector3 capsuleSegA(0, -capsuleShape->getHeight() * decimal(0.5), 0);
                    const Vector3 capsuleSegB(0, capsuleShape->getHeight() * decimal(0.5), 0);
                    Vector3 capsuleInnerSegmentDirection = capsuleToWorld.getOrientation() * (capsuleSegB - capsuleSegA);
                    capsuleInnerSegmentDirection.normalize();

                    bool isFaceNormalInDirectionOfContactNormal = faceNormalWorld.dot(contactPoint->normal) > decimal(0.0);
                    bool isFaceNormalInContactDirection = (isCapsuleShape1 && !isFaceNormalInDirectionOfContactNormal) || (!isCapsuleShape1 && isFaceNormalInDirectionOfContactNormal);

                    // If the polyhedron face normal is orthogonal to the capsule inner segment and parallel to the contact point normal and the face normal
                    // is in direction of the contact normal (from the polyhedron point of view).
                    if (isFaceNormalInContactDirection && areOrthogonalVectors(faceNormalWorld, capsuleInnerSegmentDirection)
                        && areParallelVectors(faceNormalWorld, contactPoint->normal)) {

                        // Remove the previous contact point computed by GJK
                        narrowPhaseInfoBatch.resetContactPoints(batchIndex);

                        const Transform capsuleToWorld = isCapsuleShape1 ? narrowPhaseInfoBatch.shape1ToWorldTransforms[batchIndex] : narrowPhaseInfoBatch.shape2ToWorldTransforms[batchIndex];
                        const Transform polyhedronToCapsuleTransform = capsuleToWorld.getInverse() * polyhedronToWorld;

                        // Compute the end-points of the inner segment of the capsule
                        const Vector3 capsuleSegA(0, -capsuleShape->getHeight() * decimal(0.5), 0);
                        const Vector3 capsuleSegB(0, capsuleShape->getHeight() * decimal(0.5), 0);

                        // Convert the inner capsule segment points into the polyhedron local-space
                        const Transform capsuleToPolyhedronTransform = polyhedronToCapsuleTransform.getInverse();
                        const Vector3 capsuleSegAPolyhedronSpace = capsuleToPolyhedronTransform * capsuleSegA;
                        const Vector3 capsuleSegBPolyhedronSpace = capsuleToPolyhedronTransform * capsuleSegB;

                        const Vector3 separatingAxisCapsuleSpace = polyhedronToCapsuleTransform.getOrientation() * faceNormal;

                        if (isCapsuleShape1) {
                            faceNormalWorld = -faceNormalWorld;
                        }

                        // Compute and create two contact points
                        bool contactsFound = satAlgorithm.computeCapsulePolyhedronFaceContactPoints(f, capsuleShape->getRadius(), polyhedron, contactPoint->penetrationDepth,
                                                                  polyhedronToCapsuleTransform, faceNormalWorld, separatingAxisCapsuleSpace,
                                                                  capsuleSegAPolyhedronSpace, capsuleSegBPolyhedronSpace,
                                                                  narrowPhaseInfoBatch, batchIndex, isCapsuleShape1);
                        if (!contactsFound) {
                            noContact = true;
                            narrowPhaseInfoBatch.isColliding[batchIndex] = false;
                            break;
                        }

                        break;
                    }
                }

                if (noContact) {
                    continue;
                }
            }

            lastFrameCollisionInfo->wasUsingSAT = false;
            lastFrameCollisionInfo->wasUsingGJK = false;

            // Colision found
            narrowPhaseInfoBatch.isColliding[batchIndex] = true;
            isCollisionFound = true;
            if (stopFirstContactFound) {
                return isCollisionFound;
            }
            continue;
        }

        // If we have overlap even without the margins (deep penetration)
        if (gjkResults[batchIndex] == GJKAlgorithm::GJKResult::INTERPENETRATE) {

            // Run the SAT algorithm to find the separating axis and compute contact point
            narrowPhaseInfoBatch.isColliding[batchIndex] = satAlgorithm.testCollisionCapsuleVsConvexPolyhedron(narrowPhaseInfoBatch, batchIndex, reportContacts);

            lastFrameCollisionInfo->wasUsingGJK = false;
            lastFrameCollisionInfo->wasUsingSAT = true;

            if (narrowPhaseInfoBatch.isColliding[batchIndex]) {
                isCollisionFound = true;
                if (stopFirstContactFound) {
                    return isCollisionFound;
                }
            }
        }
    }

    return isCollisionFound;
}