/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

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.

*/

// Modified by Lasse Oorni for Urho3D

#include "BulletCollision/CollisionDispatch/btCompoundCollisionAlgorithm.h"
#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
#include "BulletCollision/CollisionShapes/btCompoundShape.h"
#include "BulletCollision/BroadphaseCollision/btDbvt.h"
#include "LinearMath/btIDebugDraw.h"
#include "LinearMath/btAabbUtil2.h"
#include "btManifoldResult.h"
#include "BulletCollision/CollisionDispatch/btCollisionObjectWrapper.h"

btShapePairCallback gCompoundChildShapePairCallback = 0;

btCompoundCollisionAlgorithm::btCompoundCollisionAlgorithm( const btCollisionAlgorithmConstructionInfo& ci,const btCollisionObjectWrapper* body0Wrap,const btCollisionObjectWrapper* body1Wrap,bool isSwapped)
:btActivatingCollisionAlgorithm(ci,body0Wrap,body1Wrap),
m_isSwapped(isSwapped),
m_sharedManifold(ci.m_manifold)
{
	m_ownsManifold = false;

	const btCollisionObjectWrapper* colObjWrap = m_isSwapped? body1Wrap : body0Wrap;
	btAssert (colObjWrap->getCollisionShape()->isCompound());
	
	const btCompoundShape* compoundShape = static_cast<const btCompoundShape*>(colObjWrap->getCollisionShape());
	m_compoundShapeRevision = compoundShape->getUpdateRevision();
	
	
	preallocateChildAlgorithms(body0Wrap,body1Wrap);
}

void	btCompoundCollisionAlgorithm::preallocateChildAlgorithms(const btCollisionObjectWrapper* body0Wrap,const btCollisionObjectWrapper* body1Wrap)
{
	const btCollisionObjectWrapper* colObjWrap = m_isSwapped? body1Wrap : body0Wrap;
	const btCollisionObjectWrapper* otherObjWrap = m_isSwapped? body0Wrap : body1Wrap;
	btAssert (colObjWrap->getCollisionShape()->isCompound());
	
	const btCompoundShape* compoundShape = static_cast<const btCompoundShape*>(colObjWrap->getCollisionShape());

	int numChildren = compoundShape->getNumChildShapes();
	int i;
	
	m_childCollisionAlgorithms.resize(numChildren);
	for (i=0;i<numChildren;i++)
	{
		if (compoundShape->getDynamicAabbTree())
		{
			m_childCollisionAlgorithms[i] = 0;
		} else
		{
			
			const btCollisionShape* childShape = compoundShape->getChildShape(i);

			btCollisionObjectWrapper childWrap(colObjWrap,childShape,colObjWrap->getCollisionObject(),colObjWrap->getWorldTransform(),-1,i);//wrong child trans, but unused (hopefully)
			m_childCollisionAlgorithms[i] = m_dispatcher->findAlgorithm(&childWrap,otherObjWrap,m_sharedManifold);
		}
	}
}

void	btCompoundCollisionAlgorithm::removeChildAlgorithms()
{
	int numChildren = m_childCollisionAlgorithms.size();
	int i;
	for (i=0;i<numChildren;i++)
	{
		if (m_childCollisionAlgorithms[i])
		{
			m_childCollisionAlgorithms[i]->~btCollisionAlgorithm();
			m_dispatcher->freeCollisionAlgorithm(m_childCollisionAlgorithms[i]);
		}
	}
}

btCompoundCollisionAlgorithm::~btCompoundCollisionAlgorithm()
{
	removeChildAlgorithms();
}




struct	btCompoundLeafCallback : btDbvt::ICollide
{

public:

	const btCollisionObjectWrapper* m_compoundColObjWrap;
	const btCollisionObjectWrapper* m_otherObjWrap;
	btDispatcher* m_dispatcher;
	const btDispatcherInfo& m_dispatchInfo;
	btManifoldResult*	m_resultOut;
	btCollisionAlgorithm**	m_childCollisionAlgorithms;
	btPersistentManifold*	m_sharedManifold;
	
	btCompoundLeafCallback (const btCollisionObjectWrapper* compoundObjWrap,const btCollisionObjectWrapper* otherObjWrap,btDispatcher* dispatcher,const btDispatcherInfo& dispatchInfo,btManifoldResult*	resultOut,btCollisionAlgorithm**	childCollisionAlgorithms,btPersistentManifold*	sharedManifold)
		:m_compoundColObjWrap(compoundObjWrap),m_otherObjWrap(otherObjWrap),m_dispatcher(dispatcher),m_dispatchInfo(dispatchInfo),m_resultOut(resultOut),
		m_childCollisionAlgorithms(childCollisionAlgorithms),
		m_sharedManifold(sharedManifold)
	{

	}


	void	ProcessChildShape(const btCollisionShape* childShape,int index)
	{
		btAssert(index>=0);
		const btCompoundShape* compoundShape = static_cast<const btCompoundShape*>(m_compoundColObjWrap->getCollisionShape());
		btAssert(index<compoundShape->getNumChildShapes());


		//backup
		btTransform	orgTrans = m_compoundColObjWrap->getWorldTransform();
		btTransform	orgInterpolationTrans = m_compoundColObjWrap->getWorldTransform();
		const btTransform& childTrans = compoundShape->getChildTransform(index);
		btTransform	newChildWorldTrans = orgTrans*childTrans ;

		//perform an AABB check first
		btVector3 aabbMin0,aabbMax0,aabbMin1,aabbMax1;
		childShape->getAabb(newChildWorldTrans,aabbMin0,aabbMax0);
		m_otherObjWrap->getCollisionShape()->getAabb(m_otherObjWrap->getWorldTransform(),aabbMin1,aabbMax1);

		if (gCompoundChildShapePairCallback)
		{
			if (!gCompoundChildShapePairCallback(m_otherObjWrap->getCollisionShape(), childShape))
				return;
		}

		if (TestAabbAgainstAabb2(aabbMin0,aabbMax0,aabbMin1,aabbMax1))
		{

			btCollisionObjectWrapper compoundWrap(this->m_compoundColObjWrap,childShape,m_compoundColObjWrap->getCollisionObject(),newChildWorldTrans,-1,index);


			//the contactpoint is still projected back using the original inverted worldtrans
			if (!m_childCollisionAlgorithms[index])
				m_childCollisionAlgorithms[index] = m_dispatcher->findAlgorithm(&compoundWrap,m_otherObjWrap,m_sharedManifold);

			
			const btCollisionObjectWrapper* tmpWrap = 0;

			///detect swapping case
			if (m_resultOut->getBody0Internal() == m_compoundColObjWrap->getCollisionObject())
			{
				tmpWrap = m_resultOut->getBody0Wrap();
				m_resultOut->setBody0Wrap(&compoundWrap);
				m_resultOut->setShapeIdentifiersA(-1,index);
			} else
			{
				tmpWrap = m_resultOut->getBody1Wrap();
				m_resultOut->setBody1Wrap(&compoundWrap);
				m_resultOut->setShapeIdentifiersB(-1,index);
			}


			m_childCollisionAlgorithms[index]->processCollision(&compoundWrap,m_otherObjWrap,m_dispatchInfo,m_resultOut);

#if 0
			if (m_dispatchInfo.m_debugDraw && (m_dispatchInfo.m_debugDraw->getDebugMode() & btIDebugDraw::DBG_DrawAabb))
			{
				btVector3 worldAabbMin,worldAabbMax;
				m_dispatchInfo.m_debugDraw->drawAabb(aabbMin0,aabbMax0,btVector3(1,1,1));
				m_dispatchInfo.m_debugDraw->drawAabb(aabbMin1,aabbMax1,btVector3(1,1,1));
			}
#endif

			if (m_resultOut->getBody0Internal() == m_compoundColObjWrap->getCollisionObject())
			{
				m_resultOut->setBody0Wrap(tmpWrap);
			} else
			{
				m_resultOut->setBody1Wrap(tmpWrap);
			}
			
		}
	}
	void		Process(const btDbvtNode* leaf)
	{
		int index = leaf->dataAsInt;

		const btCompoundShape* compoundShape = static_cast<const btCompoundShape*>(m_compoundColObjWrap->getCollisionShape());
		const btCollisionShape* childShape = compoundShape->getChildShape(index);

#if 0
		if (m_dispatchInfo.m_debugDraw && (m_dispatchInfo.m_debugDraw->getDebugMode() & btIDebugDraw::DBG_DrawAabb))
		{
			btVector3 worldAabbMin,worldAabbMax;
			btTransform	orgTrans = m_compoundColObjWrap->getWorldTransform();
			btTransformAabb(leaf->volume.Mins(),leaf->volume.Maxs(),0.,orgTrans,worldAabbMin,worldAabbMax);
			m_dispatchInfo.m_debugDraw->drawAabb(worldAabbMin,worldAabbMax,btVector3(1,0,0));
		}
#endif

		ProcessChildShape(childShape,index);

	}
};






void btCompoundCollisionAlgorithm::processCollision (const btCollisionObjectWrapper* body0Wrap,const btCollisionObjectWrapper* body1Wrap,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
{
	const btCollisionObjectWrapper* colObjWrap = m_isSwapped? body1Wrap : body0Wrap;
	const btCollisionObjectWrapper* otherObjWrap = m_isSwapped? body0Wrap : body1Wrap;

	btAssert (colObjWrap->getCollisionShape()->isCompound());
	const btCompoundShape* compoundShape = static_cast<const btCompoundShape*>(colObjWrap->getCollisionShape());

    // Urho3D: do not go further if compound does not have child shapes, to prevent assert
    if (!compoundShape->getNumChildShapes())
        return;

	///btCompoundShape might have changed:
	////make sure the internal child collision algorithm caches are still valid
	if (compoundShape->getUpdateRevision() != m_compoundShapeRevision)
	{
		///clear and update all
		removeChildAlgorithms();
		
		preallocateChildAlgorithms(body0Wrap,body1Wrap);
	}


	const btDbvt* tree = compoundShape->getDynamicAabbTree();
	//use a dynamic aabb tree to cull potential child-overlaps
	btCompoundLeafCallback  callback(colObjWrap,otherObjWrap,m_dispatcher,dispatchInfo,resultOut,&m_childCollisionAlgorithms[0],m_sharedManifold);

	///we need to refresh all contact manifolds
	///note that we should actually recursively traverse all children, btCompoundShape can nested more then 1 level deep
	///so we should add a 'refreshManifolds' in the btCollisionAlgorithm
	{
		int i;
		btManifoldArray manifoldArray;
		for (i=0;i<m_childCollisionAlgorithms.size();i++)
		{
			if (m_childCollisionAlgorithms[i])
			{
				m_childCollisionAlgorithms[i]->getAllContactManifolds(manifoldArray);
				for (int m=0;m<manifoldArray.size();m++)
				{
					if (manifoldArray[m]->getNumContacts())
					{
						resultOut->setPersistentManifold(manifoldArray[m]);
						resultOut->refreshContactPoints();
						resultOut->setPersistentManifold(0);//??necessary?
					}
				}
				manifoldArray.resize(0);
			}
		}
	}

	if (tree)
	{

		btVector3 localAabbMin,localAabbMax;
		btTransform otherInCompoundSpace;
		otherInCompoundSpace = colObjWrap->getWorldTransform().inverse() * otherObjWrap->getWorldTransform();
		otherObjWrap->getCollisionShape()->getAabb(otherInCompoundSpace,localAabbMin,localAabbMax);

		const ATTRIBUTE_ALIGNED16(btDbvtVolume)	bounds=btDbvtVolume::FromMM(localAabbMin,localAabbMax);
		//process all children, that overlap with  the given AABB bounds
		tree->collideTV(tree->m_root,bounds,callback);

	} else
	{
		//iterate over all children, perform an AABB check inside ProcessChildShape
		int numChildren = m_childCollisionAlgorithms.size();
		int i;
		for (i=0;i<numChildren;i++)
		{
			callback.ProcessChildShape(compoundShape->getChildShape(i),i);
		}
	}

	{
				//iterate over all children, perform an AABB check inside ProcessChildShape
		int numChildren = m_childCollisionAlgorithms.size();
		int i;
		btManifoldArray	manifoldArray;
        const btCollisionShape* childShape = 0;
        btTransform	orgTrans;
        btTransform	orgInterpolationTrans;
        btTransform	newChildWorldTrans;
        btVector3 aabbMin0,aabbMax0,aabbMin1,aabbMax1;        
        
		for (i=0;i<numChildren;i++)
		{
			if (m_childCollisionAlgorithms[i])
			{
				childShape = compoundShape->getChildShape(i);
			//if not longer overlapping, remove the algorithm
                orgTrans = colObjWrap->getWorldTransform();
                orgInterpolationTrans = colObjWrap->getWorldTransform();
				const btTransform& childTrans = compoundShape->getChildTransform(i);
                newChildWorldTrans = orgTrans*childTrans ;

				//perform an AABB check first
				childShape->getAabb(newChildWorldTrans,aabbMin0,aabbMax0);
				otherObjWrap->getCollisionShape()->getAabb(otherObjWrap->getWorldTransform(),aabbMin1,aabbMax1);

				if (!TestAabbAgainstAabb2(aabbMin0,aabbMax0,aabbMin1,aabbMax1))
				{
					m_childCollisionAlgorithms[i]->~btCollisionAlgorithm();
					m_dispatcher->freeCollisionAlgorithm(m_childCollisionAlgorithms[i]);
					m_childCollisionAlgorithms[i] = 0;
				}
			}
		}
	}
}

btScalar	btCompoundCollisionAlgorithm::calculateTimeOfImpact(btCollisionObject* body0,btCollisionObject* body1,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
{
	btAssert(0);
	//needs to be fixed, using btCollisionObjectWrapper and NOT modifying internal data structures
	btCollisionObject* colObj = m_isSwapped? body1 : body0;
	btCollisionObject* otherObj = m_isSwapped? body0 : body1;

	btAssert (colObj->getCollisionShape()->isCompound());
	
	btCompoundShape* compoundShape = static_cast<btCompoundShape*>(colObj->getCollisionShape());

	//We will use the OptimizedBVH, AABB tree to cull potential child-overlaps
	//If both proxies are Compound, we will deal with that directly, by performing sequential/parallel tree traversals
	//given Proxy0 and Proxy1, if both have a tree, Tree0 and Tree1, this means:
	//determine overlapping nodes of Proxy1 using Proxy0 AABB against Tree1
	//then use each overlapping node AABB against Tree0
	//and vise versa.

	btScalar hitFraction = btScalar(1.);

	int numChildren = m_childCollisionAlgorithms.size();
	int i;
    btTransform	orgTrans;
    btScalar frac;
	for (i=0;i<numChildren;i++)
	{
		//btCollisionShape* childShape = compoundShape->getChildShape(i);

		//backup
        orgTrans = colObj->getWorldTransform();
	
		const btTransform& childTrans = compoundShape->getChildTransform(i);
		//btTransform	newChildWorldTrans = orgTrans*childTrans ;
		colObj->setWorldTransform( orgTrans*childTrans );

		//btCollisionShape* tmpShape = colObj->getCollisionShape();
		//colObj->internalSetTemporaryCollisionShape( childShape );
        frac = m_childCollisionAlgorithms[i]->calculateTimeOfImpact(colObj,otherObj,dispatchInfo,resultOut);
		if (frac<hitFraction)
		{
			hitFraction = frac;
		}
		//revert back
		//colObj->internalSetTemporaryCollisionShape( tmpShape);
		colObj->setWorldTransform( orgTrans);
	}
	return hitFraction;

}



