/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  https://bulletphysics.org

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.
*/

#ifndef BT_PERSISTENT_MANIFOLD_H
#define BT_PERSISTENT_MANIFOLD_H

#include "../../LinearMath/btVector3.h"
#include "../../LinearMath/btTransform.h"
#include "btManifoldPoint.h"
class btCollisionObject;
#include "../../LinearMath/btAlignedAllocator.h"

struct btCollisionResult;
struct btCollisionObjectDoubleData;
struct btCollisionObjectFloatData;

///maximum contact breaking and merging threshold
extern btScalar gContactBreakingThreshold;

#ifndef SWIG
class btPersistentManifold;

typedef bool (*ContactDestroyedCallback)(void* userPersistentData);
typedef bool (*ContactProcessedCallback)(btManifoldPoint& cp, void* body0, void* body1);
typedef void (*ContactStartedCallback)(btPersistentManifold* const& manifold);
typedef void (*ContactEndedCallback)(btPersistentManifold* const& manifold);
extern ContactDestroyedCallback gContactDestroyedCallback;
extern ContactProcessedCallback gContactProcessedCallback;
extern ContactStartedCallback gContactStartedCallback;
extern ContactEndedCallback gContactEndedCallback;
#endif  //SWIG

//the enum starts at 1024 to avoid type conflicts with btTypedConstraint
enum btContactManifoldTypes
{
	MIN_CONTACT_MANIFOLD_TYPE = 1024,
	BT_PERSISTENT_MANIFOLD_TYPE
};

#define MANIFOLD_CACHE_SIZE 4

///btPersistentManifold is a contact point cache, it stays persistent as long as objects are overlapping in the broadphase.
///Those contact points are created by the collision narrow phase.
///The cache can be empty, or hold 1,2,3 or 4 points. Some collision algorithms (GJK) might only add one point at a time.
///updates/refreshes old contact points, and throw them away if necessary (distance becomes too large)
///reduces the cache to 4 points, when more then 4 points are added, using following rules:
///the contact point with deepest penetration is always kept, and it tries to maximuze the area covered by the points
///note that some pairs of objects might have more then one contact manifold.

//ATTRIBUTE_ALIGNED128( class) btPersistentManifold : public btTypedObject
ATTRIBUTE_ALIGNED16(class)
btPersistentManifold : public btTypedObject
{
	btManifoldPoint m_pointCache[MANIFOLD_CACHE_SIZE];

	/// this two body pointers can point to the physics rigidbody class.
	const btCollisionObject* m_body0;
	const btCollisionObject* m_body1;

	int m_cachedPoints;

	btScalar m_contactBreakingThreshold;
	btScalar m_contactProcessingThreshold;

	/// sort cached points so most isolated points come first
	int sortCachedPoints(const btManifoldPoint& pt);

	int findContactPoint(const btManifoldPoint* unUsed, int numUnused, const btManifoldPoint& pt);

public:
	BT_DECLARE_ALIGNED_ALLOCATOR();

	int m_companionIdA;
	int m_companionIdB;

	int m_index1a;

	btPersistentManifold();

	btPersistentManifold(const btCollisionObject* body0, const btCollisionObject* body1, int, btScalar contactBreakingThreshold, btScalar contactProcessingThreshold)
		: btTypedObject(BT_PERSISTENT_MANIFOLD_TYPE),
		  m_body0(body0),
		  m_body1(body1),
		  m_cachedPoints(0),
		  m_contactBreakingThreshold(contactBreakingThreshold),
		  m_contactProcessingThreshold(contactProcessingThreshold),
		  m_companionIdA(0),
		  m_companionIdB(0),
		  m_index1a(0)
	{
	}

	SIMD_FORCE_INLINE const btCollisionObject* getBody0() const { return m_body0; }
	SIMD_FORCE_INLINE const btCollisionObject* getBody1() const { return m_body1; }

	void setBodies(const btCollisionObject* body0, const btCollisionObject* body1)
	{
		m_body0 = body0;
		m_body1 = body1;
	}

	void clearUserCache(btManifoldPoint & pt);

#ifdef DEBUG_PERSISTENCY
	void DebugPersistency();
#endif  //

	SIMD_FORCE_INLINE int getNumContacts() const
	{
		return m_cachedPoints;
	}
	/// the setNumContacts API is usually not used, except when you gather/fill all contacts manually
	void setNumContacts(int cachedPoints)
	{
		m_cachedPoints = cachedPoints;
	}

	SIMD_FORCE_INLINE const btManifoldPoint& getContactPoint(int index) const
	{
		btAssert(index < m_cachedPoints);
		return m_pointCache[index];
	}

	SIMD_FORCE_INLINE btManifoldPoint& getContactPoint(int index)
	{
		btAssert(index < m_cachedPoints);
		return m_pointCache[index];
	}

	///@todo: get this margin from the current physics / collision environment
	btScalar getContactBreakingThreshold() const;

	btScalar getContactProcessingThreshold() const
	{
		return m_contactProcessingThreshold;
	}

	void setContactBreakingThreshold(btScalar contactBreakingThreshold)
	{
		m_contactBreakingThreshold = contactBreakingThreshold;
	}

	void setContactProcessingThreshold(btScalar contactProcessingThreshold)
	{
		m_contactProcessingThreshold = contactProcessingThreshold;
	}

	int getCacheEntry(const btManifoldPoint& newPoint) const;

	int addManifoldPoint(const btManifoldPoint& newPoint, bool isPredictive = false);

	void removeContactPoint(int index)
	{
		clearUserCache(m_pointCache[index]);

		int lastUsedIndex = getNumContacts() - 1;
		//		m_pointCache[index] = m_pointCache[lastUsedIndex];
		if (index != lastUsedIndex)
		{
			m_pointCache[index] = m_pointCache[lastUsedIndex];
			//get rid of duplicated userPersistentData pointer
			m_pointCache[lastUsedIndex].m_userPersistentData = 0;
			m_pointCache[lastUsedIndex].m_appliedImpulse = 0.f;
			m_pointCache[lastUsedIndex].m_prevRHS = 0.f;
			m_pointCache[lastUsedIndex].m_contactPointFlags = 0;
			m_pointCache[lastUsedIndex].m_appliedImpulseLateral1 = 0.f;
			m_pointCache[lastUsedIndex].m_appliedImpulseLateral2 = 0.f;
			m_pointCache[lastUsedIndex].m_lifeTime = 0;
		}

		btAssert(m_pointCache[lastUsedIndex].m_userPersistentData == 0);
		m_cachedPoints--;

		if (gContactEndedCallback && m_cachedPoints == 0)
		{
			gContactEndedCallback(this);
		}
	}
	void replaceContactPoint(const btManifoldPoint& newPoint, int insertIndex)
	{
		btAssert(validContactDistance(newPoint));

#define MAINTAIN_PERSISTENCY 1
#ifdef MAINTAIN_PERSISTENCY
		int lifeTime = m_pointCache[insertIndex].getLifeTime();
		btScalar appliedImpulse = m_pointCache[insertIndex].m_appliedImpulse;
		btScalar prevRHS = m_pointCache[insertIndex].m_prevRHS;
		btScalar appliedLateralImpulse1 = m_pointCache[insertIndex].m_appliedImpulseLateral1;
		btScalar appliedLateralImpulse2 = m_pointCache[insertIndex].m_appliedImpulseLateral2;

		bool replacePoint = true;
		///we keep existing contact points for friction anchors
		///if the friction force is within the Coulomb friction cone
		if (newPoint.m_contactPointFlags & BT_CONTACT_FLAG_FRICTION_ANCHOR)
		{
			//   printf("appliedImpulse=%f\n", appliedImpulse);
			//   printf("appliedLateralImpulse1=%f\n", appliedLateralImpulse1);
			//   printf("appliedLateralImpulse2=%f\n", appliedLateralImpulse2);
			//   printf("mu = %f\n", m_pointCache[insertIndex].m_combinedFriction);
			btScalar mu = m_pointCache[insertIndex].m_combinedFriction;
			btScalar eps = 0;  //we could allow to enlarge or shrink the tolerance to check against the friction cone a bit, say 1e-7
			btScalar a = appliedLateralImpulse1 * appliedLateralImpulse1 + appliedLateralImpulse2 * appliedLateralImpulse2;
			btScalar b = eps + mu * appliedImpulse;
			b = b * b;
			replacePoint = (a) > (b);
		}

		if (replacePoint)
		{
			btAssert(lifeTime >= 0);
			void* cache = m_pointCache[insertIndex].m_userPersistentData;

			m_pointCache[insertIndex] = newPoint;
			m_pointCache[insertIndex].m_userPersistentData = cache;
			m_pointCache[insertIndex].m_appliedImpulse = appliedImpulse;
			m_pointCache[insertIndex].m_prevRHS = prevRHS;
			m_pointCache[insertIndex].m_appliedImpulseLateral1 = appliedLateralImpulse1;
			m_pointCache[insertIndex].m_appliedImpulseLateral2 = appliedLateralImpulse2;
		}

		m_pointCache[insertIndex].m_lifeTime = lifeTime;
#else
		clearUserCache(m_pointCache[insertIndex]);
		m_pointCache[insertIndex] = newPoint;

#endif
	}

	bool validContactDistance(const btManifoldPoint& pt) const
	{
		return pt.m_distance1 <= getContactBreakingThreshold();
	}
	/// calculated new worldspace coordinates and depth, and reject points that exceed the collision margin
	void refreshContactPoints(const btTransform& trA, const btTransform& trB);

	SIMD_FORCE_INLINE void clearManifold()
	{
		int i;
		for (i = 0; i < m_cachedPoints; i++)
		{
			clearUserCache(m_pointCache[i]);
		}

		if (gContactEndedCallback && m_cachedPoints)
		{
			gContactEndedCallback(this);
		}
		m_cachedPoints = 0;
	}
};

#ifdef BT_USE_DOUBLE_PRECISION
#define btPersistentManifoldData btPersistentManifoldDoubleData
#define btPersistentManifoldDataName "btPersistentManifoldDoubleData"
#else
#define btPersistentManifoldData btPersistentManifoldFloatData
#define btPersistentManifoldDataName "btPersistentManifoldFloatData"
#endif  //BT_USE_DOUBLE_PRECISION

#endif  //BT_PERSISTENT_MANIFOLD_H