// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "b2_chain_circle_contact.h"
#include "b2_chain_polygon_contact.h"
#include "b2_circle_contact.h"
#include "b2_contact_solver.h"
#include "b2_edge_circle_contact.h"
#include "b2_edge_polygon_contact.h"
#include "b2_polygon_circle_contact.h"
#include "b2_polygon_contact.h"

#include "box2d/b2_contact.h"
#include "box2d/b2_block_allocator.h"
#include "box2d/b2_body.h"
#include "box2d/b2_collision.h"
#include "box2d/b2_fixture.h"
#include "box2d/b2_shape.h"
#include "box2d/b2_time_of_impact.h"
#include "box2d/b2_world.h"

b2ContactRegister b2Contact::s_registers[b2Shape::e_typeCount][b2Shape::e_typeCount];
bool b2Contact::s_initialized = false;

void b2Contact::InitializeRegisters()
{
	AddType(b2CircleContact::Create, b2CircleContact::Destroy, b2Shape::e_circle, b2Shape::e_circle);
	AddType(b2PolygonAndCircleContact::Create, b2PolygonAndCircleContact::Destroy, b2Shape::e_polygon, b2Shape::e_circle);
	AddType(b2PolygonContact::Create, b2PolygonContact::Destroy, b2Shape::e_polygon, b2Shape::e_polygon);
	AddType(b2EdgeAndCircleContact::Create, b2EdgeAndCircleContact::Destroy, b2Shape::e_edge, b2Shape::e_circle);
	AddType(b2EdgeAndPolygonContact::Create, b2EdgeAndPolygonContact::Destroy, b2Shape::e_edge, b2Shape::e_polygon);
	AddType(b2ChainAndCircleContact::Create, b2ChainAndCircleContact::Destroy, b2Shape::e_chain, b2Shape::e_circle);
	AddType(b2ChainAndPolygonContact::Create, b2ChainAndPolygonContact::Destroy, b2Shape::e_chain, b2Shape::e_polygon);
}

void b2Contact::AddType(b2ContactCreateFcn* createFcn, b2ContactDestroyFcn* destoryFcn,
						b2Shape::Type type1, b2Shape::Type type2)
{
	b2Assert(0 <= type1 && type1 < b2Shape::e_typeCount);
	b2Assert(0 <= type2 && type2 < b2Shape::e_typeCount);
	
	s_registers[type1][type2].createFcn = createFcn;
	s_registers[type1][type2].destroyFcn = destoryFcn;
	s_registers[type1][type2].primary = true;

	if (type1 != type2)
	{
		s_registers[type2][type1].createFcn = createFcn;
		s_registers[type2][type1].destroyFcn = destoryFcn;
		s_registers[type2][type1].primary = false;
	}
}

b2Contact* b2Contact::Create(b2Fixture* fixtureA, int32 indexA, b2Fixture* fixtureB, int32 indexB, b2BlockAllocator* allocator)
{
	if (s_initialized == false)
	{
		InitializeRegisters();
		s_initialized = true;
	}

	b2Shape::Type type1 = fixtureA->GetType();
	b2Shape::Type type2 = fixtureB->GetType();

	b2Assert(0 <= type1 && type1 < b2Shape::e_typeCount);
	b2Assert(0 <= type2 && type2 < b2Shape::e_typeCount);
	
	b2ContactCreateFcn* createFcn = s_registers[type1][type2].createFcn;
	if (createFcn)
	{
		if (s_registers[type1][type2].primary)
		{
			return createFcn(fixtureA, indexA, fixtureB, indexB, allocator);
		}
		else
		{
			return createFcn(fixtureB, indexB, fixtureA, indexA, allocator);
		}
	}
	else
	{
		return nullptr;
	}
}

void b2Contact::Destroy(b2Contact* contact, b2BlockAllocator* allocator)
{
	b2Assert(s_initialized == true);

	b2Fixture* fixtureA = contact->m_fixtureA;
	b2Fixture* fixtureB = contact->m_fixtureB;

	if (contact->m_manifold.pointCount > 0 &&
		fixtureA->IsSensor() == false &&
		fixtureB->IsSensor() == false)
	{
		fixtureA->GetBody()->SetAwake(true);
		fixtureB->GetBody()->SetAwake(true);
	}

	b2Shape::Type typeA = fixtureA->GetType();
	b2Shape::Type typeB = fixtureB->GetType();

	b2Assert(0 <= typeA && typeA < b2Shape::e_typeCount);
	b2Assert(0 <= typeB && typeB < b2Shape::e_typeCount);

	b2ContactDestroyFcn* destroyFcn = s_registers[typeA][typeB].destroyFcn;
	destroyFcn(contact, allocator);
}

b2Contact::b2Contact(b2Fixture* fA, int32 indexA, b2Fixture* fB, int32 indexB)
{
	m_flags = e_enabledFlag;

	m_fixtureA = fA;
	m_fixtureB = fB;

	m_indexA = indexA;
	m_indexB = indexB;

	m_manifold.pointCount = 0;

	m_prev = nullptr;
	m_next = nullptr;

	m_nodeA.contact = nullptr;
	m_nodeA.prev = nullptr;
	m_nodeA.next = nullptr;
	m_nodeA.other = nullptr;

	m_nodeB.contact = nullptr;
	m_nodeB.prev = nullptr;
	m_nodeB.next = nullptr;
	m_nodeB.other = nullptr;

	m_toiCount = 0;

	m_friction = b2MixFriction(m_fixtureA->m_friction, m_fixtureB->m_friction);
	m_restitution = b2MixRestitution(m_fixtureA->m_restitution, m_fixtureB->m_restitution);
	m_restitutionThreshold = b2MixRestitutionThreshold(m_fixtureA->m_restitutionThreshold, m_fixtureB->m_restitutionThreshold);

	m_tangentSpeed = 0.0f;
}

// Update the contact manifold and touching status.
// Note: do not assume the fixture AABBs are overlapping or are valid.
void b2Contact::Update(b2ContactListener* listener)
{
	b2Manifold oldManifold = m_manifold;

	// Re-enable this contact.
	m_flags |= e_enabledFlag;

	bool touching = false;
	bool wasTouching = (m_flags & e_touchingFlag) == e_touchingFlag;

	bool sensorA = m_fixtureA->IsSensor();
	bool sensorB = m_fixtureB->IsSensor();
	bool sensor = sensorA || sensorB;

	b2Body* bodyA = m_fixtureA->GetBody();
	b2Body* bodyB = m_fixtureB->GetBody();
	const b2Transform& xfA = bodyA->GetTransform();
	const b2Transform& xfB = bodyB->GetTransform();

	// Is this contact a sensor?
	if (sensor)
	{
		const b2Shape* shapeA = m_fixtureA->GetShape();
		const b2Shape* shapeB = m_fixtureB->GetShape();
		touching = b2TestOverlap(shapeA, m_indexA, shapeB, m_indexB, xfA, xfB);

		// Sensors don't generate manifolds.
		m_manifold.pointCount = 0;
	}
	else
	{
		Evaluate(&m_manifold, xfA, xfB);
		touching = m_manifold.pointCount > 0;

		// Match old contact ids to new contact ids and copy the
		// stored impulses to warm start the solver.
		for (int32 i = 0; i < m_manifold.pointCount; ++i)
		{
			b2ManifoldPoint* mp2 = m_manifold.points + i;
			mp2->normalImpulse = 0.0f;
			mp2->tangentImpulse = 0.0f;
			b2ContactID id2 = mp2->id;

			for (int32 j = 0; j < oldManifold.pointCount; ++j)
			{
				b2ManifoldPoint* mp1 = oldManifold.points + j;

				if (mp1->id.key == id2.key)
				{
					mp2->normalImpulse = mp1->normalImpulse;
					mp2->tangentImpulse = mp1->tangentImpulse;
					break;
				}
			}
		}

		if (touching != wasTouching)
		{
			bodyA->SetAwake(true);
			bodyB->SetAwake(true);
		}
	}

	if (touching)
	{
		m_flags |= e_touchingFlag;
	}
	else
	{
		m_flags &= ~e_touchingFlag;
	}

	if (wasTouching == false && touching == true && listener)
	{
		listener->BeginContact(this);
	}

	if (wasTouching == true && touching == false && listener)
	{
		listener->EndContact(this);
	}

	if (sensor == false && touching && listener)
	{
		listener->PreSolve(this, &oldManifold);
	}
}