#include "PrecompiledHeader.h"
#include "Physics/PhysicsSystem.h"


void dd::Systems::PhysicsSystem::RegisterComponents(ComponentFactory* cf)
{
    cf->Register<Components::CircleShape>();
    //TODO: REGISTER PHYSICS COMPONENTS HERE
}

void dd::Systems::PhysicsSystem::Initialize()
{
    m_ContactListener = new ContactListener(this);
    m_PhysicsWorld = new b2World(m_Gravity);
    m_PhysicsWorld->SetContactListener(m_ContactListener);
    InitializeWater();
    EVENT_SUBSCRIBE_MEMBER(m_SetImpulse, &PhysicsSystem::SetImpulse);
    EVENT_SUBSCRIBE_MEMBER(m_EPause, &PhysicsSystem::OnPause);
	EVENT_SUBSCRIBE_MEMBER(m_EStageCleared, &PhysicsSystem::OnStageCleared);
}

void dd::Systems::PhysicsSystem::InitializeWater()
{
    float radius = 0.13f;
    float gravityScale = 1.0f;
    CreateParticleSystem(radius, gravityScale);
}

bool dd::Systems::PhysicsSystem::SetImpulse(const Events::SetImpulse &event)
{
    auto it = m_EntitiesToBodies.find(event.Entity);
    if(it == m_EntitiesToBodies.end()) {
        LOG_ERROR("Entity: %i, Tried to set an impulse on a body that does not exsist", event.Entity);
        return false;
    }

    b2Vec2 impulse;
    impulse.x = event.Impulse.x;
    impulse.y = event.Impulse.y;

    b2Vec2 point;
    point.x = event.Point.x;
    point.y = event.Point.y;

    Impulse i;
    i.Body = it->second;
    i.Vector = impulse;
    i.Point = point;

    m_Impulses.push_back(i);
    return true;
}

void dd::Systems::PhysicsSystem::SyncEntitiesWithBodies()
{

    for (auto i : m_EntitiesToBodies) {
        EntityID entity = i.first;
        b2Body* body = i.second;

        if (body == nullptr) {
            LOG_ERROR("This body should not exist, please fix this");
            continue;
        }

        auto transformComponent = m_World->GetComponent<Components::Transform>(entity);
        if (! transformComponent) {
            continue;
            LOG_ERROR("RigidBody with no TransformComponent");
        }

        auto physicsComponent = m_World->GetComponent<Components::Physics>(entity);
        if (! physicsComponent) {
            continue;
            LOG_ERROR("RigidBody with no PhysicsComponent");
        }



        if (m_World->GetEntityParent(entity) == 0) { //TODO: Make this work with childs too
            b2Vec2 position;
            position.x = transformComponent->Position.x;
            position.y = transformComponent->Position.y;
            float angle = glm::eulerAngles(transformComponent->Orientation).z;
            body->SetTransform(position, angle);
            body->SetLinearVelocity(b2Vec2(transformComponent->Velocity.x, transformComponent->Velocity.y));
            body->SetGravityScale(physicsComponent->GravityScale);

            b2Filter filter;
            filter.categoryBits = physicsComponent->Category;
            filter.maskBits = physicsComponent->Mask;
            body->GetFixtureList()->SetFilterData(filter);

			if (physicsComponent->CollisionType == CollisionType::Type::Static) {
				body->SetType(b2_staticBody);
			}
			else if (physicsComponent->CollisionType == CollisionType::Type::Dynamic) {
				body->SetType(b2_dynamicBody);
			}
			else if (physicsComponent->CollisionType == CollisionType::Type::Kinematic) {
				body->SetType(b2_dynamicBody);
			}
        }
    }
}

void dd::Systems::PhysicsSystem::SyncBodiesWithEntities()
{
    for (auto i : m_BodiesToEntities) {
        b2Body* body = i.first;
        EntityID entity = i.second;

        if (body == nullptr) {
            LOG_ERROR("This body should not exist, please fix this");
            continue;
        }

        auto transformComponent = m_World->GetComponent<Components::Transform>(entity);
        if (! transformComponent) {
            continue;
            LOG_ERROR("RigidBody with no TransformComponent");
        }

        auto physicsComponent = m_World->GetComponent<Components::Physics>(entity);
        if (! physicsComponent) {
            continue;
            LOG_ERROR("RigidBody with no PhysicsComponent");
        }

        auto parent = m_World->GetEntityParent(entity);
        if (parent == 0) {
            auto physicsComponent = m_World->GetComponent<Components::Physics>(entity);

            if (physicsComponent->Calculate) { //TODO: REPLACE THIS WITH PARTICLE COLLISION FILTERS
                transformComponent->Position.x = transformComponent->Position.x + (transformComponent->Velocity.x * m_TimeStep);
                transformComponent->Position.y = transformComponent->Position.y + (transformComponent->Velocity.y * m_TimeStep);
            } else {
                b2Vec2 position = body->GetPosition();
                transformComponent->Position.x = position.x;
                transformComponent->Position.y = position.y;

                float angle = body->GetAngle();
                transformComponent->Orientation =  glm::quat(glm::vec3(0, 0, angle));

                b2Vec2 velocity = body->GetLinearVelocity();
                transformComponent->Velocity.x = velocity.x;
                transformComponent->Velocity.y = velocity.y;
            }
        }
    }
}

void dd::Systems::PhysicsSystem::Update(double dt)
{
	if (m_Pause) {
		return;
	}

	if (m_Travelling) {
		if (m_DistanceTravelled > 12.f) {
			m_DistanceTravelled = 0;
			m_Travelling = false;
		}

		m_DistanceTravelled += 6.0f * dt;
	}
    m_Accumulator += dt;

    while(m_Accumulator >= m_TimeStep)
    {

        UpdateParticleEmitters(dt);
        SyncEntitiesWithBodies();

        //Apply Impulses Must be done after SyncEntitiesWithBodies
        for (auto i : m_Impulses) {
            i.Body->ApplyLinearImpulse(i.Vector, i.Point, true);
        }
        m_Impulses.clear();


        //Update the PhysicsWorld
        m_PhysicsWorld->Step(m_TimeStep, m_VelocityIterations, m_PositionIterations);

        SyncBodiesWithEntities();


        for ( int e = 0; e < m_EntitiesToParticleHandle.size(); e++) {
            b2Vec2 *positionBuffer = m_ParticleSystem[e]->GetPositionBuffer();
            for (auto i : m_EntitiesToParticleHandle[e]) {
                EntityID entity = i.first;
                const b2ParticleHandle *particleH = i.second;

                b2Vec2 positionB2 = positionBuffer[particleH->GetIndex()];
                glm::vec2 position = glm::vec2(positionB2.x, positionB2.y);

                EntityID entityParent = m_World->GetEntityParent(entity);
                glm::vec3 parentTransform = glm::vec3(0.f);
                if (entityParent) {
                    auto tp = m_World->GetComponent<Components::Transform>(entityParent);
                    parentTransform = tp->Position;
                }
                auto transform = m_World->GetComponent<Components::Transform>(entity);

                transform->Position = glm::vec3(position.x, position.y, -10) - parentTransform;

            }
        }

        m_Accumulator -= dt;
    }
}

void dd::Systems::PhysicsSystem::UpdateEntity(double dt, EntityID entity, EntityID parent)
{
	if (m_Travelling) {
		auto transform = m_World->GetComponent<Components::Transform>(entity);
		if (transform != nullptr) {
			if (transform->Sticky == true) {
				return;
			}
			transform->Position.y -= 6.0f * dt;
		}
	}
}

bool dd::Systems::PhysicsSystem::OnPause(const dd::Events::Pause &event)
{
    if (event.Type != "PhysicsSystem" && event.Type != "All") {
        return false;
    }

    if (m_Pause) {
        m_Pause = false;
    } else {
        m_Pause = true;
    }
    return true;
}

void dd::Systems::PhysicsSystem::OnEntityCommit(EntityID entity)
{
    auto physicsComponent = m_World->GetComponent<Components::Physics>(entity);
    auto waterComponent = m_World->GetComponent<Components::WaterVolume>(entity);
    auto particleEmitterComponent = m_World->GetComponent<Components::ParticleEmitter>(entity);

    if (physicsComponent && waterComponent) {
        LOG_ERROR("Entity has both water and physics component, this is illegal. The police has been alerted.");
        return;
    }
    if (physicsComponent && particleEmitterComponent) {
        LOG_ERROR("Entity has both particle and physics component, this is illegal. The police has been alerted.");
        return;
    }

    if (physicsComponent) {
        auto it = m_EntitiesToBodies.find(entity);
        if(it == m_EntitiesToBodies.end()) {
            CreateBody(entity);
        } else {
            LOG_ERROR("Tried to commit a body that already exists");
        }
    } else if (waterComponent) {
        CreateParticleGroup(entity);
    } else if (particleEmitterComponent) {
        CreateParticleEmitter(entity);
    }
}


void dd::Systems::PhysicsSystem::OnEntityRemoved(EntityID entity)
{
   /* auto physics = m_World->GetComponent<Components::Physics>(entity);
    if (physics == nullptr) {
        return;
    }*/

    auto it = m_EntitiesToBodies.find(entity);
    if(it == m_EntitiesToBodies.end()) {
        LOG_ERROR("Trying to remove non-exsisting body, Entity: %i", entity);
        return;
    }

    //It told me I was removing a lot of objects, and I didn't need that information, so I commented it out.
    //LOG_INFO("Removing entity %i", entity);
    it->second->GetWorld()->DestroyBody(it->second);
    m_BodiesToEntities.erase(it->second);
    m_EntitiesToBodies.erase(entity);
    //delete body;
}


bool dd::Systems::PhysicsSystem::OnStageCleared(const dd::Events::StageCleared &event)
{
	if (event.ClearedStage < 5) {
		m_Travelling = true;
	}
	return true;
}


void dd::Systems::PhysicsSystem::CreateBody(EntityID entity)
{
    auto physicsComponent = m_World->GetComponent<Components::Physics>(entity);
    if(!physicsComponent){
        LOG_ERROR("No PhysicsComponent in CreateBody");
        return;
    }

    auto transformComponent = m_World->GetComponent<Components::Transform>(entity);
    if(!transformComponent) {
        LOG_ERROR("No TransformComponent in CreateBody");
        return;
    }

    auto absoluteTransform = m_World->GetSystem<Systems::TransformSystem>()->AbsoluteTransform(entity);

    b2BodyDef bodyDef;
    bodyDef.position.Set(absoluteTransform.Position.x, absoluteTransform.Position.y);
    bodyDef.angle = -glm::eulerAngles(absoluteTransform.Orientation).z;

    if (physicsComponent->CollisionType == CollisionType::Type::Static) {
        bodyDef.type = b2_staticBody;
    } else if (physicsComponent->CollisionType == CollisionType::Type::Dynamic) {
        bodyDef.type = b2_dynamicBody;
    } else if (physicsComponent->CollisionType == CollisionType::Type::Kinematic) {
        bodyDef.type = b2_dynamicBody;
    }

    b2Body* body = m_PhysicsWorld->CreateBody(&bodyDef);

    b2Shape* pShape;

    auto rectangleComponent = m_World->GetComponent<Components::RectangleShape>(entity);
    if (rectangleComponent) {
        b2PolygonShape* bShape = new b2PolygonShape();
        bShape->SetAsBox(rectangleComponent->Dimensions.x/2.f, rectangleComponent->Dimensions.y/2.f);
        pShape = bShape;
    } else {
        auto circleComponent = m_World->GetComponent<Components::CircleShape>(entity);
        if (circleComponent) {
            pShape = new b2CircleShape();
            pShape->m_radius = circleComponent->Radius;
        }
    }

    b2FixtureDef fixtureDef;
    fixtureDef.shape = pShape;
    fixtureDef.filter.categoryBits = physicsComponent->Category;
    fixtureDef.filter.maskBits = physicsComponent->Mask;



    fixtureDef.shape = pShape;
    fixtureDef.density = physicsComponent->Density;
    fixtureDef.restitution = 1.0f;
    fixtureDef.friction = 0.0f;
    body->CreateFixture(&fixtureDef);


    delete pShape;

    body->SetGravityScale(physicsComponent->GravityScale);
    m_EntitiesToBodies.insert(std::make_pair(entity, body));
    m_BodiesToEntities.insert(std::make_pair(body, entity));
}
void dd::Systems::PhysicsSystem::CreateParticleGroup(EntityID e)
{
    auto transform = m_World->GetComponent<Components::Transform>(e);
    if (!transform) {
        LOG_ERROR("No Transform component in CreateParticleGroup");
    }
    b2ParticleGroupDef pd;
    b2PolygonShape shape;
    auto water = m_World->GetComponent<Components::WaterVolume>(e);
    if (water) {

        shape.SetAsBox(transform->Scale.x/2.f, transform->Scale.y/2.f);
        pd.shape = &shape;
        pd.flags = b2_tensileParticle;
        pd.position.Set(transform->Position.x, transform->Position.y);
        t_ParticleGroup.push_back(m_ParticleSystem[0]->CreateParticleGroup(pd));
        b2Vec2* t_ParticlePositions = m_ParticleSystem[0]->GetPositionBuffer();
        for(int i = 0; i < m_ParticleSystem[0]->GetParticleCount(); i++){
            {
                auto t_waterparticle = m_World->CreateEntity(e);
                auto transformChild = m_World->AddComponent<Components::Transform>(t_waterparticle);

                transformChild->Position = glm::vec3(t_ParticlePositions[i].x - transform->Position.x, t_ParticlePositions[i].y - transform->Position.y, -9.5f);
                transformChild->Scale = glm::vec3(m_ParticleSystem[0]->GetRadius())/transform->Scale;
                m_World->CommitEntity(t_waterparticle);

                m_EntitiesToParticleHandle[0].insert(std::make_pair(t_waterparticle, m_ParticleSystem[0]->GetParticleHandleFromIndex(i)));
                m_ParticleHandleToEntities[0].insert(std::make_pair( m_ParticleSystem[0]->GetParticleHandleFromIndex(i), t_waterparticle));
            }

        }

    }
}

void dd::Systems::PhysicsSystem::UpdateParticleEmitters(double dt)
{
    for (int i = 0; i < m_ParticleEmitters.System.size(); i++) {
        auto e = m_ParticleEmitters.Emitter[i];
        auto pt = m_ParticleEmitters.Template[i];
        auto ps = m_ParticleEmitters.System[i];


        auto emitter = m_World->GetComponent<Components::ParticleEmitter>(e);
        auto particleTemplate = m_World->GetComponent<Components::Particle>(pt);
        emitter->TimeSinceLastSpawn += dt;
        if(emitter->TimeSinceLastSpawn < emitter->SpawnRate) {
            continue;
        }
        emitter->TimeSinceLastSpawn -= emitter->SpawnRate;
        auto templateTransform = m_World->GetComponent<Components::Transform>(pt);

        b2ParticleDef particleDef;
        particleDef.flags = particleTemplate->Flags;
        //particleDef.color TODO: Implement this if we want color mixing and shit.
        particleDef.lifetime = particleTemplate->LifeTime;
        particleDef.velocity = b2Vec2(templateTransform->Velocity.x, templateTransform->Velocity.y);
        particleDef.position = b2Vec2(templateTransform->Position.x, templateTransform->Position.y);

        auto particle = m_World->CloneEntity(pt, 0);
        m_World->RemoveComponent<Components::Template>(particle);

        auto b2Particle = ps->CreateParticle(particleDef);
        auto b2ParticleHandle = ps->GetParticleHandleFromIndex(b2Particle);
        m_EntitiesToParticleHandle[i].insert(std::make_pair(particle, b2ParticleHandle));
        m_ParticleHandleToEntities[i].insert(std::make_pair(b2ParticleHandle, particle));

        //TODO: Ta bort detta
        int particles = 0;
        for (auto i : m_EntitiesToParticleHandle)
        {
            particles += i.size();
        }
        LOG_INFO("--I have %i particles.", particles);
    }
}

void dd::Systems::PhysicsSystem::CreateParticleEmitter(EntityID entity)
{
    auto childEntities = m_World->GetEntityChildren(entity);
    if (childEntities.empty()) {
        LOG_ERROR("Particle Emitter does not have any child. Please adopt one or this will not work.");
        return;
    }
    int pf = 0;
    dd::Components::Particle* particle;
    EntityID childEntity;
    for ( auto c : childEntities ) {
        auto p = m_World->GetComponent<Components::Particle>(c);
        auto particleTemplate = m_World->GetComponent<Components::Template>(c);
        if (!p) {
            continue;
            LOG_WARNING("--Emitter's Child is not a particle.");
        }
        if(!particleTemplate) {
            LOG_ERROR("Emitter's particleChild is not a template.");
            continue;
        }
        if (pf != 0) {
            LOG_WARNING("Emitter has more than one child that is a particleTemplate, only the first one is used.");
            break;
        }
        childEntity = c;
        particle = p;
        pf++;
    }
    //TODO: Skicka med fler flaggor till particlesystemet;
    m_ParticleEmitters.System.push_back(CreateParticleSystem(particle->Radius, 0.f));
    m_ParticleEmitters.Emitter.push_back(entity);
    m_ParticleEmitters.Template.push_back(childEntity);
}


b2ParticleSystem* dd::Systems::PhysicsSystem::CreateParticleSystem(float radius, float gravityScale)
{
    std::unordered_map<EntityID, const b2ParticleHandle*> m1;
    std::unordered_map<const b2ParticleHandle*, EntityID> m2;
    m_EntitiesToParticleHandle.push_back(m1);
    m_ParticleHandleToEntities.push_back(m2);

    b2ParticleSystemDef m_ParticleSystemDef;
    m_ParticleSystemDef.radius = radius;
    m_ParticleSystemDef.gravityScale = gravityScale;

    m_ParticleSystem.push_back(m_PhysicsWorld->CreateParticleSystem(&m_ParticleSystemDef));

    return m_ParticleSystem.back();
}



dd::Systems::PhysicsSystem::~PhysicsSystem()
{
    for (auto i = m_BodiesToEntities.begin(); i != m_BodiesToEntities.end(); i++) {
        b2Body* body = i->first;
        body->GetWorld()->DestroyBody(body);
        //delete body;
    }
    m_BodiesToEntities.clear();
    m_EntitiesToBodies.clear();
    m_Impulses.clear();

    //TODO:REMOVE PARTICLE SYSTEMS

    if (m_ContactListener != nullptr) {
        delete m_ContactListener;
        m_ContactListener = nullptr;
    }

    if (m_PhysicsWorld != nullptr) {
        delete m_PhysicsWorld;
        m_PhysicsWorld = nullptr;
    }
}