// Copyright (C) 2013 Jérôme Leclercq
// This file is part of the "Nazara Engine - Graphics module"
// For conditions of distribution and use, see copyright notice in Config.hpp

#include <Nazara/Graphics/Scene.hpp>
#include <Nazara/Core/Clock.hpp>
#include <Nazara/Core/Error.hpp>
#include <Nazara/Graphics/Camera.hpp>
#include <Nazara/Graphics/ColorBackground.hpp>
#include <Nazara/Graphics/ForwardRenderTechnique.hpp>
#include <Nazara/Graphics/SceneRoot.hpp>
#include <Nazara/Renderer/Config.hpp>
#include <functional>
#include <memory>
#include <set>
#include <vector>
#include <Nazara/Graphics/Debug.hpp>

struct NzSceneImpl
{
	NzSceneImpl(NzScene* scene) :
	root(scene)
	{
	}

	std::unique_ptr<NzAbstractRenderTechnique> renderTechnique;
	std::unique_ptr<NzBackground> background;
	std::vector<NzUpdatable*> updateList;
	std::vector<NzUpdatable*> visibleUpdateList;
	NzClock updateClock;
	NzColor ambientColor = NzColor(25,25,25);
	NzSceneRoot root;
	NzCamera* activeCamera;
	bool update;
	float frameTime;
	float updateTime;
	unsigned int updatePerSecond = 60;
};

NzScene::NzScene()
{
	m_impl = new NzSceneImpl(this);
	m_impl->background.reset(new NzColorBackground);
	m_impl->renderTechnique.reset(new NzForwardRenderTechnique);
}

NzScene::~NzScene()
{
	for (NzNode* child : m_impl->root.GetChilds())
	{
		if (child->GetNodeType() == nzNodeType_Scene)
			static_cast<NzSceneNode*>(child)->SetScene(nullptr);
	}

	delete m_impl;
}

void NzScene::AddToVisibilityList(NzUpdatable* object)
{
	m_impl->visibleUpdateList.push_back(object);
}

void NzScene::Cull()
{
	NzAbstractRenderQueue* renderQueue = m_impl->renderTechnique->GetRenderQueue();
	renderQueue->Clear();

	m_impl->visibleUpdateList.clear();

	// Frustum culling
	RecursiveFrustumCull(renderQueue, m_impl->activeCamera->GetFrustum(), &m_impl->root);

	///TODO: Occlusion culling

	///TODO: Light culling
}

void NzScene::Draw()
{
	m_impl->renderTechnique->Clear(this);
	m_impl->renderTechnique->Draw(this);
}

NzCamera* NzScene::GetActiveCamera() const
{
	return m_impl->activeCamera;
}

NzColor NzScene::GetAmbientColor() const
{
	return m_impl->ambientColor;
}

NzBackground* NzScene::GetBackground() const
{
	return m_impl->background.get();
}

NzAbstractRenderTechnique* NzScene::GetRenderTechnique() const
{
	return m_impl->renderTechnique.get();
}

NzSceneNode& NzScene::GetRoot() const
{
	return m_impl->root;
}

float NzScene::GetUpdateTime() const
{
	return m_impl->updateTime;
}

unsigned int NzScene::GetUpdatePerSecond() const
{
	return m_impl->updatePerSecond;
}

void NzScene::RegisterForUpdate(NzUpdatable* object)
{
	#if NAZARA_GRAPHICS_SAFE
	if (!object)
	{
		NazaraError("Invalid object");
		return;
	}
	#endif

	m_impl->updateList.push_back(object);
}

void NzScene::SetAmbientColor(const NzColor& color)
{
	m_impl->ambientColor = color;
}

void NzScene::SetBackground(NzBackground* background)
{
	m_impl->background.reset(background);
}

void NzScene::SetRenderTechnique(NzAbstractRenderTechnique* renderTechnique)
{
	m_impl->renderTechnique.reset(renderTechnique);
}

void NzScene::SetUpdatePerSecond(unsigned int updatePerSecond)
{
	m_impl->updatePerSecond = updatePerSecond;
}

void NzScene::UnregisterForUpdate(NzUpdatable* object)
{
	#if NAZARA_GRAPHICS_SAFE
	if (!object)
	{
		NazaraError("Invalid object");
		return;
	}
	#endif

	auto it = std::find(m_impl->updateList.begin(), m_impl->updateList.end(), object);
	if (it != m_impl->updateList.end())
		m_impl->updateList.erase(it);
}

void NzScene::Update()
{
	m_impl->update = (m_impl->updatePerSecond == 0 || m_impl->updateClock.GetMilliseconds() > 1000/m_impl->updatePerSecond);
	if (m_impl->update)
	{
		m_impl->updateTime = m_impl->updateClock.GetSeconds();
		m_impl->updateClock.Restart();

		for (NzUpdatable* updatable : m_impl->updateList)
			///TODO: Multihreading
			updatable->Update();
	}
}

void NzScene::UpdateVisible()
{
	if (m_impl->update)
	{
		for (NzUpdatable* node : m_impl->visibleUpdateList)
			node->Update();
	}
}

NzScene::operator const NzSceneNode&() const
{
	return m_impl->root;
}

void NzScene::RecursiveFrustumCull(NzAbstractRenderQueue* renderQueue, const NzFrustumf& frustum, NzNode* node)
{
	for (NzNode* child : node->GetChilds())
	{
		if (child->GetNodeType() == nzNodeType_Scene)
		{
			NzSceneNode* sceneNode = static_cast<NzSceneNode*>(child);
			///TODO: Empêcher le rendu des enfants si le parent est cullé selon un flag
			sceneNode->UpdateVisibility(frustum);
			if (sceneNode->IsVisible())
				sceneNode->AddToRenderQueue(renderQueue);
		}

		if (child->HasChilds())
			RecursiveFrustumCull(renderQueue, frustum, child);
	}
}

void NzScene::SetActiveCamera(NzCamera* camera)
{
	m_impl->activeCamera = camera;
}