#include "planet/PlanetFace.h"
#include "planet/Planet.h"

PlanetFace::PlanetFace(Planet* planet, const unsigned int face) : 
	m_planet(planet), m_face(face), m_pos(glm::vec3(0.0f, 0.0f, 0.0f))
{
	// Set face normal depending on face
	switch (m_face)
	{
		case Face::FACE_BOTTOM:
			m_normal = glm::vec3(0.0f, -1.0f, 0.0f);
			break;
		case Face::FACE_TOP:
			m_normal = glm::vec3(0.0f, 1.0f, 0.0f);
			break;
		case Face::FACE_LEFT:
			m_normal = glm::vec3(-1.0f, 0.0f, 0.0f);
			break;
		case Face::FACE_RIGHT:
			m_normal = glm::vec3(1.0f, 0.0f, 0.0f);
			break;
		case Face::FACE_FRONT:
			m_normal = glm::vec3(0.0f, 0.0f, -1.0f);
			break;
		case Face::FACE_BACK:
			m_normal = glm::vec3(0.0f, 0.0f, 1.0f);
			break;
	}
	m_chunks = new ChunkManager(this, planet->getRadius());
}

PlanetFace::~PlanetFace()
{

}

void PlanetFace::draw(Camera* camera, Shader* shader)
{
	if (m_chunks)
	{
		glEnable(GL_CULL_FACE);
		glCullFace(GL_BACK);

		m_chunks->render(camera, shader);

		glDisable(GL_CULL_FACE);
	}
}

void PlanetFace::tick(Camera* camera, GLfloat dtime)
{
	if (m_chunks)
	{
		m_chunks->update(camera, dtime);
	}
}

// ******** //
//  CHUNKS  //
// ******** //

ChunkManager::ChunkManager(PlanetFace* face, GLuint chunkCount) : m_face(face)
{
	m_forceVisibilityUpdate = true;
	for (int x = 0; x < (int)chunkCount; x++)
	{
		for (int y = 0; y < (int)chunkCount; y++)
		{
			for (int z = 0; z < (int)chunkCount; z++)
			{
				m_chunks.push_back(new Chunk(m_face->getPlanet(), m_face, x * CHUNK_SIZE, y * CHUNK_SIZE, z * CHUNK_SIZE));
			}
		}
	}
}

ChunkManager::~ChunkManager()
{
	for(auto iterator = m_chunks.begin(); iterator != m_chunks.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);
		delete pChunk;
	}
}

void ChunkManager::update(Camera* camera, GLfloat dtime)
{
	updateUnload();

	updateLoad();

	updateRebuild();

	updateGenerate();

	updateFlags();

	updateVisibility(camera);

	updateRender(camera);
}

Chunk* ChunkManager::getChunk(int x, int y, int z)
{
	for(auto iterator = m_chunks.begin(); iterator != m_chunks.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if (pChunk->getX() == x && pChunk->getY() == y && pChunk->getZ() == z)
			return pChunk;
	}

	return NULL;
}

void ChunkManager::updateUnload()
{
	// Unload any chunks
	for(auto iterator = m_chunkUnloadQueue.begin(); iterator != m_chunkUnloadQueue.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if(pChunk->isLoaded())
		{
			pChunk->unload();

			m_forceVisibilityUpdate = true;
		}
	}

	// Clear the unload list (every frame)
	m_chunkUnloadQueue.clear();
}

void ChunkManager::updateLoad()
{
	int lNumOfChunksLoaded = 0;

	for(auto iterator = m_chunkLoadQueue.begin(); iterator != m_chunkLoadQueue.end() &&
				  (lNumOfChunksLoaded != ASYNC_NUM_CHUNKS_PER_FRAME); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if(pChunk->isLoaded() == false)
		{
			if(lNumOfChunksLoaded != ASYNC_NUM_CHUNKS_PER_FRAME)
			{
				pChunk->load();

				// Increase the chunks loaded count
				lNumOfChunksLoaded++;

				m_forceVisibilityUpdate = true;
			}
		}
	}

	// Clear the load list (every frame)
	m_chunkLoadQueue.clear();
}

void ChunkManager::updateRebuild()
{
	// Rebuild any chunks that are in the rebuild chunk list
	int lNumRebuiltChunkThisFrame = 0;
	for(auto iterator = m_chunkRebuildQueue.begin(); iterator != m_chunkRebuildQueue.end() &&
				  (lNumRebuiltChunkThisFrame != ASYNC_NUM_CHUNKS_PER_FRAME); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if(pChunk->isLoaded() && pChunk->isGenerated())
		{
			if(lNumRebuiltChunkThisFrame != ASYNC_NUM_CHUNKS_PER_FRAME)
			{
				pChunk->rebuildMesh();

				// If we rebuild a chunk, add it to the list of chunks that need their render flags updated
				// since we might now be empty or surrounded
				m_chunkFlagsQueue.push_back(pChunk);

				// Also add our neighbours since they might now be surrounded too (If we have neighbours)
				Chunk* pChunkXMinus = getChunk(pChunk->getX()-1, pChunk->getY(), pChunk->getZ());
				Chunk* pChunkXPlus = getChunk(pChunk->getX()+1, pChunk->getY(), pChunk->getZ());
				Chunk* pChunkYMinus = getChunk(pChunk->getX(), pChunk->getY()-1, pChunk->getZ());
				Chunk* pChunkYPlus = getChunk(pChunk->getX(), pChunk->getY()+1, pChunk->getZ());
				Chunk* pChunkZMinus = getChunk(pChunk->getX(), pChunk->getY(), pChunk->getZ()-1);
				Chunk* pChunkZPlus = getChunk(pChunk->getX(), pChunk->getY(), pChunk->getZ()+1);

				if(pChunkXMinus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkXMinus);

				if(pChunkXPlus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkXPlus);

				if(pChunkYMinus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkYMinus);

				if(pChunkYPlus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkYPlus);

				if(pChunkZMinus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkZMinus);

				if(pChunkZPlus != NULL) 
					m_chunkFlagsQueue.push_back(pChunkZPlus);

				// Only rebuild a certain number of chunks per frame
				lNumRebuiltChunkThisFrame++;

				m_forceVisibilityUpdate = true;
			}
		}
	}

	// Clear the rebuild list
	m_chunkRebuildQueue.clear();
}

void ChunkManager::updateFlags()
{
	for(auto iterator = m_chunkFlagsQueue.begin(); iterator != m_chunkFlagsQueue.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);
		pChunk->updateFlags();
		
	}

	m_chunkFlagsQueue.clear();
}

void ChunkManager::updateGenerate()
{
	// Generate any chunks that have not already been generated
	for(auto iterator = m_chunkGenerateQueue.begin(); iterator != m_chunkGenerateQueue.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if(pChunk->isLoaded() && pChunk->isGenerated() == false)
		{
			pChunk->generate();

			if(pChunk->isGenerated())
			{
				// Only force the visibility update if we actually generate the chunk, some chunks wait in the pre-generate stage...
				m_forceVisibilityUpdate = true;
			}
		}
	}

	// Clear the generate list (every frame)
	m_chunkGenerateQueue.clear();
}

void ChunkManager::updateVisibility(Camera* camera)
{
	m_forceVisibilityUpdate = false;

	m_chunksVisible.clear();

	for(auto iterator = m_chunks.begin(); iterator != m_chunks.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		// TODO: Temporary distance limit
		if (glm::abs(glm::length(camera->getPosition() - pChunk->getAbsolutePosition())) > 64.0f)
		{
			if (pChunk->isLoaded())
			{
				m_chunkUnloadQueue.push_back(pChunk);
				continue;
			}
			continue;
		}
		else
		{
			if (!pChunk->isLoaded())
			{
				m_chunkLoadQueue.push_back(pChunk);
				continue;
			}
		}

		// Generate chunk
		if (!pChunk->isGenerated())
		{
			m_chunkGenerateQueue.push_back(pChunk);
			continue;
		}

		if (pChunk->isRedrawRequired() || !pChunk->isDetailedEnough(camera))
		{
			m_chunkRebuildQueue.push_back(pChunk);
			continue;
		}

		m_chunksVisible.push_back(pChunk);
	}
}

void ChunkManager::updateRender(Camera* camera)
{
	// Clear the render list each frame BEFORE we do our tests to see what chunks should be rendered
	m_chunkRenderQueue.clear();

	for(auto iterator = m_chunksVisible.begin(); iterator != m_chunksVisible.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);

		if(pChunk != NULL)
		{
			if(pChunk->isLoaded() && pChunk->isGenerated())
			{
				if(pChunk->shouldRender()) // Early flags check so we don't always have to do the frustum check...
				{
					// TODO: fix frustum culling
					//glm::vec3 pos = pChunk->getAbsolutePosition();
					//glm::mat4 model = glm::translate(glm::mat4(1.0f), pos);

					//camera->updateFrustum(model);
					//if(camera->frustumContainsBox(glm::vec3(0.0f), glm::vec3((float)CHUNK_SIZE / 2)) > 0)
					//{
						m_chunkRenderQueue.push_back(pChunk);
					//}
				}
			}
		}
	}
}

void ChunkManager::render(Camera* camera, Shader* shader)
{
	// Render only the chunks that should be rendered
	for(auto iterator = m_chunkRenderQueue.begin(); iterator != m_chunkRenderQueue.end(); ++iterator)
	{
		Chunk* pChunk = (*iterator);
		pChunk->draw(camera, shader);
	}
}