#include <Chunk.h>
#include <Block.h>
#include <World.h>

#include <ScopCore.h>

#define POS_TO_INDEX(posx, posz) (posx * CHUNK_SIZE.x + posz)

constexpr Scop::Vec2ui SPRITE_SIZE = { 16, 16 };
constexpr Scop::Vec2ui ATLAS_SIZE = { 64, 64 };
constexpr Scop::Vec2f SPRITE_UNIT = Scop::Vec2f(SPRITE_SIZE) / Scop::Vec2f(ATLAS_SIZE);

constexpr std::array<std::array<Scop::Vec2ui, 3>, BlocksCount> BLOCKS_TO_ATLAS = {
	//                                   TOP                 BOTTOM                   SIDE
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 0, 0 } }, // Air
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 1, 1 }, Scop::Vec2ui{ 1, 1 }, Scop::Vec2ui{ 1, 1 } }, // Water
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 0, 0 } }, // Dirt
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 1, 0 }, Scop::Vec2ui{ 1, 0 }, Scop::Vec2ui{ 1, 0 } }, // Stone
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 2, 0 }, Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 3, 0 } }, // Grass
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 0, 1 }, Scop::Vec2ui{ 0, 1 }, Scop::Vec2ui{ 0, 1 } }, // Sand
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 2, 1 }, Scop::Vec2ui{ 2, 1 }, Scop::Vec2ui{ 2, 1 } }, // Snow
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 2, 1 }, Scop::Vec2ui{ 0, 0 }, Scop::Vec2ui{ 3, 1 } }, // SnowyGrass
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 0, 2 }, Scop::Vec2ui{ 0, 2 }, Scop::Vec2ui{ 0, 2 } }, // Cactus
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 1, 2 }, Scop::Vec2ui{ 1, 2 }, Scop::Vec2ui{ 1, 2 } }, // Ice
	std::array<Scop::Vec2ui, 3>{ Scop::Vec2ui{ 2, 2 }, Scop::Vec2ui{ 2, 2 }, Scop::Vec2ui{ 3, 2 } }, // SandStone
};

enum class Side : std::uint8_t
{
	Top = 0,
	Bottom,
	Side
};

struct WaterData
{
	double time;
};

Scop::Vec2f GetAtlasOffset(BlockType type, Side side)
{
	Scop::Vec2ui pos = BLOCKS_TO_ATLAS[static_cast<std::uint32_t>(type)][static_cast<std::uint8_t>(side)];
	return Scop::Vec2f(Scop::Vec2f(pos.x, SPRITE_SIZE.y - pos.y - 1) * SPRITE_UNIT);
}

Chunk::Chunk(World& world, Scop::Vec2i offset) : m_offset(offset), m_position(std::move(offset) * Scop::Vec2i{ CHUNK_SIZE.x, CHUNK_SIZE.z }), m_world(world)
{
}

void Chunk::GenerateChunk()
{
	if(p_actor)
		return;
	for(auto& y: m_data)
	{
		std::unique_lock guard(m_data_mutex);
		std::memset(y.data(), 0, y.size() * sizeof(std::uint32_t));
	}

	for(std::uint32_t x = 0; x < CHUNK_SIZE.x; x++)
	{
		for(std::uint32_t z = 0; z < CHUNK_SIZE.z; z++)
		{
			std::unique_lock guard(m_data_mutex);
			std::memcpy(m_data[POS_TO_INDEX(x, z)].data(), m_world.GetNoiseGenerator().GetBlocks(m_position + Scop::Vec2i(x, z)).data(), CHUNK_SIZE.y * sizeof(std::uint32_t));
		}
	}
}

void Chunk::GenerateMesh()
{
	if(p_actor || p_water_actor)
		return;

	std::uint32_t mesh_offset = 0;
	std::uint32_t water_offset = 0;
	m_mesh_data.reserve(CHUNK_VOLUME);
	m_mesh_index_data.reserve(CHUNK_VOLUME * 4);
	m_water_mesh_data.reserve(CHUNK_VOLUME);
	m_water_mesh_index_data.reserve(CHUNK_VOLUME * 4);

	for(std::int32_t x = 0; x < CHUNK_SIZE.x; x++)
	{
		for(std::int32_t z = 0; z < CHUNK_SIZE.z; z++)
		{
			for(std::int32_t y = 0; y < CHUNK_SIZE.y; y++)
			{
				BlockType type = static_cast<BlockType>(GetBlock(Scop::Vec3i(x, y, z)));
				if(type == BlockType::Air)
					continue;

				bool is_water = (type == BlockType::Water);
				std::vector<Scop::Vertex>& mesh_data = (is_water ? m_water_mesh_data : m_mesh_data);
				std::vector<std::uint32_t>& index_data = (is_water ? m_water_mesh_index_data : m_mesh_index_data);
				std::uint32_t& offset = (is_water ? water_offset : mesh_offset);

				Scop::Vec4f base_color = is_water ? Scop::Vec4f{ 0.5f, 0.2f, 0.1f, 0.95f } : Scop::Vec4f{ 1.0f };
				std::uint32_t invalid_limit = is_water ? static_cast<std::uint32_t>(BlockType::Air) : static_cast<std::uint32_t>(BlockType::Water);

				if(GetBlock(Scop::Vec3i(x, y, z + 1)) <= invalid_limit)
				{
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 1);

					for(std::uint32_t i = 0; i < 4; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int u = static_cast<int>(BLOCK_MESH[i].position.x);
							int v = static_cast<int>(BLOCK_MESH[i].position.y);
							bool occ1 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + v, z + 1)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x + u, y + (v == 0 ? -1 : 1), z + 1)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + (v == 0 ? -1 : 1), z + 1)) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						if(is_water && (i == 1 || i == 3) && GetBlock(Scop::Vec3i(x, y + 1, z)) != static_cast<std::uint32_t>(BlockType::Water))
							vertex_pos.w = 0.0;
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Side) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}

				if(GetBlock(Scop::Vec3i(x, y, z - 1)) <= invalid_limit)
				{
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 0);

					for(std::uint32_t i = 4; i < 8; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int local_index = i - 4;
							int u = static_cast<int>(BLOCK_MESH[i].position.x);
							int v = static_cast<int>(BLOCK_MESH[i].position.y);

							bool occ1 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + v, z - 1)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x + u, y + (v == 0 ? -1 : 1), z - 1)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + (v == 0 ? -1 : 1), z - 1)) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						if(is_water && (i == 5 || i == 7) && GetBlock(Scop::Vec3i(x, y + 1, z)) != static_cast<std::uint32_t>(BlockType::Water))
							vertex_pos.w = 0.0;
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Side) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}

				if(std::uint32_t value = GetBlock(Scop::Vec3i(x, y + 1, z)); !is_water ? value <= invalid_limit : value != static_cast<std::uint32_t>(BlockType::Water)) // We want top face water even under blocks
				{
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 3);

					for(std::uint32_t i = 8; i < 12; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int local_index = i - 8;
							int u = static_cast<int>(BLOCK_MESH[i].position.x);
							int v = static_cast<int>(BLOCK_MESH[i].position.z);

							bool occ1 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + 1, z + v)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x + u, y + 1, z + (v == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y + 1, z + (v == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						if(is_water)
							vertex_pos.w = 0.0;
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Top) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}

				if(GetBlock(Scop::Vec3i(x, y - 1, z)) <= invalid_limit)
				{
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 2);

					for(std::uint32_t i = 12; i < 16; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int local_index = i - 12;
							int u = static_cast<int>(BLOCK_MESH[i].position.x);
							int v = static_cast<int>(BLOCK_MESH[i].position.z);

							bool occ1 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y - 1, z + v)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x + u, y - 1, z + (v == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x + (u == 0 ? -1 : 1), y - 1,z  + (v == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Bottom) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}

				if(GetBlock(Scop::Vec3i(x + 1, y, z)) <= invalid_limit)
				{
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 1);
					index_data.push_back(offset + 0);

					for(std::uint32_t i = 16; i < 20; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int local_index = i - 16;
							int u = static_cast<int>(BLOCK_MESH[i].position.z);
							int v = static_cast<int>(BLOCK_MESH[i].position.y);

							bool occ1 = (GetBlock(Scop::Vec3i(x + 1, y + v, z + (u == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x + 1, y + (v == 0 ? -1 : 1), z + u)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x + 1, y + (v == 0 ? -1 : 1), z + (u == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						if(is_water && (i == 17 || i == 19) && GetBlock(Scop::Vec3i(x, y + 1, z)) != static_cast<std::uint32_t>(BlockType::Water))
							vertex_pos.w = 0.0;
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Side) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}

				if(GetBlock(Scop::Vec3i(x - 1, y, z)) <= invalid_limit)
				{
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 2);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 0);
					index_data.push_back(offset + 3);
					index_data.push_back(offset + 1);

					for(std::uint32_t i = 20; i < 24; i++)
					{
						Scop::Vec4f vertex_color;
						if(!is_water)
						{
							int local_index = i - 20;
							int u = static_cast<int>(BLOCK_MESH[i].position.z);
							int v = static_cast<int>(BLOCK_MESH[i].position.y);

							bool occ1 = (GetBlock(Scop::Vec3i(x - 1, y + v, z + (u == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ2 = (GetBlock(Scop::Vec3i(x - 1, y + (v == 0 ? -1 : 1), z + u)) != static_cast<std::uint32_t>(BlockType::Air));
							bool occ3 = (GetBlock(Scop::Vec3i(x - 1, y + (v == 0 ? -1 : 1), z + (u == 0 ? -1 : 1))) != static_cast<std::uint32_t>(BlockType::Air));

							int occ_count = (occ1 ? 1 : 0) + (occ2 ? 1 : 0) + (occ3 ? 1 : 0);
							float ao = 1.0f - (occ_count * 0.2f);

							vertex_color = Scop::Vec4f(Scop::Vec3f(base_color) * ao, 1.0f);
						}
						else
							vertex_color = base_color;
						Scop::Vec4f vertex_pos = BLOCK_MESH[i].position + Scop::Vec3f(x, y, z);
						if(is_water && (i == 21 || i == 23) && GetBlock(Scop::Vec3i(x, y + 1, z)) != static_cast<std::uint32_t>(BlockType::Water))
							vertex_pos.w = 0.0;
						Scop::Vec2f uv = GetAtlasOffset(type, Side::Side) + (Scop::Vec2f(SPRITE_UNIT) * BLOCK_MESH[i].uv);
						mesh_data.push_back(Scop::Vertex(vertex_pos, vertex_color, BLOCK_MESH[i].normal, uv));
					}

					offset += 4;
				}
			}
		}
	}
}

void Chunk::UploadMesh()
{
	if(!p_actor && !m_mesh_data.empty() && !m_mesh_index_data.empty())
	{
		std::shared_ptr<Scop::Mesh> mesh = std::make_shared<Scop::Mesh>();
		mesh->AddSubMesh({ std::move(m_mesh_data), std::move(m_mesh_index_data) });

		Scop::Actor& actor = m_world.GetScene().CreateActor(mesh);
		actor.GetModelRef().SetMaterial(m_world.GetBlockMaterial(), 0);
		actor.SetPosition(Scop::Vec3f(m_position.x, 0.0f, m_position.y));
		p_actor = &actor;
	}

	if(!p_water_actor && !m_water_mesh_data.empty() && !m_water_mesh_index_data.empty())
	{
		std::shared_ptr<Scop::Mesh> mesh = std::make_shared<Scop::Mesh>();
		mesh->AddSubMesh({ std::move(m_water_mesh_data), std::move(m_water_mesh_index_data) });

		Scop::Actor& actor = m_world.GetScene().CreateActor(mesh);
		actor.GetModelRef().SetMaterial(m_world.GetBlockMaterial(), 0);
		actor.SetPosition(Scop::Vec3f(m_position.x, 0.0f, m_position.y));
		actor.SetIsOpaque(false);
		actor.SetCustomPipeline({
			.pipeline = m_world.GetWaterPipeline(),
			.data{ sizeof(WaterData) }
		});
		std::memset(actor.GetCustomPipeline()->data.GetData(), 0, actor.GetCustomPipeline()->data.GetSize());

		auto object_update = [](Scop::NonOwningPtr<Scop::Scene> scene, Scop::NonOwningPtr<Scop::Actor> actor, Scop::Inputs& input, float delta)
		{
			WaterData* data = actor->GetCustomPipeline()->data.GetDataAs<WaterData>();
			data->time = static_cast<double>(SDL_GetTicks64());
		};
		using actor_hook = std::function<void(Scop::NonOwningPtr<Scop::Actor>)>;
		actor.AttachScript(std::make_shared<Scop::NativeActorScript>(actor_hook{}, object_update, actor_hook{}));
		p_water_actor = &actor;
	}
}

std::uint32_t Chunk::GetBlock(Scop::Vec3i position) const noexcept
{
	if(position.y < 0 || position.y >= CHUNK_SIZE.y) [[unlikely]] // No chunk under or above
		return static_cast<std::uint32_t>(BlockType::Dirt);
	if(position.x < 0) [[unlikely]]
	{
		Scop::NonOwningPtr<const Chunk> neighbour = m_world.GetChunk(Scop::Vec2i{ m_offset.x - 1, m_offset.y });
		return neighbour ? neighbour->GetBlock(Scop::Vec3i(CHUNK_SIZE.x - 1, position.y, position.z)) : static_cast<std::uint32_t>(BlockType::Dirt);
	}
	if(position.x >= CHUNK_SIZE.x) [[unlikely]]
	{
		Scop::NonOwningPtr<const Chunk> neighbour = m_world.GetChunk(Scop::Vec2i{ m_offset.x + 1, m_offset.y });
		return neighbour ? neighbour->GetBlock(Scop::Vec3i(0, position.y, position.z)) : static_cast<std::uint32_t>(BlockType::Dirt);
	}
	if(position.z < 0) [[unlikely]]
	{
		Scop::NonOwningPtr<const Chunk> neighbour = m_world.GetChunk(Scop::Vec2i{ m_offset.x, m_offset.y - 1 });
		return neighbour ? neighbour->GetBlock(Scop::Vec3i(position.x, position.y, CHUNK_SIZE.x - 1)) : static_cast<std::uint32_t>(BlockType::Dirt);
	}
	if(position.z >= CHUNK_SIZE.z) [[unlikely]]
	{
		Scop::NonOwningPtr<const Chunk> neighbour = m_world.GetChunk(Scop::Vec2i{ m_offset.x, m_offset.y + 1 });
		return neighbour ? neighbour->GetBlock(Scop::Vec3i(position.x, position.y, 0)) : static_cast<std::uint32_t>(BlockType::Dirt);
	}
	std::shared_lock guard(m_data_mutex);
	return m_data[POS_TO_INDEX(position.x, position.z)][position.y];
}