#include "RendererSectionData.hpp"

#include <array>

#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/matrix_inverse.hpp>
#include <optick.h>

#include "World.hpp"

inline const BlockId& GetBlockId(const Vector& pos, const std::array<BlockId, 4096> &blockIdData) {
	return blockIdData[pos.y * 256 + pos.z * 16 + pos.x];
}

inline const BlockId& GetBlockId(int x, int y, int z, const std::array<BlockId, 4096> &blockIdData) {
	return blockIdData[y * 256 + z * 16 + x];
}

glm::vec2 TransformTextureCoord(const glm::vec4& TextureAtlasCoords, const glm::vec2& UvCoords, float frames) {
	float x = TextureAtlasCoords.x;
	float y = TextureAtlasCoords.y;
	float w = TextureAtlasCoords.z;
	float h = TextureAtlasCoords.w / frames;
	glm::vec2 transformed = glm::vec2(x, 1 - y - h) + UvCoords * glm::vec2(w, h);
	return transformed;
}

//Maps [0.0, 0.5] range to [0.0, 1.0]
float MapNeg(float x) {
    float y = x * 2.0f;
    return glm::clamp(y, 0.0f, 1.0f);
}

//Maps [0.5, 1.0] range to [0.0, 1.0]
float MapPos(float x) {
    float y = (x * 2.0f) - 1.0f;
    return glm::clamp(y, 0.0f, 1.0f);
}

float InterpolateBlockLightness(const BlockLightness& light, const glm::vec3 &point) {
    float xNeg = MapNeg(point.x);
    float xPos = MapPos(point.x);
    float xNegLight = glm::mix(light.face[FaceDirection::east], light.self, xNeg);
    float xPosLight = glm::mix(light.self, light.face[FaceDirection::west], xPos);
    float xLight = (glm::max)(xNegLight, xPosLight);

    float yNeg = MapNeg(point.y);
    float yPos = MapPos(point.y);
    float yNegLight = glm::mix(light.face[FaceDirection::down], light.self, yNeg);
    float yPosLight = glm::mix(light.self, light.face[FaceDirection::up], yPos);
    float yLight = (glm::max)(yNegLight, yPosLight);

    float zNeg = MapNeg(point.z);
    float zPos = MapPos(point.z);
    float zNegLight = glm::mix(light.face[FaceDirection::south], light.self, zNeg);
    float zPosLight = glm::mix(light.self, light.face[FaceDirection::north], zPos);
    float zLight = (glm::max)(zNegLight, zPosLight);

    return (glm::max)(xLight, (glm::max)(yLight, zLight));
}

void AddFacesByBlockModel(RendererSectionData& data, const BlockFaces& model, const glm::mat4& transform, bool visibility[FaceDirection::none], const Vector &pos, const SectionsData &sections, bool smoothLighting) {
    glm::vec3 absPos = (sections.data[1][1][1].GetPosition() * 16).glm();
    for (const auto& face : model.faces) {
        if (face.visibility != FaceDirection::none) {
			FaceDirection direction = face.visibility;
			Vector directionVec = model.faceDirectionVector[direction];
			FaceDirection faceDirection = FaceDirection::none;
			for (int i = 0; i < FaceDirection::none; i++) {
				if (FaceDirectionVector[i] == directionVec) {
					faceDirection = FaceDirection(i);
					break;
				}
			}
			if (faceDirection == FaceDirection::none)
				continue;

			if (visibility[faceDirection])
				continue;
		}

		data.solidVertices.emplace_back();
		VertexData& vertexData = data.solidVertices.back();

		glm::mat4 transformed = transform * model.transform * face.transform;
		vertexData.positions[0] = transformed * glm::vec4(0, 0, 0, 1);
		vertexData.positions[1] = transformed * glm::vec4(0, 0, 1, 1);
		vertexData.positions[2] = transformed * glm::vec4(1, 0, 1, 1);
		vertexData.positions[3] = transformed * glm::vec4(1, 0, 0, 1);

        glm::vec3 normal = glm::cross(vertexData.positions[1] - vertexData.positions[0], vertexData.positions[3] - vertexData.positions[0]);
        vertexData.normal = glm::normalize(normal);

		vertexData.uvs[0] = TransformTextureCoord(face.texture, glm::vec2(0, 0), face.frames);
		vertexData.uvs[1] = TransformTextureCoord(face.texture, glm::vec2(1, 0), face.frames);
		vertexData.uvs[2] = TransformTextureCoord(face.texture, glm::vec2(1, 1), face.frames);
		vertexData.uvs[3] = TransformTextureCoord(face.texture, glm::vec2(0, 1), face.frames);

		vertexData.layerAnimationAo.r = face.layer;
		vertexData.layerAnimationAo.g = face.frames;
		vertexData.colors = face.color;

        if (smoothLighting) {
            for (size_t i = 0; i < 4; i++) {
                glm::vec3 baseLightPos = vertexData.positions[i] - absPos;
                glm::vec3 lightPos = baseLightPos + normal * 0.5f;
                glm::ivec3 basePos = glm::trunc(lightPos);
                BlockLightness light = sections.GetLight(Vector(basePos.x, basePos.y, basePos.z));
				BlockLightness skyLight = sections.GetSkyLight(Vector(basePos.x, basePos.y, basePos.z));
                vertexData.lights[i].x = InterpolateBlockLightness(light, lightPos - glm::vec3(basePos));
                vertexData.lights[i].y = InterpolateBlockLightness(skyLight, lightPos - glm::vec3(basePos));
            }
        } else {
            BlockLightness light = sections.GetLight(pos);
            BlockLightness skyLight = sections.GetSkyLight(pos);
            glm::vec2 lightness;

            lightness.x = face.visibility != FaceDirection::none ? light.face[face.visibility] : light.self;
            lightness.x = (glm::max)(lightness.x, static_cast<float>(light.self));

            lightness.y = face.visibility != FaceDirection::none ? skyLight.face[face.visibility] : skyLight.self;
            lightness.y = (glm::max)(lightness.y, static_cast<float>(skyLight.self));

            vertexData.lights[0] = lightness;
            vertexData.lights[1] = lightness;
            vertexData.lights[2] = lightness;
            vertexData.lights[3] = lightness;
        }

        vertexData.layerAnimationAo.b = model.ambientOcclusion ? 1.0f : 0.0f;
    }
}

void AddLiquidFacesByBlockModel(RendererSectionData& data, BlockId blockId, const BlockFaces& model, const glm::mat4& transform, bool visibility[FaceDirection::none], const Vector& pos, const SectionsData& sections, bool smoothLighting) {
	const ParsedFace& flowData = model.faces[0];
	const ParsedFace& stillData = model.faces[1];
	size_t addedFaces = 0;

	constexpr float highLevel = 0.9f;
	constexpr float lowLevel = 0.05f;

	constexpr float neighborLevels[] = {
		lowLevel + ((highLevel - lowLevel) / 7) * 7.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 6.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 5.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 4.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 3.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 2.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 1.0f,
		lowLevel + ((highLevel - lowLevel) / 7) * 0.0f,
	};

	uint8_t neighborsLiquids[FaceDirection::none + 1] = { 0 };
	for (size_t i = 0; i < FaceDirection::none; i++) {
		const BlockId bid = sections.GetBlockId(pos + FaceDirectionVector[i]);
		neighborsLiquids[i] = bid.id == blockId.id ? bid.state & 0b00000111 : 0;
	}
	neighborsLiquids[FaceDirection::none] = blockId.state & 0b00000111;

	const bool liquidFalling = blockId.state & 0x8;
	if (liquidFalling) {
		if (!neighborsLiquids[FaceDirection::down]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[2] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[3] = transform * glm::vec4(0, 0, 1, 1);
		}

		if (!neighborsLiquids[FaceDirection::up]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 1, 0, 1);
			vertex.positions[1] = transform * glm::vec4(0, 1, 1, 1);
			vertex.positions[2] = transform * glm::vec4(1, 1, 1, 1);
			vertex.positions[3] = transform * glm::vec4(1, 1, 0, 1);
		}

		if (!neighborsLiquids[FaceDirection::north]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[2] = transform * glm::vec4(0, 1, 0, 1);
			vertex.positions[3] = transform * glm::vec4(1, 1, 0, 1);
		}

		if (!neighborsLiquids[FaceDirection::south]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 1, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[2] = transform * glm::vec4(1, 1, 1, 1);
			vertex.positions[3] = transform * glm::vec4(0, 1, 1, 1);
		}

		if (!neighborsLiquids[FaceDirection::west]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(0, 0, 1, 1);
			vertex.positions[2] = transform * glm::vec4(0, 1, 1, 1);
			vertex.positions[3] = transform * glm::vec4(0, 1, 0, 1);
		}

		if (!neighborsLiquids[FaceDirection::east]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[2] = transform * glm::vec4(1, 1, 0, 1);
			vertex.positions[3] = transform * glm::vec4(1, 1, 1, 1);
		}
	}
	else {
		const float bLevel = neighborLevels[neighborsLiquids[FaceDirection::none]];
		const float nLevel = neighborLevels[neighborsLiquids[FaceDirection::north]];
		const float eLevel = neighborLevels[neighborsLiquids[FaceDirection::east]];
		const float sLevel = neighborLevels[neighborsLiquids[FaceDirection::south]];
		const float wLevel = neighborLevels[neighborsLiquids[FaceDirection::west]];
		const float nwLevel = neighborLevels[neighborsLiquids[FaceDirection::northWest]];
		const float neLevel = neighborLevels[neighborsLiquids[FaceDirection::northEast]];
		const float swLevel = neighborLevels[neighborsLiquids[FaceDirection::southWest]];
		const float seLevel = neighborLevels[neighborsLiquids[FaceDirection::southEast]];

		const glm::vec4 nwCorner = glm::vec4(0, _min(nLevel, wLevel, nwLevel, bLevel), 0, 1);
		const glm::vec4 neCorner = glm::vec4(1, _min(nLevel, eLevel, neLevel, bLevel), 0, 1);
		const glm::vec4 swCorner = glm::vec4(0, _min(sLevel, wLevel, swLevel, bLevel), 1, 1);
		const glm::vec4 seCorner = glm::vec4(1, _min(sLevel, eLevel, seLevel, bLevel), 1, 1);

		if (!neighborsLiquids[FaceDirection::down]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[2] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[3] = transform * glm::vec4(0, 0, 1, 1);
		}

		if (!neighborsLiquids[FaceDirection::up]) {
			addedFaces++;

			FaceDirection flowDirection = FaceDirection::none;
			if (nwCorner.y + swCorner.y > neCorner.y + seCorner.y)
				flowDirection = FaceDirection::east;
			else if (neCorner.y + seCorner.y > nwCorner.y + swCorner.y)
				flowDirection = FaceDirection::west;
			else if (nwCorner.y + neCorner.y > swCorner.y + seCorner.y)
				flowDirection = FaceDirection::south;
			else
				flowDirection = FaceDirection::north;

			glm::mat4 flowMat = glm::mat4(1.0f);

			switch (flowDirection)
			{
			case FaceDirection::east:
				break;
			case FaceDirection::west:
				break;
			case FaceDirection::south:
				break;
			case FaceDirection::north:
				break;
			default:
				break;
			}

			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * flowMat * nwCorner;
			vertex.positions[1] = transform * flowMat * swCorner;
			vertex.positions[2] = transform * flowMat * seCorner;
			vertex.positions[3] = transform * flowMat * neCorner;

			const ParsedFace &texData =
				_max(nwCorner.y, swCorner.y, seCorner.y, neCorner.y) ==
				_min(nwCorner.y, swCorner.y, seCorner.y, neCorner.y) ?
				stillData : flowData;

			vertex.uvs[0] = TransformTextureCoord(texData.texture, glm::vec2(0, 0), texData.frames);
			vertex.uvs[1] = TransformTextureCoord(texData.texture, glm::vec2(1, 0), texData.frames);
			vertex.uvs[2] = TransformTextureCoord(texData.texture, glm::vec2(1, 1), texData.frames);
			vertex.uvs[3] = TransformTextureCoord(texData.texture, glm::vec2(0, 1), texData.frames);

			vertex.layerAnimationAo.r = texData.layer;
			vertex.layerAnimationAo.g = texData.frames;

			glm::vec3 normal = glm::cross(vertex.positions[1] - vertex.positions[0], vertex.positions[3] - vertex.positions[0]);
			vertex.normal = glm::normalize(normal);
		}

		if (!neighborsLiquids[FaceDirection::north]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[2] = transform * nwCorner;
			vertex.positions[3] = transform * neCorner;
		}

		if (!neighborsLiquids[FaceDirection::south]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 1, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[2] = transform * seCorner;
			vertex.positions[3] = transform * swCorner;
		}

		if (!neighborsLiquids[FaceDirection::west]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(0, 0, 0, 1);
			vertex.positions[1] = transform * glm::vec4(0, 0, 1, 1);
			vertex.positions[2] = transform * swCorner;
			vertex.positions[3] = transform * nwCorner;
		}

		if (!neighborsLiquids[FaceDirection::east]) {
			addedFaces++;
			VertexData& vertex = data.liquidVertices.emplace_back();
			vertex.positions[0] = transform * glm::vec4(1, 0, 1, 1);
			vertex.positions[1] = transform * glm::vec4(1, 0, 0, 1);
			vertex.positions[2] = transform * neCorner;
			vertex.positions[3] = transform * seCorner;
		}
	}


	glm::vec3 absPos = (sections.data[1][1][1].GetPosition() * 16).glm();
	BlockLightness light = sections.GetLight(pos);
	BlockLightness skyLight = sections.GetSkyLight(pos);
	glm::vec2 lightness;
	lightness.x = light.self;
	lightness.y = skyLight.self;
	for (size_t i = data.liquidVertices.size() - addedFaces; i < data.liquidVertices.size(); i++) {
		VertexData& vertex = data.liquidVertices[i];

		if (glm::length(vertex.normal) < 0.5f) {
			vertex.uvs[0] = TransformTextureCoord(flowData.texture, glm::vec2(0, 0), flowData.frames);
			vertex.uvs[1] = TransformTextureCoord(flowData.texture, glm::vec2(1, 0), flowData.frames);
			vertex.uvs[2] = TransformTextureCoord(flowData.texture, glm::vec2(1, 1), flowData.frames);
			vertex.uvs[3] = TransformTextureCoord(flowData.texture, glm::vec2(0, 1), flowData.frames);

			glm::vec3 normal = glm::cross(vertex.positions[1] - vertex.positions[0], vertex.positions[3] - vertex.positions[0]);
			vertex.normal = glm::normalize(normal);

			vertex.layerAnimationAo.r = flowData.layer;
			vertex.layerAnimationAo.g = flowData.frames;
		}

		vertex.layerAnimationAo.b = 0.0f;
		vertex.colors = glm::vec3(1.0f);

		if (smoothLighting) {
			for (size_t i = 0; i < 4; i++) {
				glm::vec3 baseLightPos = vertex.positions[i] - absPos;
				glm::vec3 lightPos = baseLightPos + vertex.normal * 0.5f;
				glm::ivec3 basePos = glm::trunc(lightPos);
				BlockLightness light = sections.GetLight(Vector(basePos.x, basePos.y, basePos.z));
				BlockLightness skyLight = sections.GetSkyLight(Vector(basePos.x, basePos.y, basePos.z));
				vertex.lights[i].x = InterpolateBlockLightness(light, lightPos - glm::vec3(basePos));
				vertex.lights[i].y = InterpolateBlockLightness(skyLight, lightPos - glm::vec3(basePos));
			}
		}
		else {
			vertex.lights[0] = lightness;
			vertex.lights[1] = lightness;
			vertex.lights[2] = lightness;
			vertex.lights[3] = lightness;
		}
	}
}

BlockFaces *GetInternalBlockModel(BlockId id, std::vector<std::pair<BlockId, BlockFaces*>> &idModels) {
    for (const auto& it : idModels) {
        if (it.first == id)
            return it.second;
    }
	idModels.emplace_back(std::pair{ id, &AssetManager::GetBlockModelByBlockId(id) });
    return idModels.back().second;
}

std::array<bool[FaceDirection::none], 4096> GetBlockVisibilityData(const SectionsData &sections, const std::array<BlockId, 4096> &blockIdData, std::vector<std::pair<BlockId, BlockFaces*>> &idModels) {
	std::array<bool[FaceDirection::none], 4096> arr;
	for (int y = 0; y < 16; y++) {
		for (int z = 0; z < 16; z++) {
			for (int x = 0; x < 16; x++) {
				unsigned char value = 0;

				Vector vec(x, y, z);

				BlockId blockIdDown = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::down]);
				BlockId blockIdUp = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::up]);
				BlockId blockIdNorth = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::north]);
				BlockId blockIdSouth = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::south]);
				BlockId blockIdWest = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::west]);
				BlockId blockIdEast = sections.GetBlockId(vec + FaceDirectionVector[FaceDirection::east]);

				auto blockModelDown = GetInternalBlockModel(blockIdDown, idModels);
				auto blockModelUp = GetInternalBlockModel(blockIdUp, idModels);
				auto blockModelNorth = GetInternalBlockModel(blockIdNorth, idModels);
				auto blockModelSouth = GetInternalBlockModel(blockIdSouth, idModels);
				auto blockModelWest = GetInternalBlockModel(blockIdWest, idModels);
				auto blockModelEast = GetInternalBlockModel(blockIdEast, idModels);
				
				arr[y * 256 + z * 16 + x][FaceDirection::down] = blockIdDown.id != 0 && !blockModelDown->faces.empty() && blockModelDown->isBlock;
				arr[y * 256 + z * 16 + x][FaceDirection::up] = blockIdUp.id != 0 && !blockModelUp->faces.empty() && blockModelUp->isBlock;
				arr[y * 256 + z * 16 + x][FaceDirection::north] = blockIdNorth.id != 0 && !blockModelNorth->faces.empty() && blockModelNorth->isBlock;
				arr[y * 256 + z * 16 + x][FaceDirection::south] = blockIdSouth.id != 0 && !blockModelSouth->faces.empty() && blockModelSouth->isBlock;
				arr[y * 256 + z * 16 + x][FaceDirection::west] = blockIdWest.id != 0 && !blockModelWest->faces.empty() && blockModelWest->isBlock;
				arr[y * 256 + z * 16 + x][FaceDirection::east] = blockIdEast.id != 0 && !blockModelEast->faces.empty() && blockModelEast->isBlock;
			}
		}
	}
	return arr;
}

std::array<BlockId, 4096> SetBlockIdData(const SectionsData &sections) {
	std::array<BlockId, 4096> blockIdData;
	for (int y = 0; y < 16; y++) {
		for (int z = 0; z < 16; z++) {
			for (int x = 0; x < 16; x++) {
                blockIdData[y * 256 + z * 16 + x] = sections.data[1][1][1].GetBlockId(Vector(x, y, z));
			}
		}
	}
	return blockIdData;
}

RendererSectionData ParseSection(const SectionsData &sections, bool smoothLighting) {
	OPTICK_EVENT();
	RendererSectionData data;

	std::vector<std::pair<BlockId, BlockFaces*>> idModels;
	std::array<BlockId, 4096> blockIdData = SetBlockIdData(sections);
	std::array<bool[FaceDirection::none], 4096> blockVisibility = GetBlockVisibilityData(sections, blockIdData, idModels);

    data.hash = sections.data[1][1][1].GetHash();
    data.sectionPos = sections.data[1][1][1].GetPosition();

    glm::mat4 baseOffset = glm::translate(glm::mat4(1.0), (sections.data[1][1][1].GetPosition() * 16).glm()), transform;

	for (int y = 0; y < 16; y++) {
		for (int z = 0; z < 16; z++) {
			for (int x = 0; x < 16; x++) {
				BlockId block = GetBlockId(x, y, z, blockIdData);
				if (block.id == 0)
					continue;

				Vector vec(x, y, z);

				transform = glm::translate(baseOffset, vec.glm());

				BlockFaces *model = GetInternalBlockModel(block, idModels);
                if (model->isLiquid)
                    AddLiquidFacesByBlockModel(data, block, *model, transform, blockVisibility[y * 256 + z * 16 + x], vec, sections, smoothLighting);
                else
                    AddFacesByBlockModel(data, *model, transform, blockVisibility[y * 256 + z * 16 + x], vec, sections, smoothLighting);
			}
		}
	}

	data.solidVertices.shrink_to_fit();
	data.liquidVertices.shrink_to_fit();

	return data;
}

BlockId SectionsData::GetBlockId(const Vector &pos) const {
    Vector sectionPos = pos;
    return GetSection(sectionPos).GetBlockId(sectionPos);
}

BlockLightness SectionsData::GetLight(const Vector& pos) const {
    BlockLightness lightness;
    for (size_t i = 0; i <= FaceDirection::none; i++) {
        Vector vec = pos + FaceDirectionVector[i];
        uint8_t dirValue = GetSection(vec).GetBlockLight(vec);

        if (i == FaceDirection::none)
            lightness.self = dirValue;
        else
            lightness.face[i] = dirValue;
    }
    return lightness;
}

BlockLightness SectionsData::GetSkyLight(const Vector &pos) const {
    BlockLightness lightness;
    for (size_t i = 0; i <= FaceDirection::none; i++) {
        Vector vec = pos + FaceDirectionVector[i];
        uint8_t dirValue = GetSection(vec).GetBlockSkyLight(vec);

        if (i == FaceDirection::none)
            lightness.self = dirValue;
        else
            lightness.face[i] = dirValue;
    }
    return lightness;
}