#include "Raw.h"
#include "BinaryIO.h"
#include "Logger.h"
#include "SceneColor.h"
#include <fstream>
#include <algorithm>
#include <limits>
#include <cmath>

namespace {
constexpr uint32_t kMaxResolution = 4096;
constexpr size_t kMaxBlobBytes = 64ULL * 1024 * 1024; // 64 MiB
constexpr uint32_t kMaxChunks = 1024;
} // namespace

namespace Raw {

bool Chunk::IsValidForSceneLookup() const {
	return !sceneMap.empty() && colorMapResolution > 0 && !heightMap.empty()
		&& scaleFactor > 0.0f && width > 1 && height > 1;
}

uint8_t Chunk::GetSceneIDAtLocal(float localX, float localZ) const {
	// The nearest scene map cell
	const auto toCell = [this](float cell) {
		return static_cast<uint32_t>(std::clamp(static_cast<int32_t>(std::floor(cell + 0.5f)), 0, static_cast<int32_t>(colorMapResolution) - 1));
	};
	const uint32_t sceneIndex = toCell(sceneCellsPerUnitX * localX) * colorMapResolution + toCell(sceneCellsPerUnitZ * localZ);
	if (sceneIndex >= sceneMap.size()) return 0;
	return sceneMap[sceneIndex];
}

uint8_t Chunk::GetSceneIDAtGrid(uint32_t i, uint32_t j) const {
	return GetSceneIDAtLocal(static_cast<float>(i) * scaleFactor, static_cast<float>(j) * scaleFactor);
}

NiPoint3 Chunk::GridToWorldPos(uint32_t i, uint32_t j) const {
	const uint32_t heightIndex = i * height + j;
	const float y = heightIndex < heightMap.size() ? heightMap[heightIndex] : 0.0f;
	return NiPoint3(offsetX + static_cast<float>(i) * scaleFactor, y, offsetZ + static_cast<float>(j) * scaleFactor);
}

	/**
	 * @brief Read flair attributes from stream
	 */
	static bool ReadFlairAttributes(std::istream& stream, FlairAttributes& flair) {
		try {
			BinaryIO::BinaryRead(stream, flair.id);
			BinaryIO::BinaryRead(stream, flair.scaleFactor);
			BinaryIO::BinaryRead(stream, flair.position.x);
			BinaryIO::BinaryRead(stream, flair.position.y);
			BinaryIO::BinaryRead(stream, flair.position.z);
			BinaryIO::BinaryRead(stream, flair.rotation.x);
			BinaryIO::BinaryRead(stream, flair.rotation.y);
			BinaryIO::BinaryRead(stream, flair.rotation.z);
			BinaryIO::BinaryRead(stream, flair.colorR);
			BinaryIO::BinaryRead(stream, flair.colorG);
			BinaryIO::BinaryRead(stream, flair.colorB);
			BinaryIO::BinaryRead(stream, flair.padding);
			return true;
		} catch (const std::exception&) {
			return false;
		}
	}

	/**
	 * @brief Read mesh triangle data from stream
	 */
	static bool ReadMeshTri(std::istream& stream, MeshTri& meshTri) {
		try {
			BinaryIO::BinaryRead(stream, meshTri.meshTriListSize);
			meshTri.meshTriList.resize(meshTri.meshTriListSize);
			for (uint16_t i = 0; i < meshTri.meshTriListSize; ++i) {
				BinaryIO::BinaryRead(stream, meshTri.meshTriList[i]);
			}
			return true;
		} catch (const std::exception&) {
			return false;
		}
	}

	/**
	 * @brief Read a chunk from stream
	 */
	static bool ReadChunkData(std::istream& stream, Chunk& chunk, uint16_t version) {
		try {
			// Read basic chunk info
			BinaryIO::BinaryRead(stream, chunk.id);
			if (stream.fail()) {
				return false;
			}

			BinaryIO::BinaryRead(stream, chunk.width);
			BinaryIO::BinaryRead(stream, chunk.height);
			BinaryIO::BinaryRead(stream, chunk.offsetX);
			BinaryIO::BinaryRead(stream, chunk.offsetZ);

			if (stream.fail()) {
				return false;
			}

			// For version < 32, shader ID comes before texture IDs
			if (version < 32) {
				BinaryIO::BinaryRead(stream, chunk.shaderId);
			}

			// Read texture IDs (4 textures)
			chunk.textureIds.resize(4);
			for (int i = 0; i < 4; ++i) {
				BinaryIO::BinaryRead(stream, chunk.textureIds[i]);
			}

			if (stream.fail()) {
				return false;
			}

			// Read scale factor
			BinaryIO::BinaryRead(stream, chunk.scaleFactor);

			if (stream.fail()) {
				return false;
			}

			// Read heightmap: width * height floats, at most kMaxResolution^2 (64 MiB)
			if (chunk.width == 0 || chunk.height == 0 || chunk.width > kMaxResolution || chunk.height > kMaxResolution) {
				LOG("Chunk %u has invalid heightmap dimensions: width=%u, height=%u (max %u)", chunk.id, chunk.width, chunk.height, kMaxResolution);
				return false;
			}

			const size_t heightMapSize = static_cast<size_t>(chunk.width) * chunk.height;
			chunk.heightMap.resize(heightMapSize);
			for (size_t i = 0; i < heightMapSize; ++i) {
				BinaryIO::BinaryRead(stream, chunk.heightMap[i]);
			}

			if (stream.fail()) {
				return false;
			}

			// ColorMap
			if (version >= 32) {
				BinaryIO::BinaryRead(stream, chunk.colorMapResolution);
			} else {
				chunk.colorMapResolution = chunk.width - 1;
			}

			if (chunk.colorMapResolution > kMaxResolution) {
				LOG("Chunk colorMapResolution %u exceeds maximum %u", chunk.colorMapResolution, kMaxResolution);
				return false;
			}

			if (version >= 32) {
				const size_t colorMapPixelCount = static_cast<size_t>(chunk.colorMapResolution) * chunk.colorMapResolution * 4;
				if (colorMapPixelCount > kMaxBlobBytes) {
					LOG("Chunk colorMap size %zu exceeds maximum %zu bytes", colorMapPixelCount, kMaxBlobBytes);
					return false;
				}
				chunk.colorMap.resize(colorMapPixelCount);
				stream.read(reinterpret_cast<char*>(chunk.colorMap.data()), static_cast<std::streamsize>(colorMapPixelCount));
			} else {
				const size_t legacyColorBytes = static_cast<size_t>(chunk.width) * chunk.width * 4;
				if (legacyColorBytes > kMaxBlobBytes) {
					LOG("Chunk legacy colorMap size %zu exceeds maximum %zu bytes", legacyColorBytes, kMaxBlobBytes);
					return false;
				}
				chunk.colorMap.resize(legacyColorBytes);
				stream.read(reinterpret_cast<char*>(chunk.colorMap.data()), static_cast<std::streamsize>(legacyColorBytes));
			}

			if (stream.fail()) {
				return false;
			}

			// LightMap/diffusemap.dds (v>=32 only)
			if (version >= 32) {
				uint32_t lightMapSize;
				BinaryIO::BinaryRead(stream, lightMapSize);

				if (lightMapSize > kMaxBlobBytes) {
					LOG("Chunk lightMap size %u exceeds maximum %zu bytes", lightMapSize, kMaxBlobBytes);
					return false;
				}
				chunk.lightMap.resize(lightMapSize);
				stream.read(reinterpret_cast<char*>(chunk.lightMap.data()), static_cast<std::streamsize>(lightMapSize));

				if (stream.fail()) {
					return false;
				}
			}

			// Blend/texture map
			BinaryIO::BinaryRead(stream, chunk.textureMapResolution);

			if (chunk.textureMapResolution > kMaxResolution) {
				LOG("Chunk textureMapResolution %u exceeds maximum %u", chunk.textureMapResolution, kMaxResolution);
				return false;
			}
			const size_t textureMapPixelCount = static_cast<size_t>(chunk.textureMapResolution) * chunk.textureMapResolution * 4;
			if (textureMapPixelCount > kMaxBlobBytes) {
				LOG("Chunk textureMap size %zu exceeds maximum %zu bytes", textureMapPixelCount, kMaxBlobBytes);
				return false;
			}
			chunk.textureMap.resize(textureMapPixelCount);
			stream.read(reinterpret_cast<char*>(chunk.textureMap.data()), static_cast<std::streamsize>(textureMapPixelCount));

			if (stream.fail()) {
				return false;
			}

			// Texture settings + blend map DDS (v>=32 only)
			if (version >= 32) {
				BinaryIO::BinaryRead(stream, chunk.textureSettings);

				uint32_t blendMapDDSSize;
				BinaryIO::BinaryRead(stream, blendMapDDSSize);

				if (blendMapDDSSize > kMaxBlobBytes) {
					LOG("Chunk blendMap size %u exceeds maximum %zu bytes", blendMapDDSSize, kMaxBlobBytes);
					return false;
				}
				chunk.blendMap.resize(blendMapDDSSize);
				stream.read(reinterpret_cast<char*>(chunk.blendMap.data()), static_cast<std::streamsize>(blendMapDDSSize));

				if (stream.fail()) {
					return false;
				}
			}

			// Read flairs
			uint32_t numFlairs;
			BinaryIO::BinaryRead(stream, numFlairs);

			if (stream.fail()) {
				return false;
			}

			const size_t flairBytes = static_cast<size_t>(numFlairs) * sizeof(FlairAttributes);
			if (flairBytes > kMaxBlobBytes) {
				LOG("Chunk %u flair count %u exceeds maximum (byte size %zu > %zu)", chunk.id, numFlairs, flairBytes, kMaxBlobBytes);
				return false;
			}
			chunk.flairs.resize(numFlairs);
			for (uint32_t i = 0; i < numFlairs; ++i) {
				if (!ReadFlairAttributes(stream, chunk.flairs[i])) {
					return false;
				}
			}

			// Scene map
			if (version >= 32) {
				const size_t sceneMapSize = static_cast<size_t>(chunk.colorMapResolution) * chunk.colorMapResolution;

				if (sceneMapSize > kMaxBlobBytes) {
					LOG("Chunk sceneMap size %zu exceeds maximum %zu bytes", sceneMapSize, kMaxBlobBytes);
					return false;
				}
				chunk.sceneMap.resize(sceneMapSize);
				stream.read(reinterpret_cast<char*>(chunk.sceneMap.data()), static_cast<std::streamsize>(sceneMapSize));
			} else {
				const size_t sceneMapCells = static_cast<size_t>(chunk.colorMapResolution + 1) * (chunk.colorMapResolution + 1);
				if (sceneMapCells > kMaxBlobBytes) {
					LOG("Chunk legacy sceneMap size %zu exceeds maximum %zu bytes", sceneMapCells, kMaxBlobBytes);
					return false;
				}
				chunk.sceneMapLegacy.resize(sceneMapCells);
				stream.read(reinterpret_cast<char*>(chunk.sceneMapLegacy.data()), static_cast<std::streamsize>(sceneMapCells));
				// Like the client: version 31 uses the first colorMapResolution rows and columns, older versions are all scene 0
				chunk.sceneMap.assign(static_cast<size_t>(chunk.colorMapResolution) * chunk.colorMapResolution, 0);
				if (version == 31) {
					for (uint32_t row = 0; row < chunk.colorMapResolution; ++row) {
						for (uint32_t col = 0; col < chunk.colorMapResolution; ++col) {
							chunk.sceneMap[row * chunk.colorMapResolution + col] = chunk.sceneMapLegacy[row * (chunk.colorMapResolution + 1) + col];
						}
					}
				}
			}

			if (stream.fail()) {
				return false;
			}

			// Mesh data (v>=32 only)
			if (version < 32) {
				return true;
			}

			BinaryIO::BinaryRead(stream, chunk.vertSize);

			if (stream.fail()) {
				return false;
			}

			if (chunk.vertSize == 0) {
				return true;
			}

			const size_t vertBytes = static_cast<size_t>(chunk.vertSize) * sizeof(uint16_t);
			if (vertBytes > kMaxBlobBytes) {
				LOG("Chunk %u vertSize %u exceeds maximum (byte size %zu > %zu)", chunk.id, chunk.vertSize, vertBytes, kMaxBlobBytes);
				return false;
			}
			chunk.meshVertUsage.resize(chunk.vertSize);
			for (uint32_t i = 0; i < chunk.vertSize; ++i) {
				BinaryIO::BinaryRead(stream, chunk.meshVertUsage[i]);
			}

			if (stream.fail()) {
				return false;
			}

			chunk.meshVertSize.resize(16);
			for (int i = 0; i < 16; ++i) {
				BinaryIO::BinaryRead(stream, chunk.meshVertSize[i]);
			}

			if (stream.fail()) {
				return false;
			}

			chunk.meshTri.resize(16);
			for (int i = 0; i < 16; ++i) {
				if (!ReadMeshTri(stream, chunk.meshTri[i])) {
					return false;
				}
			}

			return true;
		} catch (const std::exception&) {
			return false;
		}
	}

	/**
	 * @brief Read a chunk and work out its scene map cell sizes
	 */
	static bool ReadChunk(std::istream& stream, Chunk& chunk, uint16_t version) {
		if (!ReadChunkData(stream, chunk, version)) return false;

		if (chunk.IsValidForSceneLookup()) {
			chunk.sceneCellSizeX = static_cast<float>(chunk.width - 1) * chunk.scaleFactor / static_cast<float>(chunk.colorMapResolution);
			chunk.sceneCellSizeZ = static_cast<float>(chunk.height - 1) * chunk.scaleFactor / static_cast<float>(chunk.colorMapResolution);
			chunk.sceneCellsPerUnitX = 1.0f / chunk.sceneCellSizeX;
			chunk.sceneCellsPerUnitZ = 1.0f / chunk.sceneCellSizeZ;
		}
		return true;
	}

	/**
	 * @brief Index the chunks by grid cell when they form a regular grid of equal chunks
	 */
	static void BuildChunkGrid(Raw& raw) {
		raw.chunkGrid.clear();
		const auto& first = raw.chunks.front();
		const float spanX = first.GetMaxX() - first.offsetX;
		const float spanZ = first.GetMaxZ() - first.offsetZ;
		if (spanX <= 0.0f || spanZ <= 0.0f) return;

		const auto countX = static_cast<uint32_t>(std::lround((raw.maxBoundsX - raw.minBoundsX) / spanX));
		const auto countZ = static_cast<uint32_t>(std::lround((raw.maxBoundsZ - raw.minBoundsZ) / spanZ));
		if (countX == 0 || countZ == 0 || static_cast<size_t>(countX) * countZ > kMaxChunks) return;

		std::vector<int32_t> grid(static_cast<size_t>(countX) * countZ, -1);
		for (size_t i = 0; i < raw.chunks.size(); ++i) {
			const auto& chunk = raw.chunks[i];
			const float cellX = (chunk.offsetX - raw.minBoundsX) / spanX;
			const float cellZ = (chunk.offsetZ - raw.minBoundsZ) / spanZ;
			const long x = std::lround(cellX);
			const long z = std::lround(cellZ);
			const bool sameSize = chunk.width == first.width && chunk.height == first.height && chunk.scaleFactor == first.scaleFactor;
			if (!sameSize || std::abs(cellX - x) > 0.01f || std::abs(cellZ - z) > 0.01f || x < 0 || z < 0
				|| x >= static_cast<long>(countX) || z >= static_cast<long>(countZ)) {
				LOG("Raw chunks are not a regular grid (chunk %u); scene lookups check every chunk", chunk.id);
				return;
			}
			auto& cell = grid[static_cast<size_t>(x) * countZ + z];
			if (cell == -1) cell = static_cast<int32_t>(i); // the client takes the first chunk that matches
		}

		raw.chunkGrid = std::move(grid);
		raw.chunkGridCountX = countX;
		raw.chunkGridCountZ = countZ;
		raw.chunkSpanX = spanX;
		raw.chunkSpanZ = spanZ;
	}

	bool ReadRaw(std::istream& stream, Raw& outRaw) {
		// Get stream size
		stream.seekg(0, std::ios::end);
		auto streamSize = stream.tellg();
		stream.seekg(0, std::ios::beg);

		if (streamSize <= 0) {
			return false;
		}

		try {
			// Read header
			BinaryIO::BinaryRead(stream, outRaw.version);

			if (stream.fail()) {
				return false;
			}

			BinaryIO::BinaryRead(stream, outRaw.dev);

			if (stream.fail()) {
				return false;
			}

			// Only read chunks if dev == 0
			if (outRaw.dev == 0) {
				BinaryIO::BinaryRead(stream, outRaw.numChunks);
				BinaryIO::BinaryRead(stream, outRaw.numChunksWidth);
				BinaryIO::BinaryRead(stream, outRaw.numChunksHeight);

				if (outRaw.numChunks > kMaxChunks) {
					LOG("Raw numChunks %u exceeds maximum %u", outRaw.numChunks, kMaxChunks);
					return false;
				}

				// Read all chunks
				outRaw.chunks.resize(outRaw.numChunks);
				for (uint32_t i = 0; i < outRaw.numChunks; ++i) {
					if (!ReadChunk(stream, outRaw.chunks[i], outRaw.version)) {
						return false;
					}
				}
				
				// Calculate terrain bounds from all chunks
				if (!outRaw.chunks.empty()) {
					outRaw.minBoundsX = std::numeric_limits<float>::max();
					outRaw.minBoundsZ = std::numeric_limits<float>::max();
					outRaw.maxBoundsX = std::numeric_limits<float>::lowest();
					outRaw.maxBoundsZ = std::numeric_limits<float>::lowest();

					for (const auto& chunk : outRaw.chunks) {
						outRaw.minBoundsX = std::min(outRaw.minBoundsX, chunk.offsetX);
						outRaw.minBoundsZ = std::min(outRaw.minBoundsZ, chunk.offsetZ);
						outRaw.maxBoundsX = std::max(outRaw.maxBoundsX, chunk.GetMaxX());
						outRaw.maxBoundsZ = std::max(outRaw.maxBoundsZ, chunk.GetMaxZ());
					}
					LOG_DEBUG("Raw terrain bounds: X[%.2f, %.2f], Z[%.2f, %.2f]",
						outRaw.minBoundsX, outRaw.maxBoundsX, outRaw.minBoundsZ, outRaw.maxBoundsZ);
					BuildChunkGrid(outRaw);
				}
			}
			return true;
		} catch (const std::exception&) {
			return false;
		}
	}

	// The client's TerrainManager::GetSceneAtPos: clamp to the terrain bounds, keep one scene cell inside the far edge,
	// find the chunk containing the position (edges moved in by 0.001) and take its nearest scene map cell
	std::optional<uint8_t> Raw::GetSceneIDAt(float x, float z) const {
		if (chunks.empty()) return std::nullopt;

		constexpr float kEdgeEpsilon = 0.001f;
		const float posX = std::clamp(x, minBoundsX, maxBoundsX);
		const float posZ = std::clamp(z, minBoundsZ, maxBoundsZ);

		const auto sceneInChunk = [&](const Chunk& chunk) -> std::optional<uint8_t> {
			if (!chunk.IsValidForSceneLookup()) return std::nullopt;
			const float chunkX = std::min(posX, maxBoundsX - chunk.sceneCellSizeX);
			const float chunkZ = std::min(posZ, maxBoundsZ - chunk.sceneCellSizeZ);
			if (chunk.offsetX - kEdgeEpsilon <= chunkX && chunkX < chunk.GetMaxX() - kEdgeEpsilon &&
				chunk.offsetZ - kEdgeEpsilon <= chunkZ && chunkZ < chunk.GetMaxZ() - kEdgeEpsilon) {
				return chunk.GetSceneIDAtLocal(chunkX - chunk.offsetX, chunkZ - chunk.offsetZ);
			}
			return std::nullopt;
		};

		if (chunkGrid.empty()) {
			for (const auto& chunk : chunks) {
				if (const auto sceneID = sceneInChunk(chunk)) return sceneID;
			}
			return std::nullopt;
		}

		// The grid cell the position falls in, checked with the client's test; for a position on a float edge the
		// neighbouring cells are checked too
		const auto toCell = [](float pos, float min, float span, uint32_t count) {
			const auto cell = static_cast<int32_t>(std::floor((pos + kEdgeEpsilon - min) / span));
			return std::clamp(cell, 0, static_cast<int32_t>(count) - 1);
		};
		const int32_t cellX = toCell(posX, minBoundsX, chunkSpanX, chunkGridCountX);
		const int32_t cellZ = toCell(posZ, minBoundsZ, chunkSpanZ, chunkGridCountZ);
		for (const int32_t offsetX : { 0, -1, 1 }) {
			for (const int32_t offsetZ : { 0, -1, 1 }) {
				const int32_t x = cellX + offsetX;
				const int32_t z = cellZ + offsetZ;
				if (x < 0 || z < 0 || x >= static_cast<int32_t>(chunkGridCountX) || z >= static_cast<int32_t>(chunkGridCountZ)) continue;
				const int32_t index = chunkGrid[static_cast<size_t>(x) * chunkGridCountZ + z];
				if (index < 0) continue;
				if (const auto sceneID = sceneInChunk(chunks[index])) return sceneID;
			}
		}
		return std::nullopt;
	}

	void GenerateTerrainMesh(const Raw& raw, TerrainMesh& outMesh) {
		outMesh.vertices.clear();
		outMesh.triangles.clear();

		if (raw.chunks.empty() || raw.version < 32) {
			return; // No scene data available
		}

		LOG_DEBUG("GenerateTerrainMesh: Processing %zu chunks", raw.chunks.size());

		uint32_t vertexOffset = 0;

		for (const auto& chunk : raw.chunks) {
			if (!chunk.IsValidForSceneLookup()) continue;

			// One vertex per heightmap point, in [i * height + j] order
			for (uint32_t i = 0; i < chunk.width; ++i) {
				for (uint32_t j = 0; j < chunk.height; ++j) {
					outMesh.vertices.emplace_back(chunk.GridToWorldPos(i, j), chunk.GetSceneIDAtGrid(i, j));
					if (i > 0 && j > 0) {
						const uint32_t currentVert = vertexOffset + chunk.height * i + j;
						const uint32_t leftVert = currentVert - 1;
						const uint32_t bottomLeftVert = vertexOffset + chunk.height * (i - 1) + j - 1;
						const uint32_t bottomVert = vertexOffset + chunk.height * (i - 1) + j;

						// First triangle
						outMesh.triangles.push_back(currentVert);
						outMesh.triangles.push_back(leftVert);
						outMesh.triangles.push_back(bottomLeftVert);

						// Second triangle
						outMesh.triangles.push_back(bottomLeftVert);
						outMesh.triangles.push_back(bottomVert);
						outMesh.triangles.push_back(currentVert);
					}
				}
			}

			vertexOffset += chunk.width * chunk.height;
		}
	}

	bool WriteTerrainMeshToOBJ(const TerrainMesh& mesh, const std::string& path) {
		try {
			std::ofstream file(path);
			if (!file.is_open()) {
				LOG("Failed to open OBJ file for writing: %s", path.c_str());
				return false;
			}

			for (const auto& v : mesh.vertices) {
				const NiColor& color = SceneColor::Get(v.sceneID);
				file << "v " << v.position.x << ' ' << v.position.y << ' ' << v.position.z
					<< ' ' << color.m_Red << ' ' << color.m_Green << ' ' << color.m_Blue << '\n';
			}

			for (size_t i = 0; i < mesh.triangles.size(); i += 3) {
				file << "f " << (mesh.triangles[i] + 1) << ' '
					<< (mesh.triangles[i + 1] + 1) << ' '
					<< (mesh.triangles[i + 2] + 1) << '\n';
			}

			file.close();
			LOG("Successfully wrote terrain mesh to OBJ: %s (%zu vertices, %zu triangles)",
				path.c_str(), mesh.vertices.size(), mesh.triangles.size() / 3);
			return true;
		} catch (const std::exception& e) {
			LOG("Exception while writing OBJ file: %s", e.what());
			return false;
		}
	}

} // namespace Raw