#include "RuntimeTextTextureCache.h"

#include "../../runtime/RuntimeJson.h"

#include <algorithm>
#include <cmath>
#include <fstream>
#include <sstream>
#include <wincodec.h>
#include <wrl/client.h>

namespace
{
constexpr GLuint kFirstTextTextureUnit = 8;
constexpr unsigned kTextTextureHeight = 128;
constexpr unsigned kTextTexturePadding = 8;
constexpr double kFontPixelsPerEm = 96.0;

std::string ReadTextFile(const std::filesystem::path& path)
{
	std::ifstream input(path, std::ios::binary);
	if (!input)
		return std::string();
	std::ostringstream buffer;
	buffer << input.rdbuf();
	return buffer.str();
}

const JsonValue* FindObjectValue(const JsonValue& object, const std::string& key)
{
	return object.isObject() ? object.find(key) : nullptr;
}

double NumberMember(const JsonValue& object, const std::string& key, double fallback = 0.0)
{
	const JsonValue* value = FindObjectValue(object, key);
	return value && value->isNumber() ? value->asNumber(fallback) : fallback;
}

struct ComThreadGuard
{
	~ComThreadGuard()
	{
		if (initialized)
			CoUninitialize();
	}

	bool Initialize()
	{
		const HRESULT result = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
		initialized = SUCCEEDED(result);
		return SUCCEEDED(result) || result == RPC_E_CHANGED_MODE;
	}

	bool initialized = false;
};
}

RuntimeTextTextureCache::~RuntimeTextTextureCache()
{
	ShutdownGl();
}

bool RuntimeTextTextureCache::Configure(const RuntimeShaderArtifact& artifact, std::string& error)
{
	ShutdownGl();
	mArtifact = artifact;

	for (const RenderCadenceCompositor::FontAtlasBuildOutput& output : artifact.fontAtlases)
	{
		Atlas atlas;
		if (!LoadAtlas(output, atlas, error))
			return false;
		mAtlases.push_back(std::move(atlas));
	}

	for (const ShaderParameterDefinition& definition : artifact.parameterDefinitions)
	{
		if (definition.type != ShaderParameterType::Text)
			continue;

		if (FindAtlas(definition.fontId) == nullptr)
		{
			error = "No prepared font atlas is available for text parameter '" + definition.id + "'.";
			return false;
		}

		TextTexture texture;
		texture.parameterId = definition.id;
		texture.fontId = definition.fontId;
		texture.maxLength = definition.maxLength == 0 ? 64 : definition.maxLength;
		mTextTextures.push_back(std::move(texture));
	}

	error.clear();
	return true;
}

void RuntimeTextTextureCache::UpdateArtifactState(const RuntimeShaderArtifact& artifact)
{
	mArtifact.parameterDefinitions = artifact.parameterDefinitions;
	mArtifact.parameterValues = artifact.parameterValues;
}

void RuntimeTextTextureCache::RefreshTextTextures(RuntimeShaderArtifact* artifactState)
{
	if (artifactState)
		artifactState->textTextureWidthScales.clear();
	for (TextTexture& textTexture : mTextTextures)
	{
		EnsureTextTexture(textTexture);
		if (artifactState)
		{
			const float scale = textTexture.width == 0
				? 1.0f
				: static_cast<float>(textTexture.liveWidth) / static_cast<float>(textTexture.width);
			artifactState->textTextureWidthScales[textTexture.parameterId] = scale;
		}
	}
}

void RuntimeTextTextureCache::BindTextTextures(GLuint program)
{
	for (std::size_t index = 0; index < mTextTextures.size(); ++index)
	{
		const TextTexture& textTexture = mTextTextures[index];
		if (textTexture.texture == 0)
			continue;
		glActiveTexture(GL_TEXTURE0 + kFirstTextTextureUnit + static_cast<GLuint>(index));
		glBindTexture(GL_TEXTURE_2D, textTexture.texture);
	}

	glUseProgram(program);
	AssignSamplerUniforms(program, mArtifact);
	glUseProgram(0);
	glActiveTexture(GL_TEXTURE0);
}

void RuntimeTextTextureCache::ShutdownGl()
{
	for (TextTexture& texture : mTextTextures)
		DestroyTexture(texture);
	mTextTextures.clear();
	mAtlases.clear();
}

void RuntimeTextTextureCache::AssignSamplerUniforms(GLuint program, const RuntimeShaderArtifact& artifact)
{
	glUseProgram(program);
	GLuint nextUnit = kFirstTextTextureUnit;
	for (const ShaderParameterDefinition& definition : artifact.parameterDefinitions)
	{
		if (definition.type != ShaderParameterType::Text)
			continue;

		const std::string samplerName = definition.id + "Texture";
		const GLint location = glGetUniformLocation(program, samplerName.c_str());
		if (location >= 0)
			glUniform1i(location, static_cast<GLint>(nextUnit));
		const std::string samplerArrayName = samplerName + "_0";
		const GLint arrayLocation = glGetUniformLocation(program, samplerArrayName.c_str());
		if (arrayLocation >= 0)
			glUniform1i(arrayLocation, static_cast<GLint>(nextUnit));
		++nextUnit;
	}
	glUseProgram(0);
}

bool RuntimeTextTextureCache::LoadAtlas(const RenderCadenceCompositor::FontAtlasBuildOutput& output, Atlas& atlas, std::string& error) const
{
	atlas.fontId = output.fontId;
	if (!LoadAtlasJson(output, atlas, error))
		return false;
	if (!LoadAtlasImage(output, atlas, error))
		return false;
	if (atlas.width == 0 || atlas.height == 0 || atlas.rgbaPixels.empty())
	{
		error = "Font atlas image is empty for font '" + output.fontId + "'.";
		return false;
	}
	return true;
}

bool RuntimeTextTextureCache::LoadAtlasJson(const RenderCadenceCompositor::FontAtlasBuildOutput& output, Atlas& atlas, std::string& error) const
{
	const std::string jsonText = ReadTextFile(output.jsonPath);
	if (jsonText.empty())
	{
		error = "Could not read font atlas json: " + output.jsonPath.string();
		return false;
	}

	JsonValue root;
	if (!ParseJson(jsonText, root, error))
		return false;

	const JsonValue* metrics = FindObjectValue(root, "metrics");
	if (metrics)
	{
		atlas.ascender = NumberMember(*metrics, "ascender", atlas.ascender);
		atlas.descender = NumberMember(*metrics, "descender", atlas.descender);
		atlas.lineHeight = NumberMember(*metrics, "lineHeight", atlas.lineHeight);
	}

	const JsonValue* glyphs = FindObjectValue(root, "glyphs");
	if (!glyphs || !glyphs->isArray())
	{
		error = "Font atlas json has no glyph array: " + output.jsonPath.string();
		return false;
	}

	for (const JsonValue& glyphJson : glyphs->asArray())
	{
		if (!glyphJson.isObject())
			continue;

		const unsigned codepoint = static_cast<unsigned>(NumberMember(glyphJson, "unicode", 0.0));
		Glyph glyph;
		glyph.advance = NumberMember(glyphJson, "advance", 0.0);

		const JsonValue* planeBounds = FindObjectValue(glyphJson, "planeBounds");
		const JsonValue* atlasBounds = FindObjectValue(glyphJson, "atlasBounds");
		if (planeBounds && atlasBounds)
		{
			glyph.planeLeft = NumberMember(*planeBounds, "left", 0.0);
			glyph.planeTop = NumberMember(*planeBounds, "top", 0.0);
			glyph.planeRight = NumberMember(*planeBounds, "right", 0.0);
			glyph.planeBottom = NumberMember(*planeBounds, "bottom", 0.0);
			glyph.atlasLeft = NumberMember(*atlasBounds, "left", 0.0);
			glyph.atlasTop = NumberMember(*atlasBounds, "top", 0.0);
			glyph.atlasRight = NumberMember(*atlasBounds, "right", 0.0);
			glyph.atlasBottom = NumberMember(*atlasBounds, "bottom", 0.0);
			glyph.hasBounds = true;
		}

		atlas.glyphsByCodepoint[codepoint] = glyph;
	}

	error.clear();
	return true;
}

bool RuntimeTextTextureCache::LoadAtlasImage(const RenderCadenceCompositor::FontAtlasBuildOutput& output, Atlas& atlas, std::string& error) const
{
	ComThreadGuard comGuard;
	if (!comGuard.Initialize())
	{
		error = "Could not initialize COM for font atlas PNG loading.";
		return false;
	}

	Microsoft::WRL::ComPtr<IWICImagingFactory> factory;
	HRESULT result = CoCreateInstance(
		CLSID_WICImagingFactory,
		nullptr,
		CLSCTX_INPROC_SERVER,
		IID_PPV_ARGS(factory.GetAddressOf()));
	if (FAILED(result))
	{
		error = "Could not create WIC imaging factory for font atlas PNG loading.";
		return false;
	}

	Microsoft::WRL::ComPtr<IWICBitmapDecoder> decoder;
	result = factory->CreateDecoderFromFilename(
		output.imagePath.wstring().c_str(),
		nullptr,
		GENERIC_READ,
		WICDecodeMetadataCacheOnLoad,
		decoder.GetAddressOf());
	if (FAILED(result))
	{
		error = "Could not decode font atlas PNG: " + output.imagePath.string();
		return false;
	}

	Microsoft::WRL::ComPtr<IWICBitmapFrameDecode> frame;
	result = decoder->GetFrame(0, frame.GetAddressOf());
	if (FAILED(result))
	{
		error = "Could not read font atlas PNG frame: " + output.imagePath.string();
		return false;
	}

	Microsoft::WRL::ComPtr<IWICFormatConverter> converter;
	result = factory->CreateFormatConverter(converter.GetAddressOf());
	if (FAILED(result))
	{
		error = "Could not create WIC format converter for font atlas PNG.";
		return false;
	}

	result = converter->Initialize(
		frame.Get(),
		GUID_WICPixelFormat32bppRGBA,
		WICBitmapDitherTypeNone,
		nullptr,
		0.0,
		WICBitmapPaletteTypeCustom);
	if (FAILED(result))
	{
		error = "Could not convert font atlas PNG to RGBA.";
		return false;
	}

	UINT width = 0;
	UINT height = 0;
	converter->GetSize(&width, &height);
	atlas.width = static_cast<unsigned>(width);
	atlas.height = static_cast<unsigned>(height);
	atlas.rgbaPixels.assign(static_cast<std::size_t>(atlas.width) * atlas.height * 4u, 0);

	const UINT stride = width * 4u;
	result = converter->CopyPixels(nullptr, stride, static_cast<UINT>(atlas.rgbaPixels.size()), atlas.rgbaPixels.data());
	if (FAILED(result))
	{
		error = "Could not copy font atlas PNG pixels.";
		return false;
	}

	error.clear();
	return true;
}

bool RuntimeTextTextureCache::EnsureTextTexture(TextTexture& texture)
{
	const ShaderParameterValue* value = FindParameterValue(mArtifact, texture.parameterId);
	const std::string text = value ? value->textValue : DefaultTextValue(mArtifact, texture.parameterId);
	if (texture.texture != 0 && texture.cachedText == text)
		return true;

	const Atlas* atlas = FindAtlas(texture.fontId);
	if (!atlas)
		return false;

	unsigned width = 0;
	unsigned height = 0;
	unsigned liveWidth = 1;
	std::vector<unsigned char> pixels = ComposeTextMask(*atlas, texture, text, width, height, liveWidth);
	if (pixels.empty() || width == 0 || height == 0)
		return false;

	if (texture.texture == 0)
		glGenTextures(1, &texture.texture);

	GLint previousUnpackAlignment = 4;
	glGetIntegerv(GL_UNPACK_ALIGNMENT, &previousUnpackAlignment);
	glBindTexture(GL_TEXTURE_2D, texture.texture);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
	if (texture.width != width || texture.height != height)
	{
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, static_cast<GLsizei>(width), static_cast<GLsizei>(height), 0, GL_RED, GL_UNSIGNED_BYTE, pixels.data());
	}
	else
	{
		glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, static_cast<GLsizei>(width), static_cast<GLsizei>(height), GL_RED, GL_UNSIGNED_BYTE, pixels.data());
	}
	glBindTexture(GL_TEXTURE_2D, 0);
	glPixelStorei(GL_UNPACK_ALIGNMENT, previousUnpackAlignment);
	glActiveTexture(GL_TEXTURE0);

	texture.cachedText = text;
	texture.width = width;
	texture.height = height;
	texture.liveWidth = liveWidth;
	return texture.texture != 0;
}

std::vector<unsigned char> RuntimeTextTextureCache::ComposeTextMask(const Atlas& atlas, const TextTexture& texture, const std::string& text, unsigned& width, unsigned& height, unsigned& liveWidth) const
{
	double advance = 0.0;
	for (unsigned char character : text)
	{
		const auto glyphIt = atlas.glyphsByCodepoint.find(character);
		if (glyphIt != atlas.glyphsByCodepoint.end())
			advance += glyphIt->second.advance;
	}

	const unsigned fixedWidth = static_cast<unsigned>(std::ceil(static_cast<double>(texture.maxLength) * kFontPixelsPerEm * 0.9)) + kTextTexturePadding * 2u;
	liveWidth = (std::max)(1u, static_cast<unsigned>(std::ceil(advance * kFontPixelsPerEm)) + kTextTexturePadding * 2u);
	width = (std::max)(fixedWidth, liveWidth);
	height = kTextTextureHeight;
	std::vector<unsigned char> mask(static_cast<std::size_t>(width) * height, 0);

	const double baseline = kTextTexturePadding + (-atlas.ascender * kFontPixelsPerEm);
	double penX = static_cast<double>(kTextTexturePadding);

	for (unsigned char character : text)
	{
		const auto glyphIt = atlas.glyphsByCodepoint.find(character);
		if (glyphIt == atlas.glyphsByCodepoint.end())
			continue;

		const Glyph& glyph = glyphIt->second;
		if (glyph.hasBounds)
		{
			const int destLeft = static_cast<int>(std::floor(penX + glyph.planeLeft * kFontPixelsPerEm));
			const int destTop = static_cast<int>(std::floor(baseline + glyph.planeTop * kFontPixelsPerEm));
			const int destRight = static_cast<int>(std::ceil(penX + glyph.planeRight * kFontPixelsPerEm));
			const int destBottom = static_cast<int>(std::ceil(baseline + glyph.planeBottom * kFontPixelsPerEm));
			const double destWidth = (std::max)(1.0, static_cast<double>(destRight - destLeft));
			const double destHeight = (std::max)(1.0, static_cast<double>(destBottom - destTop));

			for (int y = destTop; y < destBottom; ++y)
			{
				if (y < 0 || y >= static_cast<int>(height))
					continue;
				const double v = (static_cast<double>(y) + 0.5 - destTop) / destHeight;
				for (int x = destLeft; x < destRight; ++x)
				{
					if (x < 0 || x >= static_cast<int>(width))
						continue;
					const double u = (static_cast<double>(x) + 0.5 - destLeft) / destWidth;
					const double atlasX = glyph.atlasLeft + u * (glyph.atlasRight - glyph.atlasLeft);
					const double atlasY = glyph.atlasTop + v * (glyph.atlasBottom - glyph.atlasTop);
					unsigned char& destination = mask[static_cast<std::size_t>(y) * width + static_cast<std::size_t>(x)];
					destination = (std::max)(destination, SampleAtlasAlpha(atlas, atlasX, atlasY));
				}
			}
		}

		penX += glyph.advance * kFontPixelsPerEm;
	}

	for (unsigned y = 0; y < height / 2u; ++y)
	{
		unsigned char* topRow = mask.data() + static_cast<std::size_t>(y) * width;
		unsigned char* bottomRow = mask.data() + static_cast<std::size_t>(height - 1u - y) * width;
		for (unsigned x = 0; x < width; ++x)
			std::swap(topRow[x], bottomRow[x]);
	}

	return mask;
}

const RuntimeTextTextureCache::Atlas* RuntimeTextTextureCache::FindAtlas(const std::string& fontId) const
{
	for (const Atlas& atlas : mAtlases)
	{
		if (atlas.fontId == fontId)
			return &atlas;
	}
	return nullptr;
}

const ShaderParameterValue* RuntimeTextTextureCache::FindParameterValue(const RuntimeShaderArtifact& artifact, const std::string& parameterId)
{
	const auto valueIt = artifact.parameterValues.find(parameterId);
	return valueIt == artifact.parameterValues.end() ? nullptr : &valueIt->second;
}

std::string RuntimeTextTextureCache::DefaultTextValue(const RuntimeShaderArtifact& artifact, const std::string& parameterId)
{
	for (const ShaderParameterDefinition& definition : artifact.parameterDefinitions)
	{
		if (definition.id == parameterId)
			return definition.defaultTextValue;
	}
	return std::string();
}

unsigned char RuntimeTextTextureCache::SampleAtlasAlpha(const Atlas& atlas, double x, double y)
{
	const int ix = (std::max)(0, (std::min)(static_cast<int>(atlas.width) - 1, static_cast<int>(std::floor(x))));
	const int iy = (std::max)(0, (std::min)(static_cast<int>(atlas.height) - 1, static_cast<int>(std::floor(y))));
	const std::size_t pixelOffset = (static_cast<std::size_t>(iy) * atlas.width + static_cast<std::size_t>(ix)) * 4u;
	return atlas.rgbaPixels[pixelOffset + 3u];
}

void RuntimeTextTextureCache::DestroyTexture(TextTexture& texture)
{
	if (texture.texture != 0)
		glDeleteTextures(1, &texture.texture);
	texture.texture = 0;
	texture.width = 0;
	texture.height = 0;
	texture.cachedText.clear();
}