#include "ShaderTextureBindings.h"

#include "GlRenderConstants.h"
#include "TextRasterizer.h"
#include "TextureAssetLoader.h"

#include <algorithm>
#include <filesystem>

namespace
{
std::string TextValueForBinding(const RuntimeRenderState& state, const std::string& parameterId)
{
	auto valueIt = state.parameterValues.find(parameterId);
	return valueIt == state.parameterValues.end() ? std::string() : valueIt->second.textValue;
}

const ShaderFontAsset* FindFontAssetForParameter(const RuntimeRenderState& state, const ShaderParameterDefinition& definition)
{
	if (!definition.fontId.empty())
	{
		for (const ShaderFontAsset& fontAsset : state.fontAssets)
		{
			if (fontAsset.id == definition.fontId)
				return &fontAsset;
		}
	}
	return state.fontAssets.empty() ? nullptr : &state.fontAssets.front();
}
}

bool ShaderTextureBindings::LoadTextureAsset(const ShaderTextureAsset& textureAsset, GLuint& textureId, std::string& error)
{
	return ::LoadTextureAsset(textureAsset, textureId, error);
}

void ShaderTextureBindings::CreateTextBindings(const RuntimeRenderState& state, std::vector<LayerProgram::TextBinding>& textBindings)
{
	for (const ShaderParameterDefinition& definition : state.parameterDefinitions)
	{
		if (definition.type != ShaderParameterType::Text)
			continue;
		LayerProgram::TextBinding textBinding;
		textBinding.parameterId = definition.id;
		textBinding.samplerName = definition.id + "Texture";
		textBinding.fontId = definition.fontId;
		glGenTextures(1, &textBinding.texture);
		glBindTexture(GL_TEXTURE_2D, textBinding.texture);
		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);
		std::vector<unsigned char> empty(static_cast<std::size_t>(kTextTextureWidth) * kTextTextureHeight * 4, 0);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, kTextTextureWidth, kTextTextureHeight, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, empty.data());
		glBindTexture(GL_TEXTURE_2D, 0);
		textBindings.push_back(textBinding);
	}
}

bool ShaderTextureBindings::UpdateTextBindingTexture(const RuntimeRenderState& state, LayerProgram::TextBinding& textBinding, std::string& error)
{
	const std::string text = TextValueForBinding(state, textBinding.parameterId);
	if (text == textBinding.renderedText && textBinding.renderedWidth == kTextTextureWidth && textBinding.renderedHeight == kTextTextureHeight)
		return true;

	auto definitionIt = std::find_if(state.parameterDefinitions.begin(), state.parameterDefinitions.end(),
		[&textBinding](const ShaderParameterDefinition& definition) { return definition.id == textBinding.parameterId; });
	if (definitionIt == state.parameterDefinitions.end())
		return true;

	const ShaderFontAsset* fontAsset = FindFontAssetForParameter(state, *definitionIt);
	std::filesystem::path fontPath;
	if (fontAsset)
		fontPath = fontAsset->path;

	std::vector<unsigned char> sdf;
	if (!RasterizeTextSdf(text, fontPath, sdf, error))
		return false;

	GLint previousActiveTexture = 0;
	GLint previousUnpackBuffer = 0;
	glGetIntegerv(GL_ACTIVE_TEXTURE, &previousActiveTexture);
	glGetIntegerv(GL_PIXEL_UNPACK_BUFFER_BINDING, &previousUnpackBuffer);
	glActiveTexture(GL_TEXTURE0);
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
	glBindTexture(GL_TEXTURE_2D, textBinding.texture);
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, kTextTextureWidth, kTextTextureHeight, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, sdf.data());
	glBindTexture(GL_TEXTURE_2D, 0);
	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, static_cast<GLuint>(previousUnpackBuffer));
	glActiveTexture(static_cast<GLenum>(previousActiveTexture));

	textBinding.renderedText = text;
	textBinding.renderedWidth = kTextTextureWidth;
	textBinding.renderedHeight = kTextTextureHeight;
	return true;
}

GLint ShaderTextureBindings::FindSamplerUniformLocation(GLuint program, const std::string& samplerName) const
{
	GLint location = glGetUniformLocation(program, samplerName.c_str());
	if (location >= 0)
		return location;
	return glGetUniformLocation(program, (samplerName + "_0").c_str());
}