/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2021  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#include "common/Vulkan/ShaderCompiler.h"
#include "common/Vulkan/Util.h"
#include "common/Assertions.h"
#include "common/Console.h"
#include "common/StringUtil.h"
#include <cstring>
#include <fstream>
#include <memory>

// glslang includes
#include "SPIRV/GlslangToSpv.h"
#include "StandAlone/ResourceLimits.h"
#include "glslang/Public/ShaderLang.h"

namespace Vulkan::ShaderCompiler
{
	// Registers itself for cleanup via atexit
	bool InitializeGlslang();

	static unsigned s_next_bad_shader_id = 1;

	static bool glslang_initialized = false;

	static std::optional<SPIRVCodeVector> CompileShaderToSPV(
		EShLanguage stage, const char* stage_filename, std::string_view source)
	{
		if (!InitializeGlslang())
			return std::nullopt;

		std::unique_ptr<glslang::TShader> shader = std::make_unique<glslang::TShader>(stage);
		std::unique_ptr<glslang::TProgram> program;
		glslang::TShader::ForbidIncluder includer;
		EProfile profile = ECoreProfile;
		EShMessages messages = static_cast<EShMessages>(EShMsgDefault | EShMsgSpvRules | EShMsgVulkanRules);
		int default_version = 450;

		std::string full_source_code;
		const char* pass_source_code = source.data();
		int pass_source_code_length = static_cast<int>(source.size());
		shader->setStringsWithLengths(&pass_source_code, &pass_source_code_length, 1);

		auto DumpBadShader = [&](const char* msg) {
			std::string filename = StringUtil::StdStringFromFormat("bad_shader_%u.txt", s_next_bad_shader_id++);
			Console.Error("CompileShaderToSPV: %s, writing to %s", msg, filename.c_str());

			std::ofstream ofs(filename.c_str(), std::ofstream::out | std::ofstream::binary);
			if (ofs.is_open())
			{
				ofs << source;
				ofs << "\n";

				ofs << msg << std::endl;
				ofs << "Shader Info Log:" << std::endl;
				ofs << shader->getInfoLog() << std::endl;
				ofs << shader->getInfoDebugLog() << std::endl;
				if (program)
				{
					ofs << "Program Info Log:" << std::endl;
					ofs << program->getInfoLog() << std::endl;
					ofs << program->getInfoDebugLog() << std::endl;
				}

				ofs.close();
			}
		};

		if (!shader->parse(
				&glslang::DefaultTBuiltInResource, default_version, profile, false, true, messages, includer))
		{
			DumpBadShader("Failed to parse shader");
			return std::nullopt;
		}

		// Even though there's only a single shader, we still need to link it to generate SPV
		program = std::make_unique<glslang::TProgram>();
		program->addShader(shader.get());
		if (!program->link(messages))
		{
			DumpBadShader("Failed to link program");
			return std::nullopt;
		}

		glslang::TIntermediate* intermediate = program->getIntermediate(stage);
		if (!intermediate)
		{
			DumpBadShader("Failed to generate SPIR-V");
			return std::nullopt;
		}

		SPIRVCodeVector out_code;
		spv::SpvBuildLogger logger;
		glslang::GlslangToSpv(*intermediate, out_code, &logger);

		// Write out messages
		// Temporary: skip if it contains "Warning, version 450 is not yet complete; most version-specific
		// features are present, but some are missing."
		if (std::strlen(shader->getInfoLog()) > 108)
			Console.Warning("Shader info log: %s", shader->getInfoLog());
		if (std::strlen(shader->getInfoDebugLog()) > 0)
			Console.Warning("Shader debug info log: %s", shader->getInfoDebugLog());
		if (std::strlen(program->getInfoLog()) > 25)
			Console.Warning("Program info log: %s", program->getInfoLog());
		if (std::strlen(program->getInfoDebugLog()) > 0)
			Console.Warning("Program debug info log: %s", program->getInfoDebugLog());
		std::string spv_messages = logger.getAllMessages();
		if (!spv_messages.empty())
			Console.Warning("SPIR-V conversion messages: %s", spv_messages.c_str());

		return out_code;
	}

	bool InitializeGlslang()
	{
		if (glslang_initialized)
			return true;

		if (!glslang::InitializeProcess())
		{
			pxFailRel("Failed to initialize glslang shader compiler");
			return false;
		}

		std::atexit(DeinitializeGlslang);
		glslang_initialized = true;
		return true;
	}

	void DeinitializeGlslang()
	{
		if (!glslang_initialized)
			return;

		glslang::FinalizeProcess();
		glslang_initialized = false;
	}

	std::optional<SPIRVCodeVector> CompileVertexShader(std::string_view source_code)
	{
		return CompileShaderToSPV(EShLangVertex, "vs", source_code);
	}

	std::optional<SPIRVCodeVector> CompileGeometryShader(std::string_view source_code)
	{
		return CompileShaderToSPV(EShLangGeometry, "gs", source_code);
	}

	std::optional<SPIRVCodeVector> CompileFragmentShader(std::string_view source_code)
	{
		return CompileShaderToSPV(EShLangFragment, "ps", source_code);
	}

	std::optional<SPIRVCodeVector> CompileComputeShader(std::string_view source_code)
	{
		return CompileShaderToSPV(EShLangCompute, "cs", source_code);
	}

	std::optional<ShaderCompiler::SPIRVCodeVector> CompileShader(Type type, std::string_view source_code, bool debug)
	{
		switch (type)
		{
			case Type::Vertex:
				return CompileShaderToSPV(EShLangVertex, "vs", source_code);

			case Type::Geometry:
				return CompileShaderToSPV(EShLangGeometry, "gs", source_code);

			case Type::Fragment:
				return CompileShaderToSPV(EShLangFragment, "ps", source_code);

			case Type::Compute:
				return CompileShaderToSPV(EShLangCompute, "cs", source_code);

			default:
				return std::nullopt;
		}
	}
} // namespace Vulkan::ShaderCompiler