/*  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 <atomic>
#include <cstdarg>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>

#include "Loader.h"

#ifndef _WIN32
#include <dlfcn.h>
#endif

#ifdef __APPLE__
#include <mach-o/dyld.h>
#endif

extern "C" {

#define VULKAN_MODULE_ENTRY_POINT(name, required) PFN_##name pcsx2_##name;
#define VULKAN_INSTANCE_ENTRY_POINT(name, required) PFN_##name pcsx2_##name;
#define VULKAN_DEVICE_ENTRY_POINT(name, required) PFN_##name pcsx2_##name;
#include "EntryPoints.inl"
#undef VULKAN_DEVICE_ENTRY_POINT
#undef VULKAN_INSTANCE_ENTRY_POINT
#undef VULKAN_MODULE_ENTRY_POINT

}

namespace Vulkan
{
	void ResetVulkanLibraryFunctionPointers()
	{
#define VULKAN_MODULE_ENTRY_POINT(name, required) pcsx2_##name = nullptr;
#define VULKAN_INSTANCE_ENTRY_POINT(name, required) pcsx2_##name = nullptr;
#define VULKAN_DEVICE_ENTRY_POINT(name, required) pcsx2_##name = nullptr;
#include "EntryPoints.inl"
#undef VULKAN_DEVICE_ENTRY_POINT
#undef VULKAN_INSTANCE_ENTRY_POINT
#undef VULKAN_MODULE_ENTRY_POINT
	}

#if defined(_WIN32)

	static HMODULE vulkan_module;
	static std::atomic_int vulkan_module_ref_count = {0};

	bool LoadVulkanLibrary()
	{
		// Not thread safe if a second thread calls the loader whilst the first is still in-progress.
		if (vulkan_module)
		{
			vulkan_module_ref_count++;
			return true;
		}

		vulkan_module = LoadLibraryA("vulkan-1.dll");
		if (!vulkan_module)
		{
			std::fprintf(stderr, "Failed to load vulkan-1.dll\n");
			return false;
		}

		bool required_functions_missing = false;
		auto LoadFunction = [&](FARPROC* func_ptr, const char* name, bool is_required) {
			*func_ptr = GetProcAddress(vulkan_module, name);
			if (!(*func_ptr) && is_required)
			{
				std::fprintf(stderr, "Vulkan: Failed to load required module function %s\n", name);
				required_functions_missing = true;
			}
		};

#define VULKAN_MODULE_ENTRY_POINT(name, required) LoadFunction(reinterpret_cast<FARPROC*>(&name), #name, required);
#include "EntryPoints.inl"
#undef VULKAN_MODULE_ENTRY_POINT

		if (required_functions_missing)
		{
			ResetVulkanLibraryFunctionPointers();
			FreeLibrary(vulkan_module);
			vulkan_module = nullptr;
			return false;
		}

		vulkan_module_ref_count++;
		return true;
	}

	void UnloadVulkanLibrary()
	{
		if ((--vulkan_module_ref_count) > 0)
			return;

		ResetVulkanLibraryFunctionPointers();
		FreeLibrary(vulkan_module);
		vulkan_module = nullptr;
	}

#else

	static void* vulkan_module;
	static std::atomic_int vulkan_module_ref_count = {0};

	bool LoadVulkanLibrary()
	{
		// Not thread safe if a second thread calls the loader whilst the first is still in-progress.
		if (vulkan_module)
		{
			vulkan_module_ref_count++;
			return true;
		}

#if defined(__APPLE__)
		// Check if a path to a specific Vulkan library has been specified.
		char* libvulkan_env = getenv("LIBVULKAN_PATH");
		if (libvulkan_env)
			vulkan_module = dlopen(libvulkan_env, RTLD_NOW);
		if (!vulkan_module)
		{
			unsigned path_size = 0;
			_NSGetExecutablePath(nullptr, &path_size);
			std::string path;
			path.resize(path_size);
			if (_NSGetExecutablePath(path.data(), &path_size) == 0)
			{
				path[path_size] = 0;

				size_t pos = path.rfind('/');
				if (pos != std::string::npos)
				{
					path.erase(pos);
					path += "/../Frameworks/libvulkan.dylib";
					vulkan_module = dlopen(path.c_str(), RTLD_NOW);
					if (!vulkan_module)
					{
						path.erase(pos);
						path += "/../Frameworks/libMoltenVK.dylib";
						vulkan_module = dlopen(path.c_str(), RTLD_NOW);
					}
				}
			}
		}
		if (!vulkan_module)
		{
			vulkan_module = dlopen("libvulkan.dylib", RTLD_NOW);
			if (!vulkan_module)
				vulkan_module = dlopen("libMoltenVK.dylib", RTLD_NOW);
		}
#else
		// Names of libraries to search. Desktop should use libvulkan.so.1 or libvulkan.so.
		static const char* search_lib_names[] = {"libvulkan.so.1", "libvulkan.so"};
		for (size_t i = 0; i < sizeof(search_lib_names) / sizeof(search_lib_names[0]); i++)
		{
			vulkan_module = dlopen(search_lib_names[i], RTLD_NOW);
			if (vulkan_module)
				break;
		}
#endif

		if (!vulkan_module)
		{
			std::fprintf(stderr, "Failed to load or locate libvulkan.so\n");
			return false;
		}

		bool required_functions_missing = false;
		auto LoadFunction = [&](void** func_ptr, const char* name, bool is_required) {
			*func_ptr = dlsym(vulkan_module, name);
			if (!(*func_ptr) && is_required)
			{
				std::fprintf(stderr, "Vulkan: Failed to load required module function %s\n", name);
				required_functions_missing = true;
			}
		};

#define VULKAN_MODULE_ENTRY_POINT(name, required) LoadFunction(reinterpret_cast<void**>(&name), #name, required);
#include "EntryPoints.inl"
#undef VULKAN_MODULE_ENTRY_POINT

		if (required_functions_missing)
		{
			ResetVulkanLibraryFunctionPointers();
			dlclose(vulkan_module);
			vulkan_module = nullptr;
			return false;
		}

		vulkan_module_ref_count++;
		return true;
	}

	void UnloadVulkanLibrary()
	{
		if ((--vulkan_module_ref_count) > 0)
			return;

		ResetVulkanLibraryFunctionPointers();
		dlclose(vulkan_module);
		vulkan_module = nullptr;
	}

#endif

	bool LoadVulkanInstanceFunctions(VkInstance instance)
	{
		bool required_functions_missing = false;
		auto LoadFunction = [&](PFN_vkVoidFunction* func_ptr, const char* name, bool is_required) {
			*func_ptr = vkGetInstanceProcAddr(instance, name);
			if (!(*func_ptr) && is_required)
			{
				std::fprintf(stderr, "Vulkan: Failed to load required instance function %s\n", name);
				required_functions_missing = true;
			}
		};

#define VULKAN_INSTANCE_ENTRY_POINT(name, required) \
	LoadFunction(reinterpret_cast<PFN_vkVoidFunction*>(&name), #name, required);
#include "EntryPoints.inl"
#undef VULKAN_INSTANCE_ENTRY_POINT

		return !required_functions_missing;
	}

	bool LoadVulkanDeviceFunctions(VkDevice device)
	{
		bool required_functions_missing = false;
		auto LoadFunction = [&](PFN_vkVoidFunction* func_ptr, const char* name, bool is_required) {
			*func_ptr = vkGetDeviceProcAddr(device, name);
			if (!(*func_ptr) && is_required)
			{
				std::fprintf(stderr, "Vulkan: Failed to load required device function %s\n", name);
				required_functions_missing = true;
			}
		};

#define VULKAN_DEVICE_ENTRY_POINT(name, required) \
	LoadFunction(reinterpret_cast<PFN_vkVoidFunction*>(&name), #name, required);
#include "EntryPoints.inl"
#undef VULKAN_DEVICE_ENTRY_POINT

		return !required_functions_missing;
	}

} // namespace Vulkan