#include "Entrypoint/Backend.hpp"
#include "Model/GlobalStates.hpp"
#include "UI/Localization.hpp"
#include "UI/States.hpp"
#include "UI/UI.hpp"
#include "Utils/I18n.hpp"
#include "Utils/ScopeGuard.hpp"
#include "Utils/Sigslot.hpp"

#include <IconsFontAwesome.h>
#include <imgui.h>
#include <argparse/argparse.hpp>
#include <filesystem>
#include <iostream>
#include <memory>
#include <stdexcept>
#include <string>
#include <string_view>

namespace fs = std::filesystem;
using namespace std::literals::string_literals;
using namespace std::literals::string_view_literals;

static std::unique_ptr<RenderingBackend> CreateDefaultBackend() {
#if PLATFORM_WIN32
#	if BUILD_CORE_WITH_DX12_BACKEND
	if (auto backend = RenderingBackend::CreateDx12Backend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_DX11_BACKEND
	if (auto backend = RenderingBackend::CreateDx11Backend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_VULKAN_BACKEND
	if (auto backend = RenderingBackend::CreateVulkanBackend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_OPENGL3_BACKEND
	if (auto backend = RenderingBackend::CreateOpenGL3Backend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_OPENGL2_BACKEND
	if (auto backend = RenderingBackend::CreateOpenGL2Backend()) {
		return backend;
	}
#	endif
#elif PLATFORM_MACOS
	// We currently only support using metal on macos
	return RenderingBackend::CreateMetalBackend();
#elif PLATFORM_LINUX
#	if BUILD_CORE_WITH_VULKAN_BACKEND
	if (auto backend = RenderingBackend::CreateVulkanBackend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_OPENGL3_BACKEND
	if (auto backend = RenderingBackend::CreateOpenGL3Backend()) {
		return backend;
	}
#	endif
#	if BUILD_CORE_WITH_OPENGL2_BACKEND
	if (auto backend = RenderingBackend::CreateOpenGL2Backend()) {
		return backend;
	}
#	endif
#endif

	return nullptr;
}

static std::unique_ptr<RenderingBackend> CreateBackend(std::string_view option) {
	if (option == "default") {
		return CreateDefaultBackend();
	} else if (option == "opengl2") {
		return RenderingBackend::CreateOpenGL2Backend();
	} else if (option == "opengl3") {
		return RenderingBackend::CreateOpenGL3Backend();
	} else if (option == "vulkan") {
		return RenderingBackend::CreateVulkanBackend();
	} else if (option == "dx11") {
		return RenderingBackend::CreateDx11Backend();
	} else if (option == "dx12") {
		return RenderingBackend::CreateDx12Backend();
	} else if (option == "metal") {
		return RenderingBackend::CreateMetalBackend();
	} else {
		std::string message;
		message += "Unknown backend '";
		message += option;
		message += "'.\n";
		throw std::runtime_error(message);
	}
}

int main(int argc, char* argv[]) {
	argparse::ArgumentParser parser;
	parser.add_argument("--global-data-directory")
		.help("Directory in which global data (such as recently used projects) are saved to. Use 'default' to use the default directory on each platform.")
		.default_value("default"s);
	parser.add_argument("--rendering-backend")
		.help("Which rendering backend to use. If equals 'default', the preferred API for each platform will be used")
		.default_value("default"s);

	try {
		parser.parse_args(argc, argv);
	} catch (const std::runtime_error& error) {
		std::cout << error.what() << '\n';
		std::cout << parser;
		return -1;
	}

	auto backendOption = parser.get<std::string>("--rendering-backend");
	auto backend = CreateBackend(backendOption);

	auto& io = ImGui::GetIO();

	// Disable saving window positions
	io.IniFilename = nullptr;
	// Disable log (dump widget tree) file, we don't trigger it but just to be safe
	io.LogFilename = nullptr;

	// Light mode because all major OS's default theme is white
	// TODO follow system theme
	ImGui::StyleColorsLight();

	// Configure default fonts
	{
		// Includes latin alphabet, although for some reason smaller than if rendered using 18 point NotoSans regular
		io.Fonts->AddFontFromFileTTF("fonts/NotoSansSC-Regular.otf", 18, nullptr, io.Fonts->GetGlyphRangesChineseFull());

		ImWchar iconRanges[] = { ICON_MIN_FA, ICON_MAX_FA };
		ImFontConfig config;
		config.MergeMode = true;
		io.Fonts->AddFontFromFileTTF("fonts/FontAwesome5-Solid.otf", 14, &config, iconRanges);
	}

	// Initialize localization utilities
	{
		I18n::OnLanguageChange.Connect([]() { LocaleStrings::Instance = std::make_unique<LocaleStrings>(); });
		// Do i18n initialization after linking reload signals, so that when SetLanguage() is called, the locale strings will be initialized (without us writing the code another time outside the slot)
		I18n::Init();
		I18n::SetLanguage("zh_CN");
		// All of our usage are cached in XxxTranslation objects, no need to keep key -> entry mappings anymore
		I18n::Unload();
	}

	auto dataDirOption = parser.get<std::string>("--global-data-directory");
	if (dataDirOption == "default") {
		GlobalStates::Init();
	} else {
		fs::path path(dataDirOption);
		if (fs::exists(path)) {
			GlobalStates::Init(std::move(path));
		} else {
			GlobalStates::Init();
		}
	}
	DEFER { GlobalStates::Shutdown(); };

	UIState::Init();
	DEFER { UIState::Shutdown(); };

	// Main loop
	backend->RunUntilWindowClose(&UI::MainWindow);

	return 0;
}