#include "App.hpp"

#include "AppConfig.hpp"
#include "EditorNotification.hpp"
#include "Ires.hpp"
#include "Mesh.hpp"
#include "Shader.hpp"

#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>

#include <backends/imgui_impl_glfw.h>
#include <backends/imgui_impl_opengl2.h>
#include <backends/imgui_impl_opengl3.h>
#include <glad/glad.h>
#include <imgui.h>
#include <cstdlib>
#include <cxxopts.hpp>
#include <filesystem>
#include <string>

namespace fs = std::filesystem;

static void GlfwErrorCallback(int error, const char* description) {
	fprintf(stderr, "Glfw Error %d: %s\n", error, description);
}

static void GlfwMouseCallback(GLFWwindow* window, int button, int action, int mods) {
	if (ImGui::GetIO().WantCaptureMouse) {
		return;
	}

	App* app = static_cast<App*>(glfwGetWindowUserPointer(window));
	app->HandleMouse(button, action);
}

static void GlfwMouseMotionCallback(GLFWwindow* window, double xOff, double yOff) {
	if (ImGui::GetIO().WantCaptureMouse) {
		return;
	}

	App* app = static_cast<App*>(glfwGetWindowUserPointer(window));
	app->HandleMouseMotion(xOff, yOff);
}

static void GlfwKeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods) {
	if (ImGui::GetIO().WantCaptureKeyboard) {
		return;
	}

	GLFWkeyboard* keyboard = glfwGetLastActiveKeyboard();
	if (keyboard) {
		App* app = static_cast<App*>(glfwGetWindowUserPointer(window));
		app->HandleKey(keyboard, key, action);
	}
}

int main(int argc, char* argv[]) {
	using namespace Tags;

	constexpr auto kImGuiBackend = "imgui-backend";
	constexpr auto kGameDataDir = "game-data-directory";
	constexpr auto kGameAssetDir = "game-asset-directory";

	cxxopts::Options options(std::string(AppConfig::kAppName), "");
	// clang-format off
	options.add_options()
	(kImGuiBackend, "ImGui backend. Options: opengl2, opengl3. Leave empty to default.", cxxopts::value<std::string>())
	(kGameAssetDir, "Directory in which assets are looked up from. Can be relative paths to the executable.", cxxopts::value<std::string>()->default_value("."))
	(kGameDataDir, "Directory in which game data (such as saves and options) are saved to. Leave empty to use the default directory on each platform.", cxxopts::value<std::string>())
	;
	// clang-format on
	auto args = options.parse(argc, argv);

	bool imguiUseOpenGL3;
	{
		auto imguiBackend = args[kImGuiBackend].as<std::string>();
		if (imguiBackend == "opengl2") {
			imguiUseOpenGL3 = false;
		} else if (imguiBackend == "opengl3") {
			imguiUseOpenGL3 = true;
		} else {
			// TODO support more backends?
			imguiUseOpenGL3 = false;
		}
	}

	{
		auto assetDir = args[kGameAssetDir].as<std::string>();

		fs::path assetDirPath(assetDir);
		if (!fs::exists(assetDirPath)) {
			fprintf(stderr, "Invalid asset directory.\n");
			return -4;
		}

		AppConfig::assetDir = std::move(assetDir);
		AppConfig::assetDirPath = std::move(assetDirPath);
	}

	if (args.count(kGameDataDir) > 0) {
		auto dataDir = args[kGameDataDir].as<std::string>();

		fs::path dataDirPath(dataDir);
		fs::create_directories(dataDir);

		AppConfig::dataDir = std::move(dataDir);
		AppConfig::dataDirPath = std::move(dataDirPath);
	} else {
		// TODO platform default path
		AppConfig::dataDir = ".";
		AppConfig::dataDirPath = fs::path(".");
	}

	if (!glfwInit()) {
		return -1;
	}

	glfwSetErrorCallback(&GlfwErrorCallback);

	// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
	// GL ES 2.0 + GLSL 100
	const char* imguiGlslVersion = "#version 100";
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
	glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
#elif defined(__APPLE__)
	// GL 3.2 + GLSL 150
	const char* imguiGlslVersion = "#version 150";
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
#else
	// GL 3.0 + GLSL 130
	const char* imguiGlslVersion = "#version 130";
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
#endif

	App app;

	GLFWwindow* window = glfwCreateWindow(1280, 720, "ImGui Command Palette Example", nullptr, nullptr);
	if (window == nullptr) {
		return -2;
	}

	glfwSetWindowUserPointer(window, &app);

	// Window callbacks are retained by ImGui GLFW backend
	glfwSetKeyCallback(window, &GlfwKeyCallback);
	glfwSetMouseButtonCallback(window, &GlfwMouseCallback);
	glfwSetCursorPosCallback(window, &GlfwMouseMotionCallback);

	glfwMakeContextCurrent(window);
	glfwSwapInterval(1);

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		return -3;
	}

	IMGUI_CHECKVERSION();
	ImGui::CreateContext();

	ImGui_ImplGlfw_InitForOpenGL(window, true);
	if (imguiUseOpenGL3) {
		ImGui_ImplOpenGL3_Init(imguiGlslVersion);
	} else {
		ImGui_ImplOpenGL2_Init();
	}

	ShaderManager::instance = new ShaderManager();
	IresManager::instance = new IresManager();

	ShaderManager::instance->DiscoverShaders();
	IresManager::instance->DiscoverFilesDesignatedLocation();

	gVformatStandard.Attach(new VertexFormat());
	gVformatStandard->AddElement(VertexElementFormat{
		.bindingIndex = 0,
		.type = VET_Float3,
		.semantic = VES_Position,
	});
	gVformatStandard->AddElement(VertexElementFormat{
		.bindingIndex = 1,
		.type = VET_Float2,
		.semantic = VES_TexCoords1,
	});
	gVformatStandard->AddElement(VertexElementFormat{
		.bindingIndex = 1,
		.type = VET_Ubyte4Norm,
		.semantic = VES_Color1,
	});

	gVformatStandardPacked.Attach(new VertexFormat());
	gVformatStandardPacked->AddElement(VertexElementFormat{
		.bindingIndex = 0,
		.type = VET_Float3,
		.semantic = VES_Position,
	});
	gVformatStandardPacked->AddElement(VertexElementFormat{
		.bindingIndex = 0,
		.type = VET_Float2,
		.semantic = VES_TexCoords1,
	});
	gVformatStandardPacked->AddElement(VertexElementFormat{
		.bindingIndex = 0,
		.type = VET_Ubyte4Norm,
		.semantic = VES_Color1,
	});

	app.Init();
	while (!glfwWindowShouldClose(window)) {
		glfwPollEvents();

		int fbWidth, fbHeight;
		glfwGetFramebufferSize(window, &fbWidth, &fbHeight);
		glViewport(0, 0, fbWidth, fbHeight);
		auto clearColor = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
		glClearColor(clearColor.x * clearColor.w, clearColor.y * clearColor.w, clearColor.z * clearColor.w, clearColor.w);
		glClear(GL_COLOR_BUFFER_BIT);

		{ // Regular draw
			app.Update();
			app.Draw();
		}

		{ // ImGui stuff
			if (imguiUseOpenGL3) {
				ImGui_ImplOpenGL3_NewFrame();
			} else {
				ImGui_ImplOpenGL2_NewFrame();
			}
			ImGui_ImplGlfw_NewFrame();
			ImGui::NewFrame();

			app.Show();
			ImGui::ShowNotifications();

			ImGui::Render();
			if (imguiUseOpenGL3) {
				ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
			} else {
				ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
			}
		}

		glfwSwapBuffers(window);
	}
	app.Shutdown();

	if (imguiUseOpenGL3) {
		ImGui_ImplOpenGL3_Shutdown();
	} else {
		ImGui_ImplOpenGL2_Shutdown();
	}
	ImGui_ImplGlfw_Shutdown();

	ImGui::DestroyContext();

	glfwDestroyWindow(window);
	glfwTerminate();

	return 0;
}