package io.gitlab.jfronny.glaunch;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import imgui.ImGui;
import imgui.ImGuiIO;
import imgui.flag.ImGuiConfigFlags;
import imgui.gl3.ImGuiImplGl3;
import imgui.glfw.ImGuiImplGlfw;
import io.gitlab.jfronny.glaunch.gson.MinecraftArgumentDeserializer;
import io.gitlab.jfronny.glaunch.model.MinecraftArgument;
import io.gitlab.jfronny.glaunch.windows.MainWindow;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.GL;
import org.lwjgl.opengl.GL32;
import org.lwjgl.system.MemoryStack;
import org.lwjgl.system.MemoryUtil;

import java.io.IOException;
import java.nio.IntBuffer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.LinkedHashSet;
import java.util.Objects;
import java.util.Set;

//TODO generate gitignore
//TODO mods browser
//TODO load and launch instance from metadata
//TODO allow instance sync through metadata
public class GLaunch {
    public static final Set<Window> WINDOWS = new LinkedHashSet<>();
    public static final Logger LOGGER = LogManager.getFormatterLogger("GLaunch");
    public static final Gson GSON = new GsonBuilder()
            .registerTypeAdapter(MinecraftArgument.class, new MinecraftArgumentDeserializer())
            .create();
    public static final Path CACHE_DIR = Path.of("run/cache");
    public static final Path INSTANCE_DIR = Path.of("run/instances");
    public static final Path ASSETS_DIR = Path.of("run/assets");
    public static final Path LIBRARIES_DIR = Path.of("run/libraries");
    public static final Config CONFIG = new Config(); //TODO from gson

    public static void main(String[] args) throws IOException {
        LOGGER.info("Setting up cache dir");
        if (!Files.exists(CACHE_DIR)) Files.createDirectories(CACHE_DIR);
        if (!Files.exists(INSTANCE_DIR)) Files.createDirectories(INSTANCE_DIR);
        if (!Files.exists(ASSETS_DIR)) Files.createDirectories(ASSETS_DIR);
        if (!Files.exists(LIBRARIES_DIR)) Files.createDirectories(LIBRARIES_DIR);
        LOGGER.info("Initializing UI");
        WINDOWS.add(new MainWindow());
        GLaunch gLaunch = new GLaunch();
        gLaunch.init();
        gLaunch.run();
        gLaunch.dispose();
    }

    public static void open(Window window) {
        WINDOWS.add(window);
    }

    private final ImGuiImplGlfw imGuiGlfw = new ImGuiImplGlfw();
    private final ImGuiImplGl3 imGuiGl3 = new ImGuiImplGl3();

    private String glslVersion = null;

    /**
     * Pointer to the native GLFW window.
     */
    protected long handle;

    /**
     * Method to initialize application.
     */
    protected void init() {
        initWindow();
        initImGui();
        imGuiGlfw.init(handle, true);
        imGuiGl3.init(glslVersion);
    }

    /**
     * Method to dispose all used application resources and destroy its window.
     */
    protected void dispose() {
        imGuiGl3.dispose();
        imGuiGlfw.dispose();
        disposeImGui();
        disposeWindow();
    }

    /**
     * Method to create and initialize GLFW window.
     */
    protected void initWindow() {
        GLFWErrorCallback.createPrint(System.err).set();

        if (!GLFW.glfwInit()) {
            throw new IllegalStateException("Unable to initialize GLFW");
        }

        decideGlGlslVersions();

        GLFW.glfwWindowHint(GLFW.GLFW_VISIBLE, GLFW.GLFW_FALSE);
        GLFW.glfwWindowHint(GLFW.GLFW_RESIZABLE, GLFW.GLFW_FALSE);
        handle = GLFW.glfwCreateWindow(10, 10, "GLaunch", MemoryUtil.NULL, MemoryUtil.NULL);

        if (handle == MemoryUtil.NULL) {
            throw new RuntimeException("Failed to create the GLFW window");
        }

        try (MemoryStack stack = MemoryStack.stackPush()) {
            final IntBuffer pWidth = stack.mallocInt(1); // int*
            final IntBuffer pHeight = stack.mallocInt(1); // int*

            GLFW.glfwGetWindowSize(handle, pWidth, pHeight);
            final GLFWVidMode vidmode = Objects.requireNonNull(GLFW.glfwGetVideoMode(GLFW.glfwGetPrimaryMonitor()));
            GLFW.glfwSetWindowPos(handle, (vidmode.width() - pWidth.get(0)) / 2, (vidmode.height() - pHeight.get(0)) / 2);
        }

        GLFW.glfwMakeContextCurrent(handle);

        GL.createCapabilities();

        GLFW.glfwSwapInterval(GLFW.GLFW_TRUE);

        //GLFW.glfwShowWindow(handle);

        clearBuffer();
        renderBuffer();

        GLFW.glfwSetWindowSizeCallback(handle, new GLFWWindowSizeCallback() {
            @Override
            public void invoke(final long window, final int width, final int height) {
                runFrame();
            }
        });
    }

    private void decideGlGlslVersions() {
        final boolean isMac = System.getProperty("os.name").toLowerCase().contains("mac");
        if (isMac) {
            glslVersion = "#version 150";
            GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MAJOR, 3);
            GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MINOR, 2);
            GLFW.glfwWindowHint(GLFW.GLFW_OPENGL_PROFILE, GLFW.GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
            GLFW.glfwWindowHint(GLFW.GLFW_OPENGL_FORWARD_COMPAT, GLFW.GLFW_TRUE);          // Required on Mac
        } else {
            glslVersion = "#version 130";
            GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MAJOR, 3);
            GLFW.glfwWindowHint(GLFW.GLFW_CONTEXT_VERSION_MINOR, 0);
        }
    }

    /**
     * Method to initialize Dear ImGui context. Could be overridden to do custom Dear ImGui setup before application start.
     */
    protected void initImGui() {
        ImGui.createContext();
        ImGuiIO io = ImGui.getIO();
        io.addConfigFlags(ImGuiConfigFlags.ViewportsEnable);
        //io.setConfigViewportsNoDecoration(false);
        io.setConfigViewportsNoAutoMerge(true);
    }

    /**
     * Main application loop.
     */
    protected void run() {
        while (!GLFW.glfwWindowShouldClose(handle)) {
            runFrame();
        }
    }

    /**
     * Method used to run the next frame.
     */
    protected void runFrame() {
        startFrame();
        process();
        endFrame();
    }

    public void process() {
        if (GLaunch.WINDOWS.isEmpty()) close();
        else {
            for (Window window : GLaunch.WINDOWS.toArray(new Window[0])) {
                if (window.isNew()) window.preFirstDraw();
                ImGui.begin(window.getName());
                window.draw();
                ImGui.end();
            }
        }
    }

    /**
     * Method used to clear the OpenGL buffer.
     */
    private void clearBuffer() {
        GL32.glClear(GL32.GL_COLOR_BUFFER_BIT | GL32.GL_DEPTH_BUFFER_BIT);
    }

    /**
     * Method called at the beginning of the main cycle.
     * It clears OpenGL buffer and starts an ImGui frame.
     */
    protected void startFrame() {
        clearBuffer();
        imGuiGlfw.newFrame();
        ImGui.newFrame();
    }

    /**
     * Method called in the end of the main cycle.
     * It renders ImGui and swaps GLFW buffers to show an updated frame.
     */
    protected void endFrame() {
        ImGui.render();
        imGuiGl3.renderDrawData(ImGui.getDrawData());

        if (ImGui.getIO().hasConfigFlags(ImGuiConfigFlags.ViewportsEnable)) {
            final long backupWindowPtr = GLFW.glfwGetCurrentContext();
            ImGui.updatePlatformWindows();
            ImGui.renderPlatformWindowsDefault();
            GLFW.glfwMakeContextCurrent(backupWindowPtr);
        }

        renderBuffer();
    }

    /**
     * Method to render the OpenGL buffer and poll window events.
     */
    private void renderBuffer() {
        GLFW.glfwSwapBuffers(handle);
        GLFW.glfwPollEvents();
    }

    /**
     * Method to destroy Dear ImGui context.
     */
    protected void disposeImGui() {
        ImGui.destroyContext();
    }

    /**
     * Method to destroy GLFW window.
     */
    protected void disposeWindow() {
        Callbacks.glfwFreeCallbacks(handle);
        GLFW.glfwDestroyWindow(handle);
        GLFW.glfwTerminate();
        Objects.requireNonNull(GLFW.glfwSetErrorCallback(null)).free();
    }

    public void close() {
        GLFW.glfwSetWindowShouldClose(handle, true);
    }
}