Inceptum/src/main/java/io/gitlab/jfronny/inceptum/InceptumGui.java

package io.gitlab.jfronny.inceptum;

import imgui.ImGui;
import imgui.ImGuiIO;
import imgui.flag.ImGuiConfigFlags;
import imgui.gl3.ImGuiImplGl3;
import imgui.glfw.ImGuiImplGlfw;
import io.gitlab.jfronny.inceptum.util.api.account.AccountManager;
import io.gitlab.jfronny.inceptum.windows.MainWindow;
import io.gitlab.jfronny.inceptum.windows.Window;
import org.lwjgl.glfw.Callbacks;
import org.lwjgl.glfw.GLFW;
import org.lwjgl.glfw.GLFWErrorCallback;
import org.lwjgl.glfw.GLFWVidMode;
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.io.InputStream;
import java.nio.IntBuffer;
import java.util.LinkedHashSet;
import java.util.Objects;
import java.util.Set;

public class InceptumGui {
    public static final Set<Window> WINDOWS = new LinkedHashSet<>();
    private static final ImGuiImplGlfw imGuiGlfw = new ImGuiImplGlfw();
    private static final ImGuiImplGl3 imGuiGl3 = new ImGuiImplGl3();
    /**
     * Pointer to the native GLFW window.
     */
    protected static long handle;
    private static String glslVersion = null;

    public static void main(String[] args) {
        AccountManager.loadAccounts();
        Inceptum.LOGGER.info("Initializing UI");
        InceptumGui.WINDOWS.add(new MainWindow());
        InceptumGui.init();
        InceptumGui.run();
        InceptumGui.dispose();
    }

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

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

    /**
     * Method to dispose all used application resources and destroy its window.
     */
    public static void dispose() {
        imGuiGl3.dispose();
        imGuiGlfw.dispose();
        //TODO figure out why this is a problem
        //ImGui.destroyContext();
        Callbacks.glfwFreeCallbacks(handle);
        GLFW.glfwDestroyWindow(handle);
        GLFW.glfwTerminate();
        Objects.requireNonNull(GLFW.glfwSetErrorCallback(null)).free();
    }

    /**
     * Method to create and initialize GLFW window.
     */
    protected static 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, "Inceptum", 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);

        clearBuffer();
        renderBuffer();
    }

    private static 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 static void initImGui() {
        ImGui.createContext();
        ImGuiIO io = ImGui.getIO();
        io.addConfigFlags(ImGuiConfigFlags.ViewportsEnable);
        //io.setConfigViewportsNoDecoration(false);
        io.setConfigViewportsNoAutoMerge(true);
        //TODO use included icons (https://www.nerdfonts.com/cheat-sheet)
        //Nerd Fonts-patched ubuntu font
        try (InputStream is = Inceptum.class.getClassLoader().getResourceAsStream("font.ttf")) {
            assert is != null;
            io.setFontDefault(io.getFonts().addFontFromMemoryTTF(is.readAllBytes(), 16f));
        } catch (IOException e) {
            e.printStackTrace();
        }
        applyTheme();
    }

    /**
     * Main application loop.
     */
    public static void run() {
        while (!GLFW.glfwWindowShouldClose(handle)) {
            //frame
            clearBuffer();
            imGuiGlfw.newFrame();
            ImGui.newFrame();
            //render
            if (WINDOWS.isEmpty()) exit();
            else {
                Window[] array = WINDOWS.toArray(new Window[0]);
                for (int i = 0, arrayLength = array.length; i < arrayLength; i++) {
                    Window window = array[i];
                    if (window.isNew()) window.preFirstDraw();
                    if (ImGui.begin(window.getName() + "##" + i, window.getOpenState(), window.getFlags()))
                        window.draw();
                    ImGui.end();
                    if (!window.getOpenState().get()) window.close();
                }
            }
            //end frame
            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();
        }
    }

    private static void clearBuffer() {
        GL32.glClear(GL32.GL_COLOR_BUFFER_BIT | GL32.GL_DEPTH_BUFFER_BIT);
    }

    private static void renderBuffer() {
        GLFW.glfwSwapBuffers(handle);
        GLFW.glfwPollEvents();
    }

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

    public static void applyTheme() {
        if (Inceptum.CONFIG.darkTheme) ImGui.styleColorsDark();
        else ImGui.styleColorsLight();
    }
}