import com.mojang.blaze3d.pipeline.MainTarget;
import com.mojang.blaze3d.platform.DisplayData;
import com.mojang.blaze3d.systems.RenderSystem;
import com.mojang.authlib.properties.PropertyMap;
import net.minecraft.SharedConstants;
import net.minecraft.client.Minecraft;
import net.minecraft.client.User;
import net.minecraft.client.main.GameConfig;
import net.minecraft.server.Bootstrap;
import org.lwjgl.glfw.GLFW;
import org.lwjgl.opengl.GL11;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.net.Proxy;
import java.nio.ByteBuffer;
import java.util.Optional;
import java.util.OptionalInt;

/**
 * mcfold render probe —— 起 MC 渲染栈，渲一帧，读像素写 PNG。
 * 全程：不连服、不登录、不进主循环、不 gameplay。
 */
public class RenderProbe {

    public static void main(String[] args) throws Exception {
        String gameDir   = arg(args, "--gameDir", "/home/newqqagent/mcview/instances/default");
        String assets    = arg(args, "--assets",  "/home/newqqagent/mcview/store/vanilla-1.20.1/assets");
        String assetIdx  = arg(args, "--assetIndex", "1.20.1");
        String out       = arg(args, "--out", "/tmp/scaffold-frame.png");
        int width  = Integer.parseInt(arg(args, "--width",  "854"));
        int height = Integer.parseInt(arg(args, "--height", "480"));

        SharedConstants.tryDetectVersion();
        SharedConstants.enableDataFixerOptimizations();
        Bootstrap.bootStrap();

        File runDir = new File(gameDir);
        User user = new User("mcfold_cam", "0".repeat(32), "mcfold_cam",
                Optional.empty(), Optional.empty(), User.Type.LEGACY);
        PropertyMap props = new PropertyMap();

        GameConfig cfg = new GameConfig(
            new GameConfig.UserData(user, props, props, Proxy.NO_PROXY),
            new DisplayData(width, height, OptionalInt.empty(), OptionalInt.empty(), false),
            new GameConfig.FolderData(runDir, new File(runDir, "resourcepacks"), new File(assets), assetIdx),
            new GameConfig.GameData(false, "mcfold", "release", false, false),
            new GameConfig.QuickPlayData(null, null, null, null)
        );

        RenderSystem.initRenderThread();
        RenderSystem.beginInitialization();
        Minecraft mc = new Minecraft(cfg);
        RenderSystem.finishInitialization();

        System.out.println("[probe] constructed. w=" + mc.getWindow().getWidth()
                + " h=" + mc.getWindow().getHeight());

        // ★ 渲染一帧：照抄 Minecraft.render() 的实测序列（反编译 nout2/.../Minecraft.java:1110-1140）
        MainTarget target = (MainTarget) mc.getMainRenderTarget();
        for (int frame = 0; frame < 3; frame++) {
            RenderSystem.clear(16640, Minecraft.ON_OSX);
            target.bindWrite(true);
            mc.gameRenderer.render(0.0F, 0L, true);
            target.unbindWrite();
            target.blitToScreen(mc.getWindow().getWidth(), mc.getWindow().getHeight());
            mc.getWindow().updateDisplay();
            System.out.println("[probe] frame " + frame + " rendered");
        }

        // ★ 读像素：从 GL 后台缓冲直接读（比截屏更可靠，且不依赖 X）
        GL11.glReadBuffer(GL11.GL_BACK);
        int w = mc.getWindow().getWidth(), h = mc.getWindow().getHeight();
        ByteBuffer buf = org.lwjgl.BufferUtils.createByteBuffer(w * h * 4);
        GL11.glReadPixels(0, 0, w, h, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buf);

        BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        // GL 原点在左下，PNG 在左上，需翻转
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w; x++) {
                int i = ((h - 1 - y) * w + x) * 4;
                int r = buf.get(i) & 0xFF, g = buf.get(i + 1) & 0xFF, b = buf.get(i + 2) & 0xFF;
                img.setRGB(x, y, (r << 16) | (g << 8) | b);
            }
        }
        ImageIO.write(img, "png", new File(out));
        System.out.println("[probe] wrote " + out + " (" + w + "x" + h + ")");

        // 统计非黑像素，证明真的画了东西（而非空缓冲）
        long nonBlack = 0; int total = w * h;
        for (int p : img.getRGB(0, 0, w, h, null, 0, w)) if ((p & 0xFFFFFF) != 0) nonBlack++;
        System.out.println("[probe] non-black pixels = " + nonBlack + "/" + total
                + " (" + (100.0 * nonBlack / total) + "%)");

        GLFW.glfwTerminate();
        System.out.println("[probe] DONE");
        System.exit(0);
    }

    private static String arg(String[] a, String key, String def) {
        for (int i = 0; i < a.length - 1; i++) if (a[i].equals(key)) return a[i + 1];
        return def;
    }
}