import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.mojang.blaze3d.pipeline.MainTarget;
import com.mojang.blaze3d.platform.DisplayData;
import com.mojang.blaze3d.systems.RenderSystem;
import com.mojang.authlib.GameProfile;
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.client.multiplayer.ClientLevel;
import net.minecraft.client.multiplayer.ClientPacketListener;
import net.minecraft.client.telemetry.TelemetryEventSender;
import net.minecraft.client.telemetry.WorldSessionTelemetryManager;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Holder;
import net.minecraft.core.RegistryAccess;
import net.minecraft.core.registries.BuiltInRegistries;
import net.minecraft.core.registries.Registries;
import net.minecraft.network.Connection;
import net.minecraft.network.FriendlyByteBuf;
import net.minecraft.network.protocol.PacketFlow;
import net.minecraft.resources.RegistryDataLoader;
import net.minecraft.resources.ResourceKey;
import net.minecraft.resources.ResourceLocation;
import net.minecraft.server.Bootstrap;
import net.minecraft.server.packs.resources.ResourceManager;
import net.minecraft.util.profiling.InactiveProfiler;
import net.minecraft.world.Difficulty;
import net.minecraft.world.level.ChunkPos;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.LightLayer;
import net.minecraft.world.level.block.Block;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.chunk.DataLayer;
import net.minecraft.world.level.chunk.LevelChunk;
import net.minecraft.world.level.chunk.LevelChunkSection;
import net.minecraft.world.level.dimension.DimensionType;
import org.lwjgl.opengl.GL11;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Proxy;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.Base64;
import java.util.Optional;
import java.util.OptionalInt;
import java.util.UUID;

/**
 * mcfold 渲染服务：常驻进程，NDJSON(行分隔 JSON) 协议，由 Python 侧驱动。
 *
 * 设计约束（用户 2026-09-25）：
 *   - 不起完整客户端：不跑主循环、不连服、不登录、不作玩家
 *   - 我们的世界数据喂给官方渲染器出图
 *
 * 协议（stdin/stdout 各一行一个 JSON）：
 *   → {"id":1,"cmd":"chunk","cx":0,"cz":0,"data":"<b64>","heightmaps":null}
 *   → {"id":2,"cmd":"camera","x":8,"y":70,"z":8,"yaw":0,"pitch":0}
 *   → {"id":3,"cmd":"render","frames":60,"out":"/tmp/a.png"}
 *   ← {"id":3,"ok":true,"width":854,"height":480,"chunksRendered":29,
 *      "distinctColors":1450,"image":"<b64 png>"}
 *
 * 启动就绪时主动发 {"event":"ready"}。
 *
 * ★ 关键实现点（全部实测得来，详见 scaffold/README.md）：
 *   1. tryDetectVersion 必须先于 Bootstrap.bootStrap
 *   2. FolderData 顺序 (gameDir, resourcePackDir, assets, assetIndex)，assetIndex 用落盘名
 *   3. 资源必须手工同步重载（各 listener 的 public reload()），不能 join Minecraft 的
 *   4. LoadingOverlay + ReceivingLevelScreen 都要清，否则渲出加载屏
 *   5. 每帧 mc.tick() 才能推进区块网格重建队列
 *   6. 读像素必须绑 FBO
 *   7. chunk 数据走官方 replaceWithPacketData（与网络包同路径）
 */
public class McfoldRenderServer {

    static final Gson GSON = new Gson();
    static final PrintStream OUT = new PrintStream(
            new java.io.FileOutputStream(java.io.FileDescriptor.out), true, StandardCharsets.UTF_8);

    static Minecraft mc;
    static ClientLevel level;
    static int width = 854, height = 480;

    public static void main(String[] args) throws Exception {
        // stdout 只放协议 JSON，MC 的 INFO/WARN 全部赶到 stderr
        System.setOut(new PrintStream(new java.io.FileOutputStream(java.io.FileDescriptor.err), true));

        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");
        width  = Integer.parseInt(arg(args, "--width",  "854"));
        height = Integer.parseInt(arg(args, "--height", "480"));

        try {
            boot(gameDir, assets, assetIdx);
        } catch (Throwable t) {
            emitError(null, "启动失败: " + t);
            t.printStackTrace(System.err);
            System.exit(1);
        }
        event("ready", null);

        BufferedReader in = new BufferedReader(new InputStreamReader(System.in, StandardCharsets.UTF_8));
        String line;
        while ((line = in.readLine()) != null) {
            line = line.trim();
            if (line.isEmpty()) continue;
            JsonObject req;
            try {
                req = JsonParser.parseString(line).getAsJsonObject();
            } catch (Exception e) {
                emitError(null, "非法 JSON: " + e.getMessage());
                continue;
            }
            Integer id = req.has("id") ? req.get("id").getAsInt() : null;
            try {
                handle(id, req);
            } catch (Throwable t) {
                emitError(id, t.toString());
                t.printStackTrace(System.err);
            }
        }
        System.exit(0);
    }

    // ---------------- 协议处理 ----------------

    static void handle(Integer id, JsonObject req) throws Exception {
        String cmd = req.get("cmd").getAsString();
        switch (cmd) {
            case "shutdown": {
                JsonObject r = new JsonObject(); r.addProperty("ok", true);
                emit(id, r);
                System.exit(0);
            }
            case "chunk": {
                int cx = req.get("cx").getAsInt(), cz = req.get("cz").getAsInt();
                byte[] data = decode(req.get("data").getAsString());
                var resp = applyChunk(cx, cz, data);
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.add("result", resp);
                emit(id, r);
                break;
            }
            case "chunks": {
                JsonArray items = req.getAsJsonArray("items");
                int ok = 0, failed = 0;
                String firstErr = null;
                for (JsonElement el : items) {
                    JsonObject it = el.getAsJsonObject();
                    try {
                        applyChunk(it.get("cx").getAsInt(), it.get("cz").getAsInt(),
                                   decode(it.get("data").getAsString()));
                        ok++;
                    } catch (Throwable t) {
                        failed++;
                        if (firstErr == null) {
                            firstErr = it.get("cx") + "," + it.get("cz") + ": " + t;
                        }
                    }
                }
                levelRendererAllChanged();
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("injected", ok);
                r.addProperty("failed", failed);
                if (firstErr != null) r.addProperty("firstError", firstErr);
                var cache2 = (net.minecraft.client.multiplayer.ClientChunkCache) level.getChunkSource();
                r.addProperty("loadedChunks", cache2.getLoadedChunksCount());
                emit(id, r);
                break;
            }
            case "setblocks": {
                // ★ 世代无关：Python 只做路由，方块写入、调色板组装、入 cache
                //   全部由 Java 用官方 API 完成 —— 版本差异不落回 Python。
                //   载荷：sections[].rle = [[stateId,count],...]，按 (y,z,x) 线性序覆盖该 section 4096 格。
                //   优势：协议位打包（历代改过）不再由 Python 复制；入 cache 走官方
                //        ClientboundLevelChunkPacketData(LevelChunk) → getReadBuffer()，
                //        签名两代一致，**无需反射**。
                int cx = req.get("cx").getAsInt(), cz = req.get("cz").getAsInt();
                LevelChunk chunk = new LevelChunk(level, new ChunkPos(cx, cz));
                LevelChunkSection[] sections = chunk.getSections();
                int placed = 0;
                long cells = 0;
                for (JsonElement se : req.getAsJsonArray("sections")) {
                    JsonObject so = se.getAsJsonObject();
                    int si = so.get("index").getAsInt();
                    if (si < 0 || si >= sections.length) continue;
                    LevelChunkSection sec = sections[si];
                    int x = 0, y = 0, z = 0;
                    for (JsonElement re : so.getAsJsonArray("rle")) {
                        JsonArray pair = re.getAsJsonArray();
                        int stateId = pair.get(0).getAsInt();
                        int count = pair.get(1).getAsInt();
                        BlockState st = stateId == 0 ? null : Block.stateById(stateId);
                        for (int i = 0; i < count; i++) {
                            if (st != null) { sec.setBlockState(x, y, z, st); placed++; }
                            cells++;
                            if (++x == 16) { x = 0; if (++z == 16) { z = 0; y++; } }
                        }
                    }
                }
                // 光照（无光照数据则全亮，否则地形全黑）
                var light = level.getChunkSource().getLightEngine();
                for (int sy = level.getMinSection(); sy < level.getMaxSection(); sy++) {
                    DataLayer sky = new DataLayer();
                    for (int lx = 0; lx < 16; lx++)
                        for (int ly = 0; ly < 16; ly++)
                            for (int lz = 0; lz < 16; lz++) sky.set(lx, ly, lz, 15);
                    light.queueSectionData(LightLayer.SKY, net.minecraft.core.SectionPos.of(cx, sy, cz), sky);
                    light.queueSectionData(LightLayer.BLOCK, net.minecraft.core.SectionPos.of(cx, sy, cz), sky);
                }
                // ★ 官方序列化 → 官方入口入 cache（两代签名一致）
                var pkt = new net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData(chunk);
                level.getChunkSource().replaceWithPacketData(cx, cz,
                        pkt.getReadBuffer(), pkt.getHeightmaps(),
                        new java.util.function.Consumer<
                            net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData.BlockEntityTagOutput>() {
                            @Override public void accept(
                                net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData.BlockEntityTagOutput t) { }
                        });
                light.setLightEnabled(new ChunkPos(cx, cz), true);
                light.runLightUpdates();
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("placed", placed);
                r.addProperty("cells", cells);
                r.addProperty("sections", sections.length);
                r.addProperty("loadedChunks", level.getChunkSource().getLoadedChunksCount());
                emit(id, r);
                break;
            }
            case "camera": {
                double x = req.get("x").getAsDouble(), y = req.get("y").getAsDouble(), z = req.get("z").getAsDouble();
                float yaw = req.has("yaw") ? req.get("yaw").getAsFloat() : 0f;
                float pitch = req.has("pitch") ? req.get("pitch").getAsFloat() : 0f;
                // ★ 必须 setPosRaw + 手动更新 chunk 追踪，否则实体仍属旧区块
                mc.player.setPosRaw(x, y, z);
                mc.player.xo = x; mc.player.yo = y; mc.player.zo = z;
                mc.player.setYRot(yaw);
                mc.player.setXRot(pitch);
                mc.player.yRotO = yaw;
                mc.player.xRotO = pitch;
                mc.setCameraEntity(mc.player);
                // 视野中心跟着相机走，否则目标区域区块被 ClientChunkCache 丢弃
                level.getChunkSource().updateViewCenter((int)Math.floor(x) >> 4, (int)Math.floor(z) >> 4);
                mc.levelRenderer.allChanged();
                tickFrames(5);
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                JsonArray c = new JsonArray(); c.add(x); c.add(y); c.add(z);
                r.add("camera", c);
                emit(id, r);
                break;
            }
            case "view": {
                if (req.has("cameraType")) {
                    mc.options.setCameraType(net.minecraft.client.CameraType.valueOf(req.get("cameraType").getAsString()));
                }
                if (req.has("renderDistance")) {
                    int rd = req.get("renderDistance").getAsInt();
                    // ★ 两处都要设：renderDistance 是本地设置；
                    //   serverRenderDistance 模拟服务端下发的视距上限
                    //   （getEffectiveRenderDistance = min(两者)）
                    mc.options.renderDistance().set(rd);
                    mc.options.setServerRenderDistance(rd);
                    // ★ 必须同步 ClientChunkCache 的 storage 半径，
                    //   否则区块被 inRange 丢弃（官方靠服务端包触发 updateViewRadius）
                    level.getChunkSource().updateViewRadius(rd);
                    mc.levelRenderer.allChanged();
                }
                if (req.has("fov")) {
                    mc.options.fov().set(req.get("fov").getAsInt());
                }
                // ── 原版画质选项（光影的基础层）──
                if (req.has("graphicsMode")) {
                    mc.options.graphicsMode().set(net.minecraft.client.GraphicsStatus
                            .valueOf(req.get("graphicsMode").getAsString()));
                    mc.levelRenderer.allChanged();   // FANCY 会启用更多渲染层
                }
                if (req.has("ambientOcclusion")) {
                    mc.options.ambientOcclusion().set(req.get("ambientOcclusion").getAsBoolean());
                    mc.levelRenderer.allChanged();
                }
                if (req.has("mipmapLevels")) {
                    mc.options.mipmapLevels().set(req.get("mipmapLevels").getAsInt());
                }
                if (req.has("gamma")) {
                    mc.options.gamma().set(req.get("gamma").getAsDouble());
                }
                if (req.has("entityShadows")) {
                    mc.options.entityShadows().set(req.get("entityShadows").getAsBoolean());
                }
                if (req.has("clouds")) {
                    mc.options.cloudStatus().set(net.minecraft.client.CloudStatus
                            .valueOf(req.get("clouds").getAsString()));
                }
                if (req.has("particles")) {
                    mc.options.particles().set(net.minecraft.client.ParticleStatus
                            .valueOf(req.get("particles").getAsString()));
                }
                // ── 原版后处理链（PostChain 基础设施）──
                if (req.has("postEffect")) {
                    String eff = req.get("postEffect").getAsString();
                    if (eff.isEmpty() || eff.equals("none")) {
                        mc.gameRenderer.shutdownEffect();
                    } else {
                        // loadEffect 是包私有 → 走同包 bridge
                        net.minecraft.client.renderer.McfoldBridge.loadEffect(
                                mc.gameRenderer, new ResourceLocation(eff));
                    }
                }
                // 回包带上真实生效值，便于验证
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                JsonObject cur = new JsonObject();
                try {
                    java.lang.reflect.Field pf = net.minecraft.client.renderer.GameRenderer.class
                            .getDeclaredField("postEffect");
                    pf.setAccessible(true);
                    cur.addProperty("postEffect", pf.get(mc.gameRenderer) != null ? "active" : "none");
                } catch (Throwable ignore) {
                    cur.addProperty("postEffect", "unknown");
                }
                cur.addProperty("graphicsMode", mc.options.graphicsMode().get().name());
                cur.addProperty("ambientOcclusion", mc.options.ambientOcclusion().get());
                cur.addProperty("mipmapLevels", mc.options.mipmapLevels().get());
                cur.addProperty("gamma", mc.options.gamma().get());
                cur.addProperty("entityShadows", mc.options.entityShadows().get());
                cur.addProperty("clouds", mc.options.cloudStatus().get().name());
                cur.addProperty("renderDistance", mc.options.getEffectiveRenderDistance());
                r.add("current", cur);
                emit(id, r);
                break;
            }
            case "capacity": {
                // ★ 世界尺寸由运行时提供 —— Python 不硬编码版本相关常量。
                //   这些方法都在 LevelHeightAccessor 上（Level 实现），两代 API 一致。
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("sectionsCount", level.getSectionsCount());
                r.addProperty("minSection", level.getMinSection());
                r.addProperty("maxSection", level.getMaxSection());
                r.addProperty("minBuildHeight", level.getMinBuildHeight());
                r.addProperty("maxBuildHeight", level.getMaxBuildHeight());
                r.addProperty("height", level.getHeight());
                // 生物群系默认 id（不硬编码 1）
                try {
                    var bio = mc.level.registryAccess().registryOrThrow(Registries.BIOME);
                    var key = bio.getKey(bio.byId(1));
                    r.addProperty("defaultBiome", key != null ? key.toString() : "minecraft:plains");
                } catch (Throwable t) {
                    r.addProperty("defaultBiome", "minecraft:plains");
                }
                emit(id, r);
                break;
            }
            case "registry": {
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("blockCount", BuiltInRegistries.BLOCK.size());
                r.addProperty("stateCount", Block.BLOCK_STATE_REGISTRY.size());
                emit(id, r);
                break;
            }
            case "lookup": {
                int sid = req.get("stateId").getAsInt();
                BlockState st = Block.stateById(sid);
                ResourceLocation key = BuiltInRegistries.BLOCK.getKey(st.getBlock());
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("stateId", sid);
                r.addProperty("block", key.toString());
                r.addProperty("state", st.toString());
                r.addProperty("inRange", sid >= 0 && sid < Block.BLOCK_STATE_REGISTRY.size());
                emit(id, r);
                break;
            }
            case "fog": {
                // 关雾：fogStart/fogEnd 是 levelRenderer 内部状态；
                // 更简单可靠的是加大 renderDistance + 用 BLOCK 光照
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                emit(id, r);
                break;
            }
            case "resolve": {
                // ★ 方块名(+属性) → state id。存档 palette 是名字，网络载荷要 id，
                //   而这个名字→id 的权威映射只有客户端注册表有。
                //   入参: {"cmd":"resolve","blocks":["minecraft:oak_log[axis=y]", ...]}
                JsonArray arr = req.getAsJsonArray("blocks");
                // ★ parseForBlock 要 HolderLookup（不是 Registry）。
                //   用**静态注册表**的 asLookup()：它是方块名→id 的权威来源
                //   （mod 方块也注册在这里），且两代 API 一致。
                //   不用 mc.level.registryAccess() —— 1.21 上它来自 cookie，
                //   只含 worldgen 那批注册表，查 block 会报 "Registry not found"（实测）。
                var reg = BuiltInRegistries.BLOCK.asLookup();
                JsonArray out = new JsonArray();
                int unknown = 0;
                for (JsonElement el : arr) {
                    String spec = el.getAsString();
                    int sid;
                    try {
                        var res = net.minecraft.commands.arguments.blocks.BlockStateParser
                                .parseForBlock(reg, spec, false);
                        sid = Block.getId(res.blockState());
                    } catch (Throwable t) {
                        sid = -1; unknown++;
                    }
                    out.add(sid);
                }
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.add("ids", out);
                r.addProperty("unknown", unknown);
                r.addProperty("total", arr.size());
                emit(id, r);
                break;
            }
            case "debug": {
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("playerPos", mc.player.getX() + "," + mc.player.getY() + "," + mc.player.getZ());
                int pcx = (int)Math.floor(mc.player.getX()) >> 4, pcz = (int)Math.floor(mc.player.getZ()) >> 4;
                r.addProperty("playerChunk", pcx + "," + pcz);
                var cc = (net.minecraft.client.multiplayer.ClientChunkCache) level.getChunkSource();
                r.addProperty("loadedChunks", cc.getLoadedChunksCount());
                r.addProperty("chunksRendered", mc.levelRenderer.countRenderedChunks());
                r.addProperty("hasRenderedAllChunks", mc.levelRenderer.hasRenderedAllChunks());
                var got = cc.getChunk(pcx, pcz, net.minecraft.world.level.chunk.ChunkStatus.FULL, false);
                r.addProperty("chunkAtPlayer", got != null ? got.getClass().getSimpleName() : "null");
                if (got != null) {
                    // 扫描玩家所在列，找最高的非空气方块
                    int top = Integer.MIN_VALUE;
                    for (int y = level.getMaxBuildHeight() - 1; y >= level.getMinBuildHeight(); y--) {
                        var st = got.getBlockState(new BlockPos(
                                (int)Math.floor(mc.player.getX()) & 15, y, (int)Math.floor(mc.player.getZ()) & 15));
                        if (!st.isAir()) {
                            top = y;
                            r.addProperty("topSolidY", y);
                            r.addProperty("topSolidBlock", BuiltInRegistries.BLOCK.getKey(st.getBlock()).toString());
                            r.addProperty("topSolidProps", st.toString());
                            break;
                        }
                    }
                    if (top == Integer.MIN_VALUE) r.addProperty("topSolidY", "none");
                }
                // viewCenter
                r.addProperty("fogStart", String.valueOf(mc.options.renderDistance().get()));
                emit(id, r);
                break;
            }
            case "viewport": {
                // ★ viewCenter 决定 ClientChunkCache 收哪些区块（超范围会被丢弃）
                int cx = req.get("cx").getAsInt(), cz = req.get("cz").getAsInt();
                if (req.has("radius")) {
                    level.getChunkSource().updateViewRadius(req.get("radius").getAsInt());
                }
                level.getChunkSource().updateViewCenter(cx, cz);
                JsonObject r = new JsonObject();
                r.addProperty("ok", true);
                r.addProperty("viewCenter", cx + "," + cz);
                emit(id, r);
                break;
            }
            case "render": {
                int frames = req.has("frames") ? req.get("frames").getAsInt() : 60;
                String out = req.has("out") ? req.get("out").getAsString() : null;
                if (req.has("width")) width = req.get("width").getAsInt();
                if (req.has("height")) height = req.get("height").getAsInt();
                render(id, frames, out);
                break;
            }
            default:
                emitError(id, "未知命令: " + cmd);
        }
    }

    static JsonObject applyChunk(int cx, int cz, byte[] data) {
        // ★ 官方路径：ClientChunkCache.replaceWithPacketData
        //   内部：new LevelChunk + chunk.replaceWithPacketData(buf, heightmaps, consumer)
        //   与网络包 handleLevelChunkWithLight 完全同一路径
        FriendlyByteBuf buf = new FriendlyByteBuf(io.netty.buffer.Unpooled.wrappedBuffer(data));
        var cache = level.getChunkSource();
        // 显式匿名类而非 lambda：lambda 参数类型推断在此处会失败（实测）
        net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData.BlockEntityTagOutput beOut =
                new net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData.BlockEntityTagOutput() {
                    @Override public void accept(BlockPos bp,
                            net.minecraft.world.level.block.entity.BlockEntityType<?> type,
                            net.minecraft.nbt.CompoundTag tag) { }
                };
        // ★ 参数是 Consumer<BlockEntityTagOutput>（消费这个接口本身），不是该接口的方法签名。
        //   LevelChunk.replaceWithPacketData 内部会调 beOut.accept(...)，这里直接空实现。
        cache.replaceWithPacketData(cx, cz, buf, new net.minecraft.nbt.CompoundTag(), out -> {});
        // 无光照数据 ⇒ 显式全亮，否则地形全黑
        var light = cache.getLightEngine();
        for (int sy = level.getMinSection(); sy < level.getMaxSection(); sy++) {
            DataLayer sky = new DataLayer();
            for (int x = 0; x < 16; x++)
                for (int y = 0; y < 16; y++)
                    for (int z = 0; z < 16; z++) sky.set(x, y, z, 15);
            light.queueSectionData(LightLayer.SKY, net.minecraft.core.SectionPos.of(cx, sy, cz), sky);
            light.queueSectionData(LightLayer.BLOCK, net.minecraft.core.SectionPos.of(cx, sy, cz), sky);
        }
        light.setLightEnabled(new ChunkPos(cx, cz), true);
        int upd = light.runLightUpdates();
        JsonObject r = new JsonObject();
        r.addProperty("lightUpdates", upd);
        return r;
    }

    static void levelRendererAllChanged() {
        mc.levelRenderer.allChanged();
    }

    /** tick + 渲染各帧（区块网格重建队列靠 tick 推进） */
    static void tickFrames(int n) {
        MainTarget target = (MainTarget) mc.getMainRenderTarget();
        for (int f = 0; f < n; f++) {
            try { mc.tick(); } catch (Throwable ignore) {}
            RenderSystem.clear(16640, Minecraft.ON_OSX);
            target.bindWrite(true);
            mc.gameRenderer.render(0.0F, (long) f * 16_000_000L, true);
            target.unbindWrite();
            target.blitToScreen(mc.getWindow().getWidth(), mc.getWindow().getHeight());
            mc.getWindow().updateDisplay();
        }
    }

    static void render(Integer id, int frames, String out) throws Exception {
        tickFrames(frames);

        MainTarget target = (MainTarget) mc.getMainRenderTarget();
        int w = mc.getWindow().getWidth(), h = mc.getWindow().getHeight();
        org.lwjgl.opengl.GL30.glBindFramebuffer(org.lwjgl.opengl.GL30.GL_FRAMEBUFFER, target.frameBufferId);
        GL11.glReadBuffer(org.lwjgl.opengl.GL30.GL_COLOR_ATTACHMENT0);
        var buf = org.lwjgl.BufferUtils.createByteBuffer(w * h * 4);
        GL11.glReadPixels(0, 0, w, h, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buf);
        org.lwjgl.opengl.GL30.glBindFramebuffer(org.lwjgl.opengl.GL30.GL_FRAMEBUFFER, 0);

        BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        java.util.Set<Integer> colors = new java.util.HashSet<>();
        for (int y = 0; y < h; y++)
            for (int x = 0; x < w; x++) {
                int i = ((h - 1 - y) * w + x) * 4;
                int rgb = ((buf.get(i) & 0xFF) << 16) | ((buf.get(i + 1) & 0xFF) << 8) | (buf.get(i + 2) & 0xFF);
                img.setRGB(x, y, rgb);
                colors.add(rgb);
            }

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ImageIO.write(img, "png", bos);
        byte[] png = bos.toByteArray();
        if (out != null) ImageIO.write(img, "png", new File(out));

        JsonObject r = new JsonObject();
        r.addProperty("ok", true);
        r.addProperty("width", w);
        r.addProperty("height", h);
        r.addProperty("chunksRendered", mc.levelRenderer.countRenderedChunks());
        r.addProperty("hasRenderedAllChunks", mc.levelRenderer.hasRenderedAllChunks());
        r.addProperty("distinctColors", colors.size());
        JsonArray cam = new JsonArray();
        cam.add(mc.player.getX()); cam.add(mc.player.getY()); cam.add(mc.player.getZ());
        r.add("camera", cam);
        if (out != null) r.addProperty("path", out);
        r.addProperty("image", Base64.getEncoder().encodeToString(png));
        emit(id, r);
    }

    // ---------------- 启动 ----------------

    static void boot(String gameDir, String assets, String assetIdx) throws Exception {
        SharedConstants.tryDetectVersion();
        SharedConstants.enableDataFixerOptimizations();
        Bootstrap.bootStrap();

        File runDir = new File(gameDir);
        runDir.mkdirs();
        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();
        mc = new Minecraft(cfg);
        RenderSystem.finishInitialization();
        System.err.println("[mcfold] Minecraft constructed");

        reloadResources(mc);
        System.err.println("[mcfold] resources reloaded");

        Connection conn = new Connection(PacketFlow.CLIENTBOUND);
        GameProfile profile = new GameProfile(UUID.randomUUID(), "mcfold_cam");
        WorldSessionTelemetryManager telemetry = new WorldSessionTelemetryManager(
                TelemetryEventSender.DISABLED, false, Duration.ZERO, "");
        ClientPacketListener listener = new ClientPacketListener(mc, null, conn, null, profile, telemetry);

        var packs = net.minecraft.server.packs.repository.ServerPacksSource.createPackRepository(
                new File(runDir, "datapacks").toPath());
        packs.reload();
        ResourceManager dataRm = new net.minecraft.server.packs.resources.MultiPackResourceManager(
                net.minecraft.server.packs.PackType.SERVER_DATA,
                java.util.List.of(packs.getPack("vanilla").open()));
        var all = new java.util.ArrayList<RegistryDataLoader.RegistryData<?>>();
        all.addAll(RegistryDataLoader.WORLDGEN_REGISTRIES);
        all.addAll(RegistryDataLoader.DIMENSION_REGISTRIES);
        RegistryAccess.Frozen loaded = RegistryDataLoader.load(dataRm, listener.registryAccess(), all);
        var layered = net.minecraft.client.multiplayer.ClientRegistryLayer.createRegistryAccess()
                .replaceFrom(net.minecraft.client.multiplayer.ClientRegistryLayer.REMOTE,
                             new RegistryAccess.Frozen[]{loaded});
        var rf = ClientPacketListener.class.getDeclaredField("registryAccess");
        rf.setAccessible(true);
        rf.set(listener, layered);

        Holder<DimensionType> dimHolder = loaded.registryOrThrow(Registries.DIMENSION_TYPE)
                .getHolderOrThrow(ResourceKey.create(Registries.DIMENSION_TYPE, new ResourceLocation("overworld")));
        var levelData = new ClientLevel.ClientLevelData(Difficulty.NORMAL, false, false);
        level = new ClientLevel(listener, levelData, Level.OVERWORLD, dimHolder,
                Math.max(8, mc.options.renderDistance().get()), 8,
                () -> InactiveProfiler.INSTANCE, mc.levelRenderer, false, 0L);
        mc.setLevel(level);

        var player = new net.minecraft.client.player.LocalPlayer(mc, level, listener,
                new net.minecraft.stats.StatsCounter(), new net.minecraft.client.ClientRecipeBook(), false, false);
        player.setPos(8.0, 70.0, 8.0);
        mc.player = player;
        mc.setCameraEntity(player);
        mc.gameMode = new net.minecraft.client.multiplayer.MultiPlayerGameMode(mc, listener);

        net.minecraft.client.renderer.McfoldBridge.reloadShaders(mc.gameRenderer, mc.getResourceManager());

        mc.setOverlay(null);
        mc.setScreen(null);
        mc.options.setCameraType(net.minecraft.client.CameraType.THIRD_PERSON_BACK);
        System.err.println("[mcfold] boot done");
    }

    /** 同步驱动各 reload listener（不能 join Minecraft 的 reloadResourcePacks：等主循环 → 死锁）*/
    static void reloadResources(Minecraft mc) throws Exception {
        var rmF = Minecraft.class.getDeclaredField("resourceManager");
        rmF.setAccessible(true);
        var rm = (net.minecraft.server.packs.resources.ReloadableResourceManager) rmF.get(mc);
        mc.getResourcePackRepository().reload();

        var barrier = new net.minecraft.server.packs.resources.PreparableReloadListener.PreparationBarrier() {
            @Override public <T> java.util.concurrent.CompletableFuture<T> wait(T t) {
                return java.util.concurrent.CompletableFuture.completedFuture(t);
            }
        };
        var prof = InactiveProfiler.INSTANCE;
        java.util.concurrent.Executor sync = Runnable::run;

        for (var listener : reloadListeners(rm)) {
            String name = listener.getName();
            try {
                var fut = listener.reload(barrier, rm, prof, prof, sync, sync);
                long deadline = System.currentTimeMillis() + 60_000;
                while (!fut.isDone() && System.currentTimeMillis() < deadline) Thread.sleep(10);
                if (fut.isDone()) fut.join();
                else System.err.println("[mcfold]   TIMEOUT " + name);
            } catch (Throwable e) {
                System.err.println("[mcfold]   FAILED " + name + ": " + e);
            }
        }
    }

    @SuppressWarnings("unchecked")
    static java.util.List<net.minecraft.server.packs.resources.PreparableReloadListener> reloadListeners(Object rm) throws Exception {
        for (var f : rm.getClass().getDeclaredFields()) {
            if (java.util.List.class.isAssignableFrom(f.getType())) {
                f.setAccessible(true);
                Object v = f.get(rm);
                if (v instanceof java.util.List<?> l && !l.isEmpty()
                        && l.get(0) instanceof net.minecraft.server.packs.resources.PreparableReloadListener) {
                    return (java.util.List<net.minecraft.server.packs.resources.PreparableReloadListener>) l;
                }
            }
        }
        throw new IllegalStateException("reload listeners not found");
    }

    // ---------------- 工具 ----------------

    static byte[] decode(String b64) {
        return Base64.getDecoder().decode(b64);
    }

    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;
    }

    static synchronized void emit(Integer id, JsonObject obj) {
        if (id != null) obj.addProperty("id", id);
        OUT.println(GSON.toJson(obj));
        OUT.flush();
    }

    static void emitError(Integer id, String msg) {
        JsonObject o = new JsonObject();
        o.addProperty("ok", false);
        o.addProperty("error", msg);
        emit(id, o);
    }

    static void event(String name, JsonObject payload) {
        JsonObject o = new JsonObject();
        o.addProperty("event", name);
        if (payload != null) o.add("payload", payload);
        OUT.println(GSON.toJson(o));
        OUT.flush();
    }
}