ModsMod/src/main/java/io/gitlab/jfronny/modsmod/ModsMod.java

package io.gitlab.jfronny.modsmod;

import io.gitlab.jfronny.libjf.Libjf;
import net.fabricmc.loader.FabricLoader;
import net.fabricmc.loader.discovery.ModCandidate;
import net.fabricmc.loader.discovery.ModResolver;
import net.fabricmc.loader.discovery.RuntimeModRemapper;
import net.fabricmc.loader.launch.common.FabricLauncherBase;
import net.fabricmc.loader.metadata.LoaderModMetadata;
import net.fabricmc.loader.metadata.ModMetadataParser;
import net.fabricmc.loader.metadata.ParseMetadataException;
import net.fabricmc.loader.util.FileSystemUtil;

import java.io.IOException;
import java.net.URL;
import java.nio.file.FileSystem;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.Collections;
import java.util.HashSet;

public class ModsMod {
    static final HashSet<ModMeta> m = new HashSet<>();
    static final FabricLoader loader = FabricLoader.INSTANCE;
    public static final String MOD_ID = "modsmod";
    private static final String CACHE_NAME = MOD_ID + "cache";
    public static void prepare() throws IOException {
        //Load config
        Libjf.registerConfig(MOD_ID, Cfg.class);
        Path configDir = loader.getConfigDir();
        Path modsmodCfgFile = Libjf.getConfigs().get(MOD_ID).path;
        //make sure the modsmodcache dir is ok
        Path path = configDir.resolve(CACHE_NAME);
        if (!Files.isDirectory(path)) {
            if (Files.exists(path))
                Files.delete(path);
            Files.createDirectories(path);
        }
        //remove modsmodcache if the cache is outdated
        try {
            Path cfgCache = path.resolve("_basecfg");
            if (Files.exists(cfgCache)) {
                if (Files.isRegularFile(cfgCache)) {
                    if (!IOUtil.contentEquals(modsmodCfgFile, cfgCache)) {
                        IOUtil.clearDirectory(path);
                    }
                }
                else {
                    IOUtil.clearDirectory(path);
                }
            }
            Files.copy(modsmodCfgFile, cfgCache, StandardCopyOption.REPLACE_EXISTING);
        } catch (IOException e) {
            System.err.println("Failed to validate modsmod config cache, caching will not be available");
            e.printStackTrace();
        }
        m.clear();
        //Generate mods
        for (int i = 0; i < Cfg.modsCount; i++) {
            Path f = path.resolve("f" + (i + 1) + ".jar");
            boolean exists = Files.exists(f);
            //Do not load if cached
            if (exists) {
                if (Cfg.cache) {
                    m.add(new ModMeta(f));
                    continue;
                } else Files.delete(f);
            }
            try (FileSystem fs = FileSystemUtil.getJarFileSystem(f, true).get()) {
                //META-INF/MANIFEST.MF (java jar file spec)
                Path inf = fs.getPath("META-INF");
                Files.createDirectory(inf);
                StringBuilder sb = new StringBuilder();
                sb.append("Manifest-Version: 1.0\n");
                Files.writeString(inf.resolve("MANIFEST.MF"), sb.toString());
                sb.delete(0, sb.length());
                //fabric.mod.json (fabric mod metadata)
                sb.append("{");
                sb.append("\"schemaVersion\": 1,");
                sb.append("\"id\": \"modmod_").append(i + 1).append("\",");
                sb.append("\"version\": \"1.0\",");
                sb.append("\"name\": \"ModsMod ").append(i + 1).append("\",");
                sb.append("\"entrypoints\": {},");
                sb.append("\"custom\": {");
                if (Cfg.parent) {
                    sb.append("\"modmenu:parent\": \"modsmod\"");
                }
                sb.append("}");
                sb.append("}");
                Files.writeString(fs.getPath("fabric.mod.json"), sb.toString());
                sb.delete(0, sb.length());
            } catch (Throwable e) {
                e.printStackTrace();
            }

            System.gc();

            m.add(new ModMeta(f));
        }
        FabricLoaderInterface.synchronize(loader);
    }

    public static void init() {
        for (ModMeta f : m) {
            loadMod(f);
        }
    }

    private static void loadMod(ModMeta meta) {
        ModCandidate candidate = parseMod(meta.fs.getPath("fabric.mod.json"), meta.url);

        if (loader.isDevelopmentEnvironment()) {
            candidate = RuntimeModRemapper.remap(Collections.singletonList(candidate), ModResolver.getInMemoryFs()).stream().findFirst().get();
        }

        FabricLoaderInterface.addMod(loader, candidate);
        FabricLauncherBase.getLauncher().propose(candidate.getOriginUrl());
    }

    private static ModCandidate parseMod(Path fabricModJson, URL originUrl) {
        try {
            LoaderModMetadata info = ModMetadataParser.parseMetadata(FabricLoaderInterface.logger, fabricModJson);
            return new ModCandidate(info, originUrl, 0, true);
        } catch (IOException | ParseMetadataException e) {
            throw new IllegalStateException(e);
        }
    }
}