package io.gitlab.jfronny.resclone;

import io.gitlab.jfronny.commons.log.Logger;
import io.gitlab.jfronny.commons.serialize.gson.api.v1.GsonHolders;
import io.gitlab.jfronny.resclone.data.PackMetaLoaded;
import io.gitlab.jfronny.resclone.data.PackMetaUnloaded;
import io.gitlab.jfronny.resclone.fetchers.*;
import io.gitlab.jfronny.resclone.processors.*;
import io.gitlab.jfronny.resclone.util.PackUrlCache;
import net.fabricmc.api.EnvType;
import net.fabricmc.api.ModInitializer;
import net.fabricmc.loader.api.FabricLoader;

import java.io.IOException;
import java.net.URI;
import java.nio.file.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Resclone implements ModInitializer {
    public static final Map<String, PackFetcher> FETCHER_INSTANCES = new LinkedHashMap<>();
    public static final Set<PackProcessor> PROCESSORS = new LinkedHashSet<>();
    public static final Set<PackMetaLoaded> DOWNLOADED_PACKS = new LinkedHashSet<>();
    public static final Set<PackMetaLoaded> NEW_PACKS = new LinkedHashSet<>(); // Client-only!

    public static final String MOD_ID = "resclone";
    public static final Logger LOGGER = Logger.forName(MOD_ID);
    public static final String USER_AGENT = "jfmods/" + MOD_ID + "/" + FabricLoader.getInstance()
            .getModContainer(MOD_ID).orElseThrow()
            .getMetadata()
            .getVersion()
            .getFriendlyString();

    public static PackUrlCache urlCache;

    public static int packCount = 0;

    @Override
    public void onInitialize() {
        LOGGER.info("Initialising Resclone.");
        GsonHolders.registerSerializer();

        urlCache = new PackUrlCache(getConfigPath().resolve("urlCache.properties"));
        FETCHER_INSTANCES.clear();
        PROCESSORS.clear();
        DOWNLOADED_PACKS.clear();

        addProcessor(new RootPathProcessor()); //This should be run before any other processor to make sure the path is valid
        addFetcher(new BasicFileFetcher());
        addFetcher(new GitHubFetcher());
        addFetcher(new CurseforgeFetcher());
        addFetcher(new ModrinthFetcher());
        if (FabricLoader.getInstance().getEnvironmentType() == EnvType.CLIENT) addProcessor(new PruneVanillaProcessor());
        addProcessor(new RemoveEmptyProcessor());
        reload();

        LOGGER.info("Installed {} resource pack{}.", packCount, packCount == 1 ? "" : "s");
    }

    public void addFetcher(PackFetcher fetcher) {
        FETCHER_INSTANCES.put(fetcher.getSourceTypeName(), fetcher);
    }

    public void addProcessor(PackProcessor processor) {
        PROCESSORS.add(processor);
    }

    public void addPack(String fetcher, String pack, String name) {
        addPack(fetcher, pack, name, false);
    }

    public void addPack(String fetcher, String pack, String name, boolean forceRedownload) {
        addPack(fetcher, pack, name, forceRedownload, false);
    }

    public void addPack(String fetcher, String pack, String name, boolean forceRedownload, boolean forceEnable) {
        RescloneConfig.packs.add(new PackMetaUnloaded(fetcher, pack, name, forceRedownload, forceEnable));
    }

    public void reload() {
        Set<PackMetaLoaded> metas = new LinkedHashSet<>();
        if (RescloneConfig.packs.isEmpty()) {
            LOGGER.info("No resclone pack was specified, add one");
        }
        else {
            try {
                ExecutorService pool = Executors.newFixedThreadPool(RescloneConfig.packs.size());
                for (PackMetaUnloaded s : RescloneConfig.packs) {
                    pool.submit(generateTask(s, metas));
                }
                pool.shutdown();
                if (!pool.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS)) {
                    LOGGER.error("Download timed out. This shouldn't be possible");
                }
            } catch (InterruptedException e) {
                LOGGER.error("Could not execute pack download task", e);
            }
        }
        urlCache.save();
        DOWNLOADED_PACKS.clear();
        DOWNLOADED_PACKS.addAll(metas);

        if (RescloneConfig.pruneUnused) pruneCache();
    }

    private Runnable generateTask(PackMetaUnloaded meta, Set<PackMetaLoaded> metas) {
        return () -> {
            try {
                if (!FETCHER_INSTANCES.containsKey(meta.fetcher))
                    throw new Exception("Invalid fetcher: " + meta.fetcher);
                Path cacheDir = getConfigPath().resolve("cache");
                PackMetaLoaded p;
                try {
                    boolean isNew = !urlCache.containsKey(meta.source);
                    //Download
                    PackFetcher.Result fr = FETCHER_INSTANCES.get(meta.fetcher).get(meta.source, cacheDir, meta.forceDownload);
                    p = new PackMetaLoaded(fr.downloadPath(), meta.name, meta.forceEnable);
                    metas.add(p);
                    if (isNew && FabricLoader.getInstance().getEnvironmentType() == EnvType.CLIENT) NEW_PACKS.add(p);
                    if (fr.freshDownload()) {
                        //Process
                        Map<String, String> props = new HashMap<>();
                        props.put("create", "false");
                        URI zipfile = URI.create("jar:" + p.zipPath().toUri());
                        try (FileSystem zipfs = FileSystems.newFileSystem(zipfile, props)) {
                            for (PackProcessor processor : PROCESSORS) {
                                processor.process(zipfs);
                            }
                        } catch (Throwable e) {
                            LOGGER.error("Could not run pack processors on " + p.zipPath(), e);
                        }
                    }
                } catch (Throwable e) {
                    throw new Exception("Failed to download pack", e);
                }
            } catch (Throwable e) {
                LOGGER.error("Encountered issue while preparing " + meta.name, e);
            }
        };
    }

    private void pruneCache() {
        Set<Path> loadedPacks = DOWNLOADED_PACKS.stream().map(PackMetaLoaded::zipPath).collect(Collectors.toUnmodifiableSet());
        Set<Path> toDelete = new HashSet<>();
        try (Stream<Path> cacheEntries = Files.list(getConfigPath().resolve("cache"))) {
            cacheEntries
                    .filter(s -> !Files.isRegularFile(s) || !loadedPacks.contains(s))
                    .forEach(toDelete::add);
        } catch (IOException e) {
            LOGGER.error("Could find cache entries to prune", e);
        }
        if (!toDelete.isEmpty()) {
            LOGGER.info("Pruning " + toDelete.size() + " unused cache entries");
            for (Path path : toDelete) {
                try {
                    Files.delete(path);
                } catch (IOException e) {
                    LOGGER.error("Could not delete unused cache entry: " + path, e);
                }
            }
        }
    }

    public static Path getConfigPath() {
        Path configPath = FabricLoader.getInstance().getConfigDir().resolve(MOD_ID);
        if (!Files.isDirectory(configPath.resolve("cache"))) {
            try {
                Files.createDirectories(configPath.resolve("cache"));
            } catch (IOException e) {
                LOGGER.error("Could not create cache directory", e);
            }
        }
        return configPath;
    }
}