package io.gitlab.jfronny.inceptum.launcher.system.instance;

import gsoncompile.extensions.io.gitlab.jfronny.inceptum.launcher.model.inceptum.InstanceMeta.GC_InstanceMeta;
import io.gitlab.jfronny.commons.io.JFiles;
import io.gitlab.jfronny.commons.throwable.ThrowingConsumer;
import io.gitlab.jfronny.inceptum.common.MetaHolder;
import io.gitlab.jfronny.inceptum.common.Utils;
import io.gitlab.jfronny.inceptum.launcher.model.inceptum.InstanceMeta;
import io.gitlab.jfronny.inceptum.launcher.util.FileBackedRef;

import java.io.Closeable;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.*;

public class InstanceList {
    private static final Map<Path, IEntry> metas = new LinkedHashMap<>();
    public static final String INSTANCE_CONFIG_NAME = "instance.json";

    public static void reset() {
        synchronized (metas) {
            for (var entry : metas.entrySet()) {
                try {
                    entry.value.close();
                } catch (IOException e) {
                    Utils.LOGGER.error("Could not close reference to instance meta", e);
                }
            }
            metas.clear();
        }
    }

    public static Set<Instance> ordered() throws IOException {
        TreeSet<Instance> set = new TreeSet<>();
        forEach(set::add);
        return set.descendingSet();
    }

    public static <TEx extends Exception> void forEach(ThrowingConsumer<Instance, TEx> target) throws IOException, TEx {
        Objects.requireNonNull(target);
        if (!Files.exists(MetaHolder.INSTANCE_DIR)) Files.createDirectories(MetaHolder.INSTANCE_DIR);
        try {
            JFiles.listTo(MetaHolder.INSTANCE_DIR, path -> {
                if (!isInstance(path)) return;
                target.accept(read(path));
            });
        } catch (Exception e) {
            //noinspection unchecked
            throw (TEx) e;
        }
    }

    public static boolean isEmpty() throws IOException {
        if (!Files.exists(MetaHolder.INSTANCE_DIR)) return true;
        return JFiles.list(MetaHolder.INSTANCE_DIR, InstanceList::isInstance).isEmpty;
    }

    public static Instance read(Path instancePath) throws IOException {
        Objects.requireNonNull(instancePath);
        synchronized (metas) {
            if (!metas.containsKey(instancePath)) {
                metas[instancePath] = new IEntry(
                        instancePath,
                        new FileBackedRef<>(instancePath.resolve(INSTANCE_CONFIG_NAME), GC_InstanceMeta::read)
                );
            }
            return metas[instancePath].toPub();
        }
    }

    private static boolean isInstance(Path path) {
        return Files.isDirectory(path) && Files.exists(path.resolve(INSTANCE_CONFIG_NAME));
    }

    private record IEntry(Path path, FileBackedRef<InstanceMeta> meta) implements Closeable {
        @Override
        public String toString() {
            return path.fileName.toString();
        }

        public Instance toPub() throws IOException {
            return new Instance(path, meta.get());
        }

        @Override
        public void close() throws IOException {
            meta.close();
        }
    }
}