EpicHeads/main/java/com/songoda/epicheads/cache/ModsFileHeader.java

package com.songoda.epicheads.cache;

import com.songoda.epicheads.EpicHeads;
import com.songoda.epicheads.util.IOUtils;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashSet;
import java.util.Set;
import java.util.zip.GZIPInputStream;

public class ModsFileHeader {

	private final int version;
	private final Set<String> modNames = new HashSet<>();

	public ModsFileHeader(Set<String> modNames) {
		this(2, modNames);
	}

	public ModsFileHeader(int version, Set<String> modNames) {
		this.version = version;
		this.modNames.addAll(modNames);
	}

	public int getVersion() {
		return version;
	}

	public Set<String> getModNames() {
		return modNames;
	}

	public int getUninstalledMods(CacheFile cache) {
		int newMods = 0;

		for (String mod : modNames) {
			if (cache.hasMod(mod))
				continue;

			++newMods;
		}

		return newMods;
	}

	public void write(ObjectOutputStream stream) throws IOException {
		stream.writeInt(2);

		IOUtils.writeStringSet(stream, modNames);
	}

	public static ModsFileHeader readResource(String resource) throws IOException {
		try (InputStream stream = EpicHeads.getInstance().getResource(resource)) {
			return readCompressed(stream);
		}
	}

	public static ModsFileHeader readCompressed(InputStream is) throws IOException {
		try (GZIPInputStream zis = new GZIPInputStream(is); ObjectInputStream stream = new ObjectInputStream(zis)) {

			return read(stream);
		}
	}

	public static ModsFileHeader read(ObjectInputStream stream) throws IOException {
		int version = stream.readInt();

		switch (version) {
			case 2:
			case 1:
				Set<String> modNames = IOUtils.readStringSet(stream);

				return new ModsFileHeader(version, modNames);
			default:
				throw new UnsupportedOperationException("Unknown mods file version " + version);
		}
	}

}