/*
 * Hello Minecraft! Launcher
 * Copyright (C) 2020  huangyuhui <huanghongxun2008@126.com> and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.jackhuang.hmcl.util.io;

import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.FileSystemNotFoundException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.CodeSource;
import java.util.Optional;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

public final class JarUtils {
    private JarUtils() {
    }

    public static Optional<Path> thisJar() {
        CodeSource codeSource = JarUtils.class.getProtectionDomain().getCodeSource();
        if (codeSource == null) {
            return Optional.empty();
        }

        URL url = codeSource.getLocation();
        if (url == null) {
            return Optional.empty();
        }

        Path path;
        try {
            path = Paths.get(url.toURI());
        } catch (FileSystemNotFoundException | IllegalArgumentException | URISyntaxException e) {
            return Optional.empty();
        }

        if (!Files.isRegularFile(path)) {
            return Optional.empty();
        }

        return Optional.of(path);
    }

    public static Optional<Manifest> getManifest(Path jar) {
        try (JarFile file = new JarFile(jar.toFile())) {
            return Optional.ofNullable(file.getManifest());
        } catch (IOException e) {
            return Optional.empty();
        }
    }

    public static Optional<String> getImplementationVersion(Path jar) {
        return Optional.of(jar).flatMap(JarUtils::getManifest)
                .flatMap(manifest -> Optional.ofNullable(manifest.getMainAttributes().getValue(Attributes.Name.IMPLEMENTATION_VERSION)));
    }
}
