/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j 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 <http://www.gnu.org/licenses/>.
 */
package org.neo4j.test.jar;

import static java.util.Objects.requireNonNull;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.jar.JarOutputStream;
import java.util.zip.ZipEntry;

/**
 * Utility to create jar files containing classes from the current classpath.
 */
public final class JarBuilder {
    private JarBuilder() {}

    public static URL createJarFor(Path f, Class<?>... classesToInclude) throws IOException {
        try (JarOutputStream jarOut = new JarOutputStream(Files.newOutputStream(f))) {
            for (Class<?> target : classesToInclude) {
                String fileName = target.getName().replace('.', '/') + ".class";
                jarOut.putNextEntry(new ZipEntry(fileName));
                jarOut.write(classCompiledBytes(fileName));
                jarOut.closeEntry();
            }
        }
        return f.toUri().toURL();
    }

    public static byte[] classCompiledBytes(String fileName) throws IOException {
        try (InputStream in = JarBuilder.class.getClassLoader().getResourceAsStream(fileName)) {
            requireNonNull(in);
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            while (in.available() > 0) {
                out.write(in.read());
            }

            return out.toByteArray();
        }
    }
}
