/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardCopyOption;

import java.util.ArrayList;

import java.util.Enumeration;

import java.util.List;

import java.util.Set;

import java.util.jar.JarEntry;

import java.util.jar.JarFile;

import java.util.jar.JarOutputStream;

import java.util.stream.Collectors;

import java.util.stream.Stream;

/**

 * This class consists exclusively of static utility methods that are useful

 * for creating and manipulating JAR files.

 */

public final class JarUtils {

    private JarUtils() { }

    /**

     * Creates a JAR file.

     *

     *

     * The input files are resolved against the given directory. Any input

     * files that are directories are processed recursively.

     */

        throws IOException

    {

        // create the target directory

        Path parent = jarfile.getParent();

        if (parent != null)

            Files.createDirectories(parent);

        List<Path> entries = new ArrayList<>();

        for (Path entry : file) {

            Files.find(dir.resolve(entry), Integer.MAX_VALUE,

                        (p, attrs) -> attrs.isRegularFile())

                    .map(e -> dir.relativize(e))

                    .forEach(entries::add);

        }

        try (OutputStream out = Files.newOutputStream(jarfile);

             JarOutputStream jos = new JarOutputStream(out))

        {

            for (Path entry : entries) {

                String name = toJarEntryName(entry);

                jos.putNextEntry(new JarEntry(name));

                Files.copy(dir.resolve(entry), jos);

            }

        }

    }

    /**

     * Creates a JAR file.

     *

     * Equivalent to {@code jar cf <jarfile> -C <dir> file...}

     *

     * The input files are resolved against the given directory. Any input

     * files that are directories are processed recursively.

     */

    public static void createJarFile(Path jarfile, Path dir, String... input)

        throws IOException

    {

        Path[] paths = Stream.of(input).map(Paths::get).toArray(Path[]::new);

        createJarFile(jarfile, dir, paths);

    }

    /**

     * Creates a JAR file from the contents of a directory.

     *

     * Equivalent to {@code jar cf <jarfile> -C <dir> .}

     */

    public static void createJarFile(Path jarfile, Path dir) throws IOException {

        createJarFile(jarfile, dir, Paths.get("."));

    }

    /**

     * Update a JAR file.

     *

     * Equivalent to {@code jar uf <jarfile> -C <dir> file...}

     *

     * The input files are resolved against the given directory. Any input

     * files that are directories are processed recursively.

     */

    public static void updateJarFile(Path jarfile, Path dir, Path... file)

        throws IOException

    {

        List<Path> entries = new ArrayList<>();

        for (Path entry : file) {

            Files.find(dir.resolve(entry), Integer.MAX_VALUE,

                    (p, attrs) -> attrs.isRegularFile())

                    .map(e -> dir.relativize(e))

                    .forEach(entries::add);

        }

        Set<String> names = entries.stream()

                .map(JarUtils::toJarEntryName)

                .collect(Collectors.toSet());

        Path tmpfile = Files.createTempFile("jar", "jar");

        try (OutputStream out = Files.newOutputStream(tmpfile);

             JarOutputStream jos = new JarOutputStream(out))

        {

            // copy existing entries from the original JAR file

            try (JarFile jf = new JarFile(jarfile.toString())) {

                Enumeration<JarEntry> jentries = jf.entries();

                while (jentries.hasMoreElements()) {

                    JarEntry jentry = jentries.nextElement();

                    if (!names.contains(jentry.getName())) {

                        jos.putNextEntry(jentry);

                        jf.getInputStream(jentry).transferTo(jos);

                    }

                }

            }

            // add the new entries

            for (Path entry : entries) {

                String name = toJarEntryName(entry);

                jos.putNextEntry(new JarEntry(name));

                Files.copy(dir.resolve(entry), jos);

            }

        }

        // replace the original JAR file

        Files.move(tmpfile, jarfile, StandardCopyOption.REPLACE_EXISTING);

    }

    /**

     * Update a JAR file.

     *

     * Equivalent to {@code jar uf <jarfile> -C <dir> .}

     */

    public static void updateJarFile(Path jarfile, Path dir) throws IOException {

        updateJarFile(jarfile, dir, Paths.get("."));

    }

    /**

     * Map a file path to the equivalent name in a JAR file

     */

    private static String toJarEntryName(Path file) {

        Path normalized = file.normalize();

        return normalized.subpath(0, normalized.getNameCount())  // drop root

                .toString()

                .replace(File.separatorChar, '/');

    }

}