/*

 * Copyright (c) 2016, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 */

package jdk.internal.jmod;

import java.io.BufferedInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.stream.Stream;

import java.util.zip.ZipEntry;

import java.util.zip.ZipFile;

/**

 * Helper class to read JMOD file

 */

public class JmodFile implements AutoCloseable {

    // jmod magic number and version number

    private static final int JMOD_MAJOR_VERSION = 0x01;

    private static final int JMOD_MINOR_VERSION = 0x00;

    private static final byte[] JMOD_MAGIC_NUMBER = {

        0x4A, 0x4D, /* JM */

        JMOD_MAJOR_VERSION, JMOD_MINOR_VERSION, /* version 1.0 */

    };

    public static void checkMagic(Path file) throws IOException {

        try (InputStream in = Files.newInputStream(file);

             BufferedInputStream bis = new BufferedInputStream(in)) {

            // validate the header

            byte[] magic = new byte[4];

            bis.read(magic);

            if (magic[0] != JMOD_MAGIC_NUMBER[0] ||

                magic[1] != JMOD_MAGIC_NUMBER[1]) {

                throw new IOException("Invalid jmod file: " + file.toString());

            }

            if (magic[2] > JMOD_MAJOR_VERSION ||

                (magic[2] == JMOD_MAJOR_VERSION && magic[3] > JMOD_MINOR_VERSION)) {

                throw new IOException("Unsupported jmod version: " +

                    magic[2] + "." + magic[3] + " in " + file.toString());

            }

        }

    }

    /**

     * JMOD sections

     */

    public static enum Section {

        CLASSES("classes"),

        CONFIG("conf"),

        HEADER_FILES("include"),

        private final String jmodDir;

        private Section(String jmodDir) {

            this.jmodDir = jmodDir;

        }

        /**

         * Returns the directory name in the JMOD file corresponding to

         * this section

         */

        public String jmodDir() { return jmodDir; }

    }

    /**

     * JMOD file entry.

     *

     * Each entry corresponds to a ZipEntry whose name is:

     *   Section::jmodDir + '/' + name

     */

    public static class Entry {

        private final ZipEntry zipEntry;

        private final Section section;

        private final String name;

        private Entry(ZipEntry e) {

            String name = e.getName();

            int i = name.indexOf('/');

            if (i <= 1) {

                throw new RuntimeException("invalid jmod entry: " + name);

            }

            this.zipEntry = e;

            this.name = name.substring(i+1);

        }

        /**

         * Returns the section of this entry.

         */

        public Section section() {

            return section;

        }

        /**

         * Returns the name of this entry.

         */

        public String name() {

            return name;

        }

        /**

         * Returns the size of this entry.

         */

        public long size() {

            return zipEntry.getSize();

        }

        public ZipEntry zipEntry() {

            return zipEntry;

        }

        @Override

        public String toString() {

            return section.jmodDir() + "/" + name;

        }

        static Section section(String name) {

            }

        }

    }

    private final Path file;

    private final ZipFile zipfile;

    /**

     * Constructs a {@code JmodFile} from a given path.

     */

    public JmodFile(Path file) throws IOException {

        checkMagic(file);

        this.file = file;

        this.zipfile = new ZipFile(file.toFile());

    }

    public static void writeMagicNumber(OutputStream os) throws IOException {

        os.write(JMOD_MAGIC_NUMBER);

    }

    /**

     * Returns the {@code Entry} for a resource in a JMOD file section

     * or {@code null} if not found.

     */

    public Entry getEntry(Section section, String name) {

        String entry = section.jmodDir() + "/" + name;

        ZipEntry ze = zipfile.getEntry(entry);

        return (ze != null) ? new Entry(ze) : null;

    }

    /**

     * Opens an {@code InputStream} for reading the named entry of the given

     * section in this jmod file.

     *

     * @throws IOException if the named entry is not found, or I/O error

     *         occurs when reading it

     */

    public InputStream getInputStream(Section section, String name)

        throws IOException

    {

        String entry = section.jmodDir() + "/" + name;

        ZipEntry e = zipfile.getEntry(entry);

        if (e == null) {

            throw new IOException(name + " not found: " + file);

        }

        return zipfile.getInputStream(e);

    }

    /**

     * Opens an {@code InputStream} for reading an entry in the JMOD file.

     *

     * @throws IOException if an I/O error occurs

     */

    public InputStream getInputStream(Entry entry) throws IOException {

        return zipfile.getInputStream(entry.zipEntry());

    }

    /**

     * Returns a stream of non-directory entries in this jmod file.

     */

    public Stream<Entry> stream() {

        return zipfile.stream()

                      .filter(e -> !e.isDirectory())

                      .map(Entry::new);

    }

    @Override

    public void close() throws IOException {

        if (zipfile != null) {

            zipfile.close();

        }

    }

}