/*

 * 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

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

 *

 * 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.

 *

 */

package java.util.zip;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.charset.Charset;

import java.nio.charset.CharsetDecoder;

import java.nio.charset.CharsetEncoder;

import java.nio.charset.CoderResult;

import java.nio.charset.CodingErrorAction;

import java.util.Arrays;

/**

 * Utility class for zipfile name and comment decoding and encoding

 */

final class ZipCoder {

    String toString(byte[] ba, int length) {

        CharsetDecoder cd = decoder().reset();

        int len = (int)(length * cd.maxCharsPerByte());

        char[] ca = new char[len];

        if (len == 0)

            return new String(ca);

        ByteBuffer bb = ByteBuffer.wrap(ba, 0, length);

        CharBuffer cb = CharBuffer.wrap(ca);

        CoderResult cr = cd.decode(bb, cb, true);

        if (!cr.isUnderflow())

            throw new IllegalArgumentException(cr.toString());

        cr = cd.flush(cb);

        if (!cr.isUnderflow())

            throw new IllegalArgumentException(cr.toString());

        return new String(ca, 0, cb.position());

    }

    String toString(byte[] ba) {

        return toString(ba, ba.length);

    }

    byte[] getBytes(String s) {

        CharsetEncoder ce = encoder().reset();

        char[] ca = s.toCharArray();

        int len = (int)(ca.length * ce.maxBytesPerChar());

        byte[] ba = new byte[len];

        if (len == 0)

            return ba;

        ByteBuffer bb = ByteBuffer.wrap(ba);

        CharBuffer cb = CharBuffer.wrap(ca);

        CoderResult cr = ce.encode(cb, bb, true);

        if (!cr.isUnderflow())

            throw new IllegalArgumentException(cr.toString());

        cr = ce.flush(bb);

        if (!cr.isUnderflow())

            throw new IllegalArgumentException(cr.toString());

        if (bb.position() == ba.length)  // defensive copy?

            return ba;

        else

            return Arrays.copyOf(ba, bb.position());

    }

    // assume invoked only if "this" is not utf8

    byte[] getBytesUTF8(String s) {

        if (isutf8)

            return getBytes(s);

        if (utf8 == null)

            utf8 = new ZipCoder(Charset.forName("UTF-8"));

        return utf8.getBytes(s);

    }

    String toStringUTF8(byte[] ba, int len) {

        if (isutf8)

            return toString(ba, len);

        if (utf8 == null)

            utf8 = new ZipCoder(Charset.forName("UTF-8"));

        return utf8.toString(ba, len);

    }

    boolean isUTF8() {

        return isutf8;

    }

    private Charset cs;

    private CharsetDecoder dec;

    private CharsetEncoder enc;

    private boolean isutf8;

    private ZipCoder utf8;

    private ZipCoder(Charset cs) {

        this.cs = cs;

        this.isutf8 = cs.name().equals("UTF-8");

    }

    static ZipCoder get(Charset charset) {

        return new ZipCoder(charset);

    }

    private CharsetDecoder decoder() {

        if (dec == null) {

            dec = cs.newDecoder()

              .onMalformedInput(CodingErrorAction.REPORT)

              .onUnmappableCharacter(CodingErrorAction.REPORT);

        }

        return dec;

    }

    private CharsetEncoder encoder() {

        if (enc == null) {

            enc = cs.newEncoder()

              .onMalformedInput(CodingErrorAction.REPORT)

              .onUnmappableCharacter(CodingErrorAction.REPORT);

        }

        return enc;

    }

}