/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package org.apache.commons.compress.archivers.zip;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.charset.UnsupportedCharsetException;

Static helper functions for robustly encoding filenames in zip files.
/**
 * Static helper functions for robustly encoding filenames in zip files.
 */
public abstract class ZipEncodingHelper {


    
name of the encoding UTF-8
/**
     * name of the encoding UTF-8
     */
    static final String UTF8 = "UTF8";

    
the encoding UTF-8
/**
     * the encoding UTF-8
     */
    static final ZipEncoding UTF8_ZIP_ENCODING = getZipEncoding(UTF8);

    
Instantiates a zip encoding. An NIO based character set encoder/decoder will be returned.
As a special case, if the character set is UTF-8, the nio encoder will be configured  replace malformed and
unmappable characters with '?'. This matches existing behavior from the older fallback encoder.

    If the requested characer set cannot be found, the platform default will
    be used instead.

Params:
name – The name of the zip encoding. Specify null for the platform's default encoding.
Returns:
A zip encoding for the given encoding name./**
     * Instantiates a zip encoding. An NIO based character set encoder/decoder will be returned.
     * As a special case, if the character set is UTF-8, the nio encoder will be configured  replace malformed and
     * unmappable characters with '?'. This matches existing behavior from the older fallback encoder.
     * <p>
     *     If the requested characer set cannot be found, the platform default will
     *     be used instead.
     * </p>
     * @param name The name of the zip encoding. Specify {@code null} for
     *             the platform's default encoding.
     * @return A zip encoding for the given encoding name.
     */
    public static ZipEncoding getZipEncoding(final String name) {
        Charset cs = Charset.defaultCharset();
        if (name != null) {
            try {
                cs = Charset.forName(name);
            } catch (UnsupportedCharsetException e) { // NOSONAR we use the default encoding instead
            }
        }
        boolean useReplacement = isUTF8(cs.name());
        return new NioZipEncoding(cs, useReplacement);
    }

    
Returns whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
Params:
charsetName – If the given name is null, then check the platform's default encoding./**
     * Returns whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
     *
     * @param charsetName If the given name is null, then check the platform's default encoding.
     */
    static boolean isUTF8(String charsetName) {
        if (charsetName == null) {
            // check platform's default encoding
            charsetName = Charset.defaultCharset().name();
        }
        if (StandardCharsets.UTF_8.name().equalsIgnoreCase(charsetName)) {
            return true;
        }
        for (final String alias : StandardCharsets.UTF_8.aliases()) {
            if (alias.equalsIgnoreCase(charsetName)) {
                return true;
            }
        }
        return false;
    }

    static ByteBuffer growBufferBy(ByteBuffer buffer, int increment) {
        buffer.limit(buffer.position());
        buffer.rewind();

        final ByteBuffer on = ByteBuffer.allocate(buffer.capacity() + increment);

        on.put(buffer);
        return on;
    }
}