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/*
 * Copyright 2017-2020 Rudy De Busscher (https://www.atbash.be)
 *
 * Licensed 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 be.atbash.ee.security.octopus.nimbus.util;


import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;


/**
 * Deflate (RFC 1951) utilities.
 *
 * Based on code by Vladimir Dzhuvinov
 */
public final class DeflateUtils {


    /**
     * Omit headers and CRC fields from output, as specified by RFC 1950.
     * Note that the Deflater JavaDocs are incorrect, see
     * http://stackoverflow.com/questions/11076060/decompressing-gzipped-data-with-inflater-in-java
     */
    private static final boolean NOWRAP = true;


    /**
     * Compresses the specified byte array according to the DEFLATE
     * specification (RFC 1951).
     *
     * @param bytes The byte array to compress. Must not be {@code null}.
     * @return The compressed bytes.
     * @throws IOException If compression failed.
     */
    public static byte[] compress(byte[] bytes)
            throws IOException {

        ByteArrayOutputStream out = new ByteArrayOutputStream();


        Deflater deflater = null;
        DeflaterOutputStream def = null;
        try {
            deflater = new Deflater(Deflater.DEFLATED, NOWRAP);
            def = new DeflaterOutputStream(out, deflater);
            def.write(bytes);
        } finally {
            if (def != null) {
                def.close();
            }
            if (deflater != null) {
                deflater.end();
            }
        }

        return out.toByteArray();
    }


    /**
     * Decompresses the specified byte array according to the DEFLATE
     * specification (RFC 1951).
     *
     * @param bytes The byte array to decompress. Must not be {@code null}.
     * @return The decompressed bytes.
     * @throws IOException If decompression failed.
     */
    public static byte[] decompress(byte[] bytes)
            throws IOException {

        Inflater inflater = null;
        InflaterInputStream inf = null;
        try {
            inflater = new Inflater(NOWRAP);
            inf = new InflaterInputStream(new ByteArrayInputStream(bytes), inflater);

            ByteArrayOutputStream out = new ByteArrayOutputStream();

            // Transfer bytes from the compressed array to the output
            byte[] buf = new byte[1024];

            int len;

            while ((len = inf.read(buf)) > 0) {

                out.write(buf, 0, len);
            }

            return out.toByteArray();
        } finally {
            if (inf != null) {
                inf.close();
            }
            if (inflater != null) {
                inflater.end();
            }
        }
    }


    /**
     * Prevents public instantiation.
     */
    private DeflateUtils() {

    }
}