package org.jboss.resteasy.jose.jwe.crypto;

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.
 *
 * @author Vladimir Dzhuvinov
 * @version $version$ (2013-04-16)
 */
public 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 java.io.IOException If compression failed.
     */
    public static byte[] compress(final byte[] bytes)
            throws IOException {

        ByteArrayOutputStream out = new ByteArrayOutputStream();

        DeflaterOutputStream def = new DeflaterOutputStream(out, new Deflater(Deflater.DEFLATED, NOWRAP));
        def.write(bytes);
        def.close();

        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 java.io.IOException If decompression failed.
     */
    public static byte[] decompress(final byte[] bytes)
            throws IOException {

        InflaterInputStream inf = new InflaterInputStream(new ByteArrayInputStream(bytes), new Inflater(NOWRAP));
        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);
        }

        inf.close();
        out.close();

        return out.toByteArray();
    }

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

    }
}
