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/**
 * Copyright (c) 2011, University of Konstanz, Distributed Systems Group All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: * Redistributions of source code must retain the
 * above copyright notice, this list of conditions and the following disclaimer. * Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * * Neither the name of the University of Konstanz nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL  BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.sirix.utils;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Compression/Decompression for text values or any other data.
 *
 * @author Johannes Lichtenberger, University of Konstanz
 *
 */
public final class Compression {

  /** Logger. */
  private static final Logger LOGWRAPPER = LoggerFactory.getLogger(Compression.class);

  /** Buffer size. */
  public static final int BUFFER_SIZE = 1024;

  /** Compressor. */
  private static final Deflater mCompressor = new Deflater();

  /** Decompressor. */
  private static final Inflater mDecompressor = new Inflater();

  /** Private constructor to prevent from instantiation. */
  private Compression() {
    throw new AssertionError();
  }

  /**
   * Compress data based on the {@link Deflater}.
   *
   * @param toCompress input byte-array
   * @param level compression level (between -1 and 9 whereas 0 is the weakest and -1 is default)
   * @return compressed byte-array
   * @throws NullPointerException if {@code toCompress} is {@code null}
   */
  public static byte[] compress(final byte[] toCompress, final int level) {
    checkNotNull(toCompress);
    checkArgument(level >= -1 && level <= 9, "pLevel must be between 0 and 9!");

    // Compressed result.
    byte[] compressed = new byte[] {};

    // Set compression level.
    mCompressor.setLevel(level);

    // Give the compressor the data to compress.
    mCompressor.reset();
    mCompressor.setInput(toCompress);
    mCompressor.finish();

    /*
     * Create an expandable byte array to hold the compressed data. You cannot use an array that's the
     * same size as the orginal because there is no guarantee that the compressed data will be smaller
     * than the uncompressed data.
     */
    try (final ByteArrayOutputStream bos = new ByteArrayOutputStream(toCompress.length)) {
      // Compress the data.
      final byte[] buf = new byte[BUFFER_SIZE];
      while (!mCompressor.finished()) {
        final int count = mCompressor.deflate(buf);
        bos.write(buf, 0, count);
      }

      // Get the compressed data.
      compressed = bos.toByteArray();
    } catch (final IOException e) {
      LOGWRAPPER.error(e.getMessage(), e);
    }

    return compressed;
  }

  /**
   * Decompress data based on the {@link Inflater}.
   *
   * @param compressed input string
   * @return compressed byte-array
   * @throws NullPointerException if {@code pCompressed} is {@code null}
   */
  public static byte[] decompress(final byte[] compressed) {
    checkNotNull(compressed);

    // Reset the decompressor and give it the data to compress.
    mDecompressor.reset();
    mDecompressor.setInput(compressed);

    byte[] decompressed = new byte[] {};

    // Create an expandable byte array to hold the decompressed data.
    final ByteArrayOutputStream bos = new ByteArrayOutputStream(compressed.length);
    // Decompress the data.
    final byte[] buf = new byte[BUFFER_SIZE];
    while (!mDecompressor.finished()) {
      try {
        final int count = mDecompressor.inflate(buf);
        bos.write(buf, 0, count);
      } catch (final DataFormatException e) {
        LOGWRAPPER.error(e.getMessage(), e);
        throw new RuntimeException(e);
      }
    }
    // Get the decompressed data.
    decompressed = bos.toByteArray();
    try {
      bos.close();
    } catch (final IOException e) {
      LOGWRAPPER.error(e.getMessage(), e);
    }

    return decompressed;
  }
}