/*
 * Copyright 2017 Graz University of Technology EAAF-Core Components has been developed in a
 * cooperation between EGIZ, A-SIT Plus, A-SIT, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.2 or - as soon they will be approved by the European
 * Commission - subsequent versions of the EUPL (the "Licence"); You may not use this work except in
 * compliance with the Licence. You may obtain a copy of the Licence at:
 * https://joinup.ec.europa.eu/news/understanding-eupl-v12
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the Licence
 * is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the Licence for the specific language governing permissions and limitations under
 * the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text file for details on the
 * various modules and licenses. The "NOTICE" text file is part of the distribution. Any derivative
 * works that you distribute must include a readable copy of the "NOTICE" text file.
 */

package at.gv.egiz.eaaf.core.impl.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Utility methods for streams.
 *
 * @author Patrick Peck
 * @version $Id$
 */
public class StreamUtils {

  /**
   * Compare the contents of two <code>InputStream</code>s.
   *
   * @param is1 The 1st <code>InputStream</code> to compare.
   * @param is2 The 2nd <code>InputStream</code> to compare.
   * @return boolean <code>true</code>, if both streams contain the exactly the
   *         same content, <code>false</code> otherwise.
   * @throws IOException An error occurred reading one of the streams.
   */
  public static boolean compareStreams(final InputStream is1, final InputStream is2)
      throws IOException {

    final byte[] buf1 = new byte[256];
    final byte[] buf2 = new byte[256];
    int length1;
    int length2;

    try {
      while (true) {
        length1 = is1.read(buf1);
        length2 = is2.read(buf2);

        if (length1 != length2) {
          return false;
        }
        if (length1 <= 0) {
          return true;
        }
        if (!compareBytes(buf1, buf2, length1)) {
          return false;
        }
      }
    } catch (final IOException e) {
      throw e;
    } finally {
      // close both streams
      try {
        is1.close();
        is2.close();
      } catch (final IOException e) {
        e.printStackTrace();

      }
    }
  }

  /**
   * Compare two byte arrays, up to a given maximum length.
   *
   * @param b1     1st byte array to compare.
   * @param b2     2nd byte array to compare.
   * @param length The maximum number of bytes to compare.
   * @return <code>true</code>, if the byte arrays are equal, <code>false</code>
   *         otherwise.
   */
  private static boolean compareBytes(final byte[] b1, final byte[] b2, final int length) {
    if (b1.length != b2.length) {
      return false;
    }

    for (int i = 0; i < b1.length && i < length; i++) {
      if (b1[i] != b2[i]) {
        return false;
      }
    }

    return true;
  }

  /**
   * Reads a byte array from a stream.
   *
   * @param in The <code>InputStream</code> to read.
   * @return The bytes contained in the given <code>InputStream</code>.
   * @throws IOException on any exception thrown
   */
  public static byte[] readStream(final InputStream in) throws IOException {

    final ByteArrayOutputStream out = new ByteArrayOutputStream();
    copyStream(in, out, null);

    /*
     * ByteArrayOutputStream out = new ByteArrayOutputStream(); int b; while ((b =
     * in.read()) >= 0) out.write(b);
     *
     */
    in.close();
    return out.toByteArray();
  }

  /**
   * Reads a <code>String</code> from a stream, using given encoding.
   *
   * @param in       The <code>InputStream</code> to read.
   * @param encoding The character encoding to use for converting the bytes of the
   *                 <code>InputStream</code> into a <code>String</code>.
   * @return The content of the given <code>InputStream</code> converted into a
   *         <code>String</code>.
   * @throws IOException on any exception thrown
   */
  public static String readStream(final InputStream in, final String encoding) throws IOException {
    final ByteArrayOutputStream out = new ByteArrayOutputStream();
    copyStream(in, out, null);

    /*
     * ByteArrayOutputStream out = new ByteArrayOutputStream(); int b; while ((b =
     * in.read()) >= 0) out.write(b);
     */
    in.close();
    return out.toString(encoding);
  }

  /**
   * Reads all data (until EOF is reached) from the given source to the
   * destination stream. If the destination stream is null, all data is dropped.
   * It uses the given buffer to read data and forward it. If the buffer is null,
   * this method allocates a buffer.
   *
   * @param source      The stream providing the data.
   * @param destination The stream that takes the data. If this is null, all data
   *                    from source will be read and discarded.
   * @param buffer      The buffer to use for forwarding. If it is null, the
   *                    method allocates a buffer.
   * @exception IOException If reading from the source or writing to the
   *                        destination fails.
   */
  private static void copyStream(final InputStream source, final OutputStream destination,
      byte[] buffer) throws IOException {
    if (source == null) {
      throw new NullPointerException("Argument \"source\" must not be null.");
    }
    if (buffer == null) {
      buffer = new byte[8192];
    }

    if (destination != null) {
      int bytesRead;
      while ((bytesRead = source.read(buffer)) >= 0) {
        destination.write(buffer, 0, bytesRead);
      }
    }
  }

  // /**
  // * Gets the stack trace of the <code>Throwable</code> passed in as a string.
  // *
  // * @param t The <code>Throwable</code>.
  // * @return a String representing the stack trace of the
  // <code>Throwable</code>.
  // */
  // public static String getStackTraceAsString(final Throwable t) {
  // final ByteArrayOutputStream stackTraceBis = new ByteArrayOutputStream();
  // t.printStackTrace(new PrintStream(stackTraceBis));
  // return new String(stackTraceBis.toByteArray());
  // }
}