/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * Copyright (c) 2001 - 2013 Object Refinery Ltd, Pentaho Corporation and Contributors..  All rights reserved.
 */

package org.pentaho.reporting.engine.classic.core.modules.output.pageable.plaintext.helper;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

public class EncodingUtilities {
  /**
   * The encoding name.
   */
  private String encoding;
  /**
   * The header sequence of the encoding (-2, -1 for UTF-16).
   */
  private byte[] header;
  /**
   * A single encoded space character.
   */
  private byte[] space;
  /**
   * The header plus the single space.
   */
  private byte[] encodingHeader;

  public EncodingUtilities( final String codepage ) throws UnsupportedEncodingException {
    if ( codepage == null ) {
      throw new NullPointerException();
    }

    this.encoding = codepage;

    encodingHeader = " ".getBytes( codepage );
    final byte[] spacesWithHeader = "  ".getBytes( codepage );
    final int spaceCharLength = spacesWithHeader.length - encodingHeader.length;
    space = new byte[spaceCharLength];
    header = new byte[encodingHeader.length - spaceCharLength];

    System.arraycopy( spacesWithHeader, encodingHeader.length, space, 0, spaceCharLength );
    System.arraycopy( encodingHeader, 0, header, 0, header.length );
  }

  public byte[] getSpace() {
    return space;
  }

  public byte[] getHeader() {
    return header;
  }

  /**
   * Writes encoded text for the current encoding into the output stream.
   *
   * @param textString
   *          the text that should be written.
   * @throws java.io.IOException
   *           if an error occures.
   */
  public void writeEncodedText( final char[] textString, final OutputStream out ) throws IOException {
    if ( textString == null ) {
      throw new NullPointerException();
    }

    final StringBuffer buffer = new StringBuffer( " " );
    buffer.append( textString );
    final byte[] text = buffer.toString().getBytes( encoding );
    out.write( text, encodingHeader.length, text.length - encodingHeader.length );
  }

  /**
   * Writes encoded text for the current encoding into the output stream.
   *
   * @param textString
   *          the text that should be written.
   * @throws java.io.IOException
   *           if an error occures.
   */
  public void writeEncodedText( final String textString, final OutputStream out ) throws IOException {
    if ( textString == null ) {
      throw new NullPointerException();
    }

    final StringBuffer buffer = new StringBuffer( " " );
    buffer.append( textString );
    final byte[] text = buffer.toString().getBytes( encoding );
    out.write( text, encodingHeader.length, text.length - encodingHeader.length );
  }

  public String getEncoding() {
    return encoding;
  }

  public byte[] getEncodingHeader() {
    return header;
  }
}