/*
 * 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.gui.commonswing;

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

/**
 * This Document restricts the size of the contained plain text to the given number of characters.
 *
 * @author Thomas Morgner
 */
public class LengthLimitingDocument extends PlainDocument {

  /**
   * The maximum length.
   */
  private int maxlen;

  /**
   * Creates a new LengthLimitingDocument, with no limitation.
   */
  public LengthLimitingDocument() {
    this( -1 );
  }

  /**
   * Creates a new LengthLimitingDocument with the given limitation. No more than maxlen characters can be added to the
   * document. If maxlen is negative, then no length check is performed.
   *
   * @param maxlen
   *          the maximum number of elements in this document
   */
  public LengthLimitingDocument( final int maxlen ) {
    super();
    this.maxlen = maxlen;
  }

  /**
   * Sets the maximum number of characters for this document. Existing characters are not removed.
   *
   * @param maxlen
   *          the maximum number of characters in this document.
   */
  public void setMaxLength( final int maxlen ) {
    this.maxlen = maxlen;
  }

  /**
   * Returns the defined maximum number characters for this document.
   *
   * @return the maximum number of characters
   */
  public int getMaxLength() {
    return this.maxlen;
  }

  /**
   * Inserts the string into the document. If the length of the document would violate the maximum characters
   * restriction, then the string is cut down so that
   *
   * @param offs
   *          the offset, where the string should be inserted into the document
   * @param str
   *          the string that should be inserted
   * @param a
   *          the attribute set assigned for the document
   * @throws javax.swing.text.BadLocationException
   *           if the offset is not correct
   */
  public void insertString( final int offs, final String str, final AttributeSet a ) throws BadLocationException {
    if ( str == null ) {
      return;
    }

    if ( this.maxlen < 0 ) {
      super.insertString( offs, str, a );
    }

    final char[] numeric = str.toCharArray();
    final StringBuffer b = new StringBuffer();
    b.append( numeric, 0, Math.min( this.maxlen, numeric.length ) );
    super.insertString( offs, b.toString(), a );
  }

}