/src/main/java/org/olat/search/service/document/file/PPT2Text.java

/**
 * OLAT - Online Learning and Training<br>
 * http://www.olat.org
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); <br>
 * you may not use this file except in compliance with the License.<br>
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing,<br>
 * software distributed under the License is distributed on an "AS IS" BASIS, <br>
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. <br>
 * See the License for the specific language governing permissions and <br>
 * limitations under the License.
 * <p>
 * Copyright (c) since 2004 at Multimedia- & E-Learning Services (MELS),<br>
 * University of Zurich, Switzerland.
 * <p>
 */

package org.olat.search.service.document.file;

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

import org.apache.poi.poifs.eventfilesystem.POIFSReader;
import org.apache.poi.poifs.eventfilesystem.POIFSReaderEvent;
import org.apache.poi.poifs.eventfilesystem.POIFSReaderListener;
import org.apache.poi.poifs.filesystem.DocumentInputStream;
import org.apache.poi.util.LittleEndian;
import org.olat.core.logging.OLog;
import org.olat.core.logging.Tracing;

/**
 * @author Christian Guretzki
 */
public class PPT2Text {

	public static void extractText(final InputStream inStream, final OutputStream stream) throws IOException {
		final POIFSReader r = new POIFSReader();
		/* Register a listener for *all* documents. */
		r.registerListener(new MyPOIFSReaderListener(stream));
		r.read(inStream);
	}

	static class MyPOIFSReaderListener implements POIFSReaderListener {
		private static final OLog log = Tracing.createLoggerFor(PPT2Text.class);

		private final OutputStream oStream;

		public MyPOIFSReaderListener(final OutputStream oStream) {
			this.oStream = oStream;
		}

		@Override
		public void processPOIFSReaderEvent(final POIFSReaderEvent event) {
			int errorCounter = 0;

			try {
				DocumentInputStream dis = null;
				dis = event.getStream();

				final byte btoWrite[] = new byte[dis.available()];
				dis.read(btoWrite, 0, dis.available());
				for (int i = 0; i < btoWrite.length - 20; i++) {
					final long type = LittleEndian.getUShort(btoWrite, i + 2);
					final long size = LittleEndian.getUInt(btoWrite, i + 4);
					if (type == 4008) {
						try {
							oStream.write(btoWrite, i + 4 + 1, (int) size + 3);
						} catch (final IndexOutOfBoundsException ex) {
							errorCounter++;
						}
					}
				}
			} catch (final Exception ex) {
				// FIXME:chg: Remove general Exception later, for now make it run
				log.warn("Can not read PPT content.", ex);
			}
			if (errorCounter > 0) {
				if (log.isDebug()) {
					log.debug("Could not parse ppt properly. There were " + errorCounter + " IndexOutOfBoundsException");
				}
			}
		}
	}
}