DirectoryWatcher.java

/*******************************************************************************
 * Copyright (c) 2011-2016 Medevit OG, Medelexis AG
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Marco Descher, initial API and implementaion
 *     Lucia Amman, bug fixes and improvements
 * Sponsors: M. + P. Richter
 *******************************************************************************/
package at.medevit.elexis.gdt.tools;

import java.io.File;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.monitor.FileAlterationListener;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;

import at.medevit.elexis.gdt.constants.GDTPreferenceConstants;
import at.medevit.elexis.gdt.handler.GDTFileInputHandler;
import ch.elexis.core.data.activator.CoreHub;
import ch.rgw.tools.Log;

public class DirectoryWatcher implements FileAlterationListener {
	
	private List<File> directories;
	private FileAlterationObserver observer;
	private FileAlterationMonitor monitor;
	private static DirectoryWatcher instance = null;
	private Log logger = Log.get(DirectoryWatcher.class.getName());
	private List<FileAlterationObserver> observers;
	
	private DirectoryWatcher(){
		observers = new LinkedList<FileAlterationObserver>();
		directories = new LinkedList<File>();
		monitor = new FileAlterationMonitor(2000);
		monitor.addObserver(observer);
	}
	
	public static DirectoryWatcher getInstance(){
		if (instance == null)
			instance = new DirectoryWatcher();
		return instance;
	}
	
	public void addDirectoryToWatch(File directory){
		if (directory.isDirectory()) {
			logger.log("Adding directory: " + directory, Log.DEBUGMSG);
			FileAlterationObserver observer = new FileAlterationObserver(directory);
			directories.add(directory);
			observer.addListener(this);
			observers.add(observer);
			monitor.addObserver(observer);
			this.unwatch();
			this.watch();
		} else {
			logger.log("Invalid directory entry passed: " + directory, Log.DEBUGMSG);
		}
	}
	
	public void watch(){
		logger.log("Watching " + observers.size() + " directories.", Log.DEBUGMSG);
		
		try {
			monitor.start();
		} catch (Exception e) {
			logger.log(e.getMessage(), Log.INFOS);
		}
		
		// Need to iterate through all registered directories
		for (File directory : directories) {
			LinkedList<File> files = (LinkedList<File>) FileUtils.listFiles(directory, null, false);
			Collections.sort(files, new DateTimeAscending());
			
			for (Iterator<File> iterator = files.iterator(); iterator.hasNext();) {
				File file = (File) iterator.next();
				processFile(file);
			}
		}
	}
	
	public void unwatch(){
		logger.log("Unwatching " + observers.size() + " directories.", Log.DEBUGMSG);
		try {
			monitor.stop();
		} catch (Exception e) {
			logger.log(e.getMessage(), Log.INFOS);
		}
	}
	
	@Override
	public void onFileCreate(File file){
		logger.log("Incoming file " + file, Log.DEBUGMSG);
		processFile(file);
	}
	
	private void processFile(File file){
		if (GDTFileHelper.containsSatzNachricht(file)) {
			// TODO File may contain multiple independent GDT Messages, split!!
			GDTFileInputHandler.handle(file);
		} else {
			if (CoreHub.localCfg.get(GDTPreferenceConstants.CFG_GDT_FILETRANSFER_DELETE_NON_GDT_FILES,
				false)) {
				boolean success = file.delete();
				if (success) {
					logger.log("Deleted non GDT file " + file, Log.DEBUGMSG);
				} else {
					logger.log("Error deleting file " + file, Log.WARNINGS);
				}
			}
		}
	}
	
	@Override
	public void onFileChange(File arg0){}
	
	@Override
	public void onFileDelete(File arg0){}
	
	@Override
	public void onDirectoryChange(File arg0){}
	
	@Override
	public void onDirectoryCreate(File arg0){}
	
	@Override
	public void onDirectoryDelete(File arg0){}
	
	@Override
	public void onStart(FileAlterationObserver arg0){}
	
	@Override
	public void onStop(FileAlterationObserver arg0){}
	
	/**
	 * We need to order the files in ascending order according to their creation dateTime.
	 */
	private final class DateTimeAscending implements Comparator<File> {
		@Override
		public int compare(File arg0, File arg1){
			if (FileUtils.isFileNewer(arg0, arg1))
				return 1;
			if (FileUtils.isFileOlder(arg1, arg0))
				return -1;
			return 0;
		}
	}
}