/*
    * Copyright (C) 2007-2012 Argeo GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *         http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.argeo.maintenance.backup.vfs;
  
  import java.text.DateFormat;
  import java.time.Period;
  import java.time.ZoneId;
  import java.time.ZonedDateTime;
  import java.util.Date;
  import java.util.SortedMap;
  import java.util.TreeMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.commons.vfs2.FileObject;
  import org.apache.commons.vfs2.FileSystemManager;
  import org.apache.commons.vfs2.FileSystemOptions;
  import org.apache.commons.vfs2.Selectors;
  import org.argeo.maintenance.MaintenanceException;
  
  /** Simple backup purge which keeps backups only for a given number of days */
  public class SimpleBackupPurge implements BackupPurge {
  	private final static Log log = LogFactory.getLog(SimpleBackupPurge.class);
  
  	private Integer daysKept = 30;
  
  	@Override
  	public void purge(FileSystemManager fileSystemManager, String base, String name, DateFormat dateFormat,
  			FileSystemOptions opts) {
  		try {
  			ZonedDateTime nowDt = ZonedDateTime.now();
  			FileObject baseFo = fileSystemManager.resolveFile(base + '/' + name, opts);
  
  			SortedMap<ZonedDateTime, FileObject> toDelete = new TreeMap<ZonedDateTime, FileObject>();
  			int backupCount = 0;
  
  			// make sure base dir exists
  			baseFo.createFolder();
  
  			// scan backups and list those which should be deleted
  			for (FileObject backupFo : baseFo.getChildren()) {
  				String backupName = backupFo.getName().getBaseName();
  				Date backupDate = dateFormat.parse(backupName);
  				backupCount++;
  				ZonedDateTime backupDt = ZonedDateTime.ofInstant(backupDate.toInstant(), ZoneId.systemDefault());
  				Period sinceThen = Period.between(backupDt.toLocalDate(), nowDt.toLocalDate());
  				// new Period(backupDt, nowDt);
  				int days = sinceThen.getDays();
  				// int days = sinceThen.getMinutes();
  				if (days > daysKept) {
  					toDelete.put(backupDt, backupFo);
  				}
  			}
  
  			if (toDelete.size() != 0 && toDelete.size() == backupCount) {
  				// all backups would be deleted
  				// but we want to keep at least one
  				ZonedDateTime lastBackupDt = toDelete.firstKey();
  				FileObject keptFo = toDelete.remove(lastBackupDt);
  				log.warn("Backup " + keptFo + " kept although it is older than " + daysKept + " days.");
  			}
  
  			// delete old backups
  			for (FileObject backupFo : toDelete.values()) {
  				backupFo.delete(Selectors.SELECT_ALL);
  				if (log.isDebugEnabled())
  					log.debug("Deleted backup " + backupFo);
  			}
  		} catch (Exception e) {
  			throw new MaintenanceException("Could not purge previous backups", e);
  		}
  
  	}
  
  }