/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2006-2008 Sun Microsystems, Inc.
 * Portions Copyright 2013-2016 ForgeRock AS.
 */
package org.opends.server.loggers;

import static org.opends.messages.LoggerMessages.*;
import static org.opends.server.util.StaticUtils.*;

import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.i18n.slf4j.LocalizedLogger;
import org.forgerock.opendj.config.server.ConfigurationChangeListener;
import org.forgerock.opendj.server.config.server.FreeDiskSpaceLogRetentionPolicyCfg;
import org.opends.server.core.DirectoryServer;
import org.forgerock.opendj.config.server.ConfigChangeResult;
import org.opends.server.types.DirectoryException;

/**
 * This class implements a retention policy based on the free disk space
 * available expressed as a percentage.
 */
public class FreeDiskSpaceRetentionPolicy implements
    RetentionPolicy<FreeDiskSpaceLogRetentionPolicyCfg>,
    ConfigurationChangeListener<FreeDiskSpaceLogRetentionPolicyCfg>
{
  private static final LocalizedLogger logger = LocalizedLogger.getLoggerForThisClass();

  private long freeDiskSpace;
  private FreeDiskSpaceLogRetentionPolicyCfg config;

  @Override
  public void initializeLogRetentionPolicy(
      FreeDiskSpaceLogRetentionPolicyCfg config)
  {
    this.freeDiskSpace = config.getFreeDiskSpace();
    this.config = config;

    config.addFreeDiskSpaceChangeListener(this);
  }

  @Override
  public boolean isConfigurationChangeAcceptable(
      FreeDiskSpaceLogRetentionPolicyCfg config,
      List<LocalizableMessage> unacceptableReasons)
  {
    // Changes should always be OK
    return true;
  }

  @Override
  public ConfigChangeResult applyConfigurationChange(
      FreeDiskSpaceLogRetentionPolicyCfg config)
  {
    this.freeDiskSpace = config.getFreeDiskSpace();
    this.config = config;

    return new ConfigChangeResult();
  }

  @Override
  public File[] deleteFiles(FileNamingPolicy fileNamingPolicy)
      throws DirectoryException
  {
    File[] files = fileNamingPolicy.listFiles();
    if(files == null)
    {
      throw new DirectoryException(DirectoryServer.getCoreConfigManager().getServerErrorResultCode(),
          ERR_LOGGER_ERROR_LISTING_FILES.get(fileNamingPolicy.getInitialName()));
    }

    if(files.length <= 0)
    {
      return new File[0];
    }

    long freeSpace = 0;
    try
    {
      freeSpace = files[0].getFreeSpace();
    }
    catch (Exception e)
    {
      logger.traceException(e);
      LocalizableMessage message =
          ERR_LOGGER_ERROR_OBTAINING_FREE_SPACE.get(files[0],
              stackTraceToSingleLineString(e));
      throw new DirectoryException(DirectoryServer.getCoreConfigManager().getServerErrorResultCode(),
                                   message, e);
    }

    logger.trace("Current free disk space: %d, Required: %d", freeSpace,
          freeDiskSpace);

    if (freeSpace > freeDiskSpace)
    {
      // No cleaning needed.
      return new File[0];
    }

    long freeSpaceNeeded = freeDiskSpace - freeSpace;

    // Sort files based on last modified time.
    Arrays.sort(files, new FileComparator());

    List<File> filesToDelete = new ArrayList<>();
    long freedSpace = 0;
    for (int j = files.length - 1; j > 1; j--)
    {
      freedSpace += files[j].length();
      filesToDelete.add(files[j]);
      if (freedSpace >= freeSpaceNeeded)
      {
        break;
      }
    }
    return filesToDelete.toArray(new File[filesToDelete.size()]);
  }

  @Override
  public String toString()
  {
    return "Free Disk Retention Policy " + config.dn();
  }
}