/*
 * 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 2011-2016 ForgeRock AS.
 */
package org.opends.server.loggers;

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

import java.util.Collection;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.i18n.LocalizableMessageDescriptor.Arg3;
import org.forgerock.i18n.slf4j.LocalizedLogger;
import org.forgerock.opendj.config.server.ConfigChangeResult;
import org.forgerock.opendj.config.server.ConfigException;
import org.forgerock.opendj.ldap.ResultCode;
import org.forgerock.opendj.config.ClassPropertyDefinition;
import org.forgerock.opendj.config.server.ConfigurationAddListener;
import org.forgerock.opendj.config.server.ConfigurationChangeListener;
import org.forgerock.opendj.config.server.ConfigurationDeleteListener;
import org.forgerock.opendj.server.config.server.LogPublisherCfg;
import org.opends.server.core.DirectoryServer;
import org.opends.server.core.ServerContext;
import org.forgerock.opendj.ldap.DN;
import org.opends.server.types.InitializationException;
import org.opends.server.util.StaticUtils;

/**
 * This class defines the wrapper that will invoke all registered loggers for
 * each type of request received or response sent. If no log publishers are
 * registered, messages will be directed to standard out.
 *
 * @param <P>
 *          The type of the LogPublisher corresponding to this logger
 * @param <C>
 *          The type of the LogPublisherCfg corresponding to this logger
 */
public abstract class AbstractLogger
    <P extends LogPublisher<C>, C extends LogPublisherCfg>
    implements ConfigurationAddListener<C>, ConfigurationDeleteListener<C>,
    ConfigurationChangeListener<C>
{
  /**
   * The storage designed to store log publishers. It is helpful in abstracting
   * away the methods used to manage the collection.
   *
   * @param <P>
   *          The concrete {@link LogPublisher} type
   * @param <C>
   *          The concrete {@link LogPublisherCfg} type
   */
  protected static class LoggerStorage<P extends LogPublisher<C>,
      C extends LogPublisherCfg>
  {
    /** Defined as public to allow subclasses of {@link AbstractLogger} to instantiate it. */
    public LoggerStorage()
    {
      super();
    }

    /** The set of loggers that have been registered with the server. It will initially be empty. */
    private Collection<P> logPublishers = new CopyOnWriteArrayList<>();

    /**
     * Add a log publisher to the logger.
     *
     * @param publisher
     *          The log publisher to add.
     */
    public synchronized void addLogPublisher(P publisher)
    {
      logPublishers.add(publisher);
    }

    /**
     * Remove a log publisher from the logger.
     *
     * @param publisher
     *          The log publisher to remove.
     * @return True if the log publisher is removed or false otherwise.
     */
    public synchronized boolean removeLogPublisher(P publisher)
    {
      boolean removed = logPublishers.remove(publisher);

      if (removed)
      {
        publisher.close();
      }

      return removed;
    }

    /** Removes all existing log publishers from the logger. */
    public synchronized void removeAllLogPublishers()
    {
      StaticUtils.close(logPublishers);
      logPublishers.clear();
    }

    /**
     * Returns the logPublishers.
     *
     * @return the collection of {@link LogPublisher}s
     */
    public Collection<P> getLogPublishers()
    {
      return logPublishers;
    }
  }

  /**
   * Returns the log publishers.
   *
   * @return the collection of {@link LogPublisher}s
   */
  protected abstract Collection<P> getLogPublishers();

  /**
   * Add a log publisher to the logger.
   *
   * @param publisher
   *          The log publisher to add.
   */
  public abstract void addLogPublisher(P publisher);

  /**
   * Remove a log publisher from the logger.
   *
   * @param publisher
   *          The log publisher to remove.
   * @return True if the log publisher is removed or false otherwise.
   */
  public abstract boolean removeLogPublisher(P publisher);

  /** Removes all existing log publishers from the logger. */
  public abstract void removeAllLogPublishers();

  /**
   * Returns the java {@link ClassPropertyDefinition} for the current logger.
   *
   * @return the java {@link ClassPropertyDefinition} for the current logger.
   */
  protected abstract ClassPropertyDefinition getJavaClassPropertyDefinition();

  private final Class<P> logPublisherClass;
  private final Arg3<Object, Object, Object> invalidLoggerClassErrorMessage;
  private ServerContext serverContext;

  /**
   * The constructor for this class.
   *
   * @param logPublisherClass
   *          the log publisher class
   * @param invalidLoggerClassErrorMessage
   *          the error message to use if the logger class in invalid
   */
  AbstractLogger(
      final Class<P> logPublisherClass,
      final Arg3<Object, Object, Object>
          invalidLoggerClassErrorMessage)
  {
    this.logPublisherClass = logPublisherClass;
    this.invalidLoggerClassErrorMessage = invalidLoggerClassErrorMessage;
  }

  /**
   * Initializes all the log publishers.
   *
   * @param configs The log publisher configurations.
   * @param serverContext
   *            The server context.
   * @throws ConfigException
   *           If an unrecoverable problem arises in the process of
   *           performing the initialization as a result of the server
   *           configuration.
   * @throws InitializationException
   *           If a problem occurs during initialization that is not
   *           related to the server configuration.
   */
  public void initializeLogger(List<C> configs, ServerContext serverContext)
      throws ConfigException, InitializationException
  {
    this.serverContext = serverContext;
    for (C config : configs)
    {
      config.addChangeListener((ConfigurationChangeListener) this);

      if (config.isEnabled())
      {
        final P logPublisher = serverContext.getCommonAudit().isCommonAuditConfig(config) ?
            getLogPublisherForCommonAudit(config) : getLogPublisher(config);
        addLogPublisher(logPublisher);
      }
    }
  }

  ServerContext getServerContext()
  {
    return serverContext;
  }

  @Override
  public boolean isConfigurationAddAcceptable(C config, List<LocalizableMessage> unacceptableReasons)
  {
    return !config.isEnabled() || isJavaClassAcceptable(config, unacceptableReasons);
  }

  @Override
  public boolean isConfigurationChangeAcceptable(C config, List<LocalizableMessage> unacceptableReasons)
  {
    return !config.isEnabled() || isJavaClassAcceptable(config, unacceptableReasons);
  }

  @Override
  public ConfigChangeResult applyConfigurationAdd(C config)
  {
    final ConfigChangeResult ccr = applyConfigurationAdd0(config);
    if (ccr.getResultCode() == ResultCode.SUCCESS)
    {
      config.addChangeListener((ConfigurationChangeListener) this);
    }
    return ccr;
  }

  private ConfigChangeResult applyConfigurationAdd0(C config)
  {
    final ConfigChangeResult ccr = new ConfigChangeResult();

    if (config.isEnabled())
    {
      try
      {
        final P logPublisher = serverContext.getCommonAudit().isCommonAuditConfig(config) ?
            getLogPublisherForCommonAudit(config) : getLogPublisher(config);
        addLogPublisher(logPublisher);
      }
      catch(ConfigException e)
      {
        LocalizedLogger.getLoggerForThisClass().traceException(e);
        ccr.addMessage(e.getMessageObject());
        ccr.setResultCode(DirectoryServer.getServerErrorResultCode());
      }
      catch (Exception e)
      {
        LocalizedLogger.getLoggerForThisClass().traceException(e);
        ccr.addMessage(ERR_CONFIG_LOGGER_CANNOT_CREATE_LOGGER.get(config.dn(), stackTraceToSingleLineString(e)));
        ccr.setResultCode(DirectoryServer.getServerErrorResultCode());
      }
    }
    return ccr;
  }

  private P findLogPublisher(DN dn)
  {
    for (P publisher : getLogPublishers())
    {
      if (publisher.getDN().equals(dn))
      {
        return publisher;
      }
    }
    return null;
  }

  @Override
  public ConfigChangeResult applyConfigurationChange(C config)
  {
    final ConfigChangeResult ccr = new ConfigChangeResult();

    P logPublisher = findLogPublisher(config.dn());
    if (logPublisher == null)
    {
      if (config.isEnabled())
      {
        // Needs to be added and enabled
        return applyConfigurationAdd0(config);
      }
    }
    else
    {
      if (config.isEnabled())
      {
        // Changes to the class name cannot be
        // applied dynamically, so if the class name did change then
        // indicate that administrative action is required for that
        // change to take effect.
        String className = config.getJavaClass();
        if (!className.equals(logPublisher.getClass().getName()))
        {
          ccr.setAdminActionRequired(true);
        }
        try
        {
          CommonAudit commonAudit = serverContext.getCommonAudit();
          if (commonAudit.isCommonAuditConfig(config))
          {
            commonAudit.addOrUpdatePublisher(config);
          } // else the publisher is currently active, so we don't need to do anything.
        }
        catch (Exception e)
        {
          LocalizedLogger.getLoggerForThisClass().traceException(e);
          ccr.addMessage(ERR_CONFIG_LOGGER_CANNOT_UPDATE_LOGGER.get(config.dn(), stackTraceToSingleLineString(e)));
          ccr.setResultCode(DirectoryServer.getServerErrorResultCode());
        }
      }
      else
      {
        // The publisher is being disabled so shut down and remove.
        return applyConfigurationDelete(config);
      }
    }
    return ccr;
  }

  @Override
  public boolean isConfigurationDeleteAcceptable(C config, List<LocalizableMessage> unacceptableReasons)
  {
    return findLogPublisher(config.dn()) != null;
  }

  @Override
  public ConfigChangeResult applyConfigurationDelete(C config)
  {
    final ConfigChangeResult ccr = new ConfigChangeResult();

    P logPublisher = findLogPublisher(config.dn());
    if(logPublisher != null)
    {
      removeLogPublisher(logPublisher);
      try
      {
        CommonAudit commonAudit = serverContext.getCommonAudit();
        if (commonAudit.isExistingCommonAuditConfig(config))
        {
          commonAudit.removePublisher(config);
        }
      }
      catch (ConfigException e)
      {
        LocalizedLogger.getLoggerForThisClass().traceException(e);
        ccr.addMessage(ERR_CONFIG_LOGGER_CANNOT_DELETE_LOGGER.get(config.dn(), stackTraceToSingleLineString(e)));
        ccr.setResultCode(DirectoryServer.getServerErrorResultCode());
      }
    }
    else
    {
      ccr.setResultCode(ResultCode.NO_SUCH_OBJECT);
    }

    return ccr;
  }

  private boolean isJavaClassAcceptable(C config,
                                        List<LocalizableMessage> unacceptableReasons)
  {
    String className = config.getJavaClass();
    ClassPropertyDefinition pd = getJavaClassPropertyDefinition();
    try {
      P publisher = pd.loadClass(className, logPublisherClass).newInstance();
      return publisher.isConfigurationAcceptable(config, unacceptableReasons);
    } catch (Exception e) {
      unacceptableReasons.add(invalidLoggerClassErrorMessage.get(className, config.dn(), e));
      return false;
    }
  }

  private P getLogPublisher(C config) throws ConfigException
  {
    String className = config.getJavaClass();
    ClassPropertyDefinition pd = getJavaClassPropertyDefinition();
    try {
      P logPublisher = pd.loadClass(className, logPublisherClass).newInstance();
      logPublisher.initializeLogPublisher(config, serverContext);
      return logPublisher;
    }
    catch (Exception e)
    {
      throw new ConfigException(
          invalidLoggerClassErrorMessage.get(className, config.dn(), e), e);
    }
  }

  private P getLogPublisherForCommonAudit(C config) throws InitializationException, ConfigException
  {
    CommonAudit commonAudit = serverContext.getCommonAudit();
    commonAudit.addOrUpdatePublisher(config);
    P logPublisher = getLogPublisher(config);
    CommonAuditLogPublisher publisher = (CommonAuditLogPublisher) logPublisher;
    publisher.setRequestHandler(commonAudit.getRequestHandler(config));
    return logPublisher;
  }
}