/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2006-2008 Sun Microsystems, Inc.
 */
package org.opends.server.loggers;
import org.opends.messages.Message;

import java.util.concurrent.CopyOnWriteArrayList;
import java.util.List;
import java.util.ArrayList;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

import org.opends.server.api.DirectoryThread;
import org.opends.server.api.ErrorLogPublisher;
import org.opends.server.backends.task.Task;
import org.opends.server.loggers.debug.DebugTracer;

import org.opends.server.types.*;
import org.opends.server.admin.std.server.ErrorLogPublisherCfg;
import org.opends.server.admin.std.meta.ErrorLogPublisherCfgDefn;
import org.opends.server.admin.server.ConfigurationAddListener;
import org.opends.server.admin.server.ConfigurationDeleteListener;
import org.opends.server.admin.server.ConfigurationChangeListener;
import org.opends.server.admin.ClassPropertyDefinition;
import org.opends.server.config.ConfigException;
import org.opends.server.core.DirectoryServer;

import static org.opends.server.loggers.debug.DebugLogger.*;
import static org.opends.messages.ConfigMessages.*;
import static org.opends.server.util.StaticUtils.*;
/**
 * This class defines the wrapper that will invoke all registered error loggers
 * for each type of request received or response sent. If no error log
 * publishers are registered, messages will be directed to standard out.
 */
public class ErrorLogger implements
    ConfigurationAddListener<ErrorLogPublisherCfg>,
    ConfigurationDeleteListener<ErrorLogPublisherCfg>,
    ConfigurationChangeListener<ErrorLogPublisherCfg>
{
  /**
   * The tracer object for the debug logger.
   */
  private static final DebugTracer TRACER = getTracer();

  // The set of error loggers that have been registered with the server. It
  // will initially be empty.
  private static CopyOnWriteArrayList<ErrorLogPublisher> errorPublishers =
      new CopyOnWriteArrayList<ErrorLogPublisher>();

  // The singleton instance of this class for configuration purposes.
  private static final ErrorLogger instance = new ErrorLogger();

  /**
   * Retrieve the singleton instance of this class.
   *
   * @return The singleton instance of this logger.
   */
  public static ErrorLogger getInstance()
  {
    return instance;
  }

  /**
   * Add an error log publisher to the error logger.
   *
   * @param publisher The error log publisher to add.
   */
  public synchronized static void addErrorLogPublisher(
      ErrorLogPublisher publisher)
  {
    errorPublishers.add(publisher);
  }

  /**
   * Remove an error log publisher from the error logger.
   *
   * @param publisher The error log publisher to remove.
   * @return True if the error log publisher is removed or false otherwise.
   */
  public synchronized static boolean removeErrorLogPublisher(
      ErrorLogPublisher publisher)
  {
    boolean removed = errorPublishers.remove(publisher);

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

    return removed;
  }

  /**
   * Removes all existing error log publishers from the logger.
   */
  public synchronized static void removeAllErrorLogPublishers()
  {
    for(ErrorLogPublisher publisher : errorPublishers)
    {
      publisher.close();
    }

    errorPublishers.clear();
  }

  /**
   * Initializes all the error log publishers.
   *
   * @param configs The error log publisher configurations.
   * @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 initializeErrorLogger(List<ErrorLogPublisherCfg> configs)
      throws ConfigException, InitializationException
  {
    for(ErrorLogPublisherCfg config : configs)
    {
      config.addErrorChangeListener(this);

      if(config.isEnabled())
      {
        ErrorLogPublisher errorLogPublisher = getErrorPublisher(config);

        addErrorLogPublisher(errorLogPublisher);
      }
    }
  }

  /**
   * {@inheritDoc}
   */
  public boolean isConfigurationAddAcceptable(ErrorLogPublisherCfg config,
                                              List<Message> unacceptableReasons)
  {
    return !config.isEnabled() ||
        isJavaClassAcceptable(config, unacceptableReasons);
  }

  /**
   * {@inheritDoc}
   */
  public boolean isConfigurationChangeAcceptable(
          ErrorLogPublisherCfg config,
          List<Message> unacceptableReasons)
  {
    return !config.isEnabled() ||
        isJavaClassAcceptable(config, unacceptableReasons);
  }

  /**
   * {@inheritDoc}
   */
  public ConfigChangeResult applyConfigurationAdd(ErrorLogPublisherCfg config)
  {
    // Default result code.
    ResultCode resultCode = ResultCode.SUCCESS;
    boolean adminActionRequired = false;
    ArrayList<Message> messages = new ArrayList<Message>();

    config.addErrorChangeListener(this);

    if(config.isEnabled())
    {
      try
      {
        ErrorLogPublisher errorLogPublisher = getErrorPublisher(config);

        addErrorLogPublisher(errorLogPublisher);
      }
      catch(ConfigException e)
      {
        if (debugEnabled())
        {
          TRACER.debugCaught(DebugLogLevel.ERROR, e);
        }
        messages.add(e.getMessageObject());
        resultCode = DirectoryServer.getServerErrorResultCode();
      }
      catch (Exception e)
      {
        if (debugEnabled())
        {
          TRACER.debugCaught(DebugLogLevel.ERROR, e);
        }
        messages.add(ERR_CONFIG_LOGGER_CANNOT_CREATE_LOGGER.get(
                String.valueOf(config.dn().toString()),
                stackTraceToSingleLineString(e)));
        resultCode = DirectoryServer.getServerErrorResultCode();
      }
    }
    return new ConfigChangeResult(resultCode, adminActionRequired, messages);
  }

  /**
   * {@inheritDoc}
   */
  public ConfigChangeResult applyConfigurationChange(
      ErrorLogPublisherCfg config)
  {
    // Default result code.
    ResultCode resultCode = ResultCode.SUCCESS;
    boolean adminActionRequired = false;
    ArrayList<Message> messages = new ArrayList<Message>();

    DN dn = config.dn();

    ErrorLogPublisher errorLogPublisher = null;
    for(ErrorLogPublisher publisher : errorPublishers)
    {
      if(publisher.getDN().equals(dn))
      {
        errorLogPublisher = publisher;
        break;
      }
    }

    if(errorLogPublisher == null)
    {
      if(config.isEnabled())
      {
        // Needs to be added and enabled.
        return applyConfigurationAdd(config);
      }
    }
    else
    {
      if(config.isEnabled())
      {
        // The publisher is currently active, so we don't need to do anything.
        // 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(errorLogPublisher.getClass().getName()))
        {
          adminActionRequired = true;
        }
      }
      else
      {
        // The publisher is being disabled so shut down and remove.
        removeErrorLogPublisher(errorLogPublisher);
      }
    }

    return new ConfigChangeResult(resultCode, adminActionRequired, messages);
  }

  /**
   * {@inheritDoc}
   */
  public boolean isConfigurationDeleteAcceptable(
          ErrorLogPublisherCfg config,
          List<Message> unacceptableReasons)
  {
    DN dn = config.dn();

    ErrorLogPublisher errorLogPublisher = null;
    for(ErrorLogPublisher publisher : errorPublishers)
    {
      if(publisher.getDN().equals(dn))
      {
        errorLogPublisher = publisher;
        break;
      }
    }

    return errorLogPublisher != null;
  }

  /**
   * {@inheritDoc}
   */
  public ConfigChangeResult applyConfigurationDelete(
      ErrorLogPublisherCfg config)
  {
    // Default result code.
    ResultCode resultCode = ResultCode.SUCCESS;
    boolean adminActionRequired = false;

    ErrorLogPublisher errorLogPublisher = null;
    for(ErrorLogPublisher publisher : errorPublishers)
    {
      if(publisher.getDN().equals(config.dn()))
      {
        errorLogPublisher = publisher;
        break;
      }
    }

    if(errorLogPublisher != null)
    {
      removeErrorLogPublisher(errorLogPublisher);
    }
    else
    {
      resultCode = ResultCode.NO_SUCH_OBJECT;
    }

    return new ConfigChangeResult(resultCode, adminActionRequired);
  }

  private boolean isJavaClassAcceptable(ErrorLogPublisherCfg config,
                                        List<Message> unacceptableReasons)
  {
    String className = config.getJavaClass();
    ErrorLogPublisherCfgDefn d = ErrorLogPublisherCfgDefn.getInstance();
    ClassPropertyDefinition pd =
        d.getJavaClassPropertyDefinition();
    // Load the class and cast it to a DebugLogPublisher.
    ErrorLogPublisher publisher = null;
    Class<? extends ErrorLogPublisher> theClass;
    try {
      theClass = pd.loadClass(className, ErrorLogPublisher.class);
      publisher = theClass.newInstance();
    } catch (Exception e) {
      Message message = ERR_CONFIG_LOGGER_INVALID_ERROR_LOGGER_CLASS.get(
              className,
              config.dn().toString(),
              String.valueOf(e));
      unacceptableReasons.add(message);
      return false;
    }
    // Check that the implementation class implements the correct interface.
    try {
      // Determine the initialization method to use: it must take a
      // single parameter which is the exact type of the configuration
      // object.
      Method method = theClass.getMethod("isConfigurationAcceptable",
                                         ErrorLogPublisherCfg.class,
                                         List.class);
      Boolean acceptable = (Boolean) method.invoke(publisher, config,
                                                   unacceptableReasons);

      if (! acceptable)
      {
        return false;
      }
    } catch (Exception e) {
      Message message = ERR_CONFIG_LOGGER_INVALID_ERROR_LOGGER_CLASS.get(
              className,
              config.dn().toString(),
              String.valueOf(e));
      unacceptableReasons.add(message);
      return false;
    }
    // The class is valid as far as we can tell.
    return true;
  }

  private ErrorLogPublisher getErrorPublisher(ErrorLogPublisherCfg config)
      throws ConfigException {
    String className = config.getJavaClass();
    ErrorLogPublisherCfgDefn d = ErrorLogPublisherCfgDefn.getInstance();
    ClassPropertyDefinition pd =
        d.getJavaClassPropertyDefinition();
    // Load the class and cast it to a ErrorLogPublisher.
    Class<? extends ErrorLogPublisher> theClass;
    ErrorLogPublisher errorLogPublisher;
    try {
      theClass = pd.loadClass(className, ErrorLogPublisher.class);
      errorLogPublisher = theClass.newInstance();

      // Determine the initialization method to use: it must take a
      // single parameter which is the exact type of the configuration
      // object.
      Method method = theClass.getMethod("initializeErrorLogPublisher", config
          .configurationClass());
      method.invoke(errorLogPublisher, config);
    }
    catch (InvocationTargetException ite)
    {
      // Rethrow the exceptions thrown be the invoked method.
      Throwable e = ite.getTargetException();
      Message message = ERR_CONFIG_LOGGER_INVALID_ERROR_LOGGER_CLASS.get(
          className, config.dn().toString(), stackTraceToSingleLineString(e));
      throw new ConfigException(message, e);
    }
    catch (Exception e)
    {
      Message message = ERR_CONFIG_LOGGER_INVALID_ERROR_LOGGER_CLASS.get(
          className, config.dn().toString(), String.valueOf(e));
      throw new ConfigException(message, e);
    }

    // The error publisher has been successfully initialized.
    return errorLogPublisher;
  }



  /**
   * Writes a message to the error log using the provided information.
   *
   * @param  message   The message to be logged.
   */
  public static void logError(Message message)
  {
    for (ErrorLogPublisher publisher : errorPublishers)
    {
      publisher.logError(message);
    }

    if (Thread.currentThread() instanceof DirectoryThread)
    {
      DirectoryThread thread = (DirectoryThread) Thread.currentThread();
      Task task = thread.getAssociatedTask();
      if (task != null)
      {
        task.addLogMessage(message);
      }
    }
  }
}