/*
 * 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 legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * 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 legal-notices/CDDLv1_0.txt.
 * 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 2006-2009 Sun Microsystems, Inc.
 *      Portions Copyright 2014 ForgeRock AS
 */
package org.opends.server.loggers;

import java.util.Map;

import org.forgerock.i18n.slf4j.LocalizedLogger;

/**
 * Class for source-code tracing at the method level.
 *
 * One DebugTracer instance exists for each Java class using tracing.
 * Tracer must be registered with the DebugLogger.
 *
 * Logging is always done at a level basis, with debug log messages
 * exceeding the trace threshold being traced, others being discarded.
 */
class DebugTracer
{
  /** The class this aspect traces. */
  private String className;

  /**
   * A class that represents a settings cache entry.
   */
  private class PublisherSettings
  {
    DebugLogPublisher<?> debugPublisher;
    TraceSettings classSettings;
    Map<String, TraceSettings> methodSettings;
  }

  private PublisherSettings[] publisherSettings;

  /**
   * Construct a new DebugTracer object with cached settings obtained from
   * the provided array of publishers.
   *
   * @param className The classname to use as category for logging.
   * @param publishers The array of publishers to obtain the settings from.
   */
  @SuppressWarnings({ "unchecked", "rawtypes" })
  DebugTracer(String className, DebugLogPublisher[] publishers)
  {
    this.className = className;
    publisherSettings = new PublisherSettings[publishers.length];

    // Get the settings from all publishers.
    for(int i = 0; i < publishers.length; i++)
    {
      DebugLogPublisher publisher = publishers[i];
      PublisherSettings settings = new PublisherSettings();

      settings.debugPublisher = publisher;
      settings.classSettings = publisher.getClassSettings(className);

      // For some reason, the compiler doesn't see that
      // debugLogPublihser.getMethodSettings returns a parameterized Map.
      // This problem goes away if a parameterized verson of DebugLogPublisher
      // is used. However, we can't not use reflection to instantiate a generic
      // DebugLogPublisher<? extends DebugLogPublisherCfg> type. The only thing
      // we can do is to just supress the compiler warnings.
      settings.methodSettings = publisher.getMethodSettings(className);

      publisherSettings[i] = settings;
    }
  }

  /**
   * Log the provided message.
   *
   * @param msg
   *          message to log.
   */
  void trace(String msg)
  {
    traceException(msg, null);
  }

  /**
   * Log the provided message and exception.
   *
   * @param msg
   *          the message
   * @param exception
   *          the exception caught. May be {@code null}.
   */
  void traceException(String msg, Throwable exception)
  {
    StackTraceElement[] stackTrace = null;
    StackTraceElement[] filteredStackTrace = null;
    StackTraceElement callerFrame = null;
    final boolean hasException = (exception != null);
    for (PublisherSettings settings : publisherSettings)
    {
      TraceSettings activeSettings = settings.classSettings;
      Map<String, TraceSettings> methodSettings = settings.methodSettings;

      if (shouldLog(hasException, activeSettings) || methodSettings != null)
      {
        if (stackTrace == null)
        {
          stackTrace = Thread.currentThread().getStackTrace();
        }
        if (callerFrame == null)
        {
          callerFrame = getCallerFrame(stackTrace);
        }

        String signature = callerFrame.getMethodName();

        // Specific method settings still could exist. Try getting
        // the settings for this method.
        if (methodSettings != null)
        {
          TraceSettings mSettings = methodSettings.get(signature);

          if (mSettings == null)
          {
            // Try looking for an undecorated method name
            int idx = signature.indexOf('(');
            if (idx != -1)
            {
              mSettings = methodSettings.get(signature.substring(0, idx));
            }
          }

          // If this method does have a specific setting and it is not
          // suppose to be logged, continue.
          if (mSettings != null)
          {
            if (!shouldLog(hasException, mSettings))
            {
              continue;
            }
            else
            {
              activeSettings = mSettings;
            }
          }
        }

        String sourceLocation =
            callerFrame.getFileName() + ":" + callerFrame.getLineNumber();

        if (filteredStackTrace == null && activeSettings.getStackDepth() > 0)
        {
          StackTraceElement[] trace =
              hasException ? exception.getStackTrace() : stackTrace;
          filteredStackTrace =
              DebugStackTraceFormatter.SMART_FRAME_FILTER
                  .getFilteredStackTrace(trace);
        }

        if (hasException)
        {
          settings.debugPublisher.traceException(activeSettings, signature,
              sourceLocation, msg, exception, filteredStackTrace);
        }
        else
        {
          settings.debugPublisher.trace(activeSettings, signature,
              sourceLocation, msg, filteredStackTrace);
        }
      }
    }
  }

  /**
   * Gets the name of the class this tracer traces.
   *
   * @return The name of the class this tracer traces.
   */
  String getTracedClassName()
  {
    return className;
  }

  /**
   * Indicates if logging is enabled for at least one category
   * in a publisher.
   *
   * @return {@code true} if logging is enabled, false otherwise.
   */
  boolean enabled()
  {
    for (PublisherSettings settings : publisherSettings)
    {
      if (shouldLog(settings.classSettings) || settings.methodSettings != null)
      {
        return true;
      }
    }
    return false;
  }

  /**
   * Update the cached settings of the tracer with the settings from the
   * provided publishers.
   *
   * @param publishers The array of publishers to obtain the settings from.
   */
  @SuppressWarnings({ "unchecked", "rawtypes" })
  void updateSettings(DebugLogPublisher[] publishers)
  {
    PublisherSettings[] newSettings =
        new PublisherSettings[publishers.length];

    // Get the settings from all publishers.
    for(int i = 0; i < publishers.length; i++)
    {
      DebugLogPublisher publisher = publishers[i];
      PublisherSettings settings = new PublisherSettings();

      settings.debugPublisher = publisher;
      settings.classSettings = publisher.getClassSettings(className);

      // For some reason, the compiler doesn't see that
      // debugLogPublihser.getMethodSettings returns a parameterized Map.
      // This problem goes away if a parameterized verson of DebugLogPublisher
      // is used. However, we can't not use reflection to instantiate a generic
      // DebugLogPublisher<? extends DebugLogPublisherCfg> type. The only thing
      // we can do is to just supress the compiler warnings.
      settings.methodSettings = publisher.getMethodSettings(className);

      newSettings[i] = settings;
    }

    publisherSettings = newSettings;
  }

  /**
   * Return the caller stack frame.
   *
   * @param stackTrace The entrie stack trace frames.
   * @return the caller stack frame or null if none is found on the
   * stack trace.
   */
  private StackTraceElement getCallerFrame(StackTraceElement[] stackTrace)
  {
    if (stackTrace != null && stackTrace.length > 0)
    {
      // Skip all logging related classes
      for (StackTraceElement aStackTrace : stackTrace)
      {
        if(!isLoggingStackTraceElement(aStackTrace))
        {
          return aStackTrace;
        }
      }
    }

    return null;
  }

  /**
   * Checks if element belongs to a class responsible for logging
   * (includes the Thread class that may be used to get the stack trace).
   *
   * @param trace
   *            the trace element to check.
   * @return {@code true} if element corresponds to logging
   */
  static boolean isLoggingStackTraceElement(StackTraceElement trace)
  {
    String name = trace.getClassName();
    return name.startsWith(Thread.class.getName())
        || name.startsWith(DebugTracer.class.getName())
        || name.startsWith(OpenDJLoggerAdapter.class.getName())
        || name.startsWith(LocalizedLogger.class.getName());
  }

  /** Indicates if there is something to log. */
  private boolean shouldLog(boolean hasException, TraceSettings activeSettings)
  {
    return activeSettings.getLevel() == TraceSettings.Level.ALL
        || (hasException && activeSettings.getLevel() == TraceSettings.Level.EXCEPTIONS_ONLY);
  }

  /** Indicates if there is something to log. */
  private boolean shouldLog(TraceSettings settings)
  {
    return settings.getLevel() != TraceSettings.Level.DISABLED;
  }
}