/**
 * Copyright 2008 Google Inc.
 *
 * 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.waveprotocol.wave.common.logging;

import org.waveprotocol.wave.common.logging.AbstractLogger.Level;

/**
 * A collection of levelled loggers.
 *
 */
public interface LoggerBundle {

  /**
   * Concatenates the toString() output of each of the provided message
   * Objects and logs the result iff the supplied level is loggable by this
   * logger. That is, if the message is not loggable the messages will not be
   * stringified nor concatenated.
   *
   * @param level the level to log at
   * @param messages messages to log
   */
  void log(Level level, Object... messages);

  /**
   * Gets a TRACE level logger.
   *
   * @return a trace logger.
   */
  Logger trace();

  /**
   * Gets an ERROR level logger.
   *
   * @return an error logger.
   */
  Logger error();

  /**
   * Gets a FATAL level logger.
   *
   * @return a fatal logger.
   */
  Logger fatal();

  /**
   * Tests if this logger bundle is enabled.  If enabled, then at least one
   * logger is potentially enabled (but not necessarily - each logger has its
   * own {@link Logger#shouldLog() enabled} state.
   *
   * @return true if logging is generally enabled.
   */
  boolean isModuleEnabled();

  /**
   * NOOP implementation.
   */
  public static final LoggerBundle NOP_IMPL = new LoggerBundle() {
    @Override
    public Logger error() {
      return Logger.NOP_IMPL;
    }

    @Override
    public Logger fatal() {
      return Logger.NOP_IMPL;
    }

    @Override
    public Logger trace() {
      return Logger.NOP_IMPL;
    }

    @Override
    public boolean isModuleEnabled() {
      return false;
    }

    @Override
    public void log(Level level, Object... messages) {}
  };
}