/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.log4j;

import org.apache.log4j.spi.Filter;
import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.LoggingEvent;

/**
 * Implement this interface for your own strategies for outputting log statements.
 *
 * @author Ceki G&uuml;lc&uuml;
 */
public interface Appender {

    /**
     * Add a filter to the end of the filter list.
     *
     * @since 0.9.0
     */
    void addFilter(Filter newFilter);

    /**
     * Returns the head Filter. The Filters are organized in a linked list and so all Filters on this Appender are
     * available through the result.
     *
     * @return the head Filter or null, if no Filters are present
     * @since 1.1
     */
    public Filter getFilter();

    /**
     * Clear the list of filters by removing all the filters in it.
     *
     * @since 0.9.0
     */
    public void clearFilters();

    /**
     * Release any resources allocated within the appender such as file handles, network connections, etc.
     *
     * <p>
     * It is a programming error to append to a closed appender.
     *
     * @since 0.8.4
     */
    public void close();

    /**
     * Log in <code>Appender</code> specific way. When appropriate, Loggers will call the <code>doAppend</code> method
     * of appender implementations in order to log.
     */
    public void doAppend(LoggingEvent event);

    /**
     * Get the name of this appender.
     *
     * @return name, may be null.
     */
    public String getName();

    /**
     * Set the {@link ErrorHandler} for this appender.
     *
     * @since 0.9.0
     */
    public void setErrorHandler(ErrorHandler errorHandler);

    /**
     * Returns the {@link ErrorHandler} for this appender.
     *
     * @since 1.1
     */
    public ErrorHandler getErrorHandler();

    /**
     * Set the {@link Layout} for this appender.
     *
     * @since 0.8.1
     */
    public void setLayout(Layout layout);

    /**
     * Returns this appenders layout.
     *
     * @since 1.1
     */
    public Layout getLayout();

    /**
     * Set the name of this appender. The name is used by other components to identify this appender.
     *
     * @since 0.8.1
     */
    public void setName(String name);

    /**
     * Configurators call this method to determine if the appender requires a layout. If this method returns
     * <code>true</code>, meaning that layout is required, then the configurator will configure an layout using the
     * configuration information at its disposal. If this method returns
     * <code>false</code>, meaning that a layout is not required, then layout
     * configuration will be skipped even if there is available layout configuration information at the disposal of the
     * configurator..
     *
     * <p>
     * In the rather exceptional case, where the appender implementation admits a layout but can also work without it,
     * then the appender should return
     * <code>true</code>.
     *
     * @since 0.8.4
     */
    public boolean requiresLayout();
}
