/*
 * 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.rewrite;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.apache.log4j.Logger;
import org.apache.log4j.spi.LoggingEvent;

/**
 * This policy rewrites events where the message of the original event
 * implementes java.util.Map. All other events are passed through unmodified. If
 * the map contains a "message" entry, the value will be used as the message for
 * the rewritten event. The rewritten event will have a property set that is the
 * combination of the original property set and the other members of the message
 * map. If both the original property set and the message map contain the same
 * entry, the value from the message map will overwrite the original property
 * set.
 *
 * The combination of the RewriteAppender and this policy performs the same
 * actions as the MapFilter from log4j 1.3.
 */
public class MapRewritePolicy implements RewritePolicy {
    /**
     * {@inheritDoc}
     */
    public LoggingEvent rewrite(final LoggingEvent source) {
	Object msg = source.getMessage();
	if (msg instanceof Map) {
	    Map props = new HashMap(source.getProperties());
	    Map eventProps = (Map) msg;
	    //
	    // if the map sent in the logging request
	    // has "message" entry, use that as the message body
	    // otherwise, use the entire map.
	    //
	    Object newMsg = eventProps.get("message");
	    if (newMsg == null) {
		newMsg = msg;
	    }

	    for (Iterator iter = eventProps.entrySet().iterator(); iter.hasNext();) {
		Map.Entry entry = (Map.Entry) iter.next();
		if (!("message".equals(entry.getKey()))) {
		    props.put(entry.getKey(), entry.getValue());
		}
	    }

	    return new LoggingEvent(source.getFQNOfLoggerClass(),
		    source.getLogger() != null ? source.getLogger() : Logger.getLogger(source.getLoggerName()),
		    source.getTimeStamp(), source.getLevel(), newMsg, source.getThreadName(),
		    source.getThrowableInformation(), source.getNDC(), source.getLocationInformation(), props);
	} else {
	    return source;
	}

    }
}
