/*
 * 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.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.StringTokenizer;

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

/**
 * This policy rewrites events by adding a user-specified list of properties to
 * the event. Existing properties are not modified.
 *
 * The combination of the RewriteAppender and this policy performs the same
 * actions as the PropertyFilter from log4j 1.3.
 */

public class PropertyRewritePolicy implements RewritePolicy {
    private Map properties = Collections.EMPTY_MAP;

    public PropertyRewritePolicy() {
    }

    /**
     * Set a string representing the property name/value pairs.
     * 
     * Form: propname1=propvalue1,propname2=propvalue2
     * 
     * @param props
     */
    public void setProperties(String props) {
	Map hashTable = new HashMap();
	StringTokenizer pairs = new StringTokenizer(props, ",");
	while (pairs.hasMoreTokens()) {
	    StringTokenizer entry = new StringTokenizer(pairs.nextToken(), "=");
	    hashTable.put(entry.nextElement().toString().trim(), entry.nextElement().toString().trim());
	}
	synchronized (this) {
	    properties = hashTable;
	}
    }

    /**
     * {@inheritDoc}
     */
    public LoggingEvent rewrite(final LoggingEvent source) {
	if (!properties.isEmpty()) {
	    Map rewriteProps = new HashMap(source.getProperties());
	    for (Iterator iter = properties.entrySet().iterator(); iter.hasNext();) {
		Map.Entry entry = (Map.Entry) iter.next();
		if (!rewriteProps.containsKey(entry.getKey())) {
		    rewriteProps.put(entry.getKey(), entry.getValue());
		}
	    }

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

}
