/*
 * 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.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.HashMap;
import java.util.Map;

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

/**
 * This policy rewrites events by evaluating any JavaBean properties on the message object and adding them to the event
 * properties. If the message object has a message property, the value of that property will be used as the message for
 * the rewritten event and will not be added to the event properties. Values from the JavaBean properties will replace
 * any existing property with the same name.
 * <p>
 * The combination of the RewriteAppender and this policy performs the same actions as the ReflectionFilter from log4j
 * 1.3.
 */
public class ReflectionRewritePolicy implements RewritePolicy {
    /**
     * {@inheritDoc}
     */
    public LoggingEvent rewrite(final LoggingEvent source) {
        Object msg = source.getMessage();
        if (!(msg instanceof String)) {
            Object newMsg = msg;
            Map rewriteProps = new HashMap(source.getProperties());

            try {
                PropertyDescriptor[] props = Introspector.getBeanInfo(msg.getClass(), Object.class)
                        .getPropertyDescriptors();
                if (props.length > 0) {
                    for (int i = 0; i < props.length; i++) {
                        try {
                            Object propertyValue = props[i].getReadMethod().invoke(msg, (Object[]) null);
                            if ("message".equalsIgnoreCase(props[i].getName())) {
                                newMsg = propertyValue;
                            } else {
                                rewriteProps.put(props[i].getName(), propertyValue);
                            }
                        } catch (Exception e) {
                            LogLog.warn("Unable to evaluate property " + props[i].getName(), e);
                        }
                    }
                    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(),
                            rewriteProps);
                }
            } catch (Exception e) {
                LogLog.warn("Unable to get property descriptors", e);
            }

        }
        return source;
    }
}
