/*
 * 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.pattern;

import org.apache.log4j.spi.LoggingEvent;

import java.util.Iterator;
import java.util.Set;

import org.apache.log4j.helpers.*;

/**
 * Able to handle the contents of the LoggingEvent's Property bundle and either output the entire contents of the
 * properties in a similar format to the java.util.Hashtable.toString(), or to output the value of a specific key within
 * the property bundle when this pattern converter has the option set.
 *
 * @author Paul Smith
 * @author Ceki G&uuml;lc&uuml;
 */
public final class PropertiesPatternConverter extends LoggingEventPatternConverter {
    /**
     * Name of property to output.
     */
    private final String option;

    /**
     * Private constructor.
     *
     * @param options options, may be null.
     */
    private PropertiesPatternConverter(final String[] options) {
        super(((options != null) && (options.length > 0)) ? ("Property{" + options[0] + "}") : "Properties",
                "property");

        if ((options != null) && (options.length > 0)) {
            option = options[0];
        } else {
            option = null;
        }
    }

    /**
     * Obtains an instance of PropertiesPatternConverter.
     *
     * @param options options, may be null or first element contains name of property to format.
     * @return instance of PropertiesPatternConverter.
     */
    public static PropertiesPatternConverter newInstance(final String[] options) {
        return new PropertiesPatternConverter(options);
    }

    /**
     * {@inheritDoc}
     */
    public void format(final LoggingEvent event, final StringBuffer toAppendTo) {
        // if there is no additional options, we output every single
        // Key/Value pair for the MDC in a similar format to Hashtable.toString()
        if (option == null) {
            toAppendTo.append("{");

            try {
                Set keySet = MDCKeySetExtractor.INSTANCE.getPropertyKeySet(event);
                if (keySet != null) {
                    for (Iterator i = keySet.iterator(); i.hasNext(); ) {
                        Object item = i.next();
                        Object val = event.getMDC(item.toString());
                        toAppendTo.append("{").append(item).append(",").append(val).append("}");
                    }
                }
            } catch (Exception ex) {
                LogLog.error("Unexpected exception while extracting MDC keys", ex);
            }

            toAppendTo.append("}");
        } else {
            // otherwise they just want a single key output
            Object val = event.getMDC(option);

            if (val != null) {
                toAppendTo.append(val);
            }
        }
    }
}
