/*
 * 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.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * The class implements the pre log4j 1.3
 * org.apache.log4j.helpers.PatternConverter contract by delegating to the log4j
 * 1.3 pattern implementation.
 *
 *
 * @author Curt Arnold
 *
 */
public final class BridgePatternConverter extends org.apache.log4j.helpers.PatternConverter {
    /**
     * Pattern converters.
     */
    private LoggingEventPatternConverter[] patternConverters;

    /**
     * Field widths and alignment corresponding to pattern converters.
     */
    private FormattingInfo[] patternFields;

    /**
     * Does pattern process exceptions.
     */
    private boolean handlesExceptions;

    /**
     * Create a new instance.
     * 
     * @param pattern pattern, may not be null.
     */
    public BridgePatternConverter(final String pattern) {
	next = null;
	handlesExceptions = false;

	List converters = new ArrayList();
	List fields = new ArrayList();
	Map converterRegistry = null;

	PatternParser.parse(pattern, converters, fields, converterRegistry, PatternParser.getPatternLayoutRules());

	patternConverters = new LoggingEventPatternConverter[converters.size()];
	patternFields = new FormattingInfo[converters.size()];

	int i = 0;
	Iterator converterIter = converters.iterator();
	Iterator fieldIter = fields.iterator();

	while (converterIter.hasNext()) {
	    Object converter = converterIter.next();

	    if (converter instanceof LoggingEventPatternConverter) {
		patternConverters[i] = (LoggingEventPatternConverter) converter;
		handlesExceptions |= patternConverters[i].handlesThrowable();
	    } else {
		patternConverters[i] = new org.apache.log4j.pattern.LiteralPatternConverter("");
	    }

	    if (fieldIter.hasNext()) {
		patternFields[i] = (FormattingInfo) fieldIter.next();
	    } else {
		patternFields[i] = FormattingInfo.getDefault();
	    }

	    i++;
	}
    }

    /**
     * {@inheritDoc}
     */
    protected String convert(final LoggingEvent event) {
	//
	// code should be unreachable.
	//
	StringBuffer sbuf = new StringBuffer();
	format(sbuf, event);

	return sbuf.toString();
    }

    /**
     * Format event to string buffer.
     * 
     * @param sbuf string buffer to receive formatted event, may not be null.
     * @param e    event to format, may not be null.
     */
    public void format(final StringBuffer sbuf, final LoggingEvent e) {
	for (int i = 0; i < patternConverters.length; i++) {
	    int startField = sbuf.length();
	    patternConverters[i].format(e, sbuf);
	    patternFields[i].format(startField, sbuf);
	}
    }

    /**
     * Will return false if any of the conversion specifiers in the pattern handles
     * {@link Exception Exceptions}.
     * 
     * @return true if the pattern formats any information from exceptions.
     */
    public boolean ignoresThrowable() {
	return !handlesExceptions;
    }
}
