/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/util/DateParser.java,v 1.11 2004/11/06 19:15:42 mbecke Exp $
 * $Revision: 480424 $
 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.Locale;
import java.util.TimeZone;

A utility class for parsing HTTP dates as used in cookies and other headers.  
This class handles dates as defined by RFC 2616 section 3.3.1 as well as 
some other common non-standard formats.
Author:
Christopher Brown, Michael Becke
Deprecated:
Use DateUtil/**
 * A utility class for parsing HTTP dates as used in cookies and other headers.  
 * This class handles dates as defined by RFC 2616 section 3.3.1 as well as 
 * some other common non-standard formats.
 * 
 * @author Christopher Brown
 * @author Michael Becke
 * 
 * @deprecated Use {@link org.apache.commons.httpclient.util.DateUtil}
 */
public class DateParser {

    
Date format pattern used to parse HTTP date headers in RFC 1123 format.
/**
     * Date format pattern used to parse HTTP date headers in RFC 1123 format.
     */
    public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";

    
Date format pattern used to parse HTTP date headers in RFC 1036 format.
/**
     * Date format pattern used to parse HTTP date headers in RFC 1036 format.
     */
    public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";

    
Date format pattern used to parse HTTP date headers in ANSI C 
asctime() format.
/**
     * Date format pattern used to parse HTTP date headers in ANSI C 
     * <code>asctime()</code> format.
     */
    public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";

    private static final Collection DEFAULT_PATTERNS = Arrays.asList(
            new String[] { PATTERN_ASCTIME, PATTERN_RFC1036, PATTERN_RFC1123 } );
    
Parses a date value.  The formats used for parsing the date value are retrieved from
the default http params.
Params:
dateValue – the date value to parse
Throws:
DateParseException – if the value could not be parsed using any of the 
supported date formats
Returns:
the parsed date/**
     * Parses a date value.  The formats used for parsing the date value are retrieved from
     * the default http params.
     *
     * @param dateValue the date value to parse
     * 
     * @return the parsed date
     *
     * @throws DateParseException if the value could not be parsed using any of the 
     * supported date formats
     */
    public static Date parseDate(String dateValue) throws DateParseException {
        return parseDate(dateValue, null);
    }
    
    
Parses the date value using the given date formats.
Params:
dateValue – the date value to parse
dateFormats – the date formats to use
Throws:
DateParseException – if none of the dataFormats could parse the dateValue
Returns:
the parsed date/**
     * Parses the date value using the given date formats.
     * 
     * @param dateValue the date value to parse
     * @param dateFormats the date formats to use
     * 
     * @return the parsed date
     * 
     * @throws DateParseException if none of the dataFormats could parse the dateValue
     */
    public static Date parseDate(
        String dateValue, 
        Collection dateFormats
    ) throws DateParseException {
        
        if (dateValue == null) {
            throw new IllegalArgumentException("dateValue is null");
        }
        if (dateFormats == null) {
            dateFormats = DEFAULT_PATTERNS;
        }
        // trim single quotes around date if present
        // see issue #5279
        if (dateValue.length() > 1 
            && dateValue.startsWith("'") 
            && dateValue.endsWith("'")
        ) {
            dateValue = dateValue.substring (1, dateValue.length() - 1);
        }
        
        SimpleDateFormat dateParser = null;        
        Iterator formatIter = dateFormats.iterator();
        
        while (formatIter.hasNext()) {
            String format = (String) formatIter.next();            
            if (dateParser == null) {
                dateParser = new SimpleDateFormat(format, Locale.US);
                dateParser.setTimeZone(TimeZone.getTimeZone("GMT"));
            } else {
                dateParser.applyPattern(format);                    
            }
            try {
                return dateParser.parse(dateValue);
            } catch (ParseException pe) {
                // ignore this exception, we will try the next format
            }                
        }
        
        // we were unable to parse the date
        throw new DateParseException("Unable to parse the date " + dateValue);        
    }

    
This class should not be instantiated. /** This class should not be instantiated. */    
    private DateParser() { }
    
}