/*
 * $Header: /home/cvs/jakarta-tomcat/src/share/org/apache/tomcat/util/HttpDate.java,v 1.3 2000/02/14 04:59:42 costin Exp $
 * $Revision: 1.3 $
 * $Date: 2000/02/14 04:59:42 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * 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/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */ 


package org.apache.tomcat.util;

import java.io.IOException;
import java.io.OutputStream;
import java.util.*;
import java.text.*;
import org.apache.tomcat.core.Constants;

/**
 * This class can be used to efficiently parse and write an RFC 1123
 * formatted date in an HTTP message header.  Also supports reading the
 * RFC 1036 format and ANSI C's asctime() format, as suggested by HTTP/1.0
 * and mandated by HTTP/1.1.
 *
 * @author dac@eng.sun.com
 * @author Jason Hunter [jch@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 */

public class HttpDate extends Ascii {

    private StringManager sm =
        StringManager.getManager("org.apache.tomcat.util");

    // ONLY FOR COMPAT -- KILL ASAP -- just make sure that dependant
    // classes know what's up. ref. MimeHeaderField
    private static final String DATESTR = "Sun, 06 Nov 1994 08:49:37 GMT";
    public static final int DATELEN = DATESTR.length();
    // END COMPAT -- DON'T FORGET TO KILL
    
    // we force our locale here as all http dates are in english
    private final static Locale loc = Locale.US;

    // all http dates are expressed as time at GMT
    private final static TimeZone zone = TimeZone.getTimeZone("GMT");

    // format for RFC 1123 date string -- "Sun, 06 Nov 1994 08:49:37 GMT"
    private final static String rfc1123Pattern =
        "EEE, dd MMM yyyyy HH:mm:ss z";

    // format for RFC 1036 date string -- "Sunday, 06-Nov-94 08:49:37 GMT"
    private final static String rfc1036Pattern =
        "EEEEEEEEE, dd-MMM-yy HH:mm:ss z";

    // format for C asctime() date string -- "Sun Nov  6 08:49:37 1994"
    private final static String asctimePattern =
        "EEE MMM d HH:mm:ss yyyyy";

    private final static SimpleDateFormat rfc1123Format =
	new SimpleDateFormat(rfc1123Pattern, loc);
    
    private final static SimpleDateFormat rfc1036Format =
	new SimpleDateFormat(rfc1036Pattern, loc);
    
    private final static SimpleDateFormat asctimeFormat =
	new SimpleDateFormat(asctimePattern, loc);
    
    static {
	rfc1123Format.setTimeZone(zone);
	rfc1036Format.setTimeZone(zone);
	asctimeFormat.setTimeZone(zone);
    }
    
    // protected so that oldcookieexpiry in cookieutils can use
    // yes, this is sloppy as crap and could stand to be done better.
    protected Calendar calendar = new GregorianCalendar(zone, loc);

    public HttpDate() {
        calendar.setTime(new Date(System.currentTimeMillis()));
    }
    
    public HttpDate(long ms) {
        calendar.setTime(new Date(ms));
    }

    public void setTime() {
        calendar.setTime(new Date(System.currentTimeMillis()));
    }

    public void setTime(long ms) {
        calendar.setTime(new Date(ms));
    }
    
    public void parse(String dateString) {
        try {
            Date date = rfc1123Format.parse(dateString);
            calendar.setTime(date);
	    return;
	} catch (ParseException e) { }

        try {
            Date date = rfc1036Format.parse(dateString);
            calendar.setTime(date);
	    return;
	} catch (ParseException e) { }
	
        try {
            Date date = asctimeFormat.parse(dateString);
            calendar.setTime(date);
	    return;
        } catch (ParseException pe) {
            String msg = sm.getString("httpDate.pe", dateString);

            throw new IllegalArgumentException(msg);
        }
    }

    public void parse(byte[] b, int off, int len) {
        // ok -- so this is pretty stoopid, but the old version of this
        // source took this arg set, so we will too for now (backwards compat)
        try {
            String dateString = new String(b, off, len, Constants.DEFAULT_CHAR_ENCODING);
            parse(dateString);
        } catch (java.io.UnsupportedEncodingException e) {
            // It seems rather unlikely that the string encoding would ever fail...
            // As there is really nothing the caller can do with this specific
            // exception re-throw the exception as something expected.
            // XXX - perform byte -> character encoding at a higher level.
            throw new IllegalArgumentException(e.toString());
        }
    }

    public void write(OutputStream out) throws IOException {
        String dateString = rfc1123Format.format(calendar.getTime());
        byte[] b = dateString.getBytes();
        out.write(b);
    }

    public String toString() {
        return rfc1123Format.format(calendar.getTime());
    }

    public long getTime() {
        return calendar.getTime().getTime();
    }

    public static long getCurrentTime() {
        return System.currentTimeMillis();
    }

    // KILL, THIS IS ONLY HERE FOR TEMP COMPAT as MimeHeaderField uses it.
    public int getBytes(byte[] buf, int off, int len) {
	if (len < DATELEN) {
            String msg = sm.getString("httpDate.iae", new Integer(len));

	    throw new IllegalArgumentException(msg);
	}

	String dateString = rfc1123Format.format(calendar.getTime());
	byte[] b = dateString.getBytes();
	System.arraycopy(b, 0, buf, off, DATELEN);
	return DATELEN;
    }    
}
