/* Copyright (C) 1998, 1999  Cygnus Solutions

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.util;
import java.text.*;

/**
 * @author Per Bothner <bothner@cygnus.com>
 * @date October 24, 1998.
 */

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3,
 * "The Java Language Specification", ISBN 0-201-63451-1,
 * and O'Reilly's "Java in a Nutshell".
 * Status:  Need to re-write toString().
 *   Missing:  ToGMTString and toLocaleString.
 *   Serialization spec:  Specifies readObject/writeObject.
 */

public class Date implements java.io.Serializable, Cloneable
{
  private long millis;

  public Date() { millis = System.currentTimeMillis(); }

  public Date(long millis) { this.millis = millis; }

  public Date(int year, int month, int date, int hours,
	      int minutes, int seconds)
  {
    setTime(year, month, date, hours, minutes, seconds);
  }

  public Date(int year, int month, int date, int hours, int minutes)
  {
    setTime(year, month, date, hours, minutes, 0);
  }

  public Date(int year, int month, int date)
  {
    setTime(year, month, date, 0, 0, 0);
  }

  public Date (String s) { this(parse(s)); }

  private static int skipParens(String string, int offset)
  {
    int len = string.length();
    int p = 0;
    int i;

    for (i = offset; i < len; ++i)
      {
	if (string.charAt(i) == '(')
	  ++p;
	else if (string.charAt(i) == ')')
	  {
	    --p;
	    if (p == 0)
	      return i + 1;
	    // If we've encounted unbalanced parens, just return the
	    // leftover one as an ordinary character.  It will be
	    // caught later in parsing and cause an
	    // IllegalArgumentException.
      	    if (p < 0)
	      return i;
	  }
      }

    // Not sure what to do if `p != 0' here.
    return i;
  }

  private static int parseTz(String tok, char sign)
    throws IllegalArgumentException
  {
    int num;

    try
      {
	// parseInt doesn't handle '+' so strip off sign.
	num = Integer.parseInt(tok.substring(1));
      }
    catch (NumberFormatException ex)
      {
	throw new IllegalArgumentException(tok);
      }

    // Convert hours to minutes.
    if (num < 24)
      num *= 60;
    else
      num = (num / 100) * 60 + num % 100;

    return sign == '-' ? -num : num;
  }

  private static int parseMonth(String tok)
  {
    // Initialize strings for month names.
    // We could possibly use the fields of DateFormatSymbols but that is
    // localized and thus might not match the English words specified.
    String months[] = { "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY",
			"JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER",
			"NOVEMBER", "DECEMBER" };

    int i;
    for (i = 0; i < 12; i++)
      if (months[i].startsWith(tok))
        return i;

    // Return -1 if not found.
    return -1;
  }

  private static boolean parseDayOfWeek(String tok)
  {
    // Initialize strings for days of the week names.
    // We could possibly use the fields of DateFormatSymbols but that is
    // localized and thus might not match the English words specified.
    String daysOfWeek[] = { "SUNDAY", "MONDAY", "TUESDAY", "WEDNESDAY",
			    "THURSDAY", "FRIDAY", "SATURDAY" };

    int i;
    for (i = 0; i < 7; i++)
      if (daysOfWeek[i].startsWith(tok))
        return true;

    return false;
  }

  public static long parse(String string)
  {
    // Initialize date/time fields before parsing begins.
    int year = -1;
    int month = -1;
    int day = -1;
    int hour = -1;
    int minute = -1;
    int second = -1;
    int timezone = 0;
    boolean localTimezone = true;

    // Trim out any nested stuff in parentheses now to make parsing easier.
    StringBuffer buf = new StringBuffer();
    int off = 0;
    int openParenOffset, tmpMonth;
    while ((openParenOffset = string.indexOf('(', off)) >= 0)
      {
	// Copy part of string leading up to open paren.
	buf.append(string.substring(off, openParenOffset));
	off = skipParens(string, openParenOffset);
      }
    buf.append(string.substring(off));

    // Make all chars upper case to simplify comparisons later.
    // Also ignore commas; treat them as delimiters.
    StringTokenizer strtok =
      new StringTokenizer(buf.toString().toUpperCase(), " \t\n\r,");

    while (strtok.hasMoreTokens())
      {
	String tok = strtok.nextToken();
	char firstch = tok.charAt(0);
	if ((firstch == '+' || firstch == '-') && year >= 0)
	  {
	    timezone = parseTz(tok, firstch);
	    localTimezone = false;
	  }
	else if (firstch >= '0' && firstch <= '9')
	  {
	    while (tok != null && tok.length() > 0)
	      {
	        // A colon or slash may be valid in the number.
	        // Find the first of these before calling parseInt.
	        int colon = tok.indexOf(':');
	        int slash = tok.indexOf('/');
	        int hyphen = tok.indexOf('-');
		// We choose tok.length initially because it makes
		// processing simpler.
	        int punctOffset = tok.length();
		if (colon >= 0)
		  punctOffset = Math.min(punctOffset, colon);
	        if (slash >= 0)
	          punctOffset = Math.min(punctOffset, slash);
	        if (hyphen >= 0)
	          punctOffset = Math.min(punctOffset, hyphen);
		// Following code relies on -1 being the exceptional
		// case.
		if (punctOffset == tok.length())
		  punctOffset = -1;

	        int num;
	        try
	          {
		    num = Integer.parseInt(punctOffset < 0 ? tok :
					   tok.substring(0, punctOffset));
	          }
	        catch (NumberFormatException ex)
	          {
		    throw new IllegalArgumentException(tok);
	          }

		// TBD: Spec says year can be followed by a slash.  That might
		// make sense if using YY/MM/DD formats, but it would fail in
		// that format for years <= 70.  Also, what about 1900?  That
		// is interpreted as the year 3800; seems that the comparison
		// should be num >= 1900 rather than just > 1900.
		// What about a year of 62 - 70?  (61 or less could be a (leap)
		// second).  70/MM/DD cause an exception but 71/MM/DD is ok
		// even though there's no ambiguity in either case.
		// For the parse method, the spec as written seems too loose.
		// Until shown otherwise, we'll follow the spec as written.
	        if (num > 70 && (punctOffset < 0 || punctOffset == slash))
		  year = num > 1900 ? num - 1900 : num;
		else if (punctOffset > 0 && punctOffset == colon)
		  {
		    if (hour < 0)
		      hour = num;
		    else
		      minute = num;
		  }
		else if (punctOffset > 0 && punctOffset == slash)
		  {
		    if (month < 0)
		      month = num - 1;
		    else
		      day = num;
		  }
		else if (hour >= 0 && minute < 0)
		  minute = num;
		else if (minute >= 0 && second < 0)
		  second = num;
		else if (day < 0)
		  day = num;
		else
		  throw new IllegalArgumentException(tok);

		// Advance string if there's more to process in this token.
		if (punctOffset < 0 || punctOffset + 1 >= tok.length())
		  tok = null;
		else
		  tok = tok.substring(punctOffset + 1);
	      }
	  }
	else if (firstch >= 'A' && firstch <= 'Z')
	  {
	    if (tok.equals("AM"))
	      {
		if (hour < 1 || hour > 12)
		  throw new IllegalArgumentException(tok);
		if (hour == 12)
		  hour = 0;
	      }
	    else if (tok.equals("PM"))
	      {
		if (hour < 1 || hour > 12)
		  throw new IllegalArgumentException(tok);
		if (hour < 12)
		  hour += 12;
	      }
	    else if (parseDayOfWeek(tok))
	      ; // Ignore it; throw the token away.
	    else if (tok.equals("UT") || tok.equals("UTC") || tok.equals("GMT"))
	      localTimezone = false;
	    else if (tok.startsWith("UT") || tok.startsWith("GMT"))
	      {
		int signOffset = 3;
		if (tok.charAt(1) == 'T' && tok.charAt(2) != 'C')
		  signOffset = 2;

	        char sign = tok.charAt(signOffset);
		if (sign != '+' && sign != '-')
		  throw new IllegalArgumentException(tok);

	        timezone = parseTz(tok.substring(signOffset), sign);
	        localTimezone = false;
	      }
	    else if ((tmpMonth = parseMonth(tok)) >= 0)
	      month = tmpMonth;
	    else if (tok.length() == 3 && tok.charAt(2) == 'T')
	      {
		// Convert timezone offset from hours to minutes.
		char ch = tok.charAt(0);
		if (ch == 'E')
		  timezone = -5 * 60;
		else if (ch == 'C')
		  timezone = -6 * 60;
		else if (ch == 'M')
		  timezone = -7 * 60;
		else if (ch == 'P')
		  timezone = -8 * 60;
		else
		  throw new IllegalArgumentException(tok);

		// Shift 60 minutes for Daylight Savings Time.
		if (tok.charAt(1) == 'D')
		  timezone += 60;
		else if (tok.charAt(1) != 'S')
		  throw new IllegalArgumentException(tok);

	        localTimezone = false;
	      }
	    else
	      throw new IllegalArgumentException(tok);
	  }
	else
	  throw new IllegalArgumentException(tok);
      }

    // Unspecified minutes and seconds should default to 0.
    if (minute < 0)
      minute = 0;
    if (second < 0)
      second = 0;

    // Throw exception if any other fields have not been recognized and set.
    if (year < 0 || month < 0 || day < 0 || hour < 0)
      throw new IllegalArgumentException("Missing field");

    // Return the time in either local time or relative to GMT as parsed.
    // If no time-zone was specified, get the local one (in minutes) and
    // convert to milliseconds before adding to the UTC.
    return UTC(year, month, day, hour, minute, second) + (localTimezone ?
		new Date(year, month, day).getTimezoneOffset() * 60 * 1000:
		-timezone * 60 * 1000);
  }

  public boolean after (Date when) { return this.millis > when.millis; }
  public boolean before (Date when) { return this.millis < when.millis; }

  public boolean equals(Object obj)
  {
    return (obj != null && obj instanceof Date
	    && ((Date)obj).millis == this.millis);
  }

  public long getTime() { return millis; }

  public int hashCode()
  {
    return (int)(millis^(millis>>>32));
  }

  private void setTime(int year, int month, int date,
		       int hours, int minutes, int seconds)
  {
    Calendar cal = new GregorianCalendar(year+1900, month, date,
					 hours, minutes, seconds);
    millis = cal.getTimeInMillis();
  }

  public void setTime(long millis) { this.millis = millis; }

  private int getField (int fld)
  {
    Calendar cal = new GregorianCalendar();
    cal.setTime(this);
    return cal.get(fld);
  }

  public int getYear ()
  {
    return getField(Calendar.YEAR) - 1900;
  }

  public int getMonth ()
  {
    return getField(Calendar.MONTH);
  }

  public int getDate ()
  {
    return getField(Calendar.DATE);
  }

  public int getDay ()
  {
    return getField(Calendar.DAY_OF_WEEK) - 1;
  }

  public int getHours ()
  {
    return getField(Calendar.HOUR_OF_DAY);
  }

  public int getMinutes ()
  {
    return getField(Calendar.MINUTE);
  }

  public int getSeconds ()
  {
    return getField(Calendar.SECOND);
  }

  private void setField (int fld, int value)
  {
    Calendar cal = new GregorianCalendar();
    cal.setTime(this);
    cal.set(fld, value);
    millis = cal.getTimeInMillis();
  }

  public void setYear (int year)
  {
    setField(Calendar.YEAR, 1900 + year);
  }

  public void setMonth (int month)
  {
    setField(Calendar.MONTH, month);
  }

  public void setDate (int date)
  {
    setField(Calendar.DATE, date);
  }

  public void setHours (int hours)
  {
    setField(Calendar.HOUR_OF_DAY, hours);
  }

  public void setMinutes (int minutes)
  {
    setField(Calendar.MINUTE, minutes);
  }

  public void setSeconds (int seconds)
  {
    setField(Calendar.SECOND, seconds);
  }

  public int getTimezoneOffset ()
  {
    Calendar cal = new GregorianCalendar(); 
    cal.setTime(this);
    return - (cal.get(Calendar.ZONE_OFFSET)
	      + cal.get(Calendar.DST_OFFSET)/(60*1000));
  }

  public native String toString ();

  // TODO: toLocaleString
  // TODO: toGMTString

  public static long UTC (int year, int month, int date,
			  int hours, int minutes, int seconds)
  {
    GregorianCalendar cal = new GregorianCalendar (TimeZone.zoneGMT);
    cal.set(year+1900, month, date, hours, minutes, seconds);
    return cal.getTimeInMillis();
  }
}
