/* 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;

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

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3.
 * Status:  getAvailableIDs, getDefault, getTimeZone only know about GMT.
 */

public abstract class TimeZone implements java.io.Serializable, Cloneable
{
  public static final int SHORT = 0;
  public static final int LONG = 1;

  // The fields are as specified in Sun's "Serialized Form"
  // in the JDK 1.2 beta 4 API specification.
  String ID;

  static final TimeZone zoneGMT = new SimpleTimeZone(0, "GMT");

  private static TimeZone zoneDefault;

  public TimeZone ()
  {
  }

  public abstract int getOffset (int era, int year, int month,
				 int day, int dayOfWeek, int milliseconds);

  public abstract void setRawOffset (int offsetMillis);

  public abstract int getRawOffset ();

  public String getID () { return ID; }

  public void setID (String ID) { this.ID = ID; }

  public final String getDisplayName()
  {
    return ID;  // FIXME
  }

  // public final String getDisplayName (Local locale) { ... }  FIXME

  public final String getDisplayName (boolean daylight, int style)
  {
    return ID;  // FIXME
  }

  /*
  public final String getDisplayName (boolean daylight, int style, Locale locale)
  {
    return ID;  // FIXME
  }
  */

  public abstract boolean useDaylightTime();

  public abstract boolean inDaylightTime (Date date);

  public static synchronized TimeZone getTimeZone (String ID)
  {
    int i;
    for (i = 0; i < tzIDs.length; ++i)
      {
	if (ID.equals(tzIDs[i]))
	  break;
      }
    if (i == tzIDs.length)
      return null;

    if (timeZones[i] == null)
      {
	if (ID.equals("GMT"))
	  timeZones[i] = zoneGMT;
	else
	  timeZones[i] = new SimpleTimeZone (rawOffsets[i], tzIDs[i]);
      }

    return timeZones[i];
  }

  public static String[] getAvailableIDs()
  {
    return (String[]) tzIDs.clone();
  }

  public static String[] getAvailableIDs(int rawOffset)
  {
    int first, last;

    for (first = 0; first < rawOffsets.length; ++first)
      {
	if (rawOffset == rawOffsets[first])
	  break;
      }
    if (first == rawOffsets.length)
      return new String[0];
    for (last = first + 1; last < rawOffsets.length; ++last)
      {
	if (rawOffset != rawOffsets[last])
	  break;
      }

    String[] r = new String[last - first];
    for (int i = first; i < last; ++i)
      {
	r[i - first] = tzIDs[i];
      }

    return r;
  }

  private static synchronized TimeZone setDefault()
  {
    if (zoneDefault == null)
      {
	try
	  {
	    String id = System.getProperty("user.timezone");
	    if (id != null && ! id.equals("GMT"))
	      zoneDefault = getTimeZone(id);
	  }
	catch (Exception ex)
	  {
	  }
	if (zoneDefault == null)
	  zoneDefault = zoneGMT;
      }
    return zoneDefault;
  }

  public static TimeZone getDefault()
  {
    return zoneDefault == null ? setDefault() : zoneDefault;
  }

  public static void setDefault (TimeZone zone) { zoneDefault = zone; }

  public boolean hasSameRules (TimeZone other)
  {
    return this == other;
  }

  // public Object clone ();

  // Names of timezones.  This array is kept in parallel with
  // rawOffsets.  This list comes from the JCL 1.1 book.
  private static final String[] tzIDs =
  {
    "MIT", "HST", "AST", "PST", "PNT",
    "MST", "CST", "EST", "IET", "PRT",
    "CNT", "AGT", "BET", "CAT", "GMT",
    "ECT", "EET", "ART", "EAT", "MET",
    "NET", "PLT", "IST", "BST", "VST",
    "CTT", "JST", "ACT", "AET", "SST",
    "NST"
  };
  // This holds raw offsets in milliseconds.
  // 3600000 == 60 * 60 * 1000
  private static final int[] rawOffsets =
  {
    -11 * 3600000, -10 * 3600000, -9 * 3600000, -8 * 3600000, -7 * 3600000,
    -7 * 3600000, -6 * 3600000, -5 * 3600000, -5 * 3600000, -4 * 3600000,
    -35 * 360000, -3 * 3600000, -3 * 3600000, -1 * 3600000, 0,
    1 * 3600000, 1 * 3600000, 2 * 3600000, 3 * 3600000, 35 * 360000,
    4 * 3600000, 5 * 3600000, 55 * 360000, 6 * 3600000, 7 * 3600000,
    8 * 3600000, 9 * 3600000, 95 * 360000, 10 * 3600000, 11 * 3600000,
    12 * 3600000
  };
  // This caches all the corresponding zone objects.
  private static TimeZone[] timeZones = new TimeZone[tzIDs.length];
}