/*

 * Copyright 1996-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - All Rights Reserved

 *

 *   The original version of this source code and documentation is copyrighted

 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These

 * materials are provided under terms of a License Agreement between Taligent

 * and Sun. This technology is protected by multiple US and International

 * patents. This notice and attribution to Taligent may not be removed.

 *   Taligent is a registered trademark of Taligent, Inc.

 *

 */

package java.util;

import java.io.Serializable;

import java.lang.ref.SoftReference;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.concurrent.ConcurrentHashMap;

import sun.security.action.GetPropertyAction;

import sun.util.TimeZoneNameUtility;

import sun.util.calendar.ZoneInfo;

import sun.util.calendar.ZoneInfoFile;

/**

 * <code>TimeZone</code> represents a time zone offset, and also figures out daylight

 * savings.

 *

 * <p>

 * Typically, you get a <code>TimeZone</code> using <code>getDefault</code>

 * which creates a <code>TimeZone</code> based on the time zone where the program

 * is running. For example, for a program running in Japan, <code>getDefault</code>

 * creates a <code>TimeZone</code> object based on Japanese Standard Time.

 *

 * <p>

 * You can also get a <code>TimeZone</code> using <code>getTimeZone</code>

 * along with a time zone ID. For instance, the time zone ID for the

 * U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a

 * U.S. Pacific Time <code>TimeZone</code> object with:

 * <blockquote><pre>

 * TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");

 * </pre></blockquote>

 * You can use the <code>getAvailableIDs</code> method to iterate through

 * all the supported time zone IDs. You can then choose a

 * supported ID to get a <code>TimeZone</code>.

 * If the time zone you want is not represented by one of the

 * supported IDs, then a custom time zone ID can be specified to

 * produce a TimeZone. The syntax of a custom time zone ID is:

 *

 * <blockquote><pre>

 * <a name="CustomID"><i>CustomID:</i></a>

 *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i>

 *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <i>Minutes</i>

 *         <code>GMT</code> <i>Sign</i> <i>Hours</i>

 * <i>Sign:</i> one of

 *         <code>+ -</code>

 * <i>Hours:</i>

 *         <i>Digit</i>

 *         <i>Digit</i> <i>Digit</i>

 * <i>Minutes:</i>

 *         <i>Digit</i> <i>Digit</i>

 * <i>Digit:</i> one of

 *         <code>0 1 2 3 4 5 6 7 8 9</code>

 * </pre></blockquote>

 *

 * <i>Hours</i> must be between 0 to 23 and <i>Minutes</i> must be

 * between 00 to 59.  For example, "GMT+10" and "GMT+0010" mean ten

 * hours and ten minutes ahead of GMT, respectively.

 * <p>

 * The format is locale independent and digits must be taken from the

 * Basic Latin block of the Unicode standard. No daylight saving time

 * transition schedule can be specified with a custom time zone ID. If

 * the specified string doesn't match the syntax, <code>"GMT"</code>

 * is used.

 * <p>

 * When creating a <code>TimeZone</code>, the specified custom time

 * zone ID is normalized in the following syntax:

 * <blockquote><pre>

 * <a name="NormalizedCustomID"><i>NormalizedCustomID:</i></a>

 *         <code>GMT</code> <i>Sign</i> <i>TwoDigitHours</i> <code>:</code> <i>Minutes</i>

 * <i>Sign:</i> one of

 *         <code>+ -</code>

 * <i>TwoDigitHours:</i>

 *         <i>Digit</i> <i>Digit</i>

 * <i>Minutes:</i>

 *         <i>Digit</i> <i>Digit</i>

 * <i>Digit:</i> one of

 *         <code>0 1 2 3 4 5 6 7 8 9</code>

 * </pre></blockquote>

 * For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".

 *

 * <h4>Three-letter time zone IDs</h4>

 *

 * For compatibility with JDK 1.1.x, some other three-letter time zone IDs

 * (such as "PST", "CTT", "AST") are also supported. However, <strong>their

 * use is deprecated</strong> because the same abbreviation is often used

 * for multiple time zones (for example, "CST" could be U.S. "Central Standard

 * Time" and "China Standard Time"), and the Java platform can then only

 * recognize one of them.

 *

 *

 * @see          Calendar

 * @see          GregorianCalendar

 * @see          SimpleTimeZone

 * @author       Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu

 * @since        JDK1.1

 */

abstract public class TimeZone implements Serializable, Cloneable {

    /**

     * Sole constructor.  (For invocation by subclass constructors, typically

     * implicit.)

     */

    public TimeZone() {

    }

    /**

     * A style specifier for <code>getDisplayName()</code> indicating

     * a short name, such as "PST."

     * @see #LONG

     * @since 1.2

     */

    public static final int SHORT = 0;

    /**

     * A style specifier for <code>getDisplayName()</code> indicating

     * a long name, such as "Pacific Standard Time."

     * @see #SHORT

     * @since 1.2

     */

    public static final int LONG  = 1;

    // Constants used internally; unit is milliseconds

    private static final int ONE_MINUTE = 60*1000;

    private static final int ONE_HOUR   = 60*ONE_MINUTE;

    private static final int ONE_DAY    = 24*ONE_HOUR;

    /**

     * Cache to hold the SimpleDateFormat objects for a Locale.

     */

    private static Hashtable cachedLocaleData = new Hashtable(3);

    // Proclaim serialization compatibility with JDK 1.1

    static final long serialVersionUID = 3581463369166924961L;

    /**

     * Gets the time zone offset, for current date, modified in case of

     * daylight savings. This is the offset to add to UTC to get local time.

     * <p>

     * This method returns a historically correct offset if an

     * underlying <code>TimeZone</code> implementation subclass

     * supports historical Daylight Saving Time schedule and GMT

     * offset changes.

     *

     * @param era the era of the given date.

     * @param year the year in the given date.

     * @param month the month in the given date.

     * Month is 0-based. e.g., 0 for January.

     * @param day the day-in-month of the given date.

     * @param dayOfWeek the day-of-week of the given date.

     * @param milliseconds the milliseconds in day in <em>standard</em>

     * local time.

     *

     * @return the offset in milliseconds to add to GMT to get local time.

     *

     * @see Calendar#ZONE_OFFSET

     * @see Calendar#DST_OFFSET

     */

    public abstract int getOffset(int era, int year, int month, int day,

                                  int dayOfWeek, int milliseconds);

    /**

     * Returns the offset of this time zone from UTC at the specified

     * date. If Daylight Saving Time is in effect at the specified

     * date, the offset value is adjusted with the amount of daylight

     * saving.

     * <p>

     * This method returns a historically correct offset value if an

     * underlying TimeZone implementation subclass supports historical

     * Daylight Saving Time schedule and GMT offset changes.

     *

     * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT

     * @return the amount of time in milliseconds to add to UTC to get local time.

     *

     * @see Calendar#ZONE_OFFSET

     * @see Calendar#DST_OFFSET

     * @since 1.4

     */

    public int getOffset(long date) {

        if (inDaylightTime(new Date(date))) {

            return getRawOffset() + getDSTSavings();

        }

        return getRawOffset();

    }

    /**

     * Gets the raw GMT offset and the amount of daylight saving of this

     * time zone at the given time.

     * @param date the milliseconds (since January 1, 1970,

     * 00:00:00.000 GMT) at which the time zone offset and daylight

     * saving amount are found

     * @param offset an array of int where the raw GMT offset

     * (offset[0]) and daylight saving amount (offset[1]) are stored,

     * or null if those values are not needed. The method assumes that

     * the length of the given array is two or larger.

     * @return the total amount of the raw GMT offset and daylight

     * saving at the specified date.

     *

     * @see Calendar#ZONE_OFFSET

     * @see Calendar#DST_OFFSET

     */

    int getOffsets(long date, int[] offsets) {

        int rawoffset = getRawOffset();

        int dstoffset = 0;

        if (inDaylightTime(new Date(date))) {

            dstoffset = getDSTSavings();

        }

        if (offsets != null) {

            offsets[0] = rawoffset;

            offsets[1] = dstoffset;

        }

        return rawoffset + dstoffset;

    }

    /**

     * Sets the base time zone offset to GMT.

     * This is the offset to add to UTC to get local time.

     * <p>

     * If an underlying <code>TimeZone</code> implementation subclass

     * supports historical GMT offset changes, the specified GMT

     * offset is set as the latest GMT offset and the difference from

     * the known latest GMT offset value is used to adjust all

     * historical GMT offset values.

     *

     * @param offsetMillis the given base time zone offset to GMT.

     */

    abstract public void setRawOffset(int offsetMillis);

    /**

     * Returns the amount of time in milliseconds to add to UTC to get

     * standard time in this time zone. Because this value is not

     * affected by daylight saving time, it is called <I>raw

     * offset</I>.

     * <p>

     * If an underlying <code>TimeZone</code> implementation subclass

     * supports historical GMT offset changes, the method returns the

     * raw offset value of the current date. In Honolulu, for example,

     * its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and

     * this method always returns -36000000 milliseconds (i.e., -10

     * hours).

     *

     * @return the amount of raw offset time in milliseconds to add to UTC.

     * @see Calendar#ZONE_OFFSET

     */

    public abstract int getRawOffset();

    /**

     * Gets the ID of this time zone.

     * @return the ID of this time zone.

     */

    public String getID()

    {

        return ID;

    }

    /**

     * Sets the time zone ID. This does not change any other data in

     * the time zone object.

     * @param ID the new time zone ID.

     */

    public void setID(String ID)

    {

        if (ID == null) {

            throw new NullPointerException();

        }

        this.ID = ID;

    }

    /**

     * Returns a name of this time zone suitable for presentation to the user

     * in the default locale.

     * This method returns the long name, not including daylight savings.

     * If the display name is not available for the locale,

     * then this method returns a string in the

     * <a href="#NormalizedCustomID">normalized custom ID format</a>.

     * @return the human-readable name of this time zone in the default locale.

     * @since 1.2

     */

    public final String getDisplayName() {

        return getDisplayName(false, LONG, Locale.getDefault());

    }

    /**

     * Returns a name of this time zone suitable for presentation to the user

     * in the specified locale.

     * This method returns the long name, not including daylight savings.

     * If the display name is not available for the locale,

     * then this method returns a string in the

     * <a href="#NormalizedCustomID">normalized custom ID format</a>.

     * @param locale the locale in which to supply the display name.

     * @return the human-readable name of this time zone in the given locale.

     * @since 1.2

     */

    public final String getDisplayName(Locale locale) {

        return getDisplayName(false, LONG, locale);

    }

    /**

     * Returns a name of this time zone suitable for presentation to the user

     * in the default locale.

     * If the display name is not available for the locale, then this

     * method returns a string in the

     * <a href="#NormalizedCustomID">normalized custom ID format</a>.

     * @param daylight if true, return the daylight savings name.

     * @param style either <code>LONG</code> or <code>SHORT</code>

     * @return the human-readable name of this time zone in the default locale.

     * @since 1.2

     */

    public final String getDisplayName(boolean daylight, int style) {

        return getDisplayName(daylight, style, Locale.getDefault());

    }

    /**

     * Returns a name of this time zone suitable for presentation to the user

     * in the specified locale.

     * If the display name is not available for the locale,

     * then this method returns a string in the

     * <a href="#NormalizedCustomID">normalized custom ID format</a>.

     * @param daylight if true, return the daylight savings name.

     * @param style either <code>LONG</code> or <code>SHORT</code>

     * @param locale the locale in which to supply the display name.

     * @return the human-readable name of this time zone in the given locale.

     * @exception IllegalArgumentException style is invalid.

     * @since 1.2

     */

    public String getDisplayName(boolean daylight, int style, Locale locale) {

        if (style != SHORT && style != LONG) {

            throw new IllegalArgumentException("Illegal style: " + style);

        }

        String id = getID();

        String[] names = getDisplayNames(id, locale);

        if (names == null) {

            if (id.startsWith("GMT")) {

                char sign = id.charAt(3);

                if (sign == '+' || sign == '-') {

                    return id;

                }

            }

            int offset = getRawOffset();

            if (daylight) {

                offset += getDSTSavings();

            }

            return ZoneInfoFile.toCustomID(offset);

        }

        int index = daylight ? 3 : 1;

        if (style == SHORT) {

            index++;

        }

        return names[index];

    }

    private static class DisplayNames {

        // Cache for managing display names per timezone per locale

        // The structure is:

        //   Map(key=id, value=SoftReference(Map(key=locale, value=displaynames)))

        private static final Map<String, SoftReference<Map<Locale, String[]>>> CACHE =

            new ConcurrentHashMap<String, SoftReference<Map<Locale, String[]>>>();

    }

    private static final String[] getDisplayNames(String id, Locale locale) {

        Map<String, SoftReference<Map<Locale, String[]>>> displayNames = DisplayNames.CACHE;

        SoftReference<Map<Locale, String[]>> ref = displayNames.get(id);

        if (ref != null) {

            Map<Locale, String[]> perLocale = ref.get();

            if (perLocale != null) {

                String[] names = perLocale.get(locale);

                if (names != null) {

                    return names;

                }

                names = TimeZoneNameUtility.retrieveDisplayNames(id, locale);

                if (names != null) {

                    perLocale.put(locale, names);

                }

                return names;

            }

        }

        String[] names = TimeZoneNameUtility.retrieveDisplayNames(id, locale);

        if (names != null) {

            Map<Locale, String[]> perLocale = new ConcurrentHashMap<Locale, String[]>();

            perLocale.put(locale, names);

            ref = new SoftReference<Map<Locale, String[]>>(perLocale);

            displayNames.put(id, ref);

        }

        return names;

    }

    /**

     * Returns the amount of time to be added to local standard time

     * to get local wall clock time.

     * <p>

     * The default implementation always returns 3600000 milliseconds

     * (i.e., one hour) if this time zone observes Daylight Saving

     * Time. Otherwise, 0 (zero) is returned.

     * <p>

     * If an underlying TimeZone implementation subclass supports

     * historical Daylight Saving Time changes, this method returns

     * the known latest daylight saving value.

     *

     * @return the amount of saving time in milliseconds

     * @since 1.4

     */

    public int getDSTSavings() {

        if (useDaylightTime()) {

            return 3600000;

        }

        return 0;

    }

    /**

     * Queries if this time zone uses daylight savings time.

     * <p>

     * If an underlying <code>TimeZone</code> implementation subclass

     * supports historical Daylight Saving Time schedule changes, the

     * method refers to the latest Daylight Saving Time schedule

     * information.

     *

     * @return true if this time zone uses daylight savings time,

     * false, otherwise.

     */

    public abstract boolean useDaylightTime();

    /**

     * Queries if the given date is in daylight savings time in

     * this time zone.

     * @param date the given Date.

     * @return true if the given date is in daylight savings time,

     * false, otherwise.

     */

    abstract public boolean inDaylightTime(Date date);

    /**

     * Gets the <code>TimeZone</code> for the given ID.

     *

     * @param ID the ID for a <code>TimeZone</code>, either an abbreviation

     * such as "PST", a full name such as "America/Los_Angeles", or a custom

     * ID such as "GMT-8:00". Note that the support of abbreviations is

     * for JDK 1.1.x compatibility only and full names should be used.

     *

     * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID

     * cannot be understood.

     */

    public static synchronized TimeZone getTimeZone(String ID) {

        return getTimeZone(ID, true);

    }

    private static TimeZone getTimeZone(String ID, boolean fallback) {

        TimeZone tz = ZoneInfo.getTimeZone(ID);

        if (tz == null) {

            tz = parseCustomTimeZone(ID);

            if (tz == null && fallback) {

                tz = new ZoneInfo(GMT_ID, 0);

            }

        }

        return tz;

    }

    /**

     * Gets the available IDs according to the given time zone offset in milliseconds.

     *

     * @param rawOffset the given time zone GMT offset in milliseconds.

     * @return an array of IDs, where the time zone for that ID has

     * the specified GMT offset. For example, "America/Phoenix" and "America/Denver"

     * both have GMT-07:00, but differ in daylight savings behavior.

     * @see #getRawOffset()

     */

    public static synchronized String[] getAvailableIDs(int rawOffset) {

        return ZoneInfo.getAvailableIDs(rawOffset);

    }

    /**

     * Gets all the available IDs supported.

     * @return an array of IDs.

     */

    public static synchronized String[] getAvailableIDs() {

        return ZoneInfo.getAvailableIDs();

    }

    /**

     * Gets the platform defined TimeZone ID.

     **/

    private static native String getSystemTimeZoneID(String javaHome,

                                                     String country);

    /**

     * Gets the custom time zone ID based on the GMT offset of the

     * platform. (e.g., "GMT+08:00")

     */

    private static native String getSystemGMTOffsetID();