/*

 * Copyright (c) 1996, 2015, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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

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 *

 * 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,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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/*

 * (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.security.AccessController;

import java.security.PrivilegedAction;

import java.time.ZoneId;

import sun.security.action.GetPropertyAction;

import sun.util.calendar.ZoneInfo;

import sun.util.calendar.ZoneInfoFile;

import sun.util.locale.provider.TimeZoneNameUtility;

/**

 * <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".

 *

 * <h3>Three-letter time zone IDs</h3>

 *

 * 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        1.1

 */

    /**

     * 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;

    // 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 offsets 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.

     */

    /**

     * 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;

        this.zoneId = null;   // invalidate cache

    }

    /**

     * Returns a long standard time name of this {@code TimeZone} suitable for

     * presentation to the user in the default locale.

     *

     * <p>This method is equivalent to:

     * <blockquote><pre>

     * getDisplayName(false, {@link #LONG},

     *                Locale.getDefault({@link Locale.Category#DISPLAY}))

     * </pre></blockquote>

     *

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

     * @since 1.2

     * @see #getDisplayName(boolean, int, Locale)

     * @see Locale#getDefault(Locale.Category)

     * @see Locale.Category

     */

    public final String getDisplayName() {

        return getDisplayName(false, LONG,

                              Locale.getDefault(Locale.Category.DISPLAY));

    }

    /**

     * Returns a long standard time name of this {@code TimeZone} suitable for

     * presentation to the user in the specified {@code locale}.

     *

     * <p>This method is equivalent to:

     * <blockquote><pre>

     * getDisplayName(false, {@link #LONG}, locale)

     * </pre></blockquote>

     *

     * @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 NullPointerException if {@code locale} is {@code null}.

     * @since 1.2

     * @see #getDisplayName(boolean, int, Locale)

     */

    public final String getDisplayName(Locale locale) {

        return getDisplayName(false, LONG, locale);

    }

    /**

     * Returns a name in the specified {@code style} of this {@code TimeZone}

     * suitable for presentation to the user in the default locale. If the

     * specified {@code daylight} is {@code true}, a Daylight Saving Time name

     * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving

     * Time). Otherwise, a Standard Time name is returned.

     *

     * <p>This method is equivalent to:

     * <blockquote><pre>

     * getDisplayName(daylight, style,

     *                Locale.getDefault({@link Locale.Category#DISPLAY}))

     * </pre></blockquote>

     *

     * @param daylight {@code true} specifying a Daylight Saving Time name, or

     *                 {@code false} specifying a Standard Time name

     * @param style either {@link #LONG} or {@link #SHORT}

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

     * @exception IllegalArgumentException if {@code style} is invalid.

     * @since 1.2

     * @see #getDisplayName(boolean, int, Locale)

     * @see Locale#getDefault(Locale.Category)

     * @see Locale.Category

     * @see java.text.DateFormatSymbols#getZoneStrings()

     */

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

        return getDisplayName(daylight, style,

                              Locale.getDefault(Locale.Category.DISPLAY));

    }

    /**

     * Returns a name in the specified {@code style} of this {@code TimeZone}

     * suitable for presentation to the user in the specified {@code

     * locale}. If the specified {@code daylight} is {@code true}, a Daylight

     * Saving Time name is returned (even if this {@code TimeZone} doesn't

     * observe Daylight Saving Time). Otherwise, a Standard Time name is

     * returned.

     *

     * <p>When looking up a time zone name, the {@linkplain

     * ResourceBundle.Control#getCandidateLocales(String,Locale) default

     * <code>Locale</code> search path of <code>ResourceBundle</code>} derived

     * from the specified {@code locale} is used. (No {@linkplain

     * ResourceBundle.Control#getFallbackLocale(String,Locale) fallback

     * <code>Locale</code>} search is performed.) If a time zone name in any

     * {@code Locale} of the search path, including {@link Locale#ROOT}, is

     * found, the name is returned. Otherwise, a string in the

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

     *

     * @param daylight {@code true} specifying a Daylight Saving Time name, or

     *                 {@code false} specifying a Standard Time name

     * @param style either {@link #LONG} or {@link #SHORT}

     * @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 if {@code style} is invalid.

     * @exception NullPointerException if {@code locale} is {@code null}.

     * @since 1.2

     * @see java.text.DateFormatSymbols#getZoneStrings()

     */

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

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

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

        }

        String id = getID();

        String name = TimeZoneNameUtility.retrieveDisplayName(id, daylight, style, locale);

        if (name != null) {

            return name;

        }

        if (id.startsWith("GMT") && id.length() > 3) {

            char sign = id.charAt(3);

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

                return id;

            }

        }

        int offset = getRawOffset();

        if (daylight) {

            offset += getDSTSavings();

        }

        return ZoneInfoFile.toCustomID(offset);

    }

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

        return TimeZoneNameUtility.retrieveDisplayNames(id, locale);

    }

    /**

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

     * to get local wall clock time.

     *

     * <p>The default implementation returns 3600000 milliseconds

     * (i.e., one hour) if a call to {@link #useDaylightTime()}

     * returns {@code true}. Otherwise, 0 (zero) is returned.

     *

     * <p>If an underlying {@code TimeZone} implementation subclass

     * supports historical and future Daylight Saving Time schedule

     * changes, this method returns the amount of saving time of the

     * last known Daylight Saving Time rule that can be a future

     * prediction.

     *

     * <p>If the amount of saving time at any given time stamp is

     * required, construct a {@link Calendar} with this {@code

     * TimeZone} and the time stamp, and call {@link Calendar#get(int)

     * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}.

     *

     * @return the amount of saving time in milliseconds

     * @since 1.4

     * @see #inDaylightTime(Date)

     * @see #getOffset(long)

     * @see #getOffset(int,int,int,int,int,int)

     * @see Calendar#ZONE_OFFSET

     */

    public int getDSTSavings() {

        if (useDaylightTime()) {

            return 3600000;

        }

        return 0;

    }

    /**

     * Queries if this {@code TimeZone} uses Daylight Saving Time.

     *

     * <p>If an underlying {@code TimeZone} implementation subclass

     * supports historical and future Daylight Saving Time schedule

     * changes, this method refers to the last known Daylight Saving Time

     * rule that can be a future prediction and may not be the same as

     * the current rule. Consider calling {@link #observesDaylightTime()}

     * if the current rule should also be taken into account.

     *

     * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time,

     *         {@code false}, otherwise.

     * @see #inDaylightTime(Date)

     * @see Calendar#DST_OFFSET

     */

    public abstract boolean useDaylightTime();

    /**

     * Returns {@code true} if this {@code TimeZone} is currently in

     * Daylight Saving Time, or if a transition from Standard Time to

     * Daylight Saving Time occurs at any future time.

     *

     * <p>The default implementation returns {@code true} if

     * {@code useDaylightTime()} or {@code inDaylightTime(new Date())}

     * returns {@code true}.

     *

     * @return {@code true} if this {@code TimeZone} is currently in

     * Daylight Saving Time, or if a transition from Standard Time to

     * Daylight Saving Time occurs at any future time; {@code false}

     * otherwise.

     * @since 1.7

     * @see #useDaylightTime()

     * @see #inDaylightTime(Date)

     * @see Calendar#DST_OFFSET

     */

    public boolean observesDaylightTime() {

        return useDaylightTime() || inDaylightTime(new Date());

    }

    /**

     * Queries if the given {@code date} is in Daylight Saving Time in

     * this time zone.

     *

     * @param date the given Date.

     * @return {@code true} if the given date is in Daylight Saving Time,

     *         {@code false}, otherwise.

     */

    /**

     * 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.