/*

 * Copyright (c) 2005, 2018, 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

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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.util.locale.provider;

import java.lang.ref.SoftReference;

import java.util.LinkedList;

import java.util.List;

import java.util.Locale;

import java.util.Map;

import java.util.Objects;

import java.util.Optional;

import java.util.Set;

import java.util.concurrent.ConcurrentHashMap;

import java.util.spi.TimeZoneNameProvider;

import sun.util.calendar.ZoneInfo;

import sun.util.cldr.CLDRLocaleProviderAdapter;

import static sun.util.locale.provider.LocaleProviderAdapter.Type;

/**

 * Utility class that deals with the localized time zone names

 *

 * @author Naoto Sato

 * @author Masayoshi Okutsu

 */

public final class TimeZoneNameUtility {

    /**

     * cache to hold time zone localized strings. Keyed by Locale

     */

    private static final ConcurrentHashMap<Locale, SoftReference<String[][]>> cachedZoneData =

        new ConcurrentHashMap<>();

    /**

     * 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[]>>> cachedDisplayNames =

        new ConcurrentHashMap<>();

    /**

     * get time zone localized strings. Enumerate all keys.

     */

    public static String[][] getZoneStrings(Locale locale) {

        String[][] zones;

        SoftReference<String[][]> data = cachedZoneData.get(locale);

        if (data == null || ((zones = data.get()) == null)) {

            zones = loadZoneStrings(locale);

            data = new SoftReference<>(zones);

            cachedZoneData.put(locale, data);

        }

        return zones;

    }

    private static String[][] loadZoneStrings(Locale locale) {

        // If the provider is a TimeZoneNameProviderImpl, call its getZoneStrings

        // in order to avoid per-ID retrieval.

        LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(TimeZoneNameProvider.class, locale);

        TimeZoneNameProvider provider = adapter.getTimeZoneNameProvider();

        if (provider instanceof TimeZoneNameProviderImpl) {

            String[][] zoneStrings = ((TimeZoneNameProviderImpl)provider).getZoneStrings(locale);

            if (zoneStrings.length == 0 && locale.equals(Locale.ROOT)) {

                // Unlike other *Name provider, zoneStrings search won't do the fallback

                // name search. If the ResourceBundle found for the root locale contains no

                // zoneStrings, just use the one for English, assuming English bundle

                // contains all the tzids and their names.

                zoneStrings= getZoneStrings(Locale.ENGLISH);

            }

            return zoneStrings;

        }

        // Performs per-ID retrieval.

        Set<String> zoneIDs = LocaleProviderAdapter.forJRE().getLocaleResources(locale).getZoneIDs();

        List<String[]> zones = new LinkedList<>();

        for (String key : zoneIDs) {

            String[] names = retrieveDisplayNamesImpl(key, locale);

            if (names != null) {

                zones.add(names);

            }

        }

        String[][] zonesArray = new String[zones.size()][];

        return zones.toArray(zonesArray);

    }

    /**

     * Retrieve display names for a time zone ID.

     */

    public static String[] retrieveDisplayNames(String id, Locale locale) {

        Objects.requireNonNull(id);

        Objects.requireNonNull(locale);

        return retrieveDisplayNamesImpl(id, locale);

    }

    /**

     * Retrieves a generic time zone display name for a time zone ID.

     *

     * @param id     time zone ID

     * @param style  TimeZone.LONG or TimeZone.SHORT

     * @param locale desired Locale

     * @return the requested generic time zone display name, or null if not found.

     */

    public static String retrieveGenericDisplayName(String id, int style, Locale locale) {

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

        if (Objects.nonNull(names)) {

            return names[6 - style];

        } else {

            return null;

        }

    }

    /**

     * Retrieves a standard or daylight-saving time name for the given time zone ID.

     *

     * @param id       time zone ID

     * @param daylight true for a daylight saving time name, or false for a standard time name

     * @param style    TimeZone.LONG or TimeZone.SHORT

     * @param locale   desired Locale

     * @return the requested time zone name, or null if not found.

     */

    public static String retrieveDisplayName(String id, boolean daylight, int style, Locale locale) {

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

        if (Objects.nonNull(names)) {

            return names[(daylight ? 4 : 2) - style];

        } else {

            return null;

        }

    }

    /**

     * Converts the time zone id from LDML's 5-letter id to tzdb's id

     *

     * @param shortID       time zone short ID defined in LDML

     * @return the tzdb's time zone ID

     */

    public static Optional<String> convertLDMLShortID(String shortID) {

        return canonicalTZID(shortID);

    }

    /**

     * Returns the canonical ID for the given ID

     */

    public static Optional<String> canonicalTZID(String id) {

        return ((CLDRLocaleProviderAdapter)LocaleProviderAdapter.forType(Type.CLDR))

                    .canonicalTZID(id);

    }

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

        LocaleServiceProviderPool pool =

            LocaleServiceProviderPool.getPool(TimeZoneNameProvider.class);

        String[] names;

        Map<Locale, String[]> perLocale = null;

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

        if (Objects.nonNull(ref)) {

            perLocale = ref.get();

            if (Objects.nonNull(perLocale)) {

                names = perLocale.get(locale);

                if (Objects.nonNull(names)) {

                    return names;

                }

            }

        }

        // build names array

        names = new String[7];

        names[0] = id;

        for (int i = 1; i <= 6; i ++) {

            names[i] = pool.getLocalizedObject(TimeZoneNameGetter.INSTANCE, locale,

                    i<5 ? (i<3 ? "std" : "dst") : "generic", i%2, id);

        }

        if (Objects.isNull(perLocale)) {

            perLocale = new ConcurrentHashMap<>();

        }

        perLocale.put(locale, names);

        ref = new SoftReference<>(perLocale);

        cachedDisplayNames.put(id, ref);

        return names;

    }

    /**

     * Obtains a localized time zone strings from a TimeZoneNameProvider

     * implementation.

     */

    private static class TimeZoneNameGetter

        implements LocaleServiceProviderPool.LocalizedObjectGetter<TimeZoneNameProvider,

                                                                   String> {

        private static final TimeZoneNameGetter INSTANCE =

            new TimeZoneNameGetter();

        @Override

        public String getObject(TimeZoneNameProvider timeZoneNameProvider,

                                Locale locale,

                                String requestID,

                                Object... params) {

            assert params.length == 2;

            int style = (int) params[0];

            String tzid = (String) params[1];

            String value = getName(timeZoneNameProvider, locale, requestID, style, tzid);

            if (value == null) {

                Map<String, String> aliases = ZoneInfo.getAliasTable();

                if (aliases != null) {

                    String canonicalID = aliases.get(tzid);

                    if (canonicalID != null) {

                        value = getName(timeZoneNameProvider, locale, requestID, style, canonicalID);

                    }

                    if (value == null) {

                        value = examineAliases(timeZoneNameProvider, locale, requestID,

                                     canonicalID != null ? canonicalID : tzid, style, aliases);

                    }

                }

            }

            return value;

        }

        private static String examineAliases(TimeZoneNameProvider tznp, Locale locale,

                                             String requestID, String tzid, int style,

                                             Map<String, String> aliases) {

            for (Map.Entry<String, String> entry : aliases.entrySet()) {

                if (entry.getValue().equals(tzid)) {

                    String alias = entry.getKey();

                    String name = getName(tznp, locale, requestID, style, alias);

                    if (name != null) {

                        return name;

                    }

                    name = examineAliases(tznp, locale, requestID, alias, style, aliases);

                    if (name != null) {

                        return name;

                    }

                }

            }

            return null;

        }

        private static String getName(TimeZoneNameProvider timeZoneNameProvider,

                                      Locale locale, String requestID, int style, String tzid) {

            String value = null;

            switch (requestID) {

            case "std":

                value = timeZoneNameProvider.getDisplayName(tzid, false, style, locale);

                break;

            case "dst":

                value = timeZoneNameProvider.getDisplayName(tzid, true, style, locale);

                break;

            case "generic":

                value = timeZoneNameProvider.getGenericDisplayName(tzid, style, locale);

                break;

            }

            return value;

        }

    }

    // No instantiation

    private TimeZoneNameUtility() {

    }

}