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 * Copyright (c) 2012, 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
 * 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
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 */

package sun.util.cldr;

import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.text.spi.BreakIteratorProvider;
import java.text.spi.CollatorProvider;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.stream.Stream;
import sun.util.locale.provider.JRELocaleProviderAdapter;
import sun.util.locale.provider.LocaleProviderAdapter;
import sun.util.locale.provider.LocaleDataMetaInfo;

/**
 * LocaleProviderAdapter implementation for the CLDR locale data.
 *
 * @author Masayoshi Okutsu
 * @author Naoto Sato
 */
public class CLDRLocaleProviderAdapter extends JRELocaleProviderAdapter {

    private static final CLDRBaseLocaleDataMetaInfo baseMetaInfo = new CLDRBaseLocaleDataMetaInfo();
    // Assumption: CLDR has only one non-Base module.
    private final LocaleDataMetaInfo nonBaseMetaInfo;

    // parent locales map
    private static volatile Map<Locale, Locale> parentLocalesMap = null;

    public CLDRLocaleProviderAdapter() {
        try {
            nonBaseMetaInfo = AccessController.doPrivileged(new PrivilegedExceptionAction<LocaleDataMetaInfo>() {
                    @Override
                public LocaleDataMetaInfo run() {
                    for (LocaleDataMetaInfo ldmi : ServiceLoader.loadInstalled(LocaleDataMetaInfo.class)) {
                        if (ldmi.getType() == LocaleProviderAdapter.Type.CLDR) {
                            return ldmi;
                        }
                    }
                    return null;
                    }
                });
        }  catch (Exception e) {
            // Catch any exception, and fail gracefully as if CLDR locales do not exist.
            // It's ok ignore it if something wrong happens because there always is the
            // JRE or FALLBACK LocaleProviderAdapter that will do the right thing.
            throw new UnsupportedOperationException(e);
        }

        if (nonBaseMetaInfo == null) {
            throw new UnsupportedOperationException("CLDR locale data could not be found.");
        }
    }

    /**
     * Returns the type of this LocaleProviderAdapter
     * @return the type of this
     */
    @Override
    public LocaleProviderAdapter.Type getAdapterType() {
        return LocaleProviderAdapter.Type.CLDR;
    }

    @Override
    public BreakIteratorProvider getBreakIteratorProvider() {
        return null;
    }

    @Override
    public CollatorProvider getCollatorProvider() {
        return null;
    }

    @Override
    public Locale[] getAvailableLocales() {
        Set<String> all = createLanguageTagSet("AvailableLocales");
        Locale[] locs = new Locale[all.size()];
        int index = 0;
        for (String tag : all) {
            locs[index++] = Locale.forLanguageTag(tag);
        }
        return locs;
    }

    @Override
    protected Set<String> createLanguageTagSet(String category) {
        // Directly call Base tags, as we know it's in the base module.
        String supportedLocaleString = baseMetaInfo.availableLanguageTags(category);
        String nonBaseTags = nonBaseMetaInfo.availableLanguageTags(category);
        if (nonBaseTags != null) {
            if (supportedLocaleString != null) {
                supportedLocaleString += " " + nonBaseTags;
            } else {
                supportedLocaleString = nonBaseTags;
            }
        }
        if (supportedLocaleString == null) {
            return Collections.emptySet();
        }
        Set<String> tagset = new HashSet<>();
        StringTokenizer tokens = new StringTokenizer(supportedLocaleString);
        while (tokens.hasMoreTokens()) {
            tagset.add(tokens.nextToken());
        }
        return tagset;
    }

    // Implementation of ResourceBundleBasedAdapter
    @Override
    public List<Locale> getCandidateLocales(String baseName, Locale locale) {
        List<Locale> candidates = super.getCandidateLocales(baseName, locale);
        return applyParentLocales(baseName, candidates);
}

    private List<Locale> applyParentLocales(String baseName, List<Locale> candidates) {
        if (Objects.isNull(parentLocalesMap)) {
            Map<Locale, Locale> map = new HashMap<>();
            baseMetaInfo.parentLocales().forEach((parent, children) -> {
                Stream.of(children).forEach(child -> {
                    map.put(Locale.forLanguageTag(child), parent);
                });
            });
            parentLocalesMap = Collections.unmodifiableMap(map);
        }

        // check irregular parents
        for (int i = 0; i < candidates.size(); i++) {
            Locale l = candidates.get(i);
            Locale p = parentLocalesMap.get(l);
            if (!l.equals(Locale.ROOT) &&
                Objects.nonNull(p) &&
                !candidates.get(i+1).equals(p)) {
                List<Locale> applied = candidates.subList(0, i+1);
                applied.addAll(applyParentLocales(baseName, super.getCandidateLocales(baseName, p)));
                return applied;
            }
        }

        return candidates;
    }

    @Override
    public boolean isSupportedProviderLocale(Locale locale, Set<String> langtags) {
        return Locale.ROOT.equals(locale) ||
            langtags.contains(locale.stripExtensions().toLanguageTag());
    }
}