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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * Copyright (c) 2011-2012, Stephen Colebourne & Michael Nascimento Santos

 *

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 *  * Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 *

 *  * Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

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 *  * Neither the name of JSR-310 nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

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 */

package java.time.format;

import static java.time.temporal.ChronoField.AMPM_OF_DAY;

import static java.time.temporal.ChronoField.DAY_OF_WEEK;

import static java.time.temporal.ChronoField.MONTH_OF_YEAR;

import java.time.temporal.Chrono;

import java.time.temporal.ISOChrono;

import java.time.calendar.JapaneseChrono;

import java.time.calendar.ThaiBuddhistChrono;

import java.time.temporal.TemporalField;

import java.util.AbstractMap.SimpleImmutableEntry;

import java.util.ArrayList;

import java.util.Calendar;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Locale;

import java.util.Map;

import java.util.Map.Entry;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.ConcurrentMap;

import java.util.spi.CalendarNameProvider;

import sun.util.locale.provider.LocaleProviderAdapter;

import sun.util.locale.provider.CalendarDataUtility;

/**

 * A provider to obtain the textual form of a date-time field.

 *

 * <h3>Specification for implementors</h3>

 * Implementations must be thread-safe.

 * Implementations should cache the textual information.

 *

 * @since 1.8

 */

class DateTimeTextProvider {

    /** Cache. */

    private static final ConcurrentMap<Entry<TemporalField, Locale>, Object> CACHE = new ConcurrentHashMap<>(16, 0.75f, 2);

    /** Comparator. */

    private static final Comparator<Entry<String, Long>> COMPARATOR = new Comparator<Entry<String, Long>>() {

        @Override

        public int compare(Entry<String, Long> obj1, Entry<String, Long> obj2) {

            return obj2.getKey().length() - obj1.getKey().length();  // longest to shortest

        }

    };

    DateTimeTextProvider() {}

    /**

     * Gets the provider of text.

     *

     * @return the provider, not null

     */

    static DateTimeTextProvider getInstance() {

        return new DateTimeTextProvider();

    }

    /**

     * Gets the text for the specified field, locale and style

     * for the purpose of printing.

     * <p>

     * The text associated with the value is returned.

     * The null return value should be used if there is no applicable text, or

     * if the text would be a numeric representation of the value.

     *

     * @param field  the field to get text for, not null

     * @param value  the field value to get text for, not null

     * @param style  the style to get text for, not null

     * @param locale  the locale to get text for, not null

     * @return the text for the field value, null if no text found

     */

    public String getText(TemporalField field, long value, TextStyle style, Locale locale) {

        Object store = findStore(field, locale);

        if (store instanceof LocaleStore) {

            return ((LocaleStore) store).getText(value, style);

        }

        return null;

    }

    private static int toStyle(TextStyle style) {

        if (style == TextStyle.FULL) {

            return Calendar.LONG_FORMAT;

        } else if (style == TextStyle.SHORT) {

            return Calendar.SHORT_FORMAT;

        }

        return Calendar.NARROW_STANDALONE;

    }

    /**

     * Gets the era text for the specified chrono, value, style and locale

     * for the purpose of printing.

     * <p>

     * The era text associated with the value is returned.

     * The null return value should be used if there is no applicable text, or

     * if the text would be a numeric representation of the value.

     *

     * @param chrono the chrono to get text for, not null

     * @param value  the field value to get text for, not null

     * @param style  the style to get text for, not null

     * @param locale  the locale to get text for, not null

     * @return the era text for the value, null if no text found

     */

    public String getEraText(Chrono chrono, long value, TextStyle style, Locale locale) {

        String type = null;

        if (chrono == ISOChrono.INSTANCE) {

            type = "gregory";

        } else if (chrono == JapaneseChrono.INSTANCE) {

            type = "japanese";

            if (value == -999) {

                value = 0;

            } else {

                value += 2;

            }

        } else if (chrono == ThaiBuddhistChrono.INSTANCE) {

            type = "buddhist";

        } else {

            return null;

        }

        return CalendarDataUtility.retrieveFieldValueName(

            type, Calendar.ERA, (int)value, toStyle(style), locale);

    }

    /**

     * Gets an iterator of text to field for the specified field, locale and style

     * for the purpose of parsing.

     * <p>

     * The iterator must be returned in order from the longest text to the shortest.

     * <p>

     * The null return value should be used if there is no applicable parsable text, or

     * if the text would be a numeric representation of the value.

     * Text can only be parsed if all the values for that field-style-locale combination are unique.

     *

     * @param field  the field to get text for, not null

     * @param style  the style to get text for, null for all parsable text

     * @param locale  the locale to get text for, not null

     * @return the iterator of text to field pairs, in order from longest text to shortest text,

     *  null if the field or style is not parsable

     */

    public Iterator<Entry<String, Long>> getTextIterator(TemporalField field, TextStyle style, Locale locale) {

        Object store = findStore(field, locale);

        if (store instanceof LocaleStore) {

            return ((LocaleStore) store).getTextIterator(style);

        }

        return null;

    }

    private Object findStore(TemporalField field, Locale locale) {

        Entry<TemporalField, Locale> key = createEntry(field, locale);

        Object store = CACHE.get(key);

        if (store == null) {

            store = createStore(field, locale);

            CACHE.putIfAbsent(key, store);

            store = CACHE.get(key);

        }

        return store;

    }

    private static int toWeekDay(int calWeekDay) {

        if (calWeekDay == Calendar.SUNDAY) {

            return 7;

        } else {

            return calWeekDay - 1;

        }

    }

    private Object createStore(TemporalField field, Locale locale) {

        CalendarNameProvider provider = LocaleProviderAdapter.getAdapter(CalendarNameProvider.class, locale)

                                                             .getCalendarNameProvider();

        Map<TextStyle, Map<Long, String>> styleMap = new HashMap<>();

        if (field == MONTH_OF_YEAR) {

            Map<Long, String> map = new HashMap<>();

            for (Entry<String, Integer> entry :

                 provider.getDisplayNames("gregory", Calendar.MONTH, Calendar.LONG_FORMAT, locale).entrySet()) {

                map.put((long)(entry.getValue() + 1), entry.getKey());

            }

            styleMap.put(TextStyle.FULL, map);

            map = new HashMap<>();

            for (Entry<String, Integer> entry :

                 provider.getDisplayNames("gregory", Calendar.MONTH, Calendar.SHORT_FORMAT, locale).entrySet()) {

                map.put((long)(entry.getValue() + 1), entry.getKey());

            }

            styleMap.put(TextStyle.SHORT, map);

            map = new HashMap<>();

            for (int month = Calendar.JANUARY; month <= Calendar.DECEMBER; month++) {

                String name = provider.getDisplayName("gregory", Calendar.MONTH, month, Calendar.NARROW_STANDALONE, locale);

                if (name != null) {

                    map.put((long)(month + 1), name);

                }

            }

            if (map.size() != 0) {

                styleMap.put(TextStyle.NARROW, map);

            }

            return new LocaleStore(styleMap);

        }

        if (field == DAY_OF_WEEK) {

            Map<Long, String> map = new HashMap<>();

            for (Entry<String, Integer> entry :

                 provider.getDisplayNames("gregory", Calendar.DAY_OF_WEEK, Calendar.LONG_FORMAT, locale).entrySet()) {

                map.put((long)toWeekDay(entry.getValue()), entry.getKey());

            }

            styleMap.put(TextStyle.FULL, map);

            map = new HashMap<>();

            for (Entry<String, Integer> entry :

                 provider.getDisplayNames("gregory", Calendar.DAY_OF_WEEK, Calendar.SHORT_FORMAT, locale).entrySet()) {

                map.put((long)toWeekDay(entry.getValue()), entry.getKey());

            }

            styleMap.put(TextStyle.SHORT, map);

            map = new HashMap<>();

            for (int wday = Calendar.SUNDAY; wday <= Calendar.SATURDAY; wday++) {

                map.put((long)toWeekDay(wday),

                        provider.getDisplayName("gregory", Calendar.DAY_OF_WEEK, wday, Calendar.NARROW_FORMAT, locale));

            }

            styleMap.put(TextStyle.NARROW, map);

            return new LocaleStore(styleMap);

        }

        if (field == AMPM_OF_DAY) {

            Map<Long, String> map = new HashMap<>();

            for (Entry<String, Integer> entry :

                 provider.getDisplayNames("gregory", Calendar.AM_PM, Calendar.LONG_FORMAT, locale).entrySet()) {

                map.put((long)entry.getValue(), entry.getKey());

            }

            styleMap.put(TextStyle.FULL, map);

            styleMap.put(TextStyle.SHORT, map);  // re-use, as we don't have different data

            return new LocaleStore(styleMap);

        }

        return "";  // null marker for map

    }

    /**

     * Helper method to create an immutable entry.

     *

     * @param text  the text, not null

     * @param field  the field, not null

     * @return the entry, not null

     */

    private static <A, B> Entry<A, B> createEntry(A text, B field) {

        return new SimpleImmutableEntry<>(text, field);

    }

    /**

     * Stores the text for a single locale.

     * <p>

     * Some fields have a textual representation, such as day-of-week or month-of-year.

     * These textual representations can be captured in this class for printing

     * and parsing.

     * <p>

     * This class is immutable and thread-safe.

     */

    static final class LocaleStore {

        /**

         * Map of value to text.

         */

        private final Map<TextStyle, Map<Long, String>> valueTextMap;

        /**

         * Parsable data.

         */

        private final Map<TextStyle, List<Entry<String, Long>>> parsable;

        /**

         * Constructor.

         *

         * @param valueTextMap  the map of values to text to store, assigned and not altered, not null

         */

        LocaleStore(Map<TextStyle, Map<Long, String>> valueTextMap) {

            this.valueTextMap = valueTextMap;

            Map<TextStyle, List<Entry<String, Long>>> map = new HashMap<>();

            List<Entry<String, Long>> allList = new ArrayList<>();

            for (TextStyle style : valueTextMap.keySet()) {

                Map<String, Entry<String, Long>> reverse = new HashMap<>();

                for (Map.Entry<Long, String> entry : valueTextMap.get(style).entrySet()) {

                    if (reverse.put(entry.getValue(), createEntry(entry.getValue(), entry.getKey())) != null) {

                        // TODO: BUG: this has no effect

                        continue;  // not parsable, try next style

                    }

                }

                List<Entry<String, Long>> list = new ArrayList<>(reverse.values());

                Collections.sort(list, COMPARATOR);

                map.put(style, list);

                allList.addAll(list);

                map.put(null, allList);

            }

            Collections.sort(allList, COMPARATOR);

            this.parsable = map;

        }

        /**

         * Gets the text for the specified field value, locale and style

         * for the purpose of printing.

         *

         * @param value  the value to get text for, not null

         * @param style  the style to get text for, not null

         * @return the text for the field value, null if no text found

         */

        String getText(long value, TextStyle style) {

            Map<Long, String> map = valueTextMap.get(style);

            return map != null ? map.get(value) : null;

        }

        /**

         * Gets an iterator of text to field for the specified style for the purpose of parsing.

         * <p>

         * The iterator must be returned in order from the longest text to the shortest.

         *

         * @param style  the style to get text for, null for all parsable text

         * @return the iterator of text to field pairs, in order from longest text to shortest text,

         *  null if the style is not parsable

         */

        Iterator<Entry<String, Long>> getTextIterator(TextStyle style) {

            List<Entry<String, Long>> list = parsable.get(style);

            return list != null ? list.iterator() : null;

        }

    }

}