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

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 * 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

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

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

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 * 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

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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) 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.

 *

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

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

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR

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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

package java.time.chrono;

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

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

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

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

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

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

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

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

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

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

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

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

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

import static java.time.temporal.ChronoUnit.DAYS;

import static java.time.temporal.ChronoUnit.MONTHS;

import static java.time.temporal.ChronoUnit.WEEKS;

import static java.time.temporal.TemporalAdjusters.nextOrSame;

import java.io.DataInput;

import java.io.DataOutput;

import java.io.IOException;

import java.io.InvalidObjectException;

import java.io.ObjectInputStream;

import java.io.ObjectStreamException;

import java.io.Serializable;

import java.time.DateTimeException;

import java.time.DayOfWeek;

import java.time.format.ResolverStyle;

import java.time.temporal.ChronoField;

import java.time.temporal.TemporalAdjusters;

import java.time.temporal.TemporalField;

import java.time.temporal.ValueRange;

import java.util.Comparator;

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.concurrent.ConcurrentHashMap;

import sun.util.logging.PlatformLogger;

/**

 * An abstract implementation of a calendar system, used to organize and identify dates.

 * <p>

 * The main date and time API is built on the ISO calendar system.

 * The chronology operates behind the scenes to represent the general concept of a calendar system.

 * <p>

 * See {@link Chronology} for more details.

 *

 * @implSpec

 * This class is separated from the {@code Chronology} interface so that the static methods

 * are not inherited. While {@code Chronology} can be implemented directly, it is strongly

 * recommended to extend this abstract class instead.

 * <p>

 * This class must be implemented with care to ensure other classes operate correctly.

 * All implementations that can be instantiated must be final, immutable and thread-safe.

 * Subclasses should be Serializable wherever possible.

 *

 * @since 1.8

 */

public abstract class AbstractChronology implements Chronology {

    /**

     * Map of available calendars by ID.

     */

    private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_ID = new ConcurrentHashMap<>();

    /**

     * Map of available calendars by calendar type.

     */

    private static final ConcurrentHashMap<String, Chronology> CHRONOS_BY_TYPE = new ConcurrentHashMap<>();

    /**

     * Register a Chronology by its ID and type for lookup by {@link #of(String)}.

     * Chronologies must not be registered until they are completely constructed.

     * Specifically, not in the constructor of Chronology.

     *

     * @param chrono the chronology to register; not null

     * @return the already registered Chronology if any, may be null

     */

    static Chronology registerChrono(Chronology chrono) {

        return registerChrono(chrono, chrono.getId());

    }

    /**

     * Register a Chronology by ID and type for lookup by {@link #of(String)}.

     * Chronos must not be registered until they are completely constructed.

     * Specifically, not in the constructor of Chronology.

     *

     * @param chrono the chronology to register; not null

     * @param id the ID to register the chronology; not null

     * @return the already registered Chronology if any, may be null

     */

    static Chronology registerChrono(Chronology chrono, String id) {

        Chronology prev = CHRONOS_BY_ID.putIfAbsent(id, chrono);

        if (prev == null) {

            String type = chrono.getCalendarType();

            if (type != null) {

                CHRONOS_BY_TYPE.putIfAbsent(type, chrono);

            }

        }

        return prev;

    }

    /**

     * Initialization of the maps from id and type to Chronology.

     * The ServiceLoader is used to find and register any implementations

     * of {@link java.time.chrono.AbstractChronology} found in the bootclass loader.

     * The built-in chronologies are registered explicitly.

     * Calendars configured via the Thread's context classloader are local

     * to that thread and are ignored.

     * <p>

     * The initialization is done only once using the registration

     * of the IsoChronology as the test and the final step.

     * Multiple threads may perform the initialization concurrently.

     * Only the first registration of each Chronology is retained by the

     * ConcurrentHashMap.

     * @return true if the cache was initialized

     */

    private static boolean initCache() {

        if (CHRONOS_BY_ID.get("ISO") == null) {

            // Initialization is incomplete

            // Register built-in Chronologies

            registerChrono(HijrahChronology.INSTANCE);

            registerChrono(JapaneseChronology.INSTANCE);

            registerChrono(MinguoChronology.INSTANCE);

            registerChrono(ThaiBuddhistChronology.INSTANCE);

            // Register Chronologies from the ServiceLoader

            @SuppressWarnings("rawtypes")

            ServiceLoader<AbstractChronology> loader =  ServiceLoader.load(AbstractChronology.class, null);

            for (AbstractChronology chrono : loader) {

                String id = chrono.getId();

                if (id.equals("ISO") || registerChrono(chrono) != null) {

                    // Log the attempt to replace an existing Chronology

                    PlatformLogger logger = PlatformLogger.getLogger("java.time.chrono");

                    logger.warning("Ignoring duplicate Chronology, from ServiceLoader configuration "  + id);

                }

            }

            // finally, register IsoChronology to mark initialization is complete

            registerChrono(IsoChronology.INSTANCE);

            return true;

        }

        return false;

    }

    //-----------------------------------------------------------------------

    /**

     * Obtains an instance of {@code Chronology} from a locale.

     * <p>

     * See {@link Chronology#ofLocale(Locale)}.

     *

     * @param locale  the locale to use to obtain the calendar system, not null

     * @return the calendar system associated with the locale, not null

     * @throws java.time.DateTimeException if the locale-specified calendar cannot be found

     */

    static Chronology ofLocale(Locale locale) {

        Objects.requireNonNull(locale, "locale");

        String type = locale.getUnicodeLocaleType("ca");

        if (type == null || "iso".equals(type) || "iso8601".equals(type)) {

            return IsoChronology.INSTANCE;

        }

        // Not pre-defined; lookup by the type

        do {

            Chronology chrono = CHRONOS_BY_TYPE.get(type);

            if (chrono != null) {

                return chrono;

            }

            // If not found, do the initialization (once) and repeat the lookup

        } while (initCache());

        // Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader

        // Application provided Chronologies must not be cached

        @SuppressWarnings("rawtypes")

        ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);

        for (Chronology chrono : loader) {

            if (type.equals(chrono.getCalendarType())) {

                return chrono;

            }

        }

        throw new DateTimeException("Unknown calendar system: " + type);

    }

    //-----------------------------------------------------------------------

    /**

     * Obtains an instance of {@code Chronology} from a chronology ID or

     * calendar system type.

     * <p>

     * See {@link Chronology#of(String)}.

     *

     * @param id  the chronology ID or calendar system type, not null

     * @return the chronology with the identifier requested, not null

     * @throws java.time.DateTimeException if the chronology cannot be found

     */

    static Chronology of(String id) {

        Objects.requireNonNull(id, "id");

        do {

            Chronology chrono = of0(id);

            if (chrono != null) {

                return chrono;

            }

            // If not found, do the initialization (once) and repeat the lookup

        } while (initCache());

        // Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader

        // Application provided Chronologies must not be cached

        @SuppressWarnings("rawtypes")

        ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);

        for (Chronology chrono : loader) {

            if (id.equals(chrono.getId()) || id.equals(chrono.getCalendarType())) {

                return chrono;

            }

        }

        throw new DateTimeException("Unknown chronology: " + id);

    }

    /**

     * Obtains an instance of {@code Chronology} from a chronology ID or

     * calendar system type.

     *

     * @param id  the chronology ID or calendar system type, not null

     * @return the chronology with the identifier requested, or {@code null} if not found

     */

    private static Chronology of0(String id) {

        Chronology chrono = CHRONOS_BY_ID.get(id);

        if (chrono == null) {

            chrono = CHRONOS_BY_TYPE.get(id);

        }

        return chrono;

    }

    /**

     * Returns the available chronologies.

     * <p>

     * Each returned {@code Chronology} is available for use in the system.

     * The set of chronologies includes the system chronologies and

     * any chronologies provided by the application via ServiceLoader

     * configuration.

     *

     * @return the independent, modifiable set of the available chronology IDs, not null

     */

    static Set<Chronology> getAvailableChronologies() {

        initCache();       // force initialization

        HashSet<Chronology> chronos = new HashSet<>(CHRONOS_BY_ID.values());

        /// Add in Chronologies from the ServiceLoader configuration

        @SuppressWarnings("rawtypes")

        ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);

        for (Chronology chrono : loader) {

            chronos.add(chrono);

        }

        return chronos;

    }

    //-----------------------------------------------------------------------

    /**

     * Creates an instance.

     */

    protected AbstractChronology() {

    }

    //-----------------------------------------------------------------------

    /**

     * Resolves parsed {@code ChronoField} values into a date during parsing.

     * <p>

     * Most {@code TemporalField} implementations are resolved using the

     * resolve method on the field. By contrast, the {@code ChronoField} class

     * defines fields that only have meaning relative to the chronology.

     * As such, {@code ChronoField} date fields are resolved here in the

     * context of a specific chronology.

     * <p>

     * {@code ChronoField} instances are resolved by this method, which may

     * be overridden in subclasses.

     * <ul>

     * <li>{@code EPOCH_DAY} - If present, this is converted to a date and

     *  all other date fields are then cross-checked against the date.

     * <li>{@code PROLEPTIC_MONTH} - If present, then it is split into the

     *  {@code YEAR} and {@code MONTH_OF_YEAR}. If the mode is strict or smart

     *  then the field is validated.

     * <li>{@code YEAR_OF_ERA} and {@code ERA} - If both are present, then they

     *  are combined to form a {@code YEAR}. In lenient mode, the {@code YEAR_OF_ERA}

     *  range is not validated, in smart and strict mode it is. The {@code ERA} is

     *  validated for range in all three modes. If only the {@code YEAR_OF_ERA} is

     *  present, and the mode is smart or lenient, then the last available era

     *  is assumed. In strict mode, no era is assumed and the {@code YEAR_OF_ERA} is

     *  left untouched. If only the {@code ERA} is present, then it is left untouched.

     * <li>{@code YEAR}, {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH} -

     *  If all three are present, then they are combined to form a date.

     *  In all three modes, the {@code YEAR} is validated.

     *  If the mode is smart or strict, then the month and day are validated.

     *  If the mode is lenient, then the date is combined in a manner equivalent to

     *  creating a date on the first day of the first month in the requested year,

     *  then adding the difference in months, then the difference in days.

     *  If the mode is smart, and the day-of-month is greater than the maximum for

     *  the year-month, then the day-of-month is adjusted to the last day-of-month.

     *  If the mode is strict, then the three fields must form a valid date.

     * <li>{@code YEAR} and {@code DAY_OF_YEAR} -

     *  If both are present, then they are combined to form a date.

     *  In all three modes, the {@code YEAR} is validated.

     *  If the mode is lenient, then the date is combined in a manner equivalent to

     *  creating a date on the first day of the requested year, then adding

     *  the difference in days.

     *  If the mode is smart or strict, then the two fields must form a valid date.

     * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and

     *  {@code ALIGNED_DAY_OF_WEEK_IN_MONTH} -

     *  If all four are present, then they are combined to form a date.

     *  In all three modes, the {@code YEAR} is validated.

     *  If the mode is lenient, then the date is combined in a manner equivalent to

     *  creating a date on the first day of the first month in the requested year, then adding

     *  the difference in months, then the difference in weeks, then in days.

     *  If the mode is smart or strict, then the all four fields are validated to

     *  their outer ranges. The date is then combined in a manner equivalent to

     *  creating a date on the first day of the requested year and month, then adding

     *  the amount in weeks and days to reach their values. If the mode is strict,

     *  the date is additionally validated to check that the day and week adjustment

     *  did not change the month.

     * <li>{@code YEAR}, {@code MONTH_OF_YEAR}, {@code ALIGNED_WEEK_OF_MONTH} and

     *  {@code DAY_OF_WEEK} - If all four are present, then they are combined to

     *  form a date. The approach is the same as described above for

     *  years, months and weeks in {@code ALIGNED_DAY_OF_WEEK_IN_MONTH}.

     *  The day-of-week is adjusted as the next or same matching day-of-week once

     *  the years, months and weeks have been handled.

     * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code ALIGNED_DAY_OF_WEEK_IN_YEAR} -

     *  If all three are present, then they are combined to form a date.

     *  In all three modes, the {@code YEAR} is validated.

     *  If the mode is lenient, then the date is combined in a manner equivalent to

     *  creating a date on the first day of the requested year, then adding

     *  the difference in weeks, then in days.

     *  If the mode is smart or strict, then the all three fields are validated to

     *  their outer ranges. The date is then combined in a manner equivalent to

     *  creating a date on the first day of the requested year, then adding

     *  the amount in weeks and days to reach their values. If the mode is strict,

     *  the date is additionally validated to check that the day and week adjustment

     *  did not change the year.

     * <li>{@code YEAR}, {@code ALIGNED_WEEK_OF_YEAR} and {@code DAY_OF_WEEK} -

     *  If all three are present, then they are combined to form a date.

     *  The approach is the same as described above for years and weeks in

     *  {@code ALIGNED_DAY_OF_WEEK_IN_YEAR}. The day-of-week is adjusted as the

     *  next or same matching day-of-week once the years and weeks have been handled.

     * </ul>

     * <p>

     * The default implementation is suitable for most calendar systems.

     * If {@link java.time.temporal.ChronoField#YEAR_OF_ERA} is found without an {@link java.time.temporal.ChronoField#ERA}

     * then the last era in {@link #eras()} is used.

     * The implementation assumes a 7 day week, that the first day-of-month

     * has the value 1, that first day-of-year has the value 1, and that the

     * first of the month and year always exists.

     *

     * @param fieldValues  the map of fields to values, which can be updated, not null

     * @param resolverStyle  the requested type of resolve, not null

     * @return the resolved date, null if insufficient information to create a date

     * @throws java.time.DateTimeException if the date cannot be resolved, typically

     *  because of a conflict in the input data

     */

    @Override

    public ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {

        // check epoch-day before inventing era

        if (fieldValues.containsKey(EPOCH_DAY)) {

            return dateEpochDay(fieldValues.remove(EPOCH_DAY));

        }

        // fix proleptic month before inventing era

        resolveProlepticMonth(fieldValues, resolverStyle);

        // invent era if necessary to resolve year-of-era

        ChronoLocalDate resolved = resolveYearOfEra(fieldValues, resolverStyle);

        if (resolved != null) {

            return resolved;

        }

        // build date

        if (fieldValues.containsKey(YEAR)) {

            if (fieldValues.containsKey(MONTH_OF_YEAR)) {

                if (fieldValues.containsKey(DAY_OF_MONTH)) {

                    return resolveYMD(fieldValues, resolverStyle);

                }

                if (fieldValues.containsKey(ALIGNED_WEEK_OF_MONTH)) {

                    if (fieldValues.containsKey(ALIGNED_DAY_OF_WEEK_IN_MONTH)) {

                        return resolveYMAA(fieldValues, resolverStyle);

                    }

                    if (fieldValues.containsKey(DAY_OF_WEEK)) {

                        return resolveYMAD(fieldValues, resolverStyle);

                    }

                }

            }

            if (fieldValues.containsKey(DAY_OF_YEAR)) {

                return resolveYD(fieldValues, resolverStyle);

            }

            if (fieldValues.containsKey(ALIGNED_WEEK_OF_YEAR)) {

                if (fieldValues.containsKey(ALIGNED_DAY_OF_WEEK_IN_YEAR)) {

                    return resolveYAA(fieldValues, resolverStyle);

                }

                if (fieldValues.containsKey(DAY_OF_WEEK)) {

                    return resolveYAD(fieldValues, resolverStyle);

                }

            }

        }

        return null;

    }

    void resolveProlepticMonth(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {

        Long pMonth = fieldValues.remove(PROLEPTIC_MONTH);

        if (pMonth != null) {

            if (resolverStyle != ResolverStyle.LENIENT) {

                PROLEPTIC_MONTH.checkValidValue(pMonth);

            }

            // first day-of-month is likely to be safest for setting proleptic-month

            // cannot add to year zero, as not all chronologies have a year zero

            ChronoLocalDate chronoDate = dateNow()

                    .with(DAY_OF_MONTH, 1).with(PROLEPTIC_MONTH, pMonth);

            addFieldValue(fieldValues, MONTH_OF_YEAR, chronoDate.get(MONTH_OF_YEAR));

            addFieldValue(fieldValues, YEAR, chronoDate.get(YEAR));

        }

    }

    ChronoLocalDate resolveYearOfEra(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {

        Long yoeLong = fieldValues.remove(YEAR_OF_ERA);

        if (yoeLong != null) {

            Long eraLong = fieldValues.remove(ERA);

            int yoe;

            if (resolverStyle != ResolverStyle.LENIENT) {

                yoe = range(YEAR_OF_ERA).checkValidIntValue(yoeLong, YEAR_OF_ERA);

            } else {

                yoe = Math.toIntExact(yoeLong);

            }

            if (eraLong != null) {

                Era eraObj = eraOf(range(ERA).checkValidIntValue(eraLong, ERA));

                addFieldValue(fieldValues, YEAR, prolepticYear(eraObj, yoe));

            } else {

                if (fieldValues.containsKey(YEAR)) {

                    int year = range(YEAR).checkValidIntValue(fieldValues.get(YEAR), YEAR);

                    ChronoLocalDate chronoDate = dateYearDay(year, 1);

                    addFieldValue(fieldValues, YEAR, prolepticYear(chronoDate.getEra(), yoe));

                } else if (resolverStyle == ResolverStyle.STRICT) {

                    // do not invent era if strict

                    // reinstate the field removed earlier, no cross-check issues

                    fieldValues.put(YEAR_OF_ERA, yoeLong);

                } else {

                    List<Era> eras = eras();

                    if (eras.isEmpty()) {

                        addFieldValue(fieldValues, YEAR, yoe);

                    } else {

                        Era eraObj = eras.get(eras.size() - 1);

                        addFieldValue(fieldValues, YEAR, prolepticYear(eraObj, yoe));

                    }

                }

            }

        } else if (fieldValues.containsKey(ERA)) {

            range(ERA).checkValidValue(fieldValues.get(ERA), ERA);  // always validated

        }

        return null;

    }

    ChronoLocalDate resolveYMD(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {

        int y = range(YEAR).checkValidIntValue(fieldValues.remove(YEAR), YEAR);

        if (resolverStyle == ResolverStyle.LENIENT) {

            long months = Math.subtractExact(fieldValues.remove(MONTH_OF_YEAR), 1);

            long days = Math.subtractExact(fieldValues.remove(DAY_OF_MONTH), 1);

            return date(y, 1, 1).plus(months, MONTHS).plus(days, DAYS);

        }