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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

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 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

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

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

 */

package java.time.temporal;

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

import java.time.DateTimeException;

import java.time.format.DateTimeFormatterBuilder;

import java.time.format.TextStyle;

import java.util.Locale;

/**

 * An era in the ISO calendar system.

 * <p>

 * The ISO-8601 standard does not define eras.

 * A definition has therefore been created with two eras - 'Current era' (CE) for

 * years from 0001-01-01 (ISO) and 'Before current era' (BCE) for years before that.

 * <p>

 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code ISOEra}.

 * Use {@code getValue()} instead.</b>

 *

 * <h3>Specification for implementors</h3>

 * This is an immutable and thread-safe enum.

 *

 * @since 1.8

 */

enum ISOEra implements Era<ISOChrono> {

    /**

     * The singleton instance for the era BCE, 'Before Current Era'.

     * The 'ISO' part of the name emphasizes that this differs from the BCE

     * era in the Gregorian calendar system.

     * This has the numeric value of {@code 0}.

     */

    BCE,

    /**

     * The singleton instance for the era CE, 'Current Era'.

     * The 'ISO' part of the name emphasizes that this differs from the CE

     * era in the Gregorian calendar system.

     * This has the numeric value of {@code 1}.

     */

    CE;

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

    /**

     * Obtains an instance of {@code ISOEra} from an {@code int} value.

     * <p>

     * {@code ISOEra} is an enum representing the ISO eras of BCE/CE.

     * This factory allows the enum to be obtained from the {@code int} value.

     *

     * @param era  the BCE/CE value to represent, from 0 (BCE) to 1 (CE)

     * @return the era singleton, not null

     * @throws DateTimeException if the value is invalid

     */

    public static ISOEra of(int era) {

        switch (era) {

            case 0:

                return BCE;

            case 1:

                return CE;

            default:

                throw new DateTimeException("Invalid era: " + era);

        }

    }

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

    /**

     * Gets the numeric era {@code int} value.

     * <p>

     * The era BCE has the value 0, while the era CE has the value 1.

     *

     * @return the era value, from 0 (BCE) to 1 (CE)

     */

    @Override

    public int getValue() {

        return ordinal();

    }

    @Override

    public ISOChrono getChrono() {

        return ISOChrono.INSTANCE;

    }

    // JDK8 default methods:

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

    @Override

    public ChronoLocalDate<ISOChrono> date(int year, int month, int day) {

        return getChrono().date(this, year, month, day);

    }

    @Override

    public ChronoLocalDate<ISOChrono> dateYearDay(int year, int dayOfYear) {

        return getChrono().dateYearDay(this, year, dayOfYear);

    }

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

    @Override

    public boolean isSupported(TemporalField field) {

        if (field instanceof ChronoField) {

            return field == ERA;

        }

        return field != null && field.doIsSupported(this);

    }

    @Override

    public ValueRange range(TemporalField field) {

        if (field == ERA) {

            return field.range();

        } else if (field instanceof ChronoField) {

            throw new DateTimeException("Unsupported field: " + field.getName());

        }

        return field.doRange(this);

    }

    @Override

    public int get(TemporalField field) {

        if (field == ERA) {

            return getValue();

        }

        return range(field).checkValidIntValue(getLong(field), field);

    }

    @Override

    public long getLong(TemporalField field) {

        if (field == ERA) {

            return getValue();

        } else if (field instanceof ChronoField) {

            throw new DateTimeException("Unsupported field: " + field.getName());

        }

        return field.doGet(this);

    }

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

    @Override

    public Temporal adjustInto(Temporal temporal) {

        return temporal.with(ERA, getValue());

    }

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

    @Override

    public String getText(TextStyle style, Locale locale) {

        return new DateTimeFormatterBuilder().appendText(ERA, style).toFormatter(locale).print(this);

    }

}