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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.
 *
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 * modification, are permitted provided that the following conditions are met:
 *
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 *    this list of conditions and the following disclaimer.
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 */
package java.time.chrono;

import java.time.DateTimeException;

/**
 * An era in the Minguo calendar system.
 * <p>
 * The Minguo calendar system has two eras.
 * The current era, for years from 1 onwards, is known as the 'Republic of China' era.
 * All previous years, zero or earlier in the proleptic count or one and greater
 * in the year-of-era count, are part of the 'Before Republic of China' era.
 * <p>
 * <table summary="Minguo years and eras" cellpadding="2" cellspacing="3" border="0" >
 * <thead>
 * <tr class="tableSubHeadingColor">
 * <th class="colFirst" align="left">year-of-era</th>
 * <th class="colFirst" align="left">era</th>
 * <th class="colFirst" align="left">proleptic-year</th>
 * <th class="colLast" align="left">ISO proleptic-year</th>
 * </tr>
 * </thead>
 * <tbody>
 * <tr class="rowColor">
 * <td>2</td><td>ROC</td><td>2</td><td>1913</td>
 * </tr>
 * <tr class="altColor">
 * <td>1</td><td>ROC</td><td>1</td><td>1912</td>
 * </tr>
 * <tr class="rowColor">
 * <td>1</td><td>BEFORE_ROC</td><td>0</td><td>1911</td>
 * </tr>
 * <tr class="altColor">
 * <td>2</td><td>BEFORE_ROC</td><td>-1</td><td>1910</td>
 * </tr>
 * </tbody>
 * </table>
 * <p>
 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code MinguoEra}.
 * Use {@code getValue()} instead.</b>
 *
 * @implSpec
 * This is an immutable and thread-safe enum.
 *
 * @since 1.8
 */
public enum MinguoEra implements Era {

    /**
     * The singleton instance for the era before the current one, 'Before Republic of China Era',
     * which has the numeric value 0.
     */
    BEFORE_ROC,
    /**
     * The singleton instance for the current era, 'Republic of China Era',
     * which has the numeric value 1.
     */
    ROC;

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code MinguoEra} from an {@code int} value.
     * <p>
     * {@code MinguoEra} is an enum representing the Minguo eras of BEFORE_ROC/ROC.
     * This factory allows the enum to be obtained from the {@code int} value.
     *
     * @param minguoEra  the BEFORE_ROC/ROC value to represent, from 0 (BEFORE_ROC) to 1 (ROC)
     * @return the era singleton, not null
     * @throws DateTimeException if the value is invalid
     */
    public static MinguoEra of(int minguoEra) {
        switch (minguoEra) {
            case 0:
                return BEFORE_ROC;
            case 1:
                return ROC;
            default:
                throw new DateTimeException("Invalid era: " + minguoEra);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the numeric era {@code int} value.
     * <p>
     * The era BEFORE_ROC has the value 0, while the era ROC has the value 1.
     *
     * @return the era value, from 0 (BEFORE_ROC) to 1 (ROC)
     */
    @Override
    public int getValue() {
        return ordinal();
    }

}