content: /*
   * Copyright (c) 2012, 2019, 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
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  /*
   * 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
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package java.time.chrono;
  
  import static java.time.chrono.JapaneseDate.MEIJI_6_ISODATE;
  import static java.time.temporal.ChronoField.ERA;
  
  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.LocalDate;
  import java.time.format.DateTimeFormatterBuilder;
  import java.time.format.TextStyle;
  import java.time.temporal.ChronoField;
  import java.time.temporal.TemporalField;
  import java.time.temporal.UnsupportedTemporalTypeException;
  import java.time.temporal.ValueRange;
  import java.util.Arrays;
  import java.util.Locale;
  import java.util.Objects;
  
  import sun.util.calendar.CalendarDate;
  
  /**
   * An era in the Japanese Imperial calendar system.
   * <p>
   * The Japanese government defines the official name and start date of
   * each era. Eras are consecutive and their date ranges do not overlap,
   * so the end date of one era is always the day before the start date
   * of the next era.
   * <p>
   * The Java SE Platform supports all eras defined by the Japanese government,
   * beginning with the Meiji era. Each era is identified in the Platform by an
   * integer value and a name. The {@link #of(int)} and {@link #valueOf(String)}
   * methods may be used to obtain a singleton instance of JapaneseEra for each
   * era. The {@link #values()} method returns the singleton instances of all
   * supported eras.
   * <p>
   * For convenience, this class declares a number of public static final fields
   * that refer to singleton instances returned by the values() method.
   *
   * @apiNote
   * The fields declared in this class may evolve over time, in line with the
   * results of the {@link #values()} method. However, there is not necessarily
   * a 1:1 correspondence between the fields and the singleton instances.
   *
   * @apiNote
   * The Japanese government may announce a new era and define its start
   * date but not its official name. In this scenario, the singleton instance
   * that represents the new era may return a name that is not stable until
   * the official name is defined. Developers should exercise caution when
   * relying on the name returned by any singleton instance that does not
   * correspond to a public static final field.
   *
   * @implSpec
   * This class is immutable and thread-safe.
   *
   * @since 1.8
   */
  public final class JapaneseEra
          implements Era, Serializable {
  
      // The offset value to 0-based index from the era value.
      // i.e., getValue() + ERA_OFFSET == 0-based index
      static final int ERA_OFFSET = 2;
  
      static final sun.util.calendar.Era[] ERA_CONFIG;
  
      /**
       * The singleton instance for the 'Meiji' era (1868-01-01 - 1912-07-29)
       * which has the value -1.
       */
      public static final JapaneseEra MEIJI = new JapaneseEra(-1, LocalDate.of(1868, 1, 1));
      /**
       * The singleton instance for the 'Taisho' era (1912-07-30 - 1926-12-24)
       * which has the value 0.
       */
      public static final JapaneseEra TAISHO = new JapaneseEra(0, LocalDate.of(1912, 7, 30));
      /**
       * The singleton instance for the 'Showa' era (1926-12-25 - 1989-01-07)
       * which has the value 1.
       */
      public static final JapaneseEra SHOWA = new JapaneseEra(1, LocalDate.of(1926, 12, 25));
      /**
       * The singleton instance for the 'Heisei' era (1989-01-08 - 2019-04-30)
       * which has the value 2.
       */
      public static final JapaneseEra HEISEI = new JapaneseEra(2, LocalDate.of(1989, 1, 8));
      // Android-changed: Integrate OpenJDK support for Japanese Era Reiwa.
      /**
       * The singleton instance for the 'Reiwa' era (2019-05-01 - current)
       * which has the value 3. The end date of this era is not specified, unless
       * the Japanese Government defines it.
       */
      public static final JapaneseEra REIWA = new JapaneseEra(3, LocalDate.of(2019, 5, 1));
  
      // The number of predefined JapaneseEra constants.
      // There may be a supplemental era defined by the property.
      private static final int N_ERA_CONSTANTS = REIWA.getValue() + ERA_OFFSET;
  
      /**
       * Serialization version.
       */
      private static final long serialVersionUID = 1466499369062886794L;
  
      // array for the singleton JapaneseEra instances
      private static final JapaneseEra[] KNOWN_ERAS;
  
      static {
          ERA_CONFIG = JapaneseChronology.JCAL.getEras();
  
          KNOWN_ERAS = new JapaneseEra[ERA_CONFIG.length];
          KNOWN_ERAS[0] = MEIJI;
          KNOWN_ERAS[1] = TAISHO;
          KNOWN_ERAS[2] = SHOWA;
          KNOWN_ERAS[3] = HEISEI;
          KNOWN_ERAS[4] = REIWA;
          for (int i = N_ERA_CONSTANTS; i < ERA_CONFIG.length; i++) {
              CalendarDate date = ERA_CONFIG[i].getSinceDate();
              LocalDate isoDate = LocalDate.of(date.getYear(), date.getMonth(), date.getDayOfMonth());
              KNOWN_ERAS[i] = new JapaneseEra(i - ERA_OFFSET + 1, isoDate);
          }
      };
  
      /**
       * The era value.
       * @serial
       */
      private final transient int eraValue;
  
      // the first day of the era
      private final transient LocalDate since;
  
      /**
       * Creates an instance.
       *
       * @param eraValue  the era value, validated
       * @param since  the date representing the first date of the era, validated not null
       */
      private JapaneseEra(int eraValue, LocalDate since) {
          this.eraValue = eraValue;
          this.since = since;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Returns the Sun private Era instance corresponding to this {@code JapaneseEra}.
       *
       * @return the Sun private Era instance for this {@code JapaneseEra}.
       */
      sun.util.calendar.Era getPrivateEra() {
          return ERA_CONFIG[ordinal(eraValue)];
      }
  
      //-----------------------------------------------------------------------
      /**
       * Obtains an instance of {@code JapaneseEra} from an {@code int} value.
        * <ul>
        * <li>The value {@code 1} is associated with the 'Showa' era, because
        * it contains 1970-01-01 (ISO calendar system).</li>
        * <li>The values {@code -1} and {@code 0} are associated with two earlier
        * eras, Meiji and Taisho, respectively.</li>
        * <li>A value greater than {@code 1} is associated with a later era,
        * beginning with Heisei ({@code 2}).</li>
        * </ul>
       * <p>
        * Every instance of {@code JapaneseEra} that is returned from the {@link #values()}
        * method has an int value (available via {@link Era#getValue()} which is
        * accepted by this method.
       *
       * @param japaneseEra  the era to represent
       * @return the {@code JapaneseEra} singleton, not null
       * @throws DateTimeException if the value is invalid
       */
      public static JapaneseEra of(int japaneseEra) {
          if (japaneseEra < MEIJI.eraValue || japaneseEra + ERA_OFFSET > KNOWN_ERAS.length) {
              throw new DateTimeException("Invalid era: " + japaneseEra);
          }
          return KNOWN_ERAS[ordinal(japaneseEra)];
      }
  
      /**
       * Returns the {@code JapaneseEra} with the name.
       * <p>
       * The string must match exactly the name of the era.
       * (Extraneous whitespace characters are not permitted.)
       *
       * @param japaneseEra  the japaneseEra name; non-null
       * @return the {@code JapaneseEra} singleton, never null
       * @throws IllegalArgumentException if there is not JapaneseEra with the specified name
       */
      public static JapaneseEra valueOf(String japaneseEra) {
          Objects.requireNonNull(japaneseEra, "japaneseEra");
          for (JapaneseEra era : KNOWN_ERAS) {
              if (era.getName().equals(japaneseEra)) {
                  return era;
              }
          }
          throw new IllegalArgumentException("japaneseEra is invalid");
      }
  
      /**
       * Returns an array of JapaneseEras.
       * <p>
       * This method may be used to iterate over the JapaneseEras as follows:
       * <pre>
       * for (JapaneseEra c : JapaneseEra.values())
       *     System.out.println(c);
       * </pre>
       *
       * @return an array of JapaneseEras
       */
      public static JapaneseEra[] values() {
          return Arrays.copyOf(KNOWN_ERAS, KNOWN_ERAS.length);
      }
  
      /**
       * {@inheritDoc}
       *
       * @param style {@inheritDoc}
       * @param locale {@inheritDoc}
       */
      @Override
      public String getDisplayName(TextStyle style, Locale locale) {
          // If this JapaneseEra is a supplemental one, obtain the name from
          // the era definition.
          if (getValue() > N_ERA_CONSTANTS - ERA_OFFSET) {
              Objects.requireNonNull(locale, "locale");
              return style.asNormal() == TextStyle.NARROW ? getAbbreviation() : getName();
          }
  
          return new DateTimeFormatterBuilder()
              .appendText(ERA, style)
              .toFormatter(locale)
              .withChronology(JapaneseChronology.INSTANCE)
              .format(this == MEIJI ? MEIJI_6_ISODATE : since);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Obtains an instance of {@code JapaneseEra} from a date.
       *
       * @param date  the date, not null
       * @return the Era singleton, never null
       */
      static JapaneseEra from(LocalDate date) {
          if (date.isBefore(MEIJI_6_ISODATE)) {
              throw new DateTimeException("JapaneseDate before Meiji 6 are not supported");
          }
          for (int i = KNOWN_ERAS.length - 1; i > 0; i--) {
              JapaneseEra era = KNOWN_ERAS[i];
              if (date.compareTo(era.since) >= 0) {
                  return era;
              }
          }
          return null;
      }
  
      static JapaneseEra toJapaneseEra(sun.util.calendar.Era privateEra) {
          for (int i = ERA_CONFIG.length - 1; i >= 0; i--) {
              if (ERA_CONFIG[i].equals(privateEra)) {
                  return KNOWN_ERAS[i];
              }
          }
          return null;
      }
  
      static sun.util.calendar.Era privateEraFrom(LocalDate isoDate) {
          for (int i = KNOWN_ERAS.length - 1; i > 0; i--) {
              JapaneseEra era = KNOWN_ERAS[i];
              if (isoDate.compareTo(era.since) >= 0) {
                  return ERA_CONFIG[i];
              }
          }
          return null;
      }
  
      /**
       * Returns the index into the arrays from the Era value.
       * the eraValue is a valid Era number, -1..2.
       *
       * @param eraValue  the era value to convert to the index
       * @return the index of the current Era
       */
      private static int ordinal(int eraValue) {
          return eraValue + ERA_OFFSET - 1;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets the numeric era {@code int} value.
       * <p>
       * The {@link #SHOWA} era that contains 1970-01-01 (ISO calendar system) has the value 1.
       * Later eras are numbered from 2 ({@link #HEISEI}).
       * Earlier eras are numbered 0 ({@link #TAISHO}), -1 ({@link #MEIJI})).
       *
       * @return the era value
       */
      @Override
      public int getValue() {
          return eraValue;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets the range of valid values for the specified field.
       * <p>
       * The range object expresses the minimum and maximum valid values for a field.
       * This era is used to enhance the accuracy of the returned range.
       * If it is not possible to return the range, because the field is not supported
       * or for some other reason, an exception is thrown.
       * <p>
       * If the field is a {@link ChronoField} then the query is implemented here.
       * The {@code ERA} field returns the range.
       * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
       * <p>
       * If the field is not a {@code ChronoField}, then the result of this method
       * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
       * passing {@code this} as the argument.
       * Whether the range can be obtained is determined by the field.
       * <p>
       * The range of valid Japanese eras can change over time due to the nature
       * of the Japanese calendar system.
       *
       * @param field  the field to query the range for, not null
       * @return the range of valid values for the field, not null
       * @throws DateTimeException if the range for the field cannot be obtained
       * @throws UnsupportedTemporalTypeException if the unit is not supported
       */
      @Override  // override as super would return range from 0 to 1
      public ValueRange range(TemporalField field) {
          if (field == ERA) {
              return JapaneseChronology.INSTANCE.range(ERA);
          }
          return Era.super.range(field);
      }
  
      //-----------------------------------------------------------------------
      String getAbbreviation() {
          return ERA_CONFIG[ordinal(getValue())].getAbbreviation();
      }
  
      String getName() {
          return ERA_CONFIG[ordinal(getValue())].getName();
      }
  
      @Override
      public String toString() {
          return getName();
      }
  
      //-----------------------------------------------------------------------
      /**
       * Defend against malicious streams.
       *
       * @param s the stream to read
       * @throws InvalidObjectException always
       */
      private void readObject(ObjectInputStream s) throws InvalidObjectException {
          throw new InvalidObjectException("Deserialization via serialization delegate");
      }
  
      //-----------------------------------------------------------------------
      /**
       * Writes the object using a
       * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
       * @serialData
       * <pre>
       *  out.writeByte(5);        // identifies a JapaneseEra
       *  out.writeInt(getValue());
       * </pre>
       *
       * @return the instance of {@code Ser}, not null
       */
      private Object writeReplace() {
          return new Ser(Ser.JAPANESE_ERA_TYPE, this);
      }
  
      void writeExternal(DataOutput out) throws IOException {
          out.writeByte(this.getValue());
      }
  
      static JapaneseEra readExternal(DataInput in) throws IOException {
          byte eraValue = in.readByte();
          return JapaneseEra.of(eraValue);
      }
  
  }
  