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package sun.util.calendar;

import java.util.Locale;
import java.util.TimeZone;

The class Era represents a calendar era that defines a
period of time in which the same year numbering is used. For
example, Gregorian year 2004 is Heisei 16 in the Japanese
calendar system. An era starts at any point of time (Gregorian) that is
represented by CalendarDate.
Eras that are applicable to a particular calendar system can be obtained by calling CalendarSystem.getEras one of which can be used to specify a date in CalendarDate.
The following era names are defined in this release.

  Calendar system         Era name         Since (in Gregorian)
  -----------------------------------------------------------------------
  Japanese calendar       Meiji            1868-01-01T00:00:00 local time
                          Taisho           1912-07-30T00:00:00 local time
                          Showa            1926-12-25T00:00:00 local time
                          Heisei           1989-01-08T00:00:00 local time
                          Reiwa            2019-05-01T00:00:00 local time
  -----------------------------------------------------------------------

Author:
Masayoshi Okutsu
Since:
1.5/**
 * The class <code>Era</code> represents a calendar era that defines a
 * period of time in which the same year numbering is used. For
 * example, Gregorian year 2004 is <I>Heisei</I> 16 in the Japanese
 * calendar system. An era starts at any point of time (Gregorian) that is
 * represented by <code>CalendarDate</code>.
 *
 * <p><code>Era</code>s that are applicable to a particular calendar
 * system can be obtained by calling {@link CalendarSystem#getEras}
 * one of which can be used to specify a date in
 * <code>CalendarDate</code>.
 *
 * <p>The following era names are defined in this release.
 * <pre>{@code
 *   Calendar system         Era name         Since (in Gregorian)
 *   -----------------------------------------------------------------------
 *   Japanese calendar       Meiji            1868-01-01T00:00:00 local time
 *                           Taisho           1912-07-30T00:00:00 local time
 *                           Showa            1926-12-25T00:00:00 local time
 *                           Heisei           1989-01-08T00:00:00 local time
 *                           Reiwa            2019-05-01T00:00:00 local time
 *   -----------------------------------------------------------------------
 * }</pre>
 *
 * @author Masayoshi Okutsu
 * @since 1.5
 */

public final class Era {
    private final String name;
    private final String abbr;
    private final long since;
    private final CalendarDate sinceDate;
    private final boolean localTime;

    
Constructs an Era instance.
Params:
name – the era name (e.g., "BeforeCommonEra" for the Julian calendar system)
abbr – the abbreviation of the era name (e.g., "B.C.E." for "BeforeCommonEra")
since – the time (millisecond offset from January 1, 1970
(Gregorian) UTC or local time) when the era starts, inclusive.
localTime – true if since
specifies a local time; false if
since specifies UTC/**
     * Constructs an <code>Era</code> instance.
     *
     * @param name the era name (e.g., "BeforeCommonEra" for the Julian calendar system)
     * @param abbr the abbreviation of the era name (e.g., "B.C.E." for "BeforeCommonEra")
     * @param since the time (millisecond offset from January 1, 1970
     * (Gregorian) UTC or local time) when the era starts, inclusive.
     * @param localTime <code>true</code> if <code>since</code>
     * specifies a local time; <code>false</code> if
     * <code>since</code> specifies UTC
     */
    public Era(String name, String abbr, long since, boolean localTime) {
        this.name = name;
        this.abbr = abbr;
        this.since = since;
        this.localTime = localTime;
        Gregorian gcal = CalendarSystem.getGregorianCalendar();
        BaseCalendar.Date d = (BaseCalendar.Date) gcal.newCalendarDate(null);
        gcal.getCalendarDate(since, d);
        sinceDate = new ImmutableGregorianDate(d);
    }

    public String getName() {
        return name;
    }

    public String getDisplayName(Locale locale) {
        return name;
    }

    public String getAbbreviation() {
        return abbr;
    }

    public String getDiaplayAbbreviation(Locale locale) {
        return abbr;
    }

    public long getSince(TimeZone zone) {
        if (zone == null || !localTime) {
            return since;
        }
        int offset = zone.getOffset(since);
        return since - offset;
    }

    public CalendarDate getSinceDate() {
        return sinceDate;
    }

    public boolean isLocalTime() {
        return localTime;
    }

    public boolean equals(Object o) {
        if (!(o instanceof Era)) {
            return false;
        }
        Era that = (Era) o;
        return name.equals(that.name)
            && abbr.equals(that.abbr)
            && since == that.since
            && localTime == that.localTime;
    }

    private int hash = 0;

    public int hashCode() {
        if (hash == 0) {
            hash = name.hashCode() ^ abbr.hashCode() ^ (int)since ^ (int)(since >> 32)
                ^ (localTime ? 1 : 0);
        }
        return hash;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append('[');
        sb.append(getName()).append(" (");
        sb.append(getAbbreviation()).append(')');
        sb.append(" since ").append(getSinceDate());
        if (localTime) {
            sb.setLength(sb.length() - 1); // remove 'Z'
            sb.append(" local time");
        }
        sb.append(']');
        return sb.toString();
    }
}