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/*
 *  Copyright 2001-2009 Stephen Colebourne
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.joda.time.chrono;

import java.util.HashMap;
import java.util.Map;

import org.joda.time.Chronology;
import org.joda.time.DateTime;
import org.joda.time.DateTimeConstants;
import org.joda.time.DateTimeField;
import org.joda.time.DateTimeZone;
import org.joda.time.field.SkipDateTimeField;

/**
 * Implements the Coptic calendar system, which defines every fourth year as
 * leap, much like the Julian calendar. The year is broken down into 12 months,
 * each 30 days in length. An extra period at the end of the year is either 5
 * or 6 days in length. In this implementation, it is considered a 13th month.
 * 

* Year 1 in the Coptic calendar began on August 29, 284 CE (Julian), thus * Coptic years do not begin at the same time as Julian years. This chronology * is not proleptic, as it does not allow dates before the first Coptic year. *

* This implementation defines a day as midnight to midnight exactly as per * the ISO chronology. Some references indicate that a coptic day starts at * sunset on the previous ISO day, but this has not been confirmed and is not * implemented. *

* CopticChronology is thread-safe and immutable. * * @see Wikipedia * @see JulianChronology * * @author Brian S O'Neill * @since 1.0 */ public final class CopticChronology extends BasicFixedMonthChronology { /** Serialization lock */ private static final long serialVersionUID = -5972804258688333942L; /** * Constant value for 'Anno Martyrum' or 'Era of the Martyrs', equivalent * to the value returned for AD/CE. */ public static final int AM = DateTimeConstants.CE; /** A singleton era field. */ private static final DateTimeField ERA_FIELD = new BasicSingleEraDateTimeField("AM"); /** The lowest year that can be fully supported. */ private static final int MIN_YEAR = -292269337; /** The highest year that can be fully supported. */ private static final int MAX_YEAR = 292272708; /** Cache of zone to chronology arrays */ private static final Map cCache = new HashMap(); /** Singleton instance of a UTC CopticChronology */ private static final CopticChronology INSTANCE_UTC; static { // init after static fields INSTANCE_UTC = getInstance(DateTimeZone.UTC); } //----------------------------------------------------------------------- /** * Gets an instance of the CopticChronology. * The time zone of the returned instance is UTC. * * @return a singleton UTC instance of the chronology */ public static CopticChronology getInstanceUTC() { return INSTANCE_UTC; } /** * Gets an instance of the CopticChronology in the default time zone. * * @return a chronology in the default time zone */ public static CopticChronology getInstance() { return getInstance(DateTimeZone.getDefault(), 4); } /** * Gets an instance of the CopticChronology in the given time zone. * * @param zone the time zone to get the chronology in, null is default * @return a chronology in the specified time zone */ public static CopticChronology getInstance(DateTimeZone zone) { return getInstance(zone, 4); } /** * Gets an instance of the CopticChronology in the given time zone. * * @param zone the time zone to get the chronology in, null is default * @param minDaysInFirstWeek minimum number of days in first week of the year; default is 4 * @return a chronology in the specified time zone */ public static CopticChronology getInstance(DateTimeZone zone, int minDaysInFirstWeek) { if (zone == null) { zone = DateTimeZone.getDefault(); } CopticChronology chrono; synchronized (cCache) { CopticChronology[] chronos = cCache.get(zone); if (chronos == null) { chronos = new CopticChronology[7]; cCache.put(zone, chronos); } try { chrono = chronos[minDaysInFirstWeek - 1]; } catch (ArrayIndexOutOfBoundsException e) { throw new IllegalArgumentException ("Invalid min days in first week: " + minDaysInFirstWeek); } if (chrono == null) { if (zone == DateTimeZone.UTC) { // First create without a lower limit. chrono = new CopticChronology(null, null, minDaysInFirstWeek); // Impose lower limit and make another CopticChronology. DateTime lowerLimit = new DateTime(1, 1, 1, 0, 0, 0, 0, chrono); chrono = new CopticChronology (LimitChronology.getInstance(chrono, lowerLimit, null), null, minDaysInFirstWeek); } else { chrono = getInstance(DateTimeZone.UTC, minDaysInFirstWeek); chrono = new CopticChronology (ZonedChronology.getInstance(chrono, zone), null, minDaysInFirstWeek); } chronos[minDaysInFirstWeek - 1] = chrono; } } return chrono; } // Constructors and instance variables //----------------------------------------------------------------------- /** * Restricted constructor. */ CopticChronology(Chronology base, Object param, int minDaysInFirstWeek) { super(base, param, minDaysInFirstWeek); } /** * Serialization singleton. */ private Object readResolve() { Chronology base = getBase(); int minDays = getMinimumDaysInFirstWeek(); minDays = (minDays == 0 ? 4 : minDays); // handle rename of BaseGJChronology return base == null ? getInstance(DateTimeZone.UTC, minDays) : getInstance(base.getZone(), minDays); } // Conversion //----------------------------------------------------------------------- /** * Gets the Chronology in the UTC time zone. * * @return the chronology in UTC */ public Chronology withUTC() { return INSTANCE_UTC; } /** * Gets the Chronology in a specific time zone. * * @param zone the zone to get the chronology in, null is default * @return the chronology */ public Chronology withZone(DateTimeZone zone) { if (zone == null) { zone = DateTimeZone.getDefault(); } if (zone == getZone()) { return this; } return getInstance(zone); } //----------------------------------------------------------------------- long calculateFirstDayOfYearMillis(int year) { // Java epoch is 1970-01-01 Gregorian which is 1686-04-23 Coptic. // Calculate relative to the nearest leap year and account for the // difference later. int relativeYear = year - 1687; int leapYears; if (relativeYear <= 0) { // Add 3 before shifting right since /4 and >>2 behave differently // on negative numbers. leapYears = (relativeYear + 3) >> 2; } else { leapYears = relativeYear >> 2; // For post 1687 an adjustment is needed as jan1st is before leap day if (!isLeapYear(year)) { leapYears++; } } long millis = (relativeYear * 365L + leapYears) * (long)DateTimeConstants.MILLIS_PER_DAY; // Adjust to account for difference between 1687-01-01 and 1686-04-23. return millis + (365L - 112) * DateTimeConstants.MILLIS_PER_DAY; } //----------------------------------------------------------------------- int getMinYear() { return MIN_YEAR; } //----------------------------------------------------------------------- int getMaxYear() { return MAX_YEAR; } //----------------------------------------------------------------------- long getApproxMillisAtEpochDividedByTwo() { return (1686L * MILLIS_PER_YEAR + 112L * DateTimeConstants.MILLIS_PER_DAY) / 2; } //----------------------------------------------------------------------- protected void assemble(Fields fields) { if (getBase() == null) { super.assemble(fields); // Coptic, like Julian, has no year zero. fields.year = new SkipDateTimeField(this, fields.year); fields.weekyear = new SkipDateTimeField(this, fields.weekyear); fields.era = ERA_FIELD; fields.monthOfYear = new BasicMonthOfYearDateTimeField(this, 13); fields.months = fields.monthOfYear.getDurationField(); } } }





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