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/*
 *  Copyright 2001-2014 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.io.Serializable;
import java.util.concurrent.ConcurrentHashMap;

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;

/**
 * Implements the Islamic, or Hijri, calendar system using arithmetic rules.
 * 

* This calendar is a lunar calendar with a shorter year than ISO. * Year 1 in the Islamic calendar began on July 16, 622 CE (Julian), thus * Islamic 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 Islamic year. *

* There are two basic forms of the Islamic calendar, the tabular and the * observed. The observed form cannot easily be used by computers as it * relies on human observation of the new moon. * The tabular calendar, implemented here, is an arithmetical approximation * of the observed form that follows relatively simple rules. *

* The tabular form of the calendar defines 12 months of alternately * 30 and 29 days. The last month is extended to 30 days in a leap year. * Leap years occur according to a 30 year cycle. There are four recognised * patterns of leap years in the 30 year cycle: *

 * Years 2, 5, 7, 10, 13, 15, 18, 21, 24, 26 & 29 - 15-based, used by Microsoft
 * Years 2, 5, 7, 10, 13, 16, 18, 21, 24, 26 & 29 - 16-based, most commonly used
 * Years 2, 5, 8, 10, 13, 16, 19, 21, 24, 27 & 29 - Indian
 * Years 2, 5, 8, 11, 13, 16, 19, 21, 24, 27 & 30 - Habash al-Hasib
 * 
* You can select which pattern to use via the factory methods, or use the * default (16-based). *

* This implementation defines a day as midnight to midnight exactly as per * the ISO chronology. This correct start of day is at sunset on the previous * day, however this cannot readily be modelled and has been ignored. *

* IslamicChronology is thread-safe and immutable. * * @see Wikipedia * * @author Stephen Colebourne * @since 1.2 */ public final class IslamicChronology extends BasicChronology { /** Serialization lock */ private static final long serialVersionUID = -3663823829888L; /** * Constant value for 'Anno Hegirae', equivalent * to the value returned for AD/CE. */ public static final int AH = DateTimeConstants.CE; /** A singleton era field. */ private static final DateTimeField ERA_FIELD = new BasicSingleEraDateTimeField("AH"); /** Leap year 15-based pattern. */ public static final LeapYearPatternType LEAP_YEAR_15_BASED = new LeapYearPatternType(0, 623158436); /** Leap year 16-based pattern. */ public static final LeapYearPatternType LEAP_YEAR_16_BASED = new LeapYearPatternType(1, 623191204); /** Leap year Indian pattern. */ public static final LeapYearPatternType LEAP_YEAR_INDIAN = new LeapYearPatternType(2, 690562340); /** Leap year Habash al-Hasib pattern. */ public static final LeapYearPatternType LEAP_YEAR_HABASH_AL_HASIB = new LeapYearPatternType(3, 153692453); /** The lowest year that can be fully supported. */ private static final int MIN_YEAR = -292269337; /** * The highest year that can be fully supported. * Although calculateFirstDayOfYearMillis can go higher without * overflowing, the getYear method overflows when it adds the * approximate millis at the epoch. */ private static final int MAX_YEAR = 292271022; /** The days in a pair of months. */ private static final int MONTH_PAIR_LENGTH = 59; /** The length of the long month. */ private static final int LONG_MONTH_LENGTH = 30; /** The length of the short month. */ private static final int SHORT_MONTH_LENGTH = 29; /** The length of the long month in millis. */ private static final long MILLIS_PER_MONTH_PAIR = 59L * DateTimeConstants.MILLIS_PER_DAY; /** The length of the long month in millis. */ private static final long MILLIS_PER_MONTH = (long) (29.53056 * DateTimeConstants.MILLIS_PER_DAY); /** The length of the long month in millis. */ private static final long MILLIS_PER_LONG_MONTH = 30L * DateTimeConstants.MILLIS_PER_DAY; /** The typical millis per year. */ private static final long MILLIS_PER_YEAR = (long) (354.36667 * DateTimeConstants.MILLIS_PER_DAY); /** The typical millis per year. */ private static final long MILLIS_PER_SHORT_YEAR = 354L * DateTimeConstants.MILLIS_PER_DAY; /** The typical millis per year. */ private static final long MILLIS_PER_LONG_YEAR = 355L * DateTimeConstants.MILLIS_PER_DAY; /** The millis of 0001-01-01. */ private static final long MILLIS_YEAR_1 = -42521587200000L; // -42520809600000L; // long start = 0L - 278L * DateTimeConstants.MILLIS_PER_DAY; // long cy = 46L * MILLIS_PER_CYCLE; // 1381-01-01 // long rem = 5L * MILLIS_PER_SHORT_YEAR + // 3L * MILLIS_PER_LONG_YEAR; // 1389-01-01 /** The length of the cycle of leap years. */ private static final int CYCLE = 30; /** The millis of a 30 year cycle. */ private static final long MILLIS_PER_CYCLE = ((19L * 354L + 11L * 355L) * DateTimeConstants.MILLIS_PER_DAY); /** Cache of zone to chronology arrays */ private static final ConcurrentHashMap cCache = new ConcurrentHashMap(); /** Singleton instance of a UTC IslamicChronology */ private static final IslamicChronology INSTANCE_UTC; static { // init after static fields INSTANCE_UTC = getInstance(DateTimeZone.UTC); } /** The leap years to use. */ private final LeapYearPatternType iLeapYears; //----------------------------------------------------------------------- /** * Gets an instance of the IslamicChronology. * The time zone of the returned instance is UTC. * * @return a singleton UTC instance of the chronology */ public static IslamicChronology getInstanceUTC() { return INSTANCE_UTC; } /** * Gets an instance of the IslamicChronology in the default time zone. * * @return a chronology in the default time zone */ public static IslamicChronology getInstance() { return getInstance(DateTimeZone.getDefault(), LEAP_YEAR_16_BASED); } /** * Gets an instance of the IslamicChronology 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 IslamicChronology getInstance(DateTimeZone zone) { return getInstance(zone, LEAP_YEAR_16_BASED); } /** * Gets an instance of the IslamicChronology in the given time zone. * * @param zone the time zone to get the chronology in, null is default * @param leapYears the type defining the leap year pattern * @return a chronology in the specified time zone */ public static IslamicChronology getInstance(DateTimeZone zone, LeapYearPatternType leapYears) { if (zone == null) { zone = DateTimeZone.getDefault(); } IslamicChronology chrono; IslamicChronology[] chronos = cCache.get(zone); if (chronos == null) { chronos = new IslamicChronology[4]; IslamicChronology[] oldChronos = cCache.putIfAbsent(zone, chronos); if (oldChronos != null) { chronos = oldChronos; } } chrono = chronos[leapYears.index]; if (chrono == null) { synchronized (chronos) { chrono = chronos[leapYears.index]; if (chrono == null) { if (zone == DateTimeZone.UTC) { // First create without a lower limit. chrono = new IslamicChronology(null, null, leapYears); // Impose lower limit and make another IslamicChronology. DateTime lowerLimit = new DateTime(1, 1, 1, 0, 0, 0, 0, chrono); chrono = new IslamicChronology( LimitChronology.getInstance(chrono, lowerLimit, null), null, leapYears); } else { chrono = getInstance(DateTimeZone.UTC, leapYears); chrono = new IslamicChronology (ZonedChronology.getInstance(chrono, zone), null, leapYears); } chronos[leapYears.index] = chrono; } } } return chrono; } // Constructors and instance variables //----------------------------------------------------------------------- /** * Restricted constructor. */ IslamicChronology(Chronology base, Object param, LeapYearPatternType leapYears) { super(base, param, 4); this.iLeapYears = leapYears; } /** * Serialization singleton. */ private Object readResolve() { Chronology base = getBase(); return base == null ? getInstanceUTC() : getInstance(base.getZone()); } //----------------------------------------------------------------------- /** * Gets the leap year pattern type. * * @return the pattern type */ public LeapYearPatternType getLeapYearPatternType() { return iLeapYears; } // 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); } //----------------------------------------------------------------------- /** * Checks if this chronology instance equals another. * * @param obj the object to compare to * @return true if equal * @since 2.3 */ public boolean equals(Object obj) { if (this == obj) { return true; } if (obj instanceof IslamicChronology) { IslamicChronology chrono = (IslamicChronology) obj; return getLeapYearPatternType().index == chrono.getLeapYearPatternType().index && super.equals(obj); } return false; } /** * A suitable hash code for the chronology. * * @return the hash code * @since 1.6 */ public int hashCode() { return super.hashCode() * 13 + getLeapYearPatternType().hashCode(); } //----------------------------------------------------------------------- int getYear(long instant) { long millisIslamic = instant - MILLIS_YEAR_1; long cycles = millisIslamic / MILLIS_PER_CYCLE; long cycleRemainder = millisIslamic % MILLIS_PER_CYCLE; int year = (int) ((cycles * CYCLE) + 1L); long yearMillis = (isLeapYear(year) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR); while (cycleRemainder >= yearMillis) { cycleRemainder -= yearMillis; yearMillis = (isLeapYear(++year) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR); } return year; } long setYear(long instant, int year) { // optimsed implementation of set, due to fixed months int thisYear = getYear(instant); int dayOfYear = getDayOfYear(instant, thisYear); int millisOfDay = getMillisOfDay(instant); // Current year is leap, and day is leap. if (dayOfYear > 354 && !isLeapYear(year)) { // Moving to a non-leap year, leap day doesn't exist. dayOfYear--; } instant = getYearMonthDayMillis(year, 1, dayOfYear); instant += millisOfDay; return instant; } //----------------------------------------------------------------------- long getYearDifference(long minuendInstant, long subtrahendInstant) { // optimsed implementation of getDifference, due to fixed months int minuendYear = getYear(minuendInstant); int subtrahendYear = getYear(subtrahendInstant); // Inlined remainder method to avoid duplicate calls to get. long minuendRem = minuendInstant - getYearMillis(minuendYear); long subtrahendRem = subtrahendInstant - getYearMillis(subtrahendYear); int difference = minuendYear - subtrahendYear; if (minuendRem < subtrahendRem) { difference--; } return difference; } //----------------------------------------------------------------------- long getTotalMillisByYearMonth(int year, int month) { if (--month % 2 == 1) { month /= 2; return month * MILLIS_PER_MONTH_PAIR + MILLIS_PER_LONG_MONTH; } else { month /= 2; return month * MILLIS_PER_MONTH_PAIR; } } //----------------------------------------------------------------------- int getDayOfMonth(long millis) { // optimised for simple months int doy = getDayOfYear(millis) - 1; if (doy == 354) { return 30; } return (doy % MONTH_PAIR_LENGTH) % LONG_MONTH_LENGTH + 1; } //----------------------------------------------------------------------- boolean isLeapYear(int year) { return iLeapYears.isLeapYear(year); } //----------------------------------------------------------------------- int getDaysInYearMax() { return 355; } //----------------------------------------------------------------------- int getDaysInYear(int year) { return isLeapYear(year) ? 355 : 354; } //----------------------------------------------------------------------- int getDaysInYearMonth(int year, int month) { if (month == 12 && isLeapYear(year)) { return LONG_MONTH_LENGTH; } return (--month % 2 == 0 ? LONG_MONTH_LENGTH : SHORT_MONTH_LENGTH); } //----------------------------------------------------------------------- int getDaysInMonthMax() { return LONG_MONTH_LENGTH; } //----------------------------------------------------------------------- int getDaysInMonthMax(int month) { if (month == 12) { return LONG_MONTH_LENGTH; } return (--month % 2 == 0 ? LONG_MONTH_LENGTH : SHORT_MONTH_LENGTH); } //----------------------------------------------------------------------- int getMonthOfYear(long millis, int year) { int doyZeroBased = (int) ((millis - getYearMillis(year)) / DateTimeConstants.MILLIS_PER_DAY); if (doyZeroBased == 354) { return 12; } return ((doyZeroBased * 2) / MONTH_PAIR_LENGTH) + 1; // return (int) (doyZeroBased / 29.9f) + 1; // // int monthPairZeroBased = doyZeroBased / MONTH_PAIR_LENGTH; // int monthPairRemainder = doyZeroBased % MONTH_PAIR_LENGTH; // return (monthPairZeroBased * 2) + 1 + (monthPairRemainder >= LONG_MONTH_LENGTH ? 1 : 0); } //----------------------------------------------------------------------- long getAverageMillisPerYear() { return MILLIS_PER_YEAR; } //----------------------------------------------------------------------- long getAverageMillisPerYearDividedByTwo() { return MILLIS_PER_YEAR / 2; } //----------------------------------------------------------------------- long getAverageMillisPerMonth() { return MILLIS_PER_MONTH; } //----------------------------------------------------------------------- long calculateFirstDayOfYearMillis(int year) { if (year > MAX_YEAR) { throw new ArithmeticException("Year is too large: " + year + " > " + MAX_YEAR); } if (year < MIN_YEAR) { throw new ArithmeticException("Year is too small: " + year + " < " + MIN_YEAR); } // Java epoch is 1970-01-01 Gregorian which is 0622-07-16 Islamic. // 0001-01-01 Islamic is -42520809600000L // would prefer to calculate against year zero, but leap year // can be in that year so it doesn't work year--; long cycle = year / CYCLE; long millis = MILLIS_YEAR_1 + cycle * MILLIS_PER_CYCLE; int cycleRemainder = (year % CYCLE) + 1; for (int i = 1; i < cycleRemainder; i++) { millis += (isLeapYear(i) ? MILLIS_PER_LONG_YEAR : MILLIS_PER_SHORT_YEAR); } return millis; } //----------------------------------------------------------------------- int getMinYear() { return 1; //MIN_YEAR; } //----------------------------------------------------------------------- int getMaxYear() { return MAX_YEAR; } //----------------------------------------------------------------------- long getApproxMillisAtEpochDividedByTwo() { // Epoch 1970-01-01 ISO = 1389-10-22 Islamic return (-MILLIS_YEAR_1) / 2; } //----------------------------------------------------------------------- protected void assemble(Fields fields) { if (getBase() == null) { super.assemble(fields); fields.era = ERA_FIELD; fields.monthOfYear = new BasicMonthOfYearDateTimeField(this, 12); fields.months = fields.monthOfYear.getDurationField(); } } //----------------------------------------------------------------------- /** * Opaque object describing a leap year pattern for the Islamic Chronology. * * @since 1.2 */ public static class LeapYearPatternType implements Serializable { /** Serialization lock */ private static final long serialVersionUID = 26581275372698L; // /** Leap year raw data encoded into bits. */ // private static final int[][] LEAP_YEARS = { // {2, 5, 7, 10, 13, 15, 18, 21, 24, 26, 29}, // 623158436 // {2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29}, // 623191204 // {2, 5, 8, 10, 13, 16, 19, 21, 24, 27, 29}, // 690562340 // {0, 2, 5, 8, 11, 13, 16, 19, 21, 24, 27}, // 153692453 // }; /** The index. */ final byte index; /** The leap year pattern, a bit-based 1=true pattern. */ final int pattern; /** * Constructor. * This constructor takes a bit pattern where bits 0-29 correspond * to years 0-29 in the 30 year Islamic cycle of years. This allows * a highly efficient lookup by bit-matching. * * @param index the index * @param pattern the bit pattern */ LeapYearPatternType(int index, int pattern) { super(); this.index = (byte) index; this.pattern = pattern; } /** * Is the year a leap year. * @param year the year to query * @return true if leap */ boolean isLeapYear(int year) { int key = 1 << (year % 30); return ((pattern & key) > 0); } /** * Ensure a singleton is returned if possible. * @return the singleton instance */ private Object readResolve() { switch (index) { case 0: return LEAP_YEAR_15_BASED; case 1: return LEAP_YEAR_16_BASED; case 2: return LEAP_YEAR_INDIAN; case 3: return LEAP_YEAR_HABASH_AL_HASIB; default: return this; } } @Override public boolean equals(Object obj) { if (obj instanceof LeapYearPatternType) { return index == ((LeapYearPatternType) obj).index; } return false; } @Override public int hashCode() { return index; } } }





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