DateComponents.java

  1. /* Copyright 2002-2023 CS GROUP
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.time;

  19. import java.io.Serializable;
  20. import java.text.DecimalFormat;
  21. import java.text.DecimalFormatSymbols;
  22. import java.util.Locale;
  23. import java.util.regex.Matcher;
  24. import java.util.regex.Pattern;

  26. import org.orekit.errors.OrekitIllegalArgumentException;
  27. import org.orekit.errors.OrekitMessages;

  29. /** Class representing a date broken up as year, month and day components.
  30.  * <p>This class uses the astronomical convention for calendars,
  31.  * which is also the convention used by <code>java.util.Date</code>:
  32.  * a year zero is present between years -1 and +1, and 10 days are
  33.  * missing in 1582. The calendar used around these special dates are:</p>
  34.  * <ul>
  35.  *   <li>up to 0000-12-31 : proleptic julian calendar</li>
  36.  *   <li>from 0001-01-01 to 1582-10-04: julian calendar</li>
  37.  *   <li>from 1582-10-15: gregorian calendar</li>
  38.  * </ul>
  39.  * <p>Instances of this class are guaranteed to be immutable.</p>
  40.  * @see TimeComponents
  41.  * @see DateTimeComponents
  42.  * @author Luc Maisonobe
  43.  */
  44. public class DateComponents implements Serializable, Comparable<DateComponents> {

  46.     /** Reference epoch for julian dates: -4712-01-01.
  47.      * <p>Both <code>java.util.Date</code> and {@link DateComponents} classes
  48.      * follow the astronomical conventions and consider a year 0 between
  49.      * years -1 and +1, hence this reference date lies in year -4712 and not
  50.      * in year -4713 as can be seen in other documents or programs that obey
  51.      * a different convention (for example the <code>convcal</code> utility).</p>
  52.      */
  53.     public static final DateComponents JULIAN_EPOCH;

  55.     /** Reference epoch for modified julian dates: 1858-11-17. */
  56.     public static final DateComponents MODIFIED_JULIAN_EPOCH;

  58.     /** Reference epoch for 1950 dates: 1950-01-01. */
  59.     public static final DateComponents FIFTIES_EPOCH;

  61.     /** Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01. */
  62.     public static final DateComponents CCSDS_EPOCH;

  64.     /** Reference epoch for Galileo System Time: 1999-08-22. */
  65.     public static final DateComponents GALILEO_EPOCH;

  67.     /** Reference epoch for GPS weeks: 1980-01-06. */
  68.     public static final DateComponents GPS_EPOCH;

  70.     /** Reference epoch for QZSS weeks: 1980-01-06. */
  71.     public static final DateComponents QZSS_EPOCH;

  73.     /** Reference epoch for IRNSS weeks: 1999-08-22. */
  74.     public static final DateComponents IRNSS_EPOCH;

  76.     /** Reference epoch for BeiDou weeks: 2006-01-01. */
  77.     public static final DateComponents BEIDOU_EPOCH;

  79.     /** Reference epoch for GLONASS four-year interval number: 1996-01-01. */
  80.     public static final DateComponents GLONASS_EPOCH;

  82.     /** J2000.0 Reference epoch: 2000-01-01. */
  83.     public static final DateComponents J2000_EPOCH;

  85.     /** Java Reference epoch: 1970-01-01. */
  86.     public static final DateComponents JAVA_EPOCH;

  88.     /** Maximum supported date.
  89.      * <p>
  90.      * This is date 5881610-07-11 which corresponds to {@code Integer.MAX_VALUE}
  91.      * days after {@link #J2000_EPOCH}.
  92.      * </p>
  93.      * @since 9.0
  94.      */
  95.     public static final DateComponents MAX_EPOCH;

  97.     /** Maximum supported date.
  98.      * <p>
  99.      * This is date -5877490-03-03, which corresponds to {@code Integer.MIN_VALUE}
  100.      * days before {@link #J2000_EPOCH}.
  101.      * </p>
  102.      * @since 9.0
  103.      */
  104.     public static final DateComponents MIN_EPOCH;

  106.     /** Serializable UID. */
  107.     private static final long serialVersionUID = -2462694707837970938L;

  109.     /** Factory for proleptic julian calendar (up to 0000-12-31). */
  110.     private static final YearFactory PROLEPTIC_JULIAN_FACTORY = new ProlepticJulianFactory();

  112.     /** Factory for julian calendar (from 0001-01-01 to 1582-10-04). */
  113.     private static final YearFactory JULIAN_FACTORY           = new JulianFactory();

  115.     /** Factory for gregorian calendar (from 1582-10-15). */
  116.     private static final YearFactory GREGORIAN_FACTORY        = new GregorianFactory();

  118.     /** Factory for leap years. */
  119.     private static final MonthDayFactory LEAP_YEAR_FACTORY    = new LeapYearFactory();

  121.     /** Factory for non-leap years. */
  122.     private static final MonthDayFactory COMMON_YEAR_FACTORY  = new CommonYearFactory();

  124.     /** Formatting symbols used in {@link #toString()}. */
  125.     private static final DecimalFormatSymbols US_SYMBOLS = new DecimalFormatSymbols(Locale.US);

  127.     /** Format for years. */
  128.     private static final DecimalFormat FOUR_DIGITS = new DecimalFormat("0000", US_SYMBOLS);

  130.     /** Format for months and days. */
  131.     private static final DecimalFormat TWO_DIGITS  = new DecimalFormat("00", US_SYMBOLS);

  133.     /** Offset between J2000 epoch and modified julian day epoch. */
  134.     private static final int MJD_TO_J2000 = 51544;

  136.     /** Basic and extended format calendar date. */
  137.     private static final Pattern CALENDAR_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d)-?(\\d\\d)$");

  139.     /** Basic and extended format ordinal date. */
  140.     private static final Pattern ORDINAL_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?(\\d\\d\\d)$");

  142.     /** Basic and extended format week date. */
  143.     private static final Pattern WEEK_FORMAT = Pattern.compile("^(-?\\d\\d\\d\\d)-?W(\\d\\d)-?(\\d)$");

  145.     static {
  146.         // this static statement makes sure the reference epoch are initialized
  147.         // once AFTER the various factories have been set up
  148.         JULIAN_EPOCH          = new DateComponents(-4712,  1,  1);
  149.         MODIFIED_JULIAN_EPOCH = new DateComponents(1858, 11, 17);
  150.         FIFTIES_EPOCH         = new DateComponents(1950, 1, 1);
  151.         CCSDS_EPOCH           = new DateComponents(1958, 1, 1);
  152.         GALILEO_EPOCH         = new DateComponents(1999, 8, 22);
  153.         GPS_EPOCH             = new DateComponents(1980, 1, 6);
  154.         QZSS_EPOCH            = new DateComponents(1980, 1, 6);
  155.         IRNSS_EPOCH           = new DateComponents(1999, 8, 22);
  156.         BEIDOU_EPOCH          = new DateComponents(2006, 1, 1);
  157.         GLONASS_EPOCH         = new DateComponents(1996, 1, 1);
  158.         J2000_EPOCH           = new DateComponents(2000, 1, 1);
  159.         JAVA_EPOCH            = new DateComponents(1970, 1, 1);
  160.         MAX_EPOCH             = new DateComponents(Integer.MAX_VALUE);
  161.         MIN_EPOCH             = new DateComponents(Integer.MIN_VALUE);
  162.     }

  164.     /** Year number. */
  165.     private final int year;

  167.     /** Month number. */
  168.     private final int month;

  170.     /** Day number. */
  171.     private final int day;

  173.     /** Build a date from its components.
  174.      * @param year year number (may be 0 or negative for BC years)
  175.      * @param month month number from 1 to 12
  176.      * @param day day number from 1 to 31
  177.      * @exception IllegalArgumentException if inconsistent arguments
  178.      * are given (parameters out of range, february 29 for non-leap years,
  179.      * dates during the gregorian leap in 1582 ...)
  180.      */
  181.     public DateComponents(final int year, final int month, final int day)
  182.         throws IllegalArgumentException {

  184.         // very rough range check
  185.         // (just to avoid ArrayOutOfboundException in MonthDayFactory later)
  186.         if (month < 1 || month > 12) {
  187.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_MONTH, month);
  188.         }

  190.         // start by trusting the parameters
  191.         this.year  = year;
  192.         this.month = month;
  193.         this.day   = day;

  195.         // build a check date from the J2000 day
  196.         final DateComponents check = new DateComponents(getJ2000Day());

  198.         // check the parameters for mismatch
  199.         // (i.e. invalid date components, like 29 february on non-leap years)
  200.         if (year != check.year || month != check.month || day != check.day) {
  201.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_YEAR_MONTH_DAY,
  202.                                                       year, month, day);
  203.         }

  205.     }

  207.     /** Build a date from its components.
  208.      * @param year year number (may be 0 or negative for BC years)
  209.      * @param month month enumerate
  210.      * @param day day number from 1 to 31
  211.      * @exception IllegalArgumentException if inconsistent arguments
  212.      * are given (parameters out of range, february 29 for non-leap years,
  213.      * dates during the gregorian leap in 1582 ...)
  214.      */
  215.     public DateComponents(final int year, final Month month, final int day)
  216.         throws IllegalArgumentException {
  217.         this(year, month.getNumber(), day);
  218.     }

  220.     /** Build a date from a year and day number.
  221.      * @param year year number (may be 0 or negative for BC years)
  222.      * @param dayNumber day number in the year from 1 to 366
  223.      * @exception IllegalArgumentException if dayNumber is out of range
  224.      * with respect to year
  225.      */
  226.     public DateComponents(final int year, final int dayNumber)
  227.         throws IllegalArgumentException {
  228.         this(J2000_EPOCH, new DateComponents(year - 1, 12, 31).getJ2000Day() + dayNumber);
  229.         if (dayNumber != getDayOfYear()) {
  230.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DAY_NUMBER_IN_YEAR,
  231.                                                      dayNumber, year);
  232.         }
  233.     }

  235.     /** Build a date from its offset with respect to a {@link #J2000_EPOCH}.
  236.      * @param offset offset with respect to a {@link #J2000_EPOCH}
  237.      * @see #getJ2000Day()
  238.      */
  239.     public DateComponents(final int offset) {

  241.         // we follow the astronomical convention for calendars:
  242.         // we consider a year zero and 10 days are missing in 1582
  243.         // from 1582-10-15: gregorian calendar
  244.         // from 0001-01-01 to 1582-10-04: julian calendar
  245.         // up to 0000-12-31 : proleptic julian calendar
  246.         YearFactory yFactory = GREGORIAN_FACTORY;
  247.         if (offset < -152384) {
  248.             if (offset > -730122) {
  249.                 yFactory = JULIAN_FACTORY;
  250.             } else {
  251.                 yFactory = PROLEPTIC_JULIAN_FACTORY;
  252.             }
  253.         }
  254.         year = yFactory.getYear(offset);
  255.         final int dayInYear = offset - yFactory.getLastJ2000DayOfYear(year - 1);

  257.         // handle month/day according to the year being a common or leap year
  258.         final MonthDayFactory mdFactory =
  259.             yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
  260.         month = mdFactory.getMonth(dayInYear);
  261.         day   = mdFactory.getDay(dayInYear, month);

  263.     }

  265.     /** Build a date from its offset with respect to a reference epoch.
  266.      * <p>This constructor is mainly useful to build a date from a modified
  267.      * julian day (using {@link #MODIFIED_JULIAN_EPOCH}) or a GPS week number
  268.      * (using {@link #GPS_EPOCH}).</p>
  269.      * @param epoch reference epoch
  270.      * @param offset offset with respect to a reference epoch
  271.      * @see #DateComponents(int)
  272.      * @see #getMJD()
  273.      */
  274.     public DateComponents(final DateComponents epoch, final int offset) {
  275.         this(epoch.getJ2000Day() + offset);
  276.     }

  278.     /** Build a date from week components.
  279.      * <p>The calendar week number is a number between 1 and 52 or 53 depending
  280.      * on the year. Week 1 is defined by ISO as the one that includes the first
  281.      * Thursday of a year. Week 1 may therefore start the previous year and week
  282.      * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
  283.      * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
  284.      * is in fact the first day of year 1995). This date would beAnother example is calendar date
  285.      * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
  286.      * first week of 1997 is in fact the last day of year 1996).</p>
  287.      * @param wYear year associated to week numbering
  288.      * @param week week number in year, from 1 to 52 or 53
  289.      * @param dayOfWeek day of week, from 1 (Monday) to 7 (Sunday)
  290.      * @return a builded date
  291.      * @exception IllegalArgumentException if inconsistent arguments
  292.      * are given (parameters out of range, week 53 on a 52 weeks year ...)
  293.      */
  294.     public static DateComponents createFromWeekComponents(final int wYear, final int week, final int dayOfWeek)
  295.         throws IllegalArgumentException {

  297.         final DateComponents firstWeekMonday = new DateComponents(getFirstWeekMonday(wYear));
  298.         final DateComponents d = new DateComponents(firstWeekMonday, 7 * week + dayOfWeek - 8);

  300.         // check the parameters for invalid date components
  301.         if (week != d.getCalendarWeek() || dayOfWeek != d.getDayOfWeek()) {
  302.             throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_WEEK_DATE,
  303.                                                      wYear, week, dayOfWeek);
  304.         }

  306.         return d;

  308.     }

  310.     /** Parse a string in ISO-8601 format to build a date.
  311.      * <p>The supported formats are:
  312.      * <ul>
  313.      *   <li>basic format calendar date: YYYYMMDD</li>
  314.      *   <li>extended format calendar date: YYYY-MM-DD</li>
  315.      *   <li>basic format ordinal date: YYYYDDD</li>
  316.      *   <li>extended format ordinal date: YYYY-DDD</li>
  317.      *   <li>basic format week date: YYYYWwwD</li>
  318.      *   <li>extended format week date: YYYY-Www-D</li>
  319.      * </ul>
  320.      *
  321.      * <p> As shown by the list above, only the complete representations defined in section 4.1
  322.      * of ISO-8601 standard are supported, neither expended representations nor representations
  323.      * with reduced accuracy are supported.
  324.      *
  325.      * <p>
  326.      * Parsing a single integer as a julian day is <em>not</em> supported as it may be ambiguous
  327.      * with either the basic format calendar date or the basic format ordinal date depending
  328.      * on the number of digits.
  329.      * </p>
  330.      * @param string string to parse
  331.      * @return a parsed date
  332.      * @exception IllegalArgumentException if string cannot be parsed
  333.      */
  334.     public static  DateComponents parseDate(final String string) {

  336.         // is the date a calendar date ?
  337.         final Matcher calendarMatcher = CALENDAR_FORMAT.matcher(string);
  338.         if (calendarMatcher.matches()) {
  339.             return new DateComponents(Integer.parseInt(calendarMatcher.group(1)),
  340.                                       Integer.parseInt(calendarMatcher.group(2)),
  341.                                       Integer.parseInt(calendarMatcher.group(3)));
  342.         }

  344.         // is the date an ordinal date ?
  345.         final Matcher ordinalMatcher = ORDINAL_FORMAT.matcher(string);
  346.         if (ordinalMatcher.matches()) {
  347.             return new DateComponents(Integer.parseInt(ordinalMatcher.group(1)),
  348.                                       Integer.parseInt(ordinalMatcher.group(2)));
  349.         }

  351.         // is the date a week date ?
  352.         final Matcher weekMatcher = WEEK_FORMAT.matcher(string);
  353.         if (weekMatcher.matches()) {
  354.             return createFromWeekComponents(Integer.parseInt(weekMatcher.group(1)),
  355.                                             Integer.parseInt(weekMatcher.group(2)),
  356.                                             Integer.parseInt(weekMatcher.group(3)));
  357.         }

  359.         throw new OrekitIllegalArgumentException(OrekitMessages.NON_EXISTENT_DATE, string);

  361.     }

  363.     /** Get the year number.
  364.      * @return year number (may be 0 or negative for BC years)
  365.      */
  366.     public int getYear() {
  367.         return year;
  368.     }

  370.     /** Get the month.
  371.      * @return month number from 1 to 12
  372.      */
  373.     public int getMonth() {
  374.         return month;
  375.     }

  377.     /** Get the month as an enumerate.
  378.      * @return month as an enumerate
  379.      */
  380.     public Month getMonthEnum() {
  381.         return Month.getMonth(month);
  382.     }

  384.     /** Get the day.
  385.      * @return day number from 1 to 31
  386.      */
  387.     public int getDay() {
  388.         return day;
  389.     }

  391.     /** Get the day number with respect to J2000 epoch.
  392.      * @return day number with respect to J2000 epoch
  393.      */
  394.     public int getJ2000Day() {
  395.         YearFactory yFactory = GREGORIAN_FACTORY;
  396.         if (year < 1583) {
  397.             if (year < 1) {
  398.                 yFactory = PROLEPTIC_JULIAN_FACTORY;
  399.             } else if (year < 1582 || month < 10 || month < 11 && day < 5) {
  400.                 yFactory = JULIAN_FACTORY;
  401.             }
  402.         }
  403.         final MonthDayFactory mdFactory =
  404.             yFactory.isLeap(year) ? LEAP_YEAR_FACTORY : COMMON_YEAR_FACTORY;
  405.         return yFactory.getLastJ2000DayOfYear(year - 1) +
  406.                mdFactory.getDayInYear(month, day);
  407.     }

  409.     /** Get the modified julian day.
  410.      * @return modified julian day
  411.      */
  412.     public int getMJD() {
  413.         return MJD_TO_J2000 + getJ2000Day();
  414.     }

  416.     /** Get the calendar week number.
  417.      * <p>The calendar week number is a number between 1 and 52 or 53 depending
  418.      * on the year. Week 1 is defined by ISO as the one that includes the first
  419.      * Thursday of a year. Week 1 may therefore start the previous year and week
  420.      * 52 or 53 may end in the next year. As an example calendar date 1995-01-01
  421.      * corresponds to week date 1994-W52-7 (i.e. Sunday in the last week of 1994
  422.      * is in fact the first day of year 1995). Another example is calendar date
  423.      * 1996-12-31 which corresponds to week date 1997-W01-2 (i.e. Tuesday in the
  424.      * first week of 1997 is in fact the last day of year 1996).</p>
  425.      * @return calendar week number
  426.      */
  427.     public int getCalendarWeek() {
  428.         final int firstWeekMonday = getFirstWeekMonday(year);
  429.         int daysSincefirstMonday = getJ2000Day() - firstWeekMonday;
  430.         if (daysSincefirstMonday < 0) {
  431.             // we are still in a week from previous year
  432.             daysSincefirstMonday += firstWeekMonday - getFirstWeekMonday(year - 1);
  433.         } else if (daysSincefirstMonday > 363) {
  434.             // up to three days at end of year may belong to first week of next year
  435.             // (by chance, there is no need for a specific check in year 1582 ...)
  436.             final int weekYearLength = getFirstWeekMonday(year + 1) - firstWeekMonday;
  437.             if (daysSincefirstMonday >= weekYearLength) {
  438.                 daysSincefirstMonday -= weekYearLength;
  439.             }
  440.         }
  441.         return 1 + daysSincefirstMonday / 7;
  442.     }

  444.     /** Get the monday of a year first week.
  445.      * @param year year to consider
  446.      * @return day of the monday of the first weak of year
  447.      */
  448.     private static int getFirstWeekMonday(final int year) {
  449.         final int yearFirst = new DateComponents(year, 1, 1).getJ2000Day();
  450.         final int offsetToMonday = 4 - (yearFirst + 2) % 7;
  451.         return yearFirst + offsetToMonday + ((offsetToMonday > 3) ? -7 : 0);
  452.     }

  454.     /** Get the day of week.
  455.      * <p>Day of week is a number between 1 (Monday) and 7 (Sunday).</p>
  456.      * @return day of week
  457.      */
  458.     public int getDayOfWeek() {
  459.         final int dow = (getJ2000Day() + 6) % 7; // result is between -6 and +6
  460.         return (dow < 1) ? (dow + 7) : dow;
  461.     }

  463.     /** Get the day number in year.
  464.      * <p>Day number in year is between 1 (January 1st) and either 365 or
  465.      * 366 inclusive depending on year.</p>
  466.      * @return day number in year
  467.      */
  468.     public int getDayOfYear() {
  469.         return getJ2000Day() - new DateComponents(year - 1, 12, 31).getJ2000Day();
  470.     }

  472.     /** Get a string representation (ISO-8601) of the date.
  473.      * @return string representation of the date.
  474.      */
  475.     public String toString() {
  476.         return new StringBuilder().
  477.                append(FOUR_DIGITS.format(year)).append('-').
  478.                append(TWO_DIGITS.format(month)).append('-').
  479.                append(TWO_DIGITS.format(day)).
  480.                toString();
  481.     }

  483.     /** {@inheritDoc} */
  484.     public int compareTo(final DateComponents other) {
  485.         final int j2000Day = getJ2000Day();
  486.         final int otherJ2000Day = other.getJ2000Day();
  487.         if (j2000Day < otherJ2000Day) {
  488.             return -1;
  489.         } else if (j2000Day > otherJ2000Day) {
  490.             return 1;
  491.         }
  492.         return 0;
  493.     }

  495.     /** {@inheritDoc} */
  496.     public boolean equals(final Object other) {
  497.         try {
  498.             final DateComponents otherDate = (DateComponents) other;
  499.             return otherDate != null && year == otherDate.year &&
  500.                    month == otherDate.month && day == otherDate.day;
  501.         } catch (ClassCastException cce) {
  502.             return false;
  503.         }
  504.     }

  506.     /** {@inheritDoc} */
  507.     public int hashCode() {
  508.         return (year << 16) ^ (month << 8) ^ day;
  509.     }

  511.     /** Interface for dealing with years sequences according to some calendar. */
  512.     private interface YearFactory {

  514.         /** Get the year number for a given day number with respect to J2000 epoch.
  515.          * @param j2000Day day number with respect to J2000 epoch
  516.          * @return year number
  517.          */
  518.         int getYear(int j2000Day);

  520.         /** Get the day number with respect to J2000 epoch for new year's Eve.
  521.          * @param year year number
  522.          * @return day number with respect to J2000 epoch for new year's Eve
  523.          */
  524.         int getLastJ2000DayOfYear(int year);

  526.         /** Check if a year is a leap or common year.
  527.          * @param year year number
  528.          * @return true if year is a leap year
  529.          */
  530.         boolean isLeap(int year);

  532.     }

  534.     /** Class providing a years sequence compliant with the proleptic Julian calendar. */
  535.     private static class ProlepticJulianFactory implements YearFactory {

  537.         /** {@inheritDoc} */
  538.         public int getYear(final int j2000Day) {
  539.             return  (int) -((-4l * j2000Day - 2920488l) / 1461l);
  540.         }

  542.         /** {@inheritDoc} */
  543.         public int getLastJ2000DayOfYear(final int year) {
  544.             return 365 * year + (year + 1) / 4 - 730123;
  545.         }

  547.         /** {@inheritDoc} */
  548.         public boolean isLeap(final int year) {
  549.             return (year % 4) == 0;
  550.         }

  552.     }

  554.     /** Class providing a years sequence compliant with the Julian calendar. */
  555.     private static class JulianFactory implements YearFactory {

  557.         /** {@inheritDoc} */
  558.         public int getYear(final int j2000Day) {
  559.             return  (int) ((4l * j2000Day + 2921948l) / 1461l);
  560.         }

  562.         /** {@inheritDoc} */
  563.         public int getLastJ2000DayOfYear(final int year) {
  564.             return 365 * year + year / 4 - 730122;
  565.         }

  567.         /** {@inheritDoc} */
  568.         public boolean isLeap(final int year) {
  569.             return (year % 4) == 0;
  570.         }

  572.     }

  574.     /** Class providing a years sequence compliant with the Gregorian calendar. */
  575.     private static class GregorianFactory implements YearFactory {

  577.         /** {@inheritDoc} */
  578.         public int getYear(final int j2000Day) {

  580.             // year estimate
  581.             int year = (int) ((400l * j2000Day + 292194288l) / 146097l);

  583.             // the previous estimate is one unit too high in some rare cases
  584.             // (240 days in the 400 years gregorian cycle, about 0.16%)
  585.             if (j2000Day <= getLastJ2000DayOfYear(year - 1)) {
  586.                 --year;
  587.             }

  589.             // exact year
  590.             return year;

  592.         }

  594.         /** {@inheritDoc} */
  595.         public int getLastJ2000DayOfYear(final int year) {
  596.             return 365 * year + year / 4 - year / 100 + year / 400 - 730120;
  597.         }

  599.         /** {@inheritDoc} */
  600.         public boolean isLeap(final int year) {
  601.             return (year % 4) == 0 && ((year % 400) == 0 || (year % 100) != 0);
  602.         }

  604.     }

  606.     /** Interface for dealing with months sequences according to leap/common years. */
  607.     private interface MonthDayFactory {

  609.         /** Get the month number for a given day number within year.
  610.          * @param dayInYear day number within year
  611.          * @return month number
  612.          */
  613.         int getMonth(int dayInYear);

  615.         /** Get the day number for given month and day number within year.
  616.          * @param dayInYear day number within year
  617.          * @param month month number
  618.          * @return day number
  619.          */
  620.         int getDay(int dayInYear, int month);

  622.         /** Get the day number within year for given month and day numbers.
  623.          * @param month month number
  624.          * @param day day number
  625.          * @return day number within year
  626.          */
  627.         int getDayInYear(int month, int day);

  629.     }

  631.     /** Class providing the months sequence for leap years. */
  632.     private static class LeapYearFactory implements MonthDayFactory {

  634.         /** Months succession definition. */
  635.         private static final int[] PREVIOUS_MONTH_END_DAY = {
  636.             0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335
  637.         };

  639.         /** {@inheritDoc} */
  640.         public int getMonth(final int dayInYear) {
  641.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 313) / 306;
  642.         }

  644.         /** {@inheritDoc} */
  645.         public int getDay(final int dayInYear, final int month) {
  646.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  647.         }

  649.         /** {@inheritDoc} */
  650.         public int getDayInYear(final int month, final int day) {
  651.             return day + PREVIOUS_MONTH_END_DAY[month];
  652.         }

  654.     }

  656.     /** Class providing the months sequence for common years. */
  657.     private static class CommonYearFactory implements MonthDayFactory {

  659.         /** Months succession definition. */
  660.         private static final int[] PREVIOUS_MONTH_END_DAY = {
  661.             0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
  662.         };

  664.         /** {@inheritDoc} */
  665.         public int getMonth(final int dayInYear) {
  666.             return (dayInYear < 32) ? 1 : (10 * dayInYear + 323) / 306;
  667.         }

  669.         /** {@inheritDoc} */
  670.         public int getDay(final int dayInYear, final int month) {
  671.             return dayInYear - PREVIOUS_MONTH_END_DAY[month];
  672.         }

  674.         /** {@inheritDoc} */
  675.         public int getDayInYear(final int month, final int day) {
  676.             return day + PREVIOUS_MONTH_END_DAY[month];
  677.         }

  679.     }

  681. }
Created with JaCoCo 0.8.11.202310140853