/**

  * Copyright 2010 Sven Diedrichsen 

  * 

  * 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 de.jollyday.util;

 import static java.time.DayOfWeek.SATURDAY;

 import static java.time.DayOfWeek.SUNDAY;

 import static java.time.Month.APRIL;

 import static java.time.Month.DECEMBER;

 import static java.time.Month.JANUARY;

 import static java.time.Month.MARCH;

 import java.time.LocalDate;

 import java.time.chrono.ChronoLocalDate;

 import java.time.chrono.Chronology;

 import java.time.chrono.HijrahChronology;

 import java.time.temporal.ChronoField;

 import java.util.Calendar;

 import java.util.HashSet;

 import java.util.Set;

 import org.threeten.extra.chrono.CopticChronology;

 import org.threeten.extra.chrono.JulianChronology;

 import de.jollyday.Holiday;

 import de.jollyday.config.Fixed;

 /**

  * Utility class for date operations.

  * 

  * @author Sven Diedrichsen

  * @version $Id: $

  */

 public class CalendarUtil {

         private XMLUtil xmlUtil = new XMLUtil();

         /**

          * Creates the current date within the gregorian calendar.

          * 

          * @return today

          */

         public LocalDate create() {

                 return LocalDate.now();

         }

         /**

          * Creates the date within the ISO chronology.

          * 

          * @param year

          *            a int.

          * @param month

          *            a int.

          * @param day

          *            a int.

          * @return date

          */

         public LocalDate create(int year, int month, int day) {

                 return LocalDate.of(year, month, day);

         }

         /**

          * Creates the date within the provided chronology.

          * 

          * @param year

          *            a int.

          * @param month

          *            a int.

          * @param day

          *            a int.

          * @param chronology

          *            the chronology to use

          * @return date the {@link LocalDate}

          */

         public ChronoLocalDate create(int year, int month, int day, Chronology chronology) {

                 return chronology.date(year, month, day);

         }

         /**

          * Creates the date from the month/day within the specified year.

          * 

          * @param year

          *            a int.

          * @param fixed

          *            a {@link de.jollyday.config.Fixed} object.

          * @return A local date instance.

          */

         public LocalDate create(int year, Fixed fixed) {

                 return create(year, xmlUtil.getMonth(fixed.getMonth()), fixed.getDay());

         }

         /**

          * Creates a LocalDate. Does not use the Chronology of the Calendar.

          * 

          * @param c

          *            a {@link java.util.Calendar} object.

          * @return The local date representing the provided date.

          */

         public LocalDate create(final Calendar c) {

                 //TODO: javadoc needs updating

                 return LocalDate.of(c.get(Calendar.YEAR), c.get(Calendar.MONTH) + 1, c

                                 .get(Calendar.DAY_OF_MONTH));

         }

         /**

          * Returns the easter sunday for a given year.

          * 

          * @param year

          *            a int.

          * @return Easter sunday.

          */

         public LocalDate getEasterSunday(int year) {

                 if (year <= 1583) {

                         return getJulianEasterSunday(year);

                 } else {

                         return getGregorianEasterSunday(year);

                 }

         }

         /**

          * Returns the easter sunday within the julian chronology.

          * 

          * @param year

          *            a int.

          * @return julian easter sunday

          */

         public LocalDate getJulianEasterSunday(int year) {

                 int a, b, c, d, e;

                 int x, month, day;

                 a = year % 4;

                 b = year % 7;

                 c = year % 19;

                 d = (19 * c + 15) % 30;

                 e = (2 * a + 4 * b - d + 34) % 7;

                 x = d + e + 114;

                 month = x / 31;

                 day = (x % 31) + 1;

                 return LocalDate.from(JulianChronology.INSTANCE.date(year, (month == 3 ? 3 : 4), day));

         }

         /**

          * Returns the easter sunday within the gregorian chronology.

          * 

          * @param year

          *            a int.

          * @return gregorian easter sunday.

          */

         public LocalDate getGregorianEasterSunday(int year) {

                 int a, b, c, d, e, f, g, h, i, j, k, l;

                 int x, month, day;

                 a = year % 19;

                 b = year / 100;

                 c = year % 100;

                 d = b / 4;

                 e = b % 4;

                 f = (b + 8) / 25;

                 g = (b - f + 1) / 3;

                 h = (19 * a + b - d - g + 15) % 30;

                 i = c / 4;

                 j = c % 4;

                 k = (32 + 2 * e + 2 * i - h - j) % 7;

                 l = (a + 11 * h + 22 * k) / 451;

                 x = h + k - 7 * l + 114;

                 month = x / 31;

                 day = (x % 31) + 1;

                 return LocalDate.of(year, (month == 3 ? MARCH : APRIL), day);

         }

         /**

          * Returns if this date is on a wekkend.

          * 

          * @param date

          *            a {@link LocalDate} object.

          * @return is weekend

          */

         public boolean isWeekend(final LocalDate date) {

                 return date.getDayOfWeek() == SATURDAY || date.getDayOfWeek() == SUNDAY;

         }

         /**

          * Returns a set of gregorian dates within a gregorian year which equal the

          * islamic month and day. Because the islamic year is about 11 days shorter

          * than the gregorian there may be more than one occurrence of an islamic

          * date in an gregorian year. i.e.: In the gregorian year 2008 there were

          * two 1/1. They occurred on 1/10 and 12/29.

          * 

          * @param gregorianYear

          *            a int.

          * @param islamicMonth

          *            a int.

          * @param islamicDay

          *            a int.

          * @return List of gregorian dates for the islamic month/day.

          */

         public Set<LocalDate> getIslamicHolidaysInGregorianYear(int gregorianYear, int islamicMonth, int islamicDay) {

                 return getDatesFromChronologyWithinGregorianYear(islamicMonth, islamicDay, gregorianYear,

                                 HijrahChronology.INSTANCE);

         }

         /**

          * Returns a set of gregorian dates within a gregorian year which equal the

          * ethiopian orthodox month and day. Because the ethiopian orthodox year

          * different from the gregorian there may be more than one occurrence of an

          * ethiopian orthodox date in an gregorian year.

          * 

          * @param gregorianYear

          *            a int.

          * @return List of gregorian dates for the ethiopian orthodox month/day.

          * @param eoMonth

          *            a int.

          * @param eoDay

          *            a int.

          */

         public Set<LocalDate> getEthiopianOrthodoxHolidaysInGregorianYear(int gregorianYear, int eoMonth, int eoDay) {

                 return getDatesFromChronologyWithinGregorianYear(eoMonth, eoDay, gregorianYear, CopticChronology.INSTANCE);

         }

         /**

          * Searches for the occurrences of a month/day in one chronology within one

          * gregorian year.

          * 

          * @param targetMonth

          * @param targetDay

          * @param gregorianYear

          * @param targetChrono

          * @return the list of gregorian dates.

          */

         private Set<LocalDate> getDatesFromChronologyWithinGregorianYear(int targetMonth, int targetDay, int gregorianYear,

                         Chronology targetChrono) {

                 Set<LocalDate> holidays = new HashSet<>();

                 LocalDate firstGregorianDate = LocalDate.of(gregorianYear, JANUARY, 1);

                 LocalDate lastGregorianDate = LocalDate.of(gregorianYear, DECEMBER, 31);

                 ChronoLocalDate firstTargetDate = targetChrono.date(firstGregorianDate);

                 ChronoLocalDate lastTargetDate = targetChrono.date(lastGregorianDate);

                 int targetYear = firstTargetDate.get(ChronoField.YEAR);

                 final int lastYear = lastTargetDate.get(ChronoField.YEAR);

                 for (; targetYear <= lastYear;) {

                         ChronoLocalDate d = targetChrono.date(targetYear, targetMonth, targetDay);

                         if (!firstGregorianDate.isAfter(d) && !lastGregorianDate.isBefore(d)) {

                                 holidays.add(LocalDate.from(d));

                         }

                         targetYear++;

                 }

                 return holidays;

         }

         /**

          * Shows if the requested dat is contained in the Set of holidays.

          * 

          * @param holidays

          *            a {@link java.util.Set} object.

          * @param date

          *            a {@link LocalDate} object.

          * @return contains this date

          */

         public boolean contains(final Set<Holiday> holidays, final LocalDate date) {

                 for (Holiday h : holidays) {

                         if (h.getDate().equals(date)) {

                                 return true;

                         }

                 }

                 return false;

         }

 }