Provide original holiday date and observed holiday date

jollyday-core/src/main/java/de/focus_shift/jollyday/core/Holiday.java

@@ -4,6 +4,8 @@
 
 import java.time.LocalDate;
 import java.util.Locale;
+import java.util.Objects;
+import java.util.Optional;
 
 /**
  * Represents the holiday and contains the actual date and an localized
@@ -17,7 +19,11 @@ public final class Holiday implements Comparable<Holiday> {
   /**
    * The date the holiday occurs.
    */
-  private final LocalDate date;
+  private final LocalDate actualDate;
+  /**
+   * The observed date of the holiday.
+   */
+  private final LocalDate observedDate;
   /**
    * The properties key to retrieve the description with.
    */
@@ -32,26 +38,68 @@ public final class Holiday implements Comparable<Holiday> {
    * Constructs a holiday for a date using the provided properties key to
    * retrieve the description with.
    *
-   * @param date          a {@link LocalDate} object.
+   * @param actualDate    a {@link LocalDate} object.
    * @param propertiesKey a {@link java.lang.String} object.
    * @param type          a {@link HolidayType} object.
    */
-  public Holiday(final LocalDate date, final String propertiesKey, final HolidayType type) {
+  public Holiday(final LocalDate actualDate, final String propertiesKey, final HolidayType type) {
+    this(actualDate, null, propertiesKey, type);
+  }
+
+  /**
+   * Constructs a holiday for a date using the provided properties key to
+   * retrieve the description with.
+   *
+   * @param actualDate    a {@link LocalDate} object.
+   * @param observedDate  a {@link LocalDate} object.
+   * @param propertiesKey a {@link java.lang.String} object.
+   * @param type          a {@link HolidayType} object.
+   */
+  public Holiday(final LocalDate actualDate, final LocalDate observedDate, final String propertiesKey, final HolidayType type) {
     super();
     this.type = type;
-    this.date = date;
+    this.actualDate = actualDate;
+    this.observedDate = observedDate;
     this.propertiesKey = propertiesKey == null ? "" : propertiesKey;
   }
 
   /**
+   * Returns the calculated holiday date.
+   * <p>
+   * If the holiday is {@link de.focus_shift.jollyday.core.spi.Movable} and the holiday was moved, then:
+   * <ul>
+   *  <li>the observed holiday date is given</li>
+   *  <li>otherwise, the actual holiday date</li>
+   * </ul>
    * <p>
-   * Getter for the field <code>date</code>.
+   *  @return if holiday was moved the observed date, otherwise the actual date
+   */
+  public LocalDate getDate() {
+    return Optional.ofNullable(observedDate).orElse(actualDate);
+  }
+
+  /**
+   * <p>
+   * Returns the actual date.
+   * <p>
+   * If you want the observed holiday date then use {@link #getObservedDate()}
    * </p>
    *
-   * @return the holiday date
+   * @return the actual holiday date
    */
-  public LocalDate getDate() {
-    return date;
+  public LocalDate getActualDate() {
+    return actualDate;
+  }
+
+  /**
+   * <p>
+   * Getter for the field <code>observedDate</code>.
+   * </p>
+   *
+   * @return the observed holiday date
+   */
+  public LocalDate getObservedDate() {
+    return observedDate;
   }
 
   /**
@@ -86,31 +134,27 @@ public String getDescription(Locale locale) {
 
   @Override
   public boolean equals(final Object obj) {
-    if (obj == this) {
-      return true;
-    }
-    if (obj instanceof Holiday) {
-      final Holiday other = (Holiday) obj;
-      return other.date.equals(this.date) && other.propertiesKey.equals(this.propertiesKey) && type.equals(other.type);
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
     }
-    return false;
+
+    final Holiday holiday = (Holiday) obj;
+    return Objects.equals(getDate(), holiday.getDate()) &&
+      Objects.equals(propertiesKey, holiday.propertiesKey) &&
+      type == holiday.type;
   }
 
   @Override
   public int hashCode() {
     if (hashCode == 0) {
-      int hash = 1;
-      hash = hash * 31 + date.hashCode();
-      hash = hash * 31 + propertiesKey.hashCode();
-      hash = hash * 31 + type.hashCode();
-      hashCode = hash;
+      hashCode = Objects.hash(actualDate, observedDate, propertiesKey, type);
     }
     return hashCode;
   }
 
   @Override
   public String toString() {
-    return date.toString() + " (" + getDescription() + ")";
+    return actualDate.toString() + " (" + getDescription() + ")";
   }
 
   /**

jollyday-core/src/main/java/de/focus_shift/jollyday/core/parser/functions/CreateHoliday.java

@@ -8,14 +8,20 @@
 
 public class CreateHoliday implements Function<Described, Holiday> {
 
-  private final LocalDate localDate;
+  private final LocalDate date;
+  private final LocalDate observedDate;
 
-  public CreateHoliday(LocalDate localDate) {
-    this.localDate = localDate;
+  public CreateHoliday(final LocalDate date) {
+    this(date, null);
+  }
+
+  public CreateHoliday(final LocalDate date, final LocalDate observedDate) {
+    this.date = date;
+    this.observedDate = observedDate;
   }
 
   @Override
   public Holiday apply(final Described described) {
-    return new Holiday(localDate, described.descriptionPropertiesKey(), described.holidayType());
+    return new Holiday(date, observedDate, described.descriptionPropertiesKey(), described.holidayType());
   }
 }

jollyday-core/src/main/java/de/focus_shift/jollyday/core/parser/impl/ChristianHolidayParser.java

@@ -24,9 +24,11 @@ public class ChristianHolidayParser implements HolidayParser {
   public List<Holiday> parse(final Year year, final Holidays holidays) {
     return holidays.christianHolidays().stream()
       .filter(new ValidLimitation(year))
-      .map(ch -> {
-        LocalDate easterSunday = new CalculateEasterSunday(year).apply(ch.chronology());
-        switch (ch.type()) {
+      .map(christianHoliday -> {
+
+        LocalDate easterSunday = new CalculateEasterSunday(year).apply(christianHoliday.chronology());
+
+        switch (christianHoliday.type()) {
           case EASTER:
             break;
           case CLEAN_MONDAY:
@@ -76,10 +78,10 @@ public List<Holiday> parse(final Year year, final Holidays holidays) {
             easterSunday = easterSunday.plusDays(68);
             break;
           default:
-            throw new IllegalArgumentException("Unknown christian holiday type " + ch.type());
+            throw new IllegalArgumentException("Unknown christian holiday type " + christianHoliday.type());
         }
-        easterSunday = new MoveDateRelative(easterSunday).apply(ch);
-        return new CreateHoliday(easterSunday).apply(ch);
+        final LocalDate movedChristianHoliday = new MoveDateRelative(easterSunday).apply(christianHoliday);
+        return new CreateHoliday(easterSunday, movedChristianHoliday).apply(christianHoliday);
       })
       .collect(toList());
   }

jollyday-core/src/main/java/de/focus_shift/jollyday/core/parser/impl/DescribedDateHolder.java

@@ -7,17 +7,27 @@
 class DescribedDateHolder {
 
   private final LocalDate date;
+  private final LocalDate observedDate;
   private final Described described;
 
-  public DescribedDateHolder(final Described described, final LocalDate date) {
+  DescribedDateHolder(final Described described, final LocalDate date) {
+    this(described, date, null);
+  }
+
+  DescribedDateHolder(final Described described, final LocalDate date, final LocalDate observedDate) {
     this.date = date;
+    this.observedDate = observedDate;
     this.described = described;
   }
 
   public LocalDate getDate() {
     return date;
   }
 
+  public LocalDate getObservedDate() {
+    return observedDate;
+  }
+
   public Described getDescribed() {
     return described;
   }

jollyday-core/src/main/java/de/focus_shift/jollyday/core/parser/impl/FixedParser.java

@@ -22,8 +22,8 @@ public class FixedParser implements HolidayParser {
   public List<Holiday> parse(final Year year, final Holidays holidays) {
     return holidays.fixed().stream()
       .filter(new ValidLimitation(year))
-      .map(fixed -> new DescribedDateHolder(fixed, new MoveDateRelative(new FixedToLocalDate(year).apply(fixed)).apply(fixed)))
-      .map(describedDateHolder -> new CreateHoliday(describedDateHolder.getDate()).apply(describedDateHolder.getDescribed()))
+      .map(fixed -> new DescribedDateHolder(fixed, new FixedToLocalDate(year).apply(fixed), new MoveDateRelative(new FixedToLocalDate(year).apply(fixed)).apply(fixed)))
+      .map(describedDateHolder -> new CreateHoliday(describedDateHolder.getDate(), describedDateHolder.getObservedDate()).apply(describedDateHolder.getDescribed()))
       .collect(toList());
   }
 }

jollyday-core/src/main/java/de/focus_shift/jollyday/core/parser/impl/IslamicHolidayParser.java

@@ -80,8 +80,8 @@ public List<Holiday> parse(final Year year, final Holidays holidays) {
         }
 
         return islamicHolidays
-          .map(date -> new MoveDateRelative(date).apply(islamicHoliday))
-          .map(date -> new CreateHoliday(date).apply(islamicHoliday));
+          .map(date -> new DescribedDateHolder(islamicHoliday, date, new MoveDateRelative(date).apply(islamicHoliday)))
+          .map(describedDateHolder -> new CreateHoliday(describedDateHolder.getDate(), describedDateHolder.getObservedDate()).apply(islamicHoliday));
 
       })
       .collect(toList());

jollyday-core/src/test/java/de/focus_shift/jollyday/core/HolidayTest.java

@@ -50,6 +50,20 @@ void testHolidayDescription() {
     assertThat(holiday.getDescription(new Locale("nl"))).isEqualTo("Kerstmis");
   }
 
+  @Test
+  void ensureToReturnObservedDateIfPresent() {
+    final LocalDate observedDate = LocalDate.of(2011, 2, 10);
+    final Holiday holiday = new Holiday(LocalDate.of(2011, 2, 2), observedDate, "CHRISTMAS", PUBLIC_HOLIDAY);
+    assertThat(holiday.getDate()).isEqualTo(observedDate);
+  }
+
+  @Test
+  void ensureToReturnActualDateIfObservedDateIsNotPresent() {
+    final LocalDate date = LocalDate.of(2011, 2, 2);
+    final Holiday holiday = new Holiday(date, "CHRISTMAS", PUBLIC_HOLIDAY);
+    assertThat(holiday.getDate()).isEqualTo(date);
+  }
+
   @Test
   void testHolidayEquals() {
     final Holiday h1 = new Holiday(LocalDate.of(2011, 2, 2), "CHRISTMAS", PUBLIC_HOLIDAY);

jollyday-core/src/test/java/de/focus_shift/jollyday/core/parser/impl/IslamicHolidayParserTest.java

@@ -54,5 +54,7 @@ public DayOfWeek weekday() {
     // ID_UL_ADHA_2 will be on a sunday in 2022
     final List<Holiday> calculatedHoliday = sut.parse(Year.of(2022), holidays);
     assertThat(calculatedHoliday.get(0).getDate().getDayOfWeek()).isEqualTo(DayOfWeek.MONDAY);
+    assertThat(calculatedHoliday.get(0).getActualDate().getDayOfWeek()).isEqualTo(DayOfWeek.SUNDAY);
+    assertThat(calculatedHoliday.get(0).getObservedDate().getDayOfWeek()).isEqualTo(DayOfWeek.MONDAY);
   }
 }