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package com.softicar.platform.common.date;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.Objects;
/**
* Base class of all date items, including {@link Year}, {@link Month},
* {@link Week} and {@link Day}.
*
* One common property of date items is that they all have an absolute index,
* which enables a list of common operations, like iteration or comparison.
*
* @param
* the actual type of the date item
* @author Oliver Richers
*/
public abstract class DateItem> implements Comparable> {
/**
* Returns an absolute index for this date item.
*
* @return an absolute index
*/
public abstract int getAbsoluteIndex();
/**
* Returns the date item following this date item.
*
* @return the next date item
*/
public T getNext() {
return getRelative(1);
}
/**
* Returns the date item before this date item.
*
* @return the previous date item
*/
public T getPrevious() {
return getRelative(-1);
}
/**
* Returns a date item relative to this item.
*
* @param index
* the index of the other date item counted from this date item
* @return the other date item
*/
public abstract T getRelative(int index);
/**
* Returns the distance from this item to the other item.
*
* @param other
* the other item
* @return the distance to the other item
*/
public int getDistance(DateItem other) {
return other.getAbsoluteIndex() - getAbsoluteIndex();
}
/**
* Returns a range over the neighboring items.
*
* @param size
* the size of the range in each direction
* @return a range with 2*size+1 items
*/
public DateItemRange getRange(int size) {
return new DateItemRange<>(getRelative(-size), getRelative(size));
}
/**
* Returns a range over the neighboring items. NOTE: fromIndex must be less
* or equal to toIndex
*
* @param fromIndex
* index of the first item relative to this item
* @param toIndex
* index of the last item relative to this item
* @return new DateItemRange(getRelative(fromIndex),
* getRelative(toIndex));
*/
public DateItemRange getRange(int fromIndex, int toIndex) {
return new DateItemRange<>(getRelative(fromIndex), getRelative(toIndex));
}
/**
* Computes the distance from the specified other {@link DateItem} to this
* item.
*
* This is simply a subtraction of the absolute index of the other item from
* the absolute index of this item, and it will return a positive value if
* this item is later than the given item, zero if they are equal and a
* negative value otherwise.
*
* @param other
* the other date item
* @return this.getAbsoluteIndex() - other.getAbsoluteIndex()
*/
public int minus(DateItem other) {
return getAbsoluteIndex() - other.getAbsoluteIndex();
}
/**
* Returns the absolute distance between this date item and the other.
*
* @return the absolute distance, always positive
*/
public int getAbsoluteDistance(DateItem other) {
return Math.abs(minus(other));
}
/**
* Compares this date item to an other date item.
*
* This returns a positive value if this {@link DateItem} is later than the
* given {@link DateItem}, zero if equal, and otherwise a negative value.
*
* @return this.minus(other)
*/
@Override
public int compareTo(DateItem other) {
return minus(other);
}
/**
* Compares this date item to another date item.
*/
public boolean equals(DateItem other) {
if (other == null) {
return false;
}
return getAbsoluteIndex() == other.getAbsoluteIndex();
}
@Override
public boolean equals(Object other) {
if (other == null) {
return false;
}
return other.getClass() == getClass() && equals((DateItem) other);
}
@Override
public int hashCode() {
return getAbsoluteIndex();
}
public boolean isAfter(DateItem other) {
return compareTo(other) > 0;
}
public boolean isAfterOrEqual(DateItem other) {
return compareTo(other) >= 0;
}
public boolean isBefore(DateItem other) {
return compareTo(other) < 0;
}
public boolean isBeforeOrEqual(DateItem other) {
return compareTo(other) <= 0;
}
/**
* Determines whether this {@link DateItem} lies in the time period which is
* spanned by the given {@link DateItem} instances (inclusive).
*
* Returns false if the second given {@link DateItem} is before the
* first given {@link DateItem}.
*
* @param first
* the first {@link DateItem} of the period (never null)
* @param last
* the last {@link DateItem} of the period (never null)
* @return true this {@link DateItem} is in the given period;
* false otherwise
*/
public boolean isBetween(DateItem first, DateItem last) {
return isAfterOrEqual(first) && isBeforeOrEqual(last);
}
/**
* Identifies and returns the {@link DateItem} which represents the latest
* point in time, among the given {@link DateItem} instances.
*
* Returns null if the given array is empty.
*
* @param dateItems
* the {@link DateItem} instances among which the latest one
* shall be identified (never null)
* @return the latest given {@link DateItem} (may be null)
*/
@SafeVarargs
public static > T max(T...dateItems) {
return max(Arrays.asList(dateItems));
}
/**
* Identifies and returns the {@link DateItem} which represents the latest
* point in time, among the given {@link DateItem} instances.
*
* Returns null if the given {@link Collection} is empty.
*
* @param dateItems
* the {@link DateItem} instances among which the latest one
* shall be identified (never null)
* @return the latest given {@link DateItem} (may be null)
*/
public static > T max(Collection dateItems) {
return dateItems.stream().filter(Objects::nonNull).sorted(Comparator.reverseOrder()).findFirst().orElse(null);
}
/**
* Identifies and returns the {@link DateItem} which represents the earliest
* point in time, among the given {@link DateItem} instances.
*
* Returns null if the given array is empty.
*
* @param dateItems
* the {@link DateItem} instances among which the earliest one
* shall be identified (never null)
* @return the earliest given {@link DateItem} (may be null)
*/
@SafeVarargs
public static > T min(T...dateItems) {
return min(Arrays.asList(dateItems));
}
/**
* Identifies and returns the {@link DateItem} which represents the earliest
* point in time, among the given {@link DateItem} instances.
*
* Returns null if the given {@link Collection} is empty.
*
* @param dateItems
* the {@link DateItem} instances among which the earliest one
* shall be identified (never null)
* @return the earliest given {@link DateItem} (may be null)
*/
public static > T min(Collection dateItems) {
return dateItems.stream().filter(Objects::nonNull).sorted().findFirst().orElse(null);
}
}