/**
* Returns the result of {@link TimeInterval} i1 & i2 intersection, <code>null</code> if i1
* does not intersects i2 (<code>null</code> border means infinity).
*/
public static TimeInterval intersection(TimeInterval i1, TimeInterval i2) {
if (i1 == null || i2 == null) return null;
if (!intersects(i1, i2)) return null;
i1 = arrange(i1);
i2 = arrange(i2);
Instant a = null;
if (i1.getStart() == null && i2.getStart() == null) a = null;
else if (i1.getStart() == null && i2.getStart() != null) a = i2.getStart();
else if (i1.getStart() != null && i2.getStart() == null) a = i1.getStart();
else a = max(i1.getStart(), i2.getStart());
Instant b = null;
if (i1.getEnd() == null && i2.getEnd() == null) b = null;
else if (i1.getEnd() == null && i2.getEnd() != null) b = i2.getEnd();
else if (i1.getEnd() != null && i2.getEnd() == null) b = i1.getEnd();
else b = min(i1.getEnd(), i2.getEnd());
return TimeInterval.between(a, b);
}
/** Returns a re-arranged {@link TimeInterval} if borders order is reversed. */
public static TimeInterval arrange(TimeInterval i) {
if (i.getStart() != null && i.getEnd() != null && i.getStart().compareTo(i.getEnd()) > 0)
return TimeInterval.between(i.getEnd(), i.getStart());
return i;
}