Fix waiting times

They now take lab end times into account, such that average waiting time is actually reported and current waiting time does not infinitely increase after the lab.

src/main/java/nl/tudelft/queue/model/labs/AbstractSlottedLab.java

@@ -95,14 +95,26 @@ public abstract class AbstractSlottedLab<TS extends TimeSlot> extends Lab {
 
 	@Override
 	public OptionalDouble currentWaitingTime() {
+		var labEndTime = getSessionDto().getEndTime();
+		var slots = getTimeSlots().stream();
+		OptionalDouble baseWaitTime;
+		LocalDateTime effectiveEndTime;
+
+		if (labEndTime.isBefore(now())) {
+			effectiveEndTime = labEndTime;
+			baseWaitTime = OptionalDouble.of(0);
+		} else {
+			slots = slots.filter(ts -> ts.getSlot().getOpensAt().isBefore(now()));
+			effectiveEndTime = now();
+			baseWaitTime = OptionalDouble.empty();
+		}
+
 		// Find the last started timeslot with pending requests, if any.
 		// Otherwise, find the last started timeslot with requests.
 		// Then pick the first created pending request, if any. Otherwise, pick the first created request.
-		return getTimeSlots().stream()
-				.filter(ts -> ts.getSlot().getOpensAt().isBefore(now()))
-				.max(Comparator.<TimeSlot>comparingInt(ts -> ts.hasPendingRequests() ? 1 : -1)
-						.thenComparingInt(ts -> ts.getRequests().size() > 0 ? 1 : -1)
-						.thenComparing(ts -> ts.getSlot().getOpensAt()))
+		return slots.max(Comparator.<TimeSlot>comparingInt(ts -> ts.hasPendingRequests() ? 1 : -1)
+				.thenComparingInt(ts -> ts.getRequests().size() > 0 ? 1 : -1)
+				.thenComparing(ts -> ts.getSlot().getOpensAt()))
 				.stream()
 				.flatMap(ts -> ts.getRequests().stream())
 				.max(Comparator
@@ -110,7 +122,8 @@ public abstract class AbstractSlottedLab<TS extends TimeSlot> extends Lab {
 						.thenComparing(Comparator.nullsFirst(Comparator
 								.<LabRequest, LocalDateTime>comparing(Request::getCreatedAt)
 								.reversed())))
-				.map(LabRequest::sensibleWaitingTime)
-				.orElse(OptionalDouble.empty());
+				.map(r -> r.sensibleWaitingTime(effectiveEndTime))
+				.orElse(baseWaitTime);
+
 	}
 }