address PR comments

api/src/main/java/org/openmrs/module/queue/api/QueueEntryService.java

@@ -60,12 +60,15 @@ public interface QueueEntryService {
 	QueueEntry transitionQueueEntry(@NotNull QueueEntryTransition queueEntryTransition);
 
 	/**
-	 * Undos a transition by voiding the input queue entry and making its previous queue entry 
-	 * (which MUST not be null) active by setting the previous entry's end time to null. 
+	 * Undos a transition to the input queue entry by voiding it and 
+   * making its previous queue entry active by
+	 * setting the previous entry's end time to null.
 	 * 
-	 * @param queueEntry the queue entry to undo transition from
+	 * @see QueueEntryService#getPreviousQueueEntry(QueueEntry)
+	 * @param queueEntry the queue entry to undo transition to. Must be active
 	 * @return the previous queue entry, re-activated
-	 * 
+	 * @throws IllegalArgumentException if the previous queue entry does not exist
+	 * @throws IllegalStateException if multiple previous entries are identified
 	 */
 	QueueEntry undoTransition(@NotNull QueueEntry queueEntry);
 
@@ -125,11 +128,12 @@ String generateVisitQueueNumber(@NotNull Location location, @NotNull Queue queue
 	void setSortWeightGenerator(SortWeightGenerator sortWeightGenerator);
 
 	/**
-	 * Given a specified queue entry, return its previous queue entry (i.e. the queue entry the patient
-	 * transition from to get to the specified one)
+	 * Given a specified queue entry Q, return its previous queue entry P, where P has same patient and
+	 * visit as Q, and P.endedAt time is same as Q.startAt time.
 	 * 
 	 * @param queueEntry
-	 * @return the previous queue entry, if uniquely identifable; null otherwise.
+	 * @return the previous queue entry, null otherwise.
+	 * @throws IllegalStateException if multiple previous queue entries are identified
 	 */
 	QueueEntry getPreviousQueueEntry(@NotNull QueueEntry queueEntry);
 }

api/src/main/java/org/openmrs/module/queue/api/impl/QueueEntryServiceImpl.java

@@ -135,7 +135,6 @@ public QueueEntry transitionQueueEntry(QueueEntryTransition queueEntryTransition
 	 * @see QueueEntryService#undoTransition(QueueEntry)
 	 */
 	@Override
-	@Transactional
 	public QueueEntry undoTransition(@NotNull QueueEntry queueEntry) {
 		if (queueEntry.getVoided()) {
 			throw new IllegalArgumentException("cannot undo transition on a voided queue entry");
@@ -149,7 +148,7 @@ public QueueEntry undoTransition(@NotNull QueueEntry queueEntry) {
 		}
 		prevQueueEntry.setEndedAt(null);
 		prevQueueEntry = dao.createOrUpdate(prevQueueEntry);
-			
+
 		queueEntry.setVoided(true);
 		queueEntry.setVoidReason("undo transition");
 		dao.createOrUpdate(queueEntry);
@@ -252,6 +251,7 @@ private void endQueueEntry(@NotNull QueueEntry queueEntry) {
 	}
 
 	@Override
+	@Transactional(readOnly = true)
 	public QueueEntry getPreviousQueueEntry(@NotNull QueueEntry queueEntry) {
 		QueueEntrySearchCriteria criteria = new QueueEntrySearchCriteria();
 		criteria.setPatient(queueEntry.getPatient());
@@ -260,6 +260,8 @@ public QueueEntry getPreviousQueueEntry(@NotNull QueueEntry queueEntry) {
 		List<QueueEntry> prevQueueEntries = dao.getQueueEntries(criteria);
 		if (prevQueueEntries.size() == 1) {
 			return prevQueueEntries.get(0);
+		} else if(prevQueueEntries.size() > 1) {
+			throw new IllegalStateException("Multiple previous queue entries found");
 		} else {
 			return null;
 		}

api/src/test/java/org/openmrs/module/queue/api/QueueEntryServiceTest.java

@@ -286,7 +286,7 @@ public void shouldTransitionQueueEntry() {
 		assertThat(queueEntry3.getStartedAt(), equalTo(date3));
 		assertNull(queueEntry3.getEndedAt());
 	}
-
+	
 	@Test
 	public void shouldUndoTransitionQueueEntry() {
 		Patient patient1 = new Patient();
@@ -325,13 +325,13 @@ public void shouldUndoTransitionQueueEntry() {
 		criteria.setVisit(visit1);
 		criteria.setEndedOn(date2);
 		when(dao.getQueueEntries(criteria)).thenReturn(Arrays.asList(queueEntry1));
-
+		
 		// First transition test that no changes are required and all values will be pulled from existing queue entry
 		QueueEntryTransition transition1 = new QueueEntryTransition();
 		transition1.setQueueEntryToTransition(queueEntry1);
 		transition1.setTransitionDate(date2);
 		QueueEntry queueEntry2 = queueEntryService.transitionQueueEntry(transition1);
-
+		
 		queueEntryService.undoTransition(queueEntry2);
 		assertThat(queueEntry2.getVoided(), equalTo(true));
 		assertNull(queueEntry1.getEndedAt());

omod/src/main/java/org/openmrs/module/queue/web/QueueEntryTransitionRestController.java

@@ -101,8 +101,7 @@ public Object transitionQueueEntry(@RequestBody QueueEntryTransitionRequest body
 		return ConversionUtil.convertToRepresentation(newQueueEntry, Representation.REF);
 	}
 
-	@RequestMapping(value = "/rest/" + RestConstants.VERSION_1 + "/queue-entry/undo-transition", method = {
-	        RequestMethod.PUT, RequestMethod.POST })
+	@RequestMapping(value = "/rest/" + RestConstants.VERSION_1 + "/queue-entry/transition", method = RequestMethod.DELETE)
 	@ResponseBody
 	public Object undoTransition(@RequestBody UndoQueueEntryTransitionRequest body) {
 		QueueEntryService qes = services.getQueueEntryService();
@@ -111,7 +110,7 @@ public Object undoTransition(@RequestBody UndoQueueEntryTransitionRequest body)
 			QueueEntry unEndedQueueEntry = services.getQueueEntryService().undoTransition(queueEntry.get());
 			return ConversionUtil.convertToRepresentation(unEndedQueueEntry, Representation.REF);
 		} else {
-			throw new APIException("Invalid queue entry uuid: " + body);
+			throw new APIException("Invalid queue entry");
 		}
 	}
 }

omod/src/main/java/org/openmrs/module/queue/web/resources/QueueEntryResource.java

@@ -177,11 +177,11 @@ public DelegatingResourceDescription getRepresentationDescription(Representation
 			description.addProperty("locationWaitingFor", Representation.DEFAULT);
 			description.addProperty("queueComingFrom", Representation.DEFAULT);
 			description.addProperty("providerWaitingFor", Representation.DEFAULT);
-
+			
 			// gets the previous queue entry, but with REF representation so it doesn't recursively
 			// fetch more previous entries.
 			description.addProperty("previousQueueEntry", Representation.REF);
-
+			
 			description.addLink("full", ".?v=" + RestConstants.REPRESENTATION_FULL);
 		} else if (representation instanceof FullRepresentation) {
 			addSharedResourceDescriptionProperties(description);

omod/src/main/java/org/openmrs/module/queue/web/resources/parser/QueueEntrySearchCriteriaParser.java

@@ -56,12 +56,16 @@ public class QueueEntrySearchCriteriaParser {
 
 	public static final String SEARCH_PARAM_STARTED_ON_OR_BEFORE = "startedOnOrBefore";
 
+	public static final String SEARCH_PARAM_STARTED_ON = "startedOn";
+
 	public static final String SEARCH_PARAM_IS_ENDED = "isEnded";
 
 	public static final String SEARCH_PARAM_ENDED_ON_OR_AFTER = "endedOnOrAfter";
 
 	public static final String SEARCH_PARAM_ENDED_ON_OR_BEFORE = "endedOnOrBefore";
 
+	public static final String SEARCH_PARAM_ENDED_ON = "endedOn";
+
 	public static final String SEARCH_PARAM_INCLUDE_VOIDED = "includedVoided";
 
 	public static final List<String> SEARCH_PARAMETERS = Arrays.asList(SEARCH_PARAM_QUEUE, SEARCH_PARAM_LOCATION,
@@ -157,6 +161,11 @@ public QueueEntrySearchCriteria constructFromRequest(Map<String, String[]> param
 					criteria.setStartedOnOrBefore(QueueUtils.parseDate(date));
 					break;
 				}
+				case SEARCH_PARAM_STARTED_ON: {
+					String date = parameterMap.get(SEARCH_PARAM_STARTED_ON)[0];
+					criteria.setStartedOn(QueueUtils.parseDate(date));
+					break;
+				}
 				case SEARCH_PARAM_ENDED_ON_OR_AFTER: {
 					String date = parameterMap.get(SEARCH_PARAM_ENDED_ON_OR_AFTER)[0];
 					criteria.setEndedOnOrAfter(QueueUtils.parseDate(date));
@@ -167,6 +176,11 @@ public QueueEntrySearchCriteria constructFromRequest(Map<String, String[]> param
 					criteria.setEndedOnOrBefore(QueueUtils.parseDate(date));
 					break;
 				}
+				case SEARCH_PARAM_ENDED_ON: {
+					String date = parameterMap.get(SEARCH_PARAM_ENDED_ON)[0];
+					criteria.setEndedOn(QueueUtils.parseDate(date));
+					break;
+				}
 				case SEARCH_PARAM_IS_ENDED: {
 					criteria.setIsEnded(parseBoolean(parameterMap.get(SEARCH_PARAM_IS_ENDED)[0]));
 					break;