Merge pull request #227 from DartExplore/issue#226

Issue#226

src/main/java/com/dallasbymetro/backend/controller/ReadController.java

@@ -115,6 +115,7 @@ public ResponseEntity<List<String>> getAllTypes() {
     public ResponseEntity<List<StationDTO>> getStationsByConnection(
             @RequestParam(value = "currentStation", required = false) Long currentStation,
             @RequestParam(value = "maxStationConnections", required = false) Integer maxStationConnections,
+            @RequestParam(value = "maxTransfers", required = false) Integer maxTransfers,
             @RequestParam(value = "amenityIds", required = false) String amenityIdsString,
             @RequestParam(value = "types", required = false) String typesString,
             @RequestParam(value = "maxWalkTime", required = false) Integer maxWalkTime,
@@ -136,7 +137,7 @@ public ResponseEntity<List<StationDTO>> getStationsByConnection(
             typesList = Arrays.asList(typesString.split(","));
         }
 
-        List<StationDTO> stations = stationService.getStationsByConnection(currentStation, maxStationConnections, amenityIdList, typesList, maxWalkTime, returnEmpty);
+        List<StationDTO> stations = stationService.getStationsByConnection(currentStation, maxStationConnections, maxTransfers, amenityIdList, typesList, maxWalkTime, returnEmpty);
 
         return ResponseEntity.ok(stations);
     }

src/main/java/com/dallasbymetro/backend/service/StationService.java

@@ -25,5 +25,5 @@ public interface StationService {
 
     List<PointOfInterestDTO> getPOIsById(List<Long> poiIds) throws DartExploreException, ElementNotFoundException;
 
-    List<StationDTO> getStationsByConnection(Long currentStation, Integer stationConnections, List<Long> amenityIdList, List<String> typesList, Integer maxWalkTime, Boolean returnEmpty) throws DartExploreException, ElementNotFoundException;
+    List<StationDTO> getStationsByConnection(Long currentStation, Integer stationConnections, Integer maxTransfers, List<Long> amenityIdList, List<String> typesList, Integer maxWalkTime, Boolean returnEmpty) throws DartExploreException, ElementNotFoundException;
 }

src/main/java/com/dallasbymetro/backend/service/StationServiceImpl.java

@@ -11,7 +11,7 @@
 import com.dallasbymetro.backend.repository.AmenityRepository;
 import com.dallasbymetro.backend.repository.PointOfInterestRepository;
 import com.dallasbymetro.backend.repository.StationRepository;
-import com.dallasbymetro.backend.utility.Pair;
+import com.dallasbymetro.backend.utility.StationNode;
 import org.springframework.stereotype.Service;
 
 import java.util.*;
@@ -114,7 +114,7 @@ public List<PointOfInterestDTO> getPOIsById(List<Long> poiIds) throws ElementNot
     }
 
     @Override
-    public List<StationDTO> getStationsByConnection(Long currentStation, Integer stationConnections, List<Long> amenityIdList, List<String> typesList, Integer maxWalkTime, Boolean returnEmpty) throws ElementNotFoundException, DartExploreException {
+    public List<StationDTO> getStationsByConnection(Long currentStation, Integer stationConnections, Integer maxTransfers, List<Long> amenityIdList, List<String> typesList, Integer maxWalkTime, Boolean returnEmpty) throws ElementNotFoundException, DartExploreException {
         if ((currentStation == null && stationConnections != null) || (currentStation != null && stationConnections == null)) {
             throw new DartExploreException("Both currentStation and stationConnections must be provided together.");
         }
@@ -140,8 +140,8 @@ public List<StationDTO> getStationsByConnection(Long currentStation, Integer sta
 
         Station station = stationOptional.get();
 
-        // Perform BFS traversal in the service layer
-        List<Station> stationsWithinConnection = findStationsWithinConnection(station, stationConnections);
+        // Perform BFS traversal
+        List<Station> stationsWithinConnection = findStationsWithinConnection(station, stationConnections, maxTransfers);
 
         // Transform stations to StationDTOs, check that POI have required amenities, and are within walk time
         Stream<StationDTO> stream = stationsWithinConnection.stream()
@@ -172,47 +172,51 @@ private StationDTO prepareStationDTOWithFilteredPOIs(Station station, List<Long>
         return StationDTO.prepareStationDTO(station);
     }
 
-    private List<Station> findStationsWithinConnection(Station currentStation, Integer stationConnections) {
-        Queue<Pair<Station, Integer>> queue = new LinkedList<>();
-        Map<Station, Integer> visitedMap = new HashMap<>();
-
-        // Create a comparator to sort the pairs by their level and station name
-        Comparator<Pair<Station, Integer>> pairComparator = Comparator
-                .<Pair<Station, Integer>>comparingInt(Pair::getSecond)
-                .thenComparing(pair -> pair.getFirst().getName());
-
+    private List<Station> findStationsWithinConnection(Station currentStation, Integer stationConnections, Integer maxTransfers) {
+        Queue<StationNode> queue = new LinkedList<>();
+        Set<Station> visitedSet = new HashSet<>();
+        Set<Station> result = new HashSet<>();
+        if (maxTransfers == null) {
+            maxTransfers = 0;
+        }
 
-        // Use a TreeSet to keep the pairs sorted
-        Set<Pair<Station, Integer>> sortedVisitedPairs = new TreeSet<>(pairComparator);
+        // Enqueue current station with each of its colors
+        for (StationColor color : currentStation.getColor()) {
+            StationNode firstNode = new StationNode(currentStation, 0, 0, Set.of(color));
+            queue.add(firstNode);
+        }
 
-        Pair<Station, Integer> firstPair = new Pair<>(currentStation, 0);
-        queue.add(firstPair);
-        visitedMap.put(currentStation, 0);
-        sortedVisitedPairs.add(firstPair);
+        visitedSet.add(currentStation);
 
         while (!queue.isEmpty()) {
-            Pair<Station, Integer> stationPair = queue.poll();
-            Station station = stationPair.first;
-            Integer level = stationPair.second;
+            StationNode currentNode = queue.poll();
+            Station station = currentNode.station;
+            int currentLevel = currentNode.level;
+            int transferCount = currentNode.transferCount;
+            StationColor currentColor = currentNode.colors.iterator().next();
 
-            if (level < stationConnections) {
+            if (currentLevel < stationConnections) {
                 List<Station> connectedStations = stationRepository.findConnectedStations(station.getStationId());
 
                 for (Station connectedStation : connectedStations) {
-                    if (!visitedMap.containsKey(connectedStation)) {
-                        Pair<Station, Integer> nextPair = new Pair<>(connectedStation, level + 1);
-                        visitedMap.put(connectedStation, level + 1);
-                        queue.add(nextPair);
-                        sortedVisitedPairs.add(nextPair);
+                    if (!visitedSet.contains(connectedStation)) {
+                        boolean requiresTransfer = !connectedStation.getColor().contains(currentColor);
+                        int newTransferCount = requiresTransfer ? transferCount + 1 : transferCount;
+
+                        if (newTransferCount <= maxTransfers) {
+                            StationColor nextColor = requiresTransfer ? connectedStation.getColor().iterator().next() : currentColor;  // Pick the next line color
+                            StationNode nextNode = new StationNode(connectedStation, currentLevel + 1, newTransferCount, Set.of(nextColor));
+
+
+                            visitedSet.add(connectedStation);
+                            queue.add(nextNode);
+                            result.add(connectedStation);
+                        }
                     }
                 }
             }
         }
 
-        // Transform the sorted set of pairs to a list of stations
-
-        return sortedVisitedPairs.stream()
-                .map(pair -> pair.first)
-                .collect(Collectors.toList());
+        return new ArrayList<>(result);
     }
 }

src/main/java/com/dallasbymetro/backend/utility/StationNode.java

@@ -0,0 +1,20 @@
+package com.dallasbymetro.backend.utility;
+
+import com.dallasbymetro.backend.entity.Station;
+import com.dallasbymetro.backend.entity.StationColor;
+
+import java.util.Set;
+
+public class StationNode {
+    public Station station;
+    public int level;
+    public int transferCount;
+    public Set<StationColor> colors;
+
+    public StationNode(Station station, int level, int transferCount, Set<StationColor> colors) {
+        this.station = station;
+        this.level = level;
+        this.transferCount = transferCount;
+        this.colors = colors;
+    }
+}

src/main/resources/station_connections.txt

@@ -17,6 +17,16 @@ WESTMORELAND STATION,HAMPTON STATION
 HAMPTON STATION,TYLER VERNON STATION
 TYLER VERNON STATION,ZOO STATION
 ZOO STATION,8TH & CORINTH STATION
+8TH & CORINTH STATION,CEDARS STATION
+CEDARS STATION,CONVENTION CENTER STATION
+CONVENTION CENTER STATION,EBJ UNION STATION
+EBJ UNION STATION,WEST END STATION
+WEST END STATION,AKARD STATION
+AKARD STATION,ST PAUL STATION
+ST PAUL STATION,PEARL/ARTS DISTRICT STATION
+PEARL/ARTS DISTRICT STATION,CITYPLACE/UPTOWN STATION
+CITYPLACE/UPTOWN STATION,SMU/MOCKINGBIRD STATION
+SMU/MOCKINGBIRD STATION,LOVERS LANE STATION
 LOVERS LANE STATION,PARK LANE STATION
 PARK LANE STATION,WALNUT HILL STATION
 WALNUT HILL STATION,FOREST LN STATION
@@ -32,6 +42,10 @@ BURBANK STATION,INWOOD/LOVE FIELD STATION
 INWOOD/LOVE FIELD STATION,SOUTHWEST MEDICAL DISTRICT/PARKLAND
 SOUTHWEST MEDICAL DISTRICT/PARKLAND,MARKET CENTER STATION
 MARKET CENTER STATION,VICTORY STATION
+VICTORY STATION,WEST END STATION
+WEST END STATION,AKARD STATION
+AKARD STATION,ST PAUL STATION
+ST PAUL STATION,PEARL/ARTS DISTRICT STATION
 PEARL/ARTS DISTRICT STATION,DEEP ELLUM STATION
 DEEP ELLUM STATION,BAYLOR STATION
 BAYLOR STATION,FAIR PARK STATION
@@ -45,4 +59,27 @@ BELT LINE STATION,DALLAS COLLEGE NORTHLAKE CAMPUS STATION
 DALLAS COLLEGE NORTHLAKE CAMPUS STATION,HIDDEN RIDGE STATION
 HIDDEN RIDGE STATION,IRVING CONVENTION CENTER STATION
 IRVING CONVENTION CENTER STATION,LAS COLINAS URBAN CENTER STATION
-LAS COLINAS URBAN CENTER STATION,UNIVERSITY OF DALLAS STATION
+LAS COLINAS URBAN CENTER STATION,UNIVERSITY OF DALLAS STATION
+UNIVERSITY OF DALLAS STATION,BACHMAN STATION
+BACHMAN STATION,BURBANK STATION
+BURBANK STATION,INWOOD/LOVE FIELD STATION
+INWOOD/LOVE FIELD STATION,SOUTHWEST MEDICAL DISTRICT/PARKLAND
+SOUTHWEST MEDICAL DISTRICT/PARKLAND,MARKET CENTER STATION
+MARKET CENTER STATION,VICTORY STATION
+VICTORY STATION,WEST END STATION
+WEST END STATION,AKARD STATION
+AKARD STATION,ST PAUL STATION
+ST PAUL STATION,PEARL/ARTS DISTRICT STATION
+PEARL/ARTS DISTRICT STATION,CITYPLACE/UPTOWN STATION
+CITYPLACE/UPTOWN STATION,SMU/MOCKINGBIRD STATION
+SMU/MOCKINGBIRD STATION,LOVERS LANE STATION
+LOVERS LANE STATION,PARK LANE STATION
+PARK LANE STATION,WALNUT HILL STATION
+WALNUT HILL STATION,FOREST LN STATION
+FOREST LN STATION,LBJ / CENTRAL STATION
+LBJ / CENTRAL STATION,SPRING VALLEY STATION
+SPRING VALLEY STATION,ARAPAHO CENTER STATION
+ARAPAHO CENTER STATION,GALATYN PARK STATION
+GALATYN PARK STATION,CITYLINE/BUSH STATION
+CITYLINE/BUSH STATION, DOWNTOWN PLANO STATION
+DOWNTOWN PLANO STATION, PARKER ROAD STATION