Optimizations (#15)

- Add walking transfers
- Pick route with minimal walking distance, instead of stop count
- Turned `shared` into the new server, client no longer relies on `server`
- Prepare to send full route data (instead of string) to the client

src/client/lib/src/pages/home.dart

@@ -16,13 +16,19 @@ class HomePage extends ReactiveWidget<HomeModel> {
     body: Row(
       children: [
         SizedBox(
-          width: 300,
+          width: 325,
           child: Sidebar(model),
         ),
         Expanded(
           child: Card(
             child: Column(
               children: [
+                SwitchListTile(
+                  value: model.markerState == MarkerState.override,
+                  onChanged: model.overrideMarkers,
+                  title: const Text("Show stops list"),
+                  subtitle: const Text("To select a start or end stop, use the buttons below"),
+                ),
                 LatLongEditor(
                   latitudeController: model.startLatitudeController,
                   longitudeController: model.startLongitudeController,
@@ -65,7 +71,7 @@ class HomePage extends ReactiveWidget<HomeModel> {
                       markers: model.markers,
                       onTap: model.onMapTapped,
                       polylines: {
-                        for (final (index, route) in model.routes.indexed) Polyline(
+                        for (final (index, route) in model.paths.indexed) Polyline(
                           polylineId: PolylineId(index.toString()),
                           color: routeColors[index],
                           points: route,

src/client/lib/src/services/api.dart

@@ -17,36 +17,13 @@ class ApiService extends Service {
 
   Uri get _base => usingDocker
     ? Uri(path: "api/")
-    : Uri(scheme: "http", host: "localhost", port: 80);
+    : Uri(scheme: "http", host: "localhost", port: 8001);
 
-  Future<List<Trip>?> getTrips() => _client.getJsonList(
+  Future<String?> getPath({
-    _base.resolve("trips"),
-    Trip.fromJson,
-    key: "path",
-  );
-
-  Future<Path?> getPath({
-    required Coordinates start,
-    required Coordinates end,
-  }) => _client.getJsonList(
-    _base.resolve("path").replace(
-      queryParameters: {
-        "start_lat": start.lat.toString(),
-        "start_lon": start.long.toString(),
-        "end_lat": end.lat.toString(),
-        "end_lon": end.long.toString(),
-        "time": DateTime.now().millisecondsSinceEpoch.toString(),
-      },
-    ),
-    key: "path",
-    PathStep.fromJson,
-  );
-
-  Future<String?> getPath2({
     required Coordinates start,
     required Coordinates end,
   }) async {
-    final uri = Uri.parse("http://localhost:8001/path").replace(
+    final uri = _base.resolve("/path").replace(
       queryParameters: {
         "start_lat": start.lat.toString(),
         "start_lon": start.long.toString(),
@@ -64,8 +41,13 @@ class ApiService extends Service {
     }
   }
 
+  Future<List<Route>?> getRoutes() => _client.getJsonList(
+    _base.resolve("/routes"),
+    Route.fromJson,
+  );
+
   Future<List<Stop>?> getStops() => _client.getJsonList(
-    _base.resolve("stops"),
+    _base.resolve("/stops"),
     Stop.fromJson,
   );
 }

src/client/lib/src/view_models/home.dart

@@ -26,7 +26,7 @@ class HomeModel extends ViewModel with HomeMarkers {
 
   bool isSearching = false;
   bool isGoogleReady = false;
-  List<List<LatLng>> routes = [];
+  List<List<LatLng>> paths = [];
 
   @override
   Future<void> init() async {
@@ -39,14 +39,15 @@ class HomeModel extends ViewModel with HomeMarkers {
   void onMapTapped(LatLng coordinates) {
     if (!shouldShowMarkers) return;
     final marker = Marker(
-      markerId: markerId,
+      markerId: markerId ?? const MarkerId("Tapped"),
       position: coordinates,
-      icon: markerIcon,
+      icon: markerIcon ?? BitmapDescriptor.defaultMarker,
       infoWindow: InfoWindow(title: "$startOrEnd here"),
     );
     switch (markerState!) {
       case MarkerState.start: updateStart(coordinates, marker);
       case MarkerState.end: updateEnd(coordinates, marker);
+      case MarkerState.override: return;
     }
   }
 
@@ -72,17 +73,11 @@ class HomeModel extends ViewModel with HomeMarkers {
     if (end.lat == null || end.long == null) return;
     isSearching = true;
     isLoading = true;
-    final result = await services.api.getPath2(start: start as Coordinates, end: end as Coordinates);
+    final result = await services.api.getPath(start: start as Coordinates, end: end as Coordinates);
     pathText = result ?? "An error occurred";
-    // path = result;
     isLoading = false;
     if (result == null) return;
     isSearching = false;
-    // routes = [
-    //   for (final step in result) [
-    //     ...decodePolyline(step.trip.polyline),
-    //   ],
-    // ];
     notifyListeners();
   }
 }

src/client/lib/src/view_models/home_markers.dart

@@ -5,20 +5,27 @@ import "package:google_maps_flutter/google_maps_flutter.dart";
 
 enum MarkerState {
   start,
-  end;
+  end,
+  override;
 }
 
 mixin HomeMarkers on ChangeNotifier {
   MarkerState? markerState;
   bool get shouldShowMarkers => markerState != null;
 
-  List<Stop>? stops;
+  // List<Stop>? stops;
+  Map<StopID, Stop> stops = {};
+  Map<RouteID, Route> routes = {};
   Marker? _startMarker;
   Marker? _endMarker;
 
+  Iterable<Stop> getStopsForRoute(RouteID routeID) => routes[routeID]!.stops
+    .map((stopID) => stops[stopID]!);
+
   Set<Marker> get _filteredMarkers => {
-    for (final stop in stops ?? <Stop>[])
+    // for (final stop in stops ?? <Stop>[])
-      if (stop.routes.any(routesToShow.contains))
+    for (final routeID in routesToShow)
+      for (final stop in getStopsForRoute(routeID))
         Marker(
           markerId: MarkerId(stop.name),
           position: stop.coordinates.toLatLng(),
@@ -36,55 +43,67 @@ mixin HomeMarkers on ChangeNotifier {
     if (_endMarker != null) _endMarker!,
   };
 
-  Set<String> bcRouteNames = {};
+  List<Route> bcRouteNames = [];
-  Set<String> occtRouteNames = {};
+  List<Route> occtRouteNames = [];
-  Set<String> routesToShow = {};
+  Set<RouteID> routesToShow = {};
-  Map<String, int> stopCounts = {};
+  Iterable<(String, List<Route>)> get providers => [
-  Iterable<(String, List<String>)> get providers => [
+    ("OCCT", occtRouteNames),
-    ("OCCT", occtRouteNames.toList()..sort()),
+    ("BC Transit", bcRouteNames),
-    ("BC Transit", bcRouteNames.toList()..sort(compareNums)),
   ];
 
-  int parseBcNumber(String routeName) {
+  int _parseBcNumber(String routeName) {
     // eg, "53)" --> 53
     final first = routeName.split(" ").first;
     final withoutParen = first.substring(0, first.length - 1);
     return int.parse(withoutParen);
   }
 
-  int compareNums(String a, String b) =>
+  int compareBcRoutes(Route a, Route b) =>
-    parseBcNumber(a).compareTo(parseBcNumber(b));
+    _parseBcNumber(a.shortName).compareTo(_parseBcNumber(b.shortName));
 
-  MarkerId get markerId => switch (markerState!) {
+  int compareOcctRoutes(Route a, Route b) =>
+    a.shortName.compareTo(b.shortName);
+
+  MarkerId? get markerId => switch (markerState!) {
     MarkerState.start => const MarkerId("start"),
     MarkerState.end => const MarkerId("end"),
+    _ => null,
   };
 
-  BitmapDescriptor get markerIcon => switch (markerState!) {
+  BitmapDescriptor? get markerIcon => switch (markerState!) {
     MarkerState.start => BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueCyan),
     MarkerState.end => BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueGreen),
+    _ => null,
   };
 
-  String get startOrEnd => switch (markerState!) {
+  String? get startOrEnd => switch (markerState!) {
     MarkerState.start => "Start",
     MarkerState.end => "End",
+    _ => null,
   };
 
   Future<void> updateMarkers() async {
-    stops = await services.api.getStops();
+    final stopsResponse = await services.api.getStops();
-    if (stops == null) return;
+    if (stopsResponse == null) return;
-    for (final stop in stops!) {
+    stops = {
-      for (final route in stop.routes) {
+      for (final stop in stopsResponse)
-        stopCounts[route] ??= 0;
+        stop.id: stop,
-        stopCounts[route] = stopCounts[route]! + 1;
+    };
-      }
+    final routesResponse = await services.api.getRoutes();
-      final namesList = switch (stop.provider) {
+    if (routesResponse == null) return;
+    routes = {
+      for (final route in routesResponse)
+        route.id: route,
+    };
+    for (final route in routesResponse) {
+      final namesList = switch (route.provider) {
         Provider.occt => occtRouteNames,
         Provider.bc => bcRouteNames,
       };
-      namesList.addAll(stop.routes);
+      namesList.add(route);
     }
-    notifyListeners();
+    occtRouteNames.sort(compareOcctRoutes);
+    bcRouteNames.sort(compareBcRoutes);
   }
 
   void showMarkers(MarkerState newState) {
@@ -100,20 +119,28 @@ mixin HomeMarkers on ChangeNotifier {
   void onMarkerTapped(Stop stop) {
     final coordinates = stop.coordinates.toLatLng();
     final marker = Marker(
-      markerId: markerId,
+      markerId: markerId ?? MarkerId(stop.name),
       position: coordinates,
       infoWindow: InfoWindow(
         title: "$startOrEnd at ${stop.name}",
         snippet: stop.description,
       ),
-      icon: markerIcon,
+      icon: markerIcon ?? BitmapDescriptor.defaultMarker,
     );
     switch (markerState!) {
       case MarkerState.start: updateStart(coordinates, marker);
       case MarkerState.end: updateEnd(coordinates, marker);
+      case MarkerState.override: return;
     }
   }
 
+  // Flutter widget
+  // ignore: avoid_positional_boolean_parameters
+  void overrideMarkers(bool value) {
+    markerState = value ? MarkerState.override : null;
+    notifyListeners();
+  }
+
   @mustCallSuper
   void updateStart(LatLng coordinates, Marker marker) {
     _startMarker = marker;
@@ -128,11 +155,11 @@ mixin HomeMarkers on ChangeNotifier {
     notifyListeners();
   }
 
-  void showRoute(String route, {required bool shouldShow}) {
+  void showRoute(Route route, {required bool shouldShow}) {
     if (shouldShow) {
-      routesToShow.add(route);
+      routesToShow.add(route.id);
     } else {
-      routesToShow.remove(route);
+      routesToShow.remove(route.id);
     }
     notifyListeners();
   }

src/client/lib/src/widgets/sidebar.dart

@@ -13,6 +13,7 @@ class Sidebar extends ReusableReactiveWidget<HomeModel> {
       child: Column(
         children: [
           const SizedBox(height: 16),
+          if (model.markerState != null && model.markerState != MarkerState.override) ...[
             Text(
               "Select routes",
               maxLines: 1,
@@ -25,6 +26,7 @@ class Sidebar extends ReusableReactiveWidget<HomeModel> {
               style: context.textTheme.bodyMedium,
               textAlign: TextAlign.center,
             ),
+          ],
           const SizedBox(height: 8),
           if (model.shouldShowMarkers) TabBar(
             tabs: [
@@ -33,7 +35,7 @@ class Sidebar extends ReusableReactiveWidget<HomeModel> {
             ],
           ),
           if (!model.shouldShowMarkers && model.pathText != null)
-            Center(child: Text(model.pathText!, style: context.textTheme.bodySmall)),
+            SingleChildScrollView(child: Center(child: Text(model.pathText!, style: context.textTheme.bodySmall))),
           if (!model.shouldShowMarkers && model.pathText == null)
             const Center(child: Text("Choose start or end location")),
           if (model.shouldShowMarkers) Expanded(
@@ -43,12 +45,12 @@ class Sidebar extends ReusableReactiveWidget<HomeModel> {
                   ListView(
                     children: [
                       for (final route in routesList) CheckboxListTile(
-                        title: Text(route, maxLines: 1),
+                        title: Text(route.fullName, maxLines: 1),
                         subtitle: Text(
-                          "${model.stopCounts[route] ?? 0} stops",
+                          "${route.stops.length} stops",
                           maxLines: 1,
                         ),
-                        value: model.routesToShow.contains(route),
+                        value: model.routesToShow.contains(route.id),
                         onChanged: (value) => model.showRoute(route, shouldShow: value!),
                       ),
                     ],

src/shared/.gitignore

@@ -2,3 +2,5 @@
 # Created by `dart pub`
 .dart_tool/
 pubspec.lock
+path.log
+notes.md

src/shared/bin/data.dart

@@ -1,6 +1,11 @@
 import "package:shared/generator.dart";
 
-void main() async {
+void main(List<String> args) async {
+  if (args.contains("-n")) {  // dry-run
+    await Generator.stops.parse();
+    await Generator.routes.parse();
+  } else {
     await Generator.stops.generate();
     await Generator.routes.generate();
+  }
 }

src/shared/bin/path.dart

@@ -1,147 +0,0 @@
-// User-facing script
-// ignore_for_file: avoid_print
-
-import "package:a_star/a_star.dart";
-import "package:shared/generator.dart";
-import "package:shared/graph.dart";
-
-import "package:shelf_router/shelf_router.dart";
-import "package:shelf/shelf.dart";
-import "package:shelf/shelf_io.dart" as io;
-
-// const startLat = 42.0924949645996;
-// const startLong = -75.9538421630859;
-// const endLat = 42.0869369506836;
-// const endLong = -75.965934753418;
-
-const startLat = 42.092083;
-const startLong = -75.952271;
-const endLat = 42.080822;
-const endLong = -75.912529;
-
-const numStops = 5;
-
-void log(String message) {
-  // print(message);
-}
-
-Iterable<Stop> findStopsNear(Coordinates location) {
-  log("Finding stops near $location...");
-  final stopDistances = [
-    for (final stop in StopState.stops.values)
-      (stop, stop.coordinates.distanceTo(location)),
-  ];
-  stopDistances.sort((a, b) => a.$2.compareTo(b.$2));
-  return stopDistances.take(numStops).map((pair) => pair.$1);
-}
-
-void printStops(Iterable<Stop> stops) {
-  log("Found stops:");
-  for (final stop in stops) {
-    log("- ${stop.routes}, ${stop.name}");
-  }
-}
-
-Set<RouteID> findRoutes(Iterable<Stop> stops) => {
-  for (final stop in stops)
-    ...stop.routeIDs,
-};
-
-Stop findStopWithRoute(Iterable<Stop> stops, RouteID route) =>
-  stops.firstWhere((stop) => stop.routeIDs.contains(route));
-
-Future<void> init() async {
-  print("Initializing...");
-  final stops = await Generator.stops.parse();
-  final routes = await Generator.routes.parse();
-  StopState.init(routes, stops);
-}
-
-final headers = {
-  "Access-Control-Allow-Origin": "*",
-};
-
-Future<Response> handleRequest(Request request) async {
-  final startLat = double.tryParse(request.url.queryParameters["start_lat"] ?? "");
-  final startLong = double.tryParse(request.url.queryParameters["start_lon"] ?? "");
-  final endLat = double.tryParse(request.url.queryParameters["end_lat"] ?? "");
-  final endLong = double.tryParse(request.url.queryParameters["end_lon"] ?? "");
-  if (startLat == null || startLong == null || endLat == null || endLong == null) {
-    return Response.badRequest(body: "Could not parse coordinates", headers: headers);
-  }
-
-  final start = (lat: startLat, long: startLong);
-  final end = (lat: endLat, long: endLong);
-
-  // 1) Find [numStops] nearest stops by the given locations
-  log("Finding nearest stops...");
-  final startStops = findStopsNear(start);
-  printStops(startStops);
-  final endStops = findStopsNear(end);
-  printStops(endStops);
-
-  // 2) Find all routes by those stops
-  log("Finding intersecting routes");
-  final startRoutes = findRoutes(startStops);
-  final endRoutes = findRoutes(endStops);
-  log("Start routes: $startRoutes");
-  log("End routes: $endRoutes");
-
-  // 3) Check for a direct route without transfers
-  final routesInCommon = startRoutes.intersection(endRoutes);
-  if (routesInCommon.isNotEmpty) {
-    final route = routesInCommon.first;
-    final startStop = findStopWithRoute(startStops, route);
-    final endStop = findStopWithRoute(endStops, route);
-    return Response.ok("\nBoard the $route at ${startStop.name} and get off at ${endStop.name}", headers: headers);
-  }
-
-  // 4) Use A* to find a route with transfers
-  log("Using A*");
-  final paths = <Iterable<StopState>>[];
-  for (final startStop in startStops) {
-    for (final startRoute in startStop.routeIDs) {
-      for (final endStop in endStops) {
-        final state = StopState(stopID: startStop.id, goalID: endStop.id, routeID: startRoute, depth: 0);
-        log("Finding a route using ${state.hash()}");
-        final result = aStar(state);
-        if (result == null) continue;
-        paths.add(result.reconstructPath());
-      }
-    }
-  }
-
-  if (paths.isEmpty) {
-    return Response.ok("No routes found", headers: headers);
-  }
-
-  final minPath = paths.min((path) => path.length);
-  final buffer = StringBuffer();
-  buffer.writeln("Found ${paths.length} paths, here's the best one with only ${minPath.length} steps:");
-  StopState? prevStep;
-  var index = 0;
-  for (final step in minPath) {
-    index++;
-    final stop = StopState.stops[step.stopID]!;
-    final route = StopState.routes[step.routeID]!;
-    if (prevStep == null) {
-      buffer.writeln("$index. Board the ${route.provider.humanName} ${route.fullName} bus\n  at ${stop.name}");
-    } else if (index == minPath.length) {
-      buffer.writeln("$index. Get off at ${stop.name}");
-    } else if (prevStep.routeID != step.routeID) {
-      buffer.writeln("$index. Transfer to the ${route.provider.humanName} ${route.fullName}");
-    } else {
-      buffer.writeln("$index. Go to ${stop.name}");
-    }
-    prevStep = step;
-  }
-  return Response.ok(buffer.toString(), headers: headers);
-}
-
-void main() async {
-  await init();
-  final router = Router();
-  router.get("/path", handleRequest);
-  await io.serve(router.call, "localhost", 8001);
-  print("Listening on localhost:8001");
-}

src/shared/bin/server.dart

@@ -0,0 +1,25 @@
+// User-facing script
+// ignore_for_file: avoid_print
+
+import "package:shared/generator.dart";
+import "package:shared/graph.dart";
+import "package:shared/server.dart" as handlers;
+
+import "package:shelf_router/shelf_router.dart";
+import "package:shelf/shelf_io.dart" as io;
+
+Future<void> init() async {
+  print("Initializing...");
+  StopState.stops = await Generator.stops.parse();
+  StopState.routes = await Generator.routes.parse();
+}
+
+void main() async {
+  await init();
+  final router = Router();
+  router.get("/path", handlers.getPath);
+  router.get("/stops", handlers.getStops);
+  router.get("/routes", handlers.getRoutes);
+  await io.serve(router.call, "localhost", 8001);
+  print("Listening on localhost:8001");
+}

src/shared/bin/test.dart

@@ -0,0 +1,18 @@
+// User-facing script
+// ignore_for_file: avoid_print
+
+import "package:shared/generator.dart";
+
+void main(List<String> args) async {
+  final provider = args.first;
+  final routeName = args.last;
+  final routes = await Generator.routes.parse();
+  final stops = await Generator.stops.parse();
+  final routeID = RouteID(Provider.fromJson(provider), routeName);
+  final route = routes[routeID]!;
+  print("Here are the stops for $route:");
+  for (final stopID in route.stops) {
+    final stop = stops[stopID]!;
+    print("- $stop");
+  }
+}

src/shared/lib/graph.dart

@@ -1 +1,2 @@
 export "src/graph/state.dart";
+export "src/graph/algorithm.dart";

src/shared/lib/server.dart

@@ -0,0 +1,2 @@
+export "src/server/misc.dart";
+export "src/server/path.dart";

src/shared/lib/src/data/provider.dart

@@ -8,4 +8,7 @@ enum Provider {
 
   final String id;
   final String humanName;
+
+  @override
+  String toString() => humanName;
 }

src/shared/lib/src/data/route.dart

@@ -34,7 +34,7 @@ class Route with Encodable {
     fullName = json["name"],
     stops = [
       for (final stopID in (json["stops"] as List).cast<int>())
-        StopID(stopID.toString()),
+        StopID(Provider.occt, stopID.toString()),
     ];
 
   Route.fromBcCsv(CsvRow csv) :
@@ -44,6 +44,19 @@ class Route with Encodable {
     fullName = "${csv[2]}) ${csv[3]}",
     stops = [];
 
+  Route.fromJson(Json json) :
+    id = RouteID.fromJson(json["id"]),
+    provider = Provider.fromJson(json["provider"]),
+    fullName = json["full_name"],
+    shortName = json["short_name"],
+    stops = [
+      for (final stopID in json["stops"])
+        StopID.fromJson(stopID),
+    ];
+
+  @override
+  String toString() => "$provider $fullName";
+
   @override
   Json toJson() => {
     "id": id,

src/shared/lib/src/data/stop.dart

@@ -2,7 +2,8 @@ import "utils.dart";
 import "route.dart";
 import "provider.dart";
 
-extension type StopID(String id) {
+extension type StopID._(String id) {
+  StopID(Provider provider, Object value) : id = "${provider.id}_$value";
   StopID.fromJson(dynamic value) : id = value.toString();
 }
 
@@ -24,7 +25,7 @@ class Stop with Encodable {
   }) : routes = {}, routeIDs = {};
 
   Stop.fromJson(Json json) :
-    id = StopID(json["id"]),
+    id = StopID.fromJson(json["id"]),
     name = json["name"],
     description = json["description"],
     coordinates = (lat: json["latitude"], long: json["longitude"]),
@@ -36,7 +37,7 @@ class Stop with Encodable {
     };
 
   Stop.fromOcctJson(Json json) :
-    id = StopID.fromJson(json["id"]),
+    id = StopID(Provider.occt, json["id"]),
     name = json["name"],
     description = null,
     coordinates = (lat: json["lat"], long: json["lng"]),
@@ -44,6 +45,9 @@ class Stop with Encodable {
     routes = <String>{},
     routeIDs = <RouteID>{};
 
+  @override
+  String toString() => name;
+
   @override
   Map<String, dynamic> toJson() => {
     "id": id.id,

src/shared/lib/src/data/utils.dart

@@ -35,16 +35,27 @@ extension ListUtils<E> on List<E> {
       yield (i, this[i]);
     }
   }
+}
 
-  E max(int Function(E) count) => reduce((a, b) {
+extension IterableUtils<E> on Iterable<E> {
+  E max(num Function(E) count) => reduce((a, b) {
     final numA = count(a);
     final numB = count(b);
     return numA > numB ? a : b;
   });
 
-  E min(int Function(E) count) => reduce((a, b) {
+  E min(num Function(E) count) => reduce((a, b) {
     final numA = count(a);
     final numB = count(b);
     return numA < numB ? a : b;
   });
+
+  double sum(double Function(E) transform) => fold(
+    0,
+    (total, element) => total + transform(element),
+  );
+}
+
+void log(String message) {
+  // print(message);
 }

src/shared/lib/src/generator/generator.dart

@@ -3,9 +3,9 @@ import "dart:io";
 
 import "package:shared/generator.dart";
 
-class Generator<T extends Encodable> extends Parser<T> {
+class Generator<ID, T extends Encodable> extends Parser<ID, T> {
-  final Parser<T> bc;
+  final Parser<ID, T> bc;
-  final Parser<T> occt;
+  final Parser<ID, T> occt;
   final File outputFile;
 
   Generator({
@@ -15,14 +15,15 @@ class Generator<T extends Encodable> extends Parser<T> {
   });
 
   @override
-  Future<List<T>> parse() async => [
+  Future<Map<ID, T>> parse() async => {
     ...await bc.parse(),
     ...await occt.parse(),
-  ];
+  };
 
   Future<void> generate() async {
+    final allData = await parse();
     final result = [
-      for (final data in await parse())
+      for (final data in allData.values)
         data.toJson(),
     ];
     const encoder = JsonEncoder.withIndent("  ");

src/shared/lib/src/generator/routes_bc.dart

@@ -5,7 +5,7 @@ import "stops_bc.dart";
 
 typedef InOutTrips = (TripID, TripID);
 
-class BcRoutesParser extends Parser<Route> {
+class BcRoutesParser extends Parser<RouteID, Route> {
   final routesFile = File(bcDataDir / "routes.txt");
   final tripsFile = File(bcDataDir / "trips.txt");
 
@@ -31,7 +31,7 @@ class BcRoutesParser extends Parser<Route> {
   }
 
   @override
-  Future<Iterable<Route>> parse() async {
+  Future<Map<RouteID, Route>> parse() async {
     final routes = await getRoutes();
     final trips = await stopParser.getTrips();
     final tripsForRoutes = await getTripForRoutes(trips);
@@ -39,8 +39,9 @@ class BcRoutesParser extends Parser<Route> {
     for (final (routeID, route) in routes.records) {
       final longestTrip = tripsForRoutes[routeID]!;
       final stops = trips[longestTrip]!;
+      log("Chose $longestTrip as the longest trip for $routeID");
       route.stops.addAll(stops);
     }
-    return routes.values;
+    return routes;
   }
 }

src/shared/lib/src/generator/routes_occt.dart

@@ -2,12 +2,12 @@ import "dart:io";
 
 import "utils.dart";
 
-class OcctRoutesParser extends Parser<Route> {
+class OcctRoutesParser extends Parser<RouteID, Route> {
   final routesFile = File(occtDataDir / "routes.json");
 
   @override
-  Future<List<Route>> parse() async => [
+  Future<Map<RouteID, Route>> parse() async => {
     for (final routeJson in await readJson(routesFile))
-      Route.fromOcctJson(routeJson),
+      RouteID(Provider.occt, routeJson["id"]): Route.fromOcctJson(routeJson),
-  ];
+  };
 }

src/shared/lib/src/generator/stops_bc.dart

@@ -4,7 +4,7 @@ import "package:csv/csv.dart";
 
 import "utils.dart";
 
-class BcStopParser extends Parser<Stop> {
+class BcStopParser extends Parser<StopID, Stop> {
   static final tripsFile = File(bcDataDir / "stop_times.txt");
   static final routesFile = File(bcDataDir / "trips.txt");
   static final stopsFile = File(bcDataDir / "stops.txt");
@@ -15,7 +15,7 @@ class BcStopParser extends Parser<Stop> {
   Future<Map<TripID, List<StopID>>> getTrips() async {
     final result = <TripID, List<StopID>>{};
     for (final row in await readCsv(tripsFile)) {
-      result.addToList(TripID(row[0]), StopID(row[3]));
+      result.addToList(TripID(row[0]), StopID(Provider.bc, row[3]));
     }
     return result;
   }
@@ -34,7 +34,7 @@ class BcStopParser extends Parser<Stop> {
   Future<Map<StopID, Stop>> getStops() async {
     final result = <StopID, Stop>{};
     for (final row in await readCsv(stopsFile)) {
-      final stopID = StopID(row[0]);
+      final stopID = StopID(Provider.bc, row[0]);
       final name = row[2];
       final description = row[3];
       final latitude = double.parse(row[4]);
@@ -69,12 +69,12 @@ class BcStopParser extends Parser<Stop> {
   }
 
   @override
-  Future<Iterable<Stop>> parse() async {
+  Future<Map<StopID, Stop>> parse() async {
     final trips = await getTrips();
     final routes = await getRoutes();
     final stops = await getStops();
     final routeNames = await getRouteNames();
     findRoutesForStops(stops: stops.values, trips: trips, routes: routes, routeNames: routeNames);
-    return stops.values;
+    return stops;
   }
 }

src/shared/lib/src/generator/stops_occt.dart

@@ -2,7 +2,7 @@ import "dart:io";
 
 import "utils.dart";
 
-class OcctStopParser extends Parser<Stop> {
+class OcctStopParser extends Parser<StopID, Stop> {
   /// Taken from: https://binghamtonupublic.etaspot.net/service.php?service=get_stops&token=TESTING
   static final stopsFile = File(occtDataDir / "stops.json");
 
@@ -12,7 +12,7 @@ class OcctStopParser extends Parser<Stop> {
   Future<Map<StopID, Stop>> getStops() async {
     final result = <StopID, Stop>{};
     for (final stopJson in await readJson(stopsFile)) {
-      final id = StopID.fromJson(stopJson["id"]);
+      final id = StopID(Provider.occt, stopJson["id"]);
       result[id] ??= Stop.fromOcctJson(stopJson);
     }
     return result;
@@ -21,7 +21,7 @@ class OcctStopParser extends Parser<Stop> {
   Future<Map<StopID, List<RouteID>>> getRoutes() async {
     final result = <StopID, List<RouteID>>{};
     for (final json in await readJson(stopsFile)) {
-      final stopID = StopID.fromJson(json["id"]);
+      final stopID = StopID(Provider.occt, json["id"]);
       final routeID = RouteID(Provider.occt, json["rid"]);
       result.addToList(stopID, routeID);
     }
@@ -34,7 +34,7 @@ class OcctStopParser extends Parser<Stop> {
   };
 
   @override
-  Future<Iterable<Stop>> parse() async {
+  Future<Map<StopID, Stop>> parse() async {
     final stops = await getStops();
     final routes = await getRoutes();
     final routeNames = await getRouteNames();
@@ -46,6 +46,6 @@ class OcctStopParser extends Parser<Stop> {
         stop.addRoute(routeID, routeName);
       }
     }
-    return stops.values;
+    return stops;
   }
 }

src/shared/lib/src/generator/utils.dart

@@ -27,8 +27,8 @@ extension MapSetUtils<K, V> on Map<K, Set<V>> {
   }
 }
 
-abstract class Parser<T> {
+abstract class Parser<ID, T> {
-  Future<Iterable<T>> parse();
+  Future<Map<ID, T>> parse();
 }
 
 final csvConverter = CsvCodec(shouldParseNumbers: false).decoder;

src/shared/lib/src/graph/algorithm.dart

@@ -0,0 +1,60 @@
+import "package:a_star/a_star.dart";
+import "package:shared/data.dart";
+
+import "state.dart";
+
+void printStops(Iterable<Stop> stops) {
+  log("Found stops:");
+  for (final stop in stops) {
+    log("- ${stop.routes}, ${stop.name}");
+  }
+}
+
+Iterable<StopState>? findPath(Coordinates start, Coordinates end) {
+  // 1) Find [numStops] nearest stops by the given locations
+  log("Finding nearest stops...");
+  final startStops = StopState.findStopsNear(start);
+  printStops(startStops);
+  final endStops = StopState.findStopsNear(end);
+  printStops(endStops);
+
+  // 2) Use A* to find a route with transfers
+  log("Using A*");
+  final paths = <Iterable<StopState>>[];
+  for (final startStop in startStops) {
+    for (final startRouteID in startStop.routeIDs) {
+      for (final endStop in endStops) {
+        final state = StopState.start(
+          stopID: startStop.id,
+          goalID: endStop.id,
+          routeID: startRouteID,
+          startPoint: start,
+          endPoint: end,
+        );
+        log("Finding a route using ${state.hash()}");
+        final result = aStar(state, limit: 10000);
+        if (result == null) continue;
+        paths.add(result.reconstructPath());
+      }
+    }
+  }
+
+  if (paths.isEmpty) return null;
+  return paths.min(getTotalDistance);
+}
+
+double getTotalDistance(Iterable<StopState> path) =>
+  path.sum((step) => step.distanceWalked);
+
+void explainPath(Iterable<StopState> path, void Function(String) printer) {
+  var index = 0;
+  for (final step in path) {
+    index++;
+    final stop = StopState.stops[step.stopID]!;
+    if (index == path.length) {
+      printer("$index. Get off at ${stop.name}");
+    } else {
+      printer("$index. ${step.explanation}");
+    }
+  }
+}

src/shared/lib/src/graph/state.dart

@@ -1,33 +1,81 @@
 import "package:a_star/a_star.dart";
 import "package:shared/data.dart";
 
-class StopState extends AStarState<StopState> {
+enum SearchMethod {
+  start,
+  bus,
+  transfer,
+  walk;
+
+  factory SearchMethod.fromJson(String json) => values.byName(json);
+}
+
+class StopState extends AStarState<StopState> with Encodable {
   static late final Map<RouteID, Route> routes;
   static late final Map<StopID, Stop> stops;
 
-  static void init(Iterable<Route> allRoutes, Iterable<Stop> allStops) {
+  static Iterable<Stop> findStopsNear(Coordinates location) {
-    routes = {
+    const numStops = 5;
-      for (final route in allRoutes)
+    log("Finding stops near $location...");
-        route.id: route,
+    final stopDistances = [
-    };
+      for (final stop in stops.values)
-    stops = {
+        (stop, stop.coordinates.distanceTo(location)),
-      for (final stop in allStops)
+    ];
-        stop.id: stop,
+    stopDistances.sort((a, b) => a.$2.compareTo(b.$2));
-    };
+    return stopDistances.take(numStops).map((pair) => pair.$1);
   }
 
   final StopID stopID;
   final StopID goalID;
   final RouteID routeID;
+  final double distanceWalked;
+  final SearchMethod method;
   StopState({
     required this.stopID,
     required this.goalID,
     required this.routeID,
+    required this.distanceWalked,
+    required this.method,
     required super.depth,
   });
 
+  factory StopState.start({
+    required StopID stopID,
+    required StopID goalID,
+    required RouteID routeID,
+    required Coordinates startPoint,
+    required Coordinates endPoint,
+  }) {
+    final stop = stops[stopID]!;
+    final goal = stops[goalID]!;
+    final distanceToStart = startPoint.distanceTo(stop.coordinates);
+    final distanceToEnd = endPoint.distanceTo(goal.coordinates);
+    return StopState(
+      stopID: stopID,
+      goalID: goalID,
+      routeID: routeID,
+      distanceWalked: distanceToStart + distanceToEnd,
+      depth: 0,
+      method: SearchMethod.start,
+    );
+  }
+
+  factory StopState.fromJson(Json json) => StopState(
+    stopID: StopID.fromJson(json["stop_id"]),
+    routeID: RouteID.fromJson(json["route_id"]),
+    method: SearchMethod.fromJson(json["method"]),
+    depth: 0,
+    distanceWalked: 0,
+    goalID: StopID.fromJson("N/A"),
+  );
+
   @override
-  String hash() => "$stopID-$goalID-$routeID";
+  String hash() {
+    final stop = stops[stopID];
+    final goal = stops[goalID];
+    final route = routes[routeID];
+    return "${method.name}-$stop-$goal-$route";
+  }
 
   @override
   bool isGoal() => stopID == goalID;
@@ -44,30 +92,86 @@ class StopState extends AStarState<StopState> {
     final route = routes[routeID]!;
     final stop = stops[stopID]!;
     final stopIndex = route.stops.indexOf(stopID);
+    if (stopIndex == -1) return [];
     final result = <StopState>[];
 
     // 1): Go forward one stop on the same route
     final nextIndex = stopIndex + 1;
     if (nextIndex < route.stops.length) {
-      final nextStop = route.stops[nextIndex];
+      final nextStopID = route.stops[nextIndex];
-      final state = StopState(stopID: nextStop, goalID: goalID, routeID: routeID, depth: depth + 1);
+      final state = StopState(
+        stopID: nextStopID,
+        goalID: goalID,
+        routeID: routeID,
+        depth: depth + 1,
+        distanceWalked: distanceWalked,
+        method: SearchMethod.bus,
+      );
       result.add(state);
     }
 
     // 2) Go back one stop on the same route
     final prevIndex = stopIndex - 1;
     if (prevIndex > 0) {
-      final prevStop = route.stops[prevIndex];
+      final prevStopID = route.stops[prevIndex];
-      final state = StopState(stopID: prevStop, goalID: goalID, routeID: routeID, depth: depth + 1);
+      final state = StopState(
+        stopID: prevStopID,
+        goalID: goalID,
+        routeID: routeID,
+        depth: depth + 1,
+        distanceWalked: distanceWalked,
+        method: SearchMethod.bus,
+      );
       result.add(state);
     }
 
     // 3) Make any available transfers
-    for (final otherRoute in stop.routeIDs.difference({routeID})) {
+    for (final otherRouteID in stop.routeIDs.difference({routeID})) {
-      final state = StopState(stopID: stopID, goalID: goalID, routeID: otherRoute, depth: depth + 1);
+      final state = StopState(
+        stopID: stopID,
+        goalID: goalID,
+        routeID: otherRouteID,
+        depth: depth + 2,
+        distanceWalked: distanceWalked,
+        method: SearchMethod.transfer,
+      );
       result.add(state);
     }
 
+    // 4) Walk to a new stop
+    for (final otherStop in findStopsNear(stop.coordinates)) {
+      final distanceToOther = stop.coordinates.distanceTo(otherStop.coordinates);
+      for (final otherRouteID in otherStop.routeIDs) {
+        final state = StopState(
+          stopID: otherStop.id,
+          goalID: goalID,
+          routeID: otherRouteID,
+          depth: depth + 3,
+          distanceWalked: distanceWalked + distanceToOther,
+          method: SearchMethod.walk,
+        );
+        result.add(state);
+      }
+    }
+
     return result;
   }
+
+  String get explanation {
+    final route = routes[routeID]!;
+    final stop = stops[stopID]!;
+    return switch (method) {
+      SearchMethod.bus => "Go one stop to $stop",
+      SearchMethod.start => "Walk to $stop\n  and board the $route line",
+      SearchMethod.transfer => "Transfer to the $route line",
+      SearchMethod.walk => "Walk to $stop\n  and board the $route line"
+    };
+  }
+
+  @override
+  Json toJson() => {
+    "stop_id": stopID,
+    "route_id": routeID,
+    "method": method.name,
+  };
 }

src/shared/lib/src/server/misc.dart

@@ -0,0 +1,16 @@
+import "package:shared/graph.dart";
+import "package:shelf/shelf.dart";
+
+import "utils.dart";
+
+Response getStops(Request _) {
+  final stops = StopState.stops.values;
+  final jsonBody = encodeJsonList(stops);
+  return Response.ok(jsonBody, headers: corsHeaders);
+}
+
+Response getRoutes(Request _) {
+  final routes = StopState.routes.values.where((route) => !route.fullName.startsWith(")"));
+  final jsonBody = encodeJsonList(routes);
+  return Response.ok(jsonBody, headers: corsHeaders);
+}

src/shared/lib/src/server/path.dart

@@ -0,0 +1,24 @@
+import "package:shared/graph.dart";
+import "package:shelf/shelf.dart";
+
+import "utils.dart";
+
+Response getPath(Request request) {
+  final startLat = double.tryParse(request.url.queryParameters["start_lat"] ?? "");
+  final startLong = double.tryParse(request.url.queryParameters["start_lon"] ?? "");
+  final endLat = double.tryParse(request.url.queryParameters["end_lat"] ?? "");
+  final endLong = double.tryParse(request.url.queryParameters["end_lon"] ?? "");
+  if (startLat == null || startLong == null || endLat == null || endLong == null) {
+    return Response.badRequest(body: "Could not parse coordinates", headers: corsHeaders);
+  }
+
+  final start = (lat: startLat, long: startLong);
+  final end = (lat: endLat, long: endLong);
+  final path = findPath(start, end);
+  if (path == null) {
+    return Response.ok("No routes found", headers: corsHeaders);
+  }
+  final buffer = StringBuffer();
+  explainPath(path, buffer.writeln);
+  return Response.ok(buffer.toString(), headers: corsHeaders);
+}

src/shared/lib/src/server/utils.dart

@@ -0,0 +1,15 @@
+import "dart:convert";
+
+import "package:shared/generator.dart";
+
+const corsHeaders = {
+  "Access-Control-Allow-Origin": "*",
+};
+
+String encodeJsonList<T extends Encodable>(Iterable<T> data) {
+  final jsonList = [
+    for (final object in data)
+      object.toJson(),
+  ];
+  return jsonEncode(jsonList);
+}