Add stopgap ETA of 1 second when the shuttle has arrived at a stop

src/repositories/shuttle/eta/InMemorySelfUpdatingETARepository.ts

@@ -90,9 +90,25 @@ export class InMemorySelfUpdatingETARepository extends BaseInMemoryETARepository
   }
 
   private async handleShuttleUpdate(shuttle: IShuttle): Promise<void> {
+    const isAtStop = await this.shuttleRepository.checkIfShuttleIsAtStop(shuttle.id);
     const lastStop = await this.shuttleRepository.getShuttleLastStopArrival(shuttle.id);
     if (!lastStop) return;
 
+    if (isAtStop) {
+      // Update the ETA *to* the stop the shuttle is currently at,
+      // before starting from the current stop as normal.
+      // Account for cases where the shuttle arrived way earlier than
+      // expected based on the calculated ETA.
+
+      await this.addOrUpdateEta({
+        secondsRemaining: 1,
+        shuttleId: shuttle.id,
+        stopId: lastStop.stopId,
+        systemId: shuttle.systemId,
+        updatedTime: new Date(),
+      });
+    }
+
     const lastOrderedStop = await this.shuttleRepository.getOrderedStopByRouteAndStopId(shuttle.routeId, lastStop.stopId);
 
     await this.updateCascadingEta({

src/repositories/shuttle/eta/RedisSelfUpdatingETARepository.ts

@@ -102,9 +102,25 @@ export class RedisSelfUpdatingETARepository extends BaseRedisETARepository imple
   }
 
   private async handleShuttleUpdate(shuttle: IShuttle) {
+    const isAtStop = await this.shuttleRepository.checkIfShuttleIsAtStop(shuttle.id);
     const lastStop = await this.shuttleRepository.getShuttleLastStopArrival(shuttle.id);
     if (!lastStop) return;
 
+    if (isAtStop) {
+      // Update the ETA *to* the stop the shuttle is currently at,
+      // before starting from the current stop as normal.
+      // Account for cases where the shuttle arrived way earlier than
+      // expected based on the calculated ETA.
+
+      await this.addOrUpdateEta({
+        secondsRemaining: 1,
+        shuttleId: shuttle.id,
+        stopId: lastStop.stopId,
+        systemId: shuttle.systemId,
+        updatedTime: new Date(),
+      });
+    }
+
     const lastOrderedStop = await this.shuttleRepository.getOrderedStopByRouteAndStopId(shuttle.routeId, lastStop.stopId);
 
     await this.updateCascadingEta({

src/repositories/shuttle/eta/__tests__/SelfUpdatingETARepositorySharedTests.test.ts

@@ -194,6 +194,41 @@ describe.each(repositoryImplementations)('$name', (holder) => {
         currentTime, shuttleSecondArrivalTimeAtFirstStop
       );
     });
+
+    test("adds a 'stopgap' entry of 1 second when the shuttle arrives at a stop", async () => {
+      const { stop1, stop2, stop3, sampleShuttleNotInRepository: shuttle } = await setupRouteAndOrderedStops();
+
+      const shuttleSecondArrivalTimeAtFirstStop = new Date(2025, 0, 1, 12, 5, 0);
+      const currentTime = new Date(shuttleSecondArrivalTimeAtFirstStop.getTime() + 7 * 60 * 1000);
+
+      // Populating travel time data
+      await populateTravelTimeDataForStops({ currentTime, shuttle, stop1, stop2, stop3 });
+
+      // Populate ETA data
+      // Simulate shuttle running early for second stop
+      shuttle.coordinates = stop1.coordinates;
+      await shuttleRepository.addOrUpdateShuttle(
+        shuttle,
+        shuttleSecondArrivalTimeAtFirstStop.getTime()
+      );
+
+      shuttle.coordinates = stop2.coordinates;
+      // Call twice to get the ETA repository to read the correct flag
+      await shuttleRepository.addOrUpdateShuttle(
+        shuttle,
+        currentTime.getTime(),
+      );
+      await new Promise((resolve) => setTimeout(resolve, 500));
+
+      await shuttleRepository.addOrUpdateShuttle(
+        shuttle,
+        currentTime.getTime(),  // ~8 minutes early
+      );
+      await new Promise((resolve) => setTimeout(resolve, 500));
+
+      const eta = await repository.getEtaForShuttleAndStopId(shuttle.id, stop2.id);
+      expect(eta?.secondsRemaining).toEqual(1);
+    });
   });
 
   describe("handleShuttleWillLeaveStop", () => {