Add implementation and tests for ParkingStructureResolvers.ts

src/resolvers/ParkingStructureResolvers.ts

@@ -1,10 +1,31 @@
 import { Resolvers } from "../generated/graphql";
 import { ServerContext } from "../ServerContext";
+import { HistoricalParkingAverageQueryArguments } from "../repositories/parking/ParkingGetterRepository";
 
 export const ParkingStructureResolvers: Resolvers<ServerContext> = {
   ParkingStructure: {
     historicalAverages: async (parent, args, contextValue, _info) => {
-      return [];
+      const system = contextValue.findSystemById(parent.systemId);
+
+      if (!args.input?.intervalMs) {
+        return null;
+      }
+      const historicalParkingAverageQueryArguments: HistoricalParkingAverageQueryArguments = {
+        from: new Date(args.input.from),
+        intervalMs: args.input.intervalMs,
+        to: new Date(args.input.to),
+      }
+      if (Number.isNaN(historicalParkingAverageQueryArguments.from.getTime()
+        || Number.isNaN(historicalParkingAverageQueryArguments.to.getTime()))) {
+        return null;
+      }
+
+      const parkingAverages = await system?.parkingRepository?.getHistoricalAveragesOfParkingStructureCounts(parent.id, historicalParkingAverageQueryArguments);
+      if (!parkingAverages) {
+        return null;
+      }
+
+      return parkingAverages;
     }
   }
 }