project-inter-server/src/resolvers/ParkingStructureResolvers.ts

import { Resolvers } from "../generated/graphql";
import { ServerContext } from "../ServerContext";
import { HistoricalParkingAverageQueryArguments } from "../repositories/parking/ParkingGetterRepository";
import { GraphQLError } from "graphql/error";
import {
  PARKING_HISTORICAL_AVERAGE_MAXIMUM_TIMESPAN,
  PARKING_HISTORICAL_AVERAGE_MINIMUM_INTERVAL
} from "../environment";

export const ParkingStructureResolvers: Resolvers<ServerContext> = {
  ParkingStructure: {
    historicalAverages: async (parent, args, contextValue, _info) => {
      /**
       * @param errorMessage
       */
      function throwBadUserInputError(errorMessage: string) {
        throw new GraphQLError(errorMessage, {
          extensions: {
            code: 'BAD_USER_INPUT',
          }
        });
      }

      const system = contextValue.findSystemById(parent.systemId);

      if (!args.input?.intervalMs) {
        throwBadUserInputError('No interval provided');
        return null;
      }
      const queryArguments: HistoricalParkingAverageQueryArguments = {
        from: new Date(args.input.from),
        intervalMs: args.input.intervalMs,
        to: new Date(args.input.to),
      }
      if (Number.isNaN(queryArguments.from.getTime()
        || Number.isNaN(queryArguments.to.getTime()))) {
        throwBadUserInputError('One or more incorrect dates provided');
      }
      if (queryArguments.from.getTime() > queryArguments.to.getTime()) {
        throwBadUserInputError("`from` date can't be greater than the `to` date");
      }

      // Limit queries for improved performance
      if (queryArguments.to.getTime() - queryArguments.from.getTime() > PARKING_HISTORICAL_AVERAGE_MAXIMUM_TIMESPAN) {
        throwBadUserInputError('Maximum timespan exceeded');
      }
      if (queryArguments.intervalMs < PARKING_HISTORICAL_AVERAGE_MINIMUM_INTERVAL) {
        throwBadUserInputError('Provided interval is less than minimum interval');
      }

      const parkingAverages = await system?.parkingRepository?.getHistoricalAveragesOfParkingStructureCounts(parent.id, queryArguments);
      if (!parkingAverages) {
        return null;
      }

      return parkingAverages;
    }
  }
}