project-inter-server/src/repositories/ApiBasedRepository.ts

import { GetterRepository } from "./GetterRepository";
import { IEta, IOrderedStop, IRoute, IShuttle, IStop, ISystem } from "../entities/entities";

const baseUrl = "https://passiogo.com/mapGetData.php"

// TODO: implement TTL functionality
// TODO: add TTL values to everything
// TODO: remove RepositoryDataLoader and UnoptimizedInMemoryRepository
// TODO: make milliseconds (TTL) required on everything
// TODO: extract cache into its own class

export interface ApiBasedRepositoryCache {
  etasForShuttleId?: {
    [shuttleId: string]: IEta[],
  },
  etasForStopId?: {
    [stopId: string]: IEta[],
  },
  stopsBySystemId?: {
    [systemId: string]: IStop[],
  },
  stopByStopId?: {
    [stopId: string]: IStop,
  },
  shuttleByShuttleId?: {
    [shuttleId: string]: IShuttle,
  },
  shuttlesBySystemId?: {
    [systemId: string]: IShuttle[],
  },
  // To speed things up, implement caches for other data later
}

export interface ApiBasedRepositoryMillisecondTTLs {
  etasForShuttleId?: number,
  etasForStopId?: number,
  shuttleByShuttleId?: number,
  shuttlesBySystemId?: number,
}

const emptyCache: ApiBasedRepositoryCache = {
  etasForShuttleId: {},
  etasForStopId: {},
  shuttleByShuttleId: {},
  shuttlesBySystemId: {},
}

const defaultTtls: ApiBasedRepositoryMillisecondTTLs = {
  etasForShuttleId: 10000,
  etasForStopId: 10000,
}

export class ApiBasedRepository implements GetterRepository {
  private cache: ApiBasedRepositoryCache;

  constructor(
    initialCache: ApiBasedRepositoryCache | undefined = emptyCache,
    private ttls: ApiBasedRepositoryMillisecondTTLs = defaultTtls,
  ) {
    this.cache = initialCache;
  }

  /**
   * Seed the initial data in the cache, so data can be updated
   * given the correct ID.
   * Alternatively, pass in an `initialCache` with existing data
   * (useful for testing).
   * @param systemId
   */
  public async seedCacheForSystemId(systemId: string): Promise<void> {
    await this.getShuttlesBySystemId(systemId);
    await this.getShuttlesByRouteId(systemId);
    await this.getStopsBySystemId(systemId);
    await this.getSystemById(systemId);
  }

  public async getEtaForShuttleAndStopId(shuttleId: string, stopId: string): Promise<IEta | null> {
    const shuttle = await this.getShuttleById(shuttleId);
    const systemId = shuttle?.systemId;
    if (!systemId) {
      return null;
    }
    await this.updateEtasForSystemIfTTL(systemId);

    if (this.cache?.etasForStopId && this.cache.etasForStopId[stopId]) {
      const etas = this.cache.etasForStopId[stopId];
      const foundEta = etas.find((eta) => eta.stopId === stopId);
      if (foundEta) {
        return foundEta;
      }
    }

    return null;
  }

  public async getEtasForShuttleId(shuttleId: string): Promise<IEta[]> {
    const shuttle = await this.getShuttleById(shuttleId);
    const systemId = shuttle?.systemId;
    if (!systemId) {
      return [];
    }
    await this.updateEtasForSystemIfTTL(systemId);

    if (!this.cache?.etasForShuttleId || !this.cache.etasForShuttleId[shuttleId]) {
      return [];
    }

    return this.cache.etasForShuttleId[shuttleId];
  }

  public async getEtasForStopId(stopId: string): Promise<IEta[]> {
    const stop = await this.getStopById(stopId);
    const systemId = stop?.systemId;
    if (!systemId) {
      return [];
    }
    await this.updateEtasForSystemIfTTL(systemId);

    if (!this.cache?.etasForStopId || !this.cache.etasForStopId[stopId]) {
      return [];
    }

    return this.cache.etasForStopId[stopId];
  }

  public async updateEtasForSystemIfTTL(systemId: string) {
    // TODO: check if TTL
    try {
      const stops = await this.getStopsBySystemId(systemId);
      await Promise.all(stops.map(async (stop) => {
        const params = {
          eta: "3",
          stopIds: stop.id,
        };

        const query = new URLSearchParams(params).toString();
        const response = await fetch(`${baseUrl}?${query}`, {
          method: "GET",
        });
        const json = await response.json();

        if (json.ETAs && json.ETAs[stop.id]) {
          if (!this.cache.etasForStopId) {
            this.cache.etasForStopId = {};
          }
          this.cache.etasForStopId[stop.id] = [];

          // This is technically incorrect, the entire shuttle cache
          // should not be reset like this
          // TODO: restore normal cache behavior
          this.cache.etasForShuttleId = {};

          // Continue with the parsing
          json.ETAs[stop.id].forEach((jsonEta: any) => {
            // Update cache
            if (!this.cache.etasForStopId) {
              this.cache.etasForStopId = {};
            }

            if (!this.cache.etasForShuttleId) {
              this.cache.etasForShuttleId = {};
            }

            // TODO: create cache abstraction to deal with possibly undefined properties

            const shuttleId: string = jsonEta.busId;
            if (!this.cache.etasForShuttleId[shuttleId]) {
              this.cache.etasForShuttleId[shuttleId] = [];
            }

            const eta: IEta = {
              secondsRemaining: jsonEta.secondsSpent,
              shuttleId: `${shuttleId}`,
              stopId: stop.id,
              millisecondsSinceEpoch: Date.now(),
            };

            this.cache.etasForStopId[stop.id].push(eta);
            this.cache.etasForShuttleId[shuttleId].push(eta);
          });
        }
      }));

    } catch (e) {
      console.error(e);
    }
  }

  // TODO: migrate rest of logic over to this class
  public async getOrderedStopByRouteAndStopId(routeId: string, stopId: string): Promise<| null> {
    return null;
  }

  public async getOrderedStopsByRouteId(routeId: string): Promise<[]> {
    return Promise.resolve([]);
  }

  public async getOrderedStopsByStopId(stopId: string): Promise<[]> {
    return Promise.resolve([]);
  }

  public async getRouteById(routeId: string): Promise<| null> {
    return Promise.resolve(null);
  }

  public async getRoutesBySystemId(systemId: string): Promise<[]> {
    return Promise.resolve([]);
  }

  public async getShuttleById(shuttleId: string): Promise<IShuttle | null> {
    if (!this.cache.shuttleByShuttleId) return null;
    let shuttle = this.cache.shuttleByShuttleId[shuttleId];
    if (!shuttle) return null;

    // Call getShuttlesBySystemId to update the data if not TTL
    await this.updateShuttlesForSystemIfTTL(shuttle.systemId);

    shuttle = this.cache.shuttleByShuttleId[shuttleId];
    if (!shuttle) return null;
    return shuttle;
  }

  public async getShuttlesByRouteId(routeId: string): Promise<[]> {
    return Promise.resolve([]);
  }

  public async getShuttlesBySystemId(systemId: string): Promise<IShuttle[]> {
    return Promise.resolve([]);
  }

  public async updateShuttlesForSystemIfTTL(systemId: string) {
    // TODO: check if TTL
    try {
      // TODO: update shuttlesByRouteId
      // Update shuttleByShuttleId, shuttlesBySystemId
      const params = {
        getBuses: "2"
      };

      const formDataJsonObject = {
        "s0": systemId,
        "sA": "1"
      };

      const formData = new FormData();
      formData.set("json", JSON.stringify(formDataJsonObject));

      const query = new URLSearchParams(params).toString();
      const response = await fetch(`${baseUrl}?${query}`, {
        method: "POST",
        body: formData,
      });
      const json = await response.json();

      if (json.buses && json.buses["-1"] === undefined) {
        const jsonBuses = Object.values(json.buses).map((busesArr: any) => {
          return busesArr[0];
        });

        // Store shuttles by system, with the additional side effect that
        // shuttleByShuttleId is updated
        const shuttles = await Promise.all(jsonBuses.map(async (jsonBus: any) => {
          const constructedShuttle: IShuttle = {
            name: jsonBus.bus,
            coordinates: {
              latitude: parseFloat(jsonBus.latitude),
              longitude: parseFloat(jsonBus.longitude),
            },
            routeId: jsonBus.routeId,
            systemId: systemId,
            id: `${jsonBus.busId}`
          }

          if (this.cache.shuttleByShuttleId) {
            this.cache.shuttleByShuttleId[jsonBus.busId] = constructedShuttle;
          }

          return constructedShuttle;
        }));

        if (this.cache.shuttlesBySystemId) {
          this.cache.shuttlesBySystemId[systemId] = shuttles;
        }
      } else {
        console.warn(`No shuttle data available for system ID ${systemId} and JSON output
${json}`);
      }
    } catch (e) {
      console.error(e);
    }
  }

  public async getStopById(stopId: string): Promise<IStop | null> {
    if (!this.cache.stopByStopId) return null;
    const oldStop = this.cache.stopByStopId[stopId];
    if (!oldStop) return null;

    await this.updateStopsForSystemIdIfTTL(oldStop.systemId);

    const newStop = this.cache.stopByStopId[stopId];
    if (!newStop) return null;

    return newStop;
  }

  public async getStopsBySystemId(systemId: string): Promise<IStop[]> {
    await this.updateStopsForSystemIdIfTTL(systemId);

    if (!this.cache.stopsBySystemId || this.cache.stopsBySystemId[systemId]) {
      return [];
    }
    return this.cache.stopsBySystemId[systemId];
  }

  public async updateStopsForSystemIdIfTTL(systemId: string) {
    // TODO: check if TTL

    try {
      const params = {
        getStops: "2",
      };

      const formDataJsonObject = {
        "s0": systemId,
        "sA": 1
      };
      const formData = new FormData();
      formData.set("json", JSON.stringify(formDataJsonObject));

      const query = new URLSearchParams(params).toString();
      const response = await fetch(`${baseUrl}?${query}`, {
        method: "POST",
        body: formData,
      });
      const json = await response.json();

      // TODO: update polyline data
      // TODO: update ordered stop data

      if (json.stops) {
        const jsonStops = Object.values(json.stops);

        await Promise.all(jsonStops.map(async (stop: any) => {
          const constructedStop: IStop = {
            name: stop.name,
            id: stop.id,
            systemId: systemId,
            coordinates: {
              latitude: parseFloat(stop.latitude),
              longitude: parseFloat(stop.longitude),
            },
          };

          if (this.cache.stopsBySystemId) {
            this.cache.stopsBySystemId[systemId]?.push(constructedStop);
          }

          if (this.cache.stopByStopId) {
            this.cache.stopByStopId[constructedStop.id] = constructedStop;
          }
        }));
      }
    } catch (e) {
      console.error(e);
    }
  }

  public async getSystemById(systemId: string): Promise<ISystem| null> {
    return null;
  }

  public async getSystems(): Promise<[]> {
    return Promise.resolve([]);
  }

}