project-inter-server/src/loaders/repositoryDataLoader.ts

import { IOrderedStop, IRoute, IShuttle, IStop, ISystem, Repository } from "../repositories/repository";

const timeout = 10000;
const systemIdsToSupport = ["263"];
const baseUrl = "https://passiogo.com/mapGetData.php";

// Ideas to break this into smaller pieces in the future:
// Have one repository data loader running for each supported system
// Each data loader independently updates data based on frequency of usage

// TODO implement reloading of data
// Notes on this: we only need to reload ETA data frequently
// Other data can be reloaded periodically
// Detailed list:
// - ETA: reload frequently or switch to write-through approach
// - Shuttles: reload every minute
// - Routes: reload every few minutes
// - Stops: reload every few minutes
// - OrderedStops: reload every few minutes
// - Systems: reload once a day

export class RepositoryDataLoader {
  private shouldBeRunning: boolean = false;

  constructor(
    private repository: Repository,
  ) {}

  public async start() {
    if (this.shouldBeRunning) {
      console.warn("DataLoader timer is already running");
      return;
    }

    this.shouldBeRunning = true;
    await this.startFetchDataAndUpdate();
  }

  public stop() {
    this.shouldBeRunning = false;
  }

  private async startFetchDataAndUpdate() {
    if (!this.shouldBeRunning) return;

    try {
      await this.fetchAndUpdateSystemData();
      await this.fetchAndUpdateRouteDataForExistingSystems();
      await this.fetchAndUpdateStopAndPolylineDataForRoutesInExistingSystems();
      await this.fetchAndUpdateShuttleDataForExistingSystems();
      await this.fetchAndUpdateEtaDataForExistingOrderedStops();
    } catch (e) {
      console.error(e);
    } finally {
      // TODO test if memoization of shouldBeRunning works as intended,
      // I have no idea how JavaScript works
      // setTimeout(this.startFetchDataAndUpdate, timeout);
    }
  }

  private async fetchAndUpdateSystemData() {
    const params = {
      getSystems: "2",
    };
    const query = new URLSearchParams(params).toString();
    const response = await fetch(`${baseUrl}?${query}`);
    const json = await response.json()

    if (typeof json.all === "object") {
      // filter down to supported systems
      const filteredSystems = json.all.filter((jsonSystem: any) => systemIdsToSupport.includes(jsonSystem.id));
      await Promise.all(filteredSystems.map(async (system: any) => {
        const constructedSystem: ISystem = {
          id: system.id,
          name: system.fullname,
        };

        await this.repository.addOrUpdateSystem(constructedSystem);
      }));
    }
  }

  private async fetchAndUpdateRouteDataForExistingSystems() {
    const systems = await this.repository.getSystems();
    await Promise.all(systems.map(async (system) => {
      const params = {
        getRoutes: "2",
      };

      const formDataJsonObject = {
        "systemSelected0": system.id,
        "amount": "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 (typeof json.all === "object") {
        await Promise.all(json.all.map(async (jsonRoute: any) => {
          const constructedRoute: IRoute = {
            name: jsonRoute.name,
            color: jsonRoute.color,
            id: jsonRoute.myid,
            // TODO associate polyline coordinates with routes
            polylineCoordinates: [],
            systemId: system.id,
          };

          await this.repository.addOrUpdateRoute(constructedRoute);
        }))
      }
    }));
  }

  private async fetchAndUpdateStopAndPolylineDataForRoutesInExistingSystems() {
    // Fetch from the API
    // Pass JSON output into two different methods to update repository
    const systems = await this.repository.getSystems();
    await Promise.all(systems.map(async (system: any) => {
      const params = {
        getStops: "2",
      };

      const formDataJsonObject = {
        "s0": "263",
        "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();

      await this.updateStopDataForSystemAndApiResponse(system, json);
      await this.updateOrderedStopDataForExistingStops(json);
      await this.updatePolylineDataForExistingRoutesAndApiResponse(json);
    }));
  }

  private async fetchAndUpdateShuttleDataForExistingSystems() {
    const systems = await this.repository.getSystems();
    await Promise.all(systems.map(async (system: ISystem) => {
      const params = {
        getBuses: "2"
      };

      const formDataJsonObject = {
        "s0": system.id,
        "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];
        });

        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: system.id,
            id: `${jsonBus.busId}`
          }

          await this.repository.addOrUpdateShuttle(constructedShuttle);
        }))
      }
    }));
  }

  private async fetchAndUpdateEtaDataForExistingOrderedStops() {
    // TODO implement once I figure out how to associate ETA data with shuttles

    // const systems = await this.repository.getSystems();
    // await Promise.all(systems.map(async (system: ISystem) => {
    //   const stops = await this.repository.getStopsBySystemId(system.id);
    //
    //   await Promise.all(stops.map(async (stop: IStop) => {
    //     const orderedStops = await this.repository.getOrderedStopsByStopId(stop.id);
    //
    //     await Promise.all(orderedStops.map(async (orderedStop) => {
    //       const params = {
    //         eta: "3",
    //         stopIds: stop.id,
    //         routeId: orderedStop.routeId,
    //         position: orderedStop.position,
    //       };
    //
    //       // How to get shuttle ID?????????
    //       // API doesn't provide it
    //       // I might be cooked
    //     }));
    //   }));
    // }));
  }

  private async updateStopDataForSystemAndApiResponse(system: ISystem, json: any) {
    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: system.id,
          coordinates: {
            latitude: parseFloat(stop.latitude),
            longitude: parseFloat(stop.longitude),
          },
        };

        await this.repository.addOrUpdateStop(constructedStop);
      }));
    }
  }

  private async updateOrderedStopDataForExistingStops(json: any) {
    if (json.routes) {
      await Promise.all(Object.keys(json.routes).map(async (routeId) => {
        const jsonOrderedStopData: any[][] = json.routes[routeId].slice(2);

        // The API may return the same stop twice to indicate that
        // the route runs in a loop
        // If the API does not do this, assume the route is one-way
        // To account for this, check if ordered stop already exists in repo
        // If it does, write to that stop instead

        for (let index = 0; index < jsonOrderedStopData.length; index++) {
          const orderedStopDataArray = jsonOrderedStopData[index];

          const stopId = orderedStopDataArray[1];
          let constructedOrderedStop = await this.repository.getOrderedStopByRouteAndStopId(routeId, stopId)
          if (constructedOrderedStop === null) {
            constructedOrderedStop = {
              routeId,
              stopId,
              position: index + 1,
            };
          }

          if (index >= 1) {
            constructedOrderedStop.previousStop = {
              routeId,
              stopId: jsonOrderedStopData[index - 1][1],
              position: index,
            };
          }
          if (index < jsonOrderedStopData.length - 1) {
            constructedOrderedStop.nextStop = {
              routeId,
              stopId: jsonOrderedStopData[index + 1][1],
              position: index + 2,
            };
          }

          await this.repository.addOrUpdateOrderedStop(constructedOrderedStop);
        }
      }));
    }
  }

  private async updatePolylineDataForExistingRoutesAndApiResponse(json: any) {
    if (json.routePoints) {
      await Promise.all(Object.keys(json.routePoints).map(async (routeId) => {
        const routePoints = json.routePoints[routeId][0];

        const existingRoute = await this.repository.getRouteById(routeId);
        if (!existingRoute) return;

        existingRoute.polylineCoordinates = routePoints.map((point: any) => {
          return {
            latitude: parseFloat(point.lat),
            longitude: parseFloat(point.lng),
          };
        });

        await this.repository.addOrUpdateRoute(existingRoute);
      }))
    }
  }
}