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

import { RepositoryLoader } from "./RepositoryLoader";

// To break down timed loading in the future:
// Add flags to the repository indicating which data users are subscribed to
// In the loader's `fetchAll` method, check flags and update only needed data

export class TimedApiBasedRepositoryLoader {
  private shouldBeRunning: boolean = false;
  private timer: any;

  constructor(
    public loader: RepositoryLoader,
    public readonly timeoutMs: number = 10000,
  ) {
    this.startFetchDataAndUpdate = this.startFetchDataAndUpdate.bind(this);
  }

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

    this.timer = setTimeout(this.startFetchDataAndUpdate, this.timeoutMs);
  }
}