smartdata/ts/smartdata.classes.watcher.ts

import { SmartDataDbDoc } from './smartdata.classes.doc.js';
import * as plugins from './smartdata.plugins.js';

/**
 * a wrapper for the native mongodb cursor. Exposes better
 */
export class SmartdataDbWatcher<T = any> {
  // STATIC
  public readyDeferred = plugins.smartpromise.defer();

  // INSTANCE
  private changeStream: plugins.mongodb.ChangeStream<T>;

  public changeSubject = new plugins.smartrx.rxjs.Subject<T>();
  constructor(changeStreamArg: plugins.mongodb.ChangeStream<T>, smartdataDbDocArg: typeof SmartDataDbDoc) {
    this.changeStream = changeStreamArg;
    this.changeStream.on('change', async (item: T) => {
      this.changeSubject.next(smartdataDbDocArg.createInstanceFromMongoDbNativeDoc(item) as any as T);
    })
    plugins.smartdelay.delayFor(0).then(() => {
      this.readyDeferred.resolve();
    });
  }

  public async close() {
    await this.changeStream.close();
  }
}