aretherecookies-mobile/js/streams/PlacesStream.js

// @flow
import { buildPlaceRecord } from '../records/PlaceRecord';
import { Map } from 'immutable';
import foodItems$ from './FoodItemsStream';
import { getPlaceDetails } from '../apis/PlaceDetailsApi';
import { memoize } from 'ramda';
import { Observable } from 'rxjs';
import typeof FoodItemRecord from '../records/FoodItemRecord';
import { type GooglePlaceObj } from '../records/PlaceRecord';
import { setById } from '../helpers/ImmutableHelpers';

/**
 * return a promise of a place details object
 * if already requested return existing promise
 * swallow exceptions so as not to break the stream
 */
const safeGetPlaceDetails = memoize((placeId: string): Promise<?GooglePlaceObj> => {
	return getPlaceDetails(placeId).catch(error => {
		console.error(error); // eslint-disable-line no-console
		return null;
	});
});

const Places$ = foodItems$
	.mergeMap((foodItems: Map<string, FoodItemRecord>): Observable<string> => {
		return Observable.from(foodItems.toArray().map(foodItem => foodItem.placeId));
	})
	.distinct()
	.mergeMap(safeGetPlaceDetails)
	.map(buildPlaceRecord)
	.scan(setById, new Map());

export default Places$;