aretherecookies-mobile/js/streams/FoodItemsStream.js

//@flow
import { ReplaySubject, Observable } from 'rxjs';
import FoodItemRecord, { createFoodItem, type FoodItem } from '../records/FoodItemRecord';
import { setById } from '../helpers/ImmutableHelpers';
import { Map, type Record } from 'immutable';
import location$ from './LocationStream';
import { getFoodItems, type FoodItemsForLocation } from '../apis/FoodItemsApi';
import Filter$ from './FilterStream';
import Quantity$ from './QuantityStream';
import type { QuantityFragment } from '../constants/QuantityConstants';
import { type ImageFragment } from '../records/ImageRecord';
import Image$ from './ImagesStream';

const foodItemSubject: ReplaySubject<FoodItemRecord> = new ReplaySubject();

export function emitter(val?: ?FoodItemRecord) {
	foodItemSubject.next(val);
}

emitter(null);

const manualUpdate$ = foodItemSubject.scan(
	(foodItemMap: Map<string, FoodItemRecord>, foodItem: FoodItemRecord) => {
		return foodItem ? foodItemMap.set(foodItem.id, foodItem) : foodItemMap;
	},
	Map()
);

const fetchedFoodItems$ = Filter$.combineLatest(location$)
	.debounceTime(200)
	.mergeMap(([filter, loc]) => {
		if (!loc) {
			return Promise.resolve({});
		}
		return Observable.merge(Promise.resolve({}), getFoodItems({ filter, loc }));
	})
	.map(({ fooditems }: FoodItemsForLocation) => {
		if (fooditems) {
			return fooditems.map(createFoodItem).reduce(setById, new Map());
		}
		return null;
	});

export default fetchedFoodItems$
	.combineLatest(manualUpdate$, (foodItemMap: Map<string, FoodItemRecord>, manualUpdates) => {
		if (foodItemMap) {
			return foodItemMap.mergeDeep(manualUpdates);
		}
	})
	.combineLatest(
		Quantity$,
		(
			foodItems: ?Map<string, FoodItemRecord>,
			quantitiesFromStream: Map<string, QuantityFragment>
		) => {
			if (foodItems) {
				return foodItems.mergeDeep(quantitiesFromStream);
			}
		}
	)
	.combineLatest(
		Image$,
		(foodItems: ?Map<string, FoodItemRecord>, latestFromImages$: Map<String, ImageFragment>) => {
			if (foodItems) {
				return foodItems.mergeDeep(latestFromImages$);
			}
		}
	);