aretherecookies-mobile/js/streams/FoodItemsStream.js

//@flow
import { ReplaySubject, Observable } from "rxjs";
import FoodItemRecord, { createFoodItem } from "../records/FoodItemRecord";
import { setById } from "../helpers/ImmutableHelpers";
import { Map } 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.mergeDeepWith(
					(foodItem, foodItemQuantities) => foodItem.merge(foodItemQuantities),
					quantitiesFromStream
				);
			}
		}
	)
	.combineLatest(
		Image$,
		(foodItems: ?Map<string, FoodItemRecord>, latestFromImages$: Map<string, ImageFragment>) => {
			if (foodItems) {
				return foodItems.mergeDeepWith(
					// $FlowFixMe
					(foodItem: FoodItemRecord, imageFragment: ImageFragment) => {
						return foodItem.set("images", imageFragment.images);
					},
					latestFromImages$
				);
			}
		}
	);