feat: configurable status code behaviours (#340)

src/store/model/asus.ts

@@ -33,6 +33,7 @@ export const Asus: Store = {
 			url: 'https://store.asus.com/us/item/202009AM150000003/'
 		}
 	],
-	name: 'asus'
+	name: 'asus',
+	successStatusCodes: [[0, 399], 404]
 };
 

src/store/model/helpers/backoff.ts

@@ -0,0 +1,52 @@
+import {Link, Store} from '..';
+import {Logger, Print} from '../../../logger';
+import {delay, isStatusCodeInRange} from '../../../util';
+import {Config} from '../../../config';
+
+type Backoff = {
+	count: number;
+	time: number;
+};
+
+const stores: Record<string, Backoff> = {};
+
+export async function processBackoffDelay(store: Store, link: Link, statusCode: number): Promise<number> {
+	/**
+	 * We treat statusCode 0 as successful as some of the puppeteer plugins
+	 * cause side-effects resulting in an empty response object even though
+	 * the page renders fine and its content is accessible.
+	 */
+
+	let backoffStatusCodes = store.backoffStatusCodes;
+
+	if (!backoffStatusCodes) {
+		backoffStatusCodes = [403];
+	}
+
+	const isBackoff = isStatusCodeInRange(statusCode, backoffStatusCodes);
+	let backoff = stores[store.name];
+
+	if (!backoff) {
+		backoff = {count: 0, time: Config.browser.minBackoff};
+		stores[store.name] = backoff;
+	}
+
+	if (!isBackoff) {
+		if (backoff.count > 0) {
+			backoff.count--;
+			backoff.time = Math.max(backoff.time / 2, Config.browser.minBackoff);
+		}
+
+		return -1;
+	}
+
+	const backoffTime = backoff.time;
+	Logger.debug(Print.backoff(link, store, {delay: backoffTime, statusCode}, true));
+
+	await delay(backoff.time);
+
+	backoff.count++;
+	backoff.time = Math.min(backoff.time * 2, Config.browser.maxBackoff);
+
+	return backoffTime;
+}

src/store/model/store.ts

@@ -27,7 +27,15 @@ export type Labels = {
 	outOfStock?: LabelQuery;
 };
 
+export type StatusCodeRangeArray = Array<(number | [number, number])>;
+
 export type Store = {
+	/**
+	 * The range of status codes which will trigger backoff, i.e. an increasing
+	 * delay between requests. Setting an empty array will disable the feature.
+	 * If not defined, the default range will be used: 403.
+	 */
+	backoffStatusCodes?: StatusCodeRangeArray;
 	disableAdBlocker?: boolean;
 	links: Link[];
 	linksBuilder?: {
@@ -37,5 +45,12 @@ export type Store = {
 	labels: Labels;
 	name: string;
 	setupAction?: (browser: Browser) => void;
+	/**
+	 * The range of status codes which considered successful, i.e. without error
+	 * allowing request parsing to continue. Setting an empty array will cause
+	 * all requests to fail. If not defined, the default range will be used:
+	 * 0 -> 399 inclusive.
+	 */
+	successStatusCodes?: StatusCodeRangeArray;
 	waitUntil?: LoadEvent;
 };

src/store/model/zotac.ts

@@ -1,6 +1,7 @@
 import {Store} from './store';
 
 export const Zotac: Store = {
+	backoffStatusCodes: [403, 503],
 	labels: {
 		inStock: {
 			container: '.add-to-cart-wrapper',