Check if a listing is still active (#184)

* check if a listing is still active

* upgrade dependencies

lib/services/listings/listingActiveService.js

@@ -0,0 +1,104 @@
+import { deactivateListings, getActiveOrUnknownListings } from '../storage/listingsStorage.js';
+import { getProviders } from '../../utils.js';
+import logger from '../../services/logger.js';
+
+/**
+ * Runs the active-listing checker:
+ * 1) Loads all listings with unknown or active status.
+ * 2) Resolves each listing's provider and calls its `activeTester(link)`.
+ * 3) Collects listings that are no longer active and deactivates them in one batch.
+ *
+ * Concurrency: network-bound checks are executed with a configurable concurrency limit.
+ *
+ * @param {object} [opts]
+ * @param {number} [opts.concurrency=8] Max number of parallel activeTester calls.
+ * @returns {Promise<void>}
+ */
+export default async function runActiveChecker(opts = {}) {
+  const { concurrency = 4 } = opts;
+
+  const listings = getActiveOrUnknownListings();
+  if (!Array.isArray(listings) || listings.length === 0) {
+    logger.debug('No listings to check.');
+    return;
+  }
+
+  const providers = await getProviders();
+  if (!Array.isArray(providers) || providers.length === 0) {
+    logger.warn('No providers available. Skipping active checks.');
+    return;
+  }
+
+  // Build a map for O(1) provider lookup by id
+  /** @type {Record<string, any>} */
+  const providerById = Object.create(null);
+  for (const p of providers) {
+    const id = p?.metaInformation?.id;
+    if (id) providerById[id] = p;
+  }
+
+  // Small generic mapLimit to cap concurrency without extra deps
+  /**
+   * @template T, R
+   * @param {T[]} items
+   * @param {number} limit
+   * @param {(item: T, index: number) => Promise<R>} worker
+   * @returns {Promise<R[]>}
+   */
+  async function mapLimit(items, limit, worker) {
+    const results = new Array(items.length);
+    let next = 0;
+
+    async function runOne() {
+      while (next < items.length) {
+        const i = next++;
+        try {
+          results[i] = await worker(items[i], i);
+        } catch (err) {
+          results[i] = /** @type {any} */ (err);
+        }
+      }
+    }
+
+    const runners = Array.from({ length: Math.min(limit, items.length) }, runOne);
+    await Promise.all(runners);
+    return results;
+  }
+
+  /** @type {string[]} */
+  const listingsSetToInactive = [];
+
+  await mapLimit(listings, concurrency, async (listing) => {
+    const { provider: listingProviderId, link, id } = listing || {};
+
+    const matchedProvider = providerById[listingProviderId];
+    if (!matchedProvider) {
+      logger.warn('Could not find matching provider for', listingProviderId);
+      return;
+    }
+    const tester = matchedProvider?.config?.activeTester;
+    if (typeof tester !== 'function') {
+      logger.warn('No activeTester configured for', listingProviderId);
+      return;
+    }
+
+    // Contract: activeTester(link) returns 1 if active, 0 if inactive
+    let result;
+    try {
+      result = await tester(link);
+    } catch {
+      result = -1;
+    }
+
+    if (result === 0 && id) {
+      listingsSetToInactive.push(id);
+    }
+  });
+
+  if (listingsSetToInactive.length > 0) {
+    logger.info(`Setting ${listingsSetToInactive.length} listings to inactive.`);
+    deactivateListings(listingsSetToInactive);
+  } else {
+    logger.debug('No listings need to be set inactive.');
+  }
+}

lib/services/listings/listingActiveTester.js

@@ -0,0 +1,68 @@
+import fetch from 'node-fetch';
+import { randomBetween, sleep } from '../../utils.js';
+
+const maxAttempts = 3;
+
+/**
+ * Check if a listing is still active with up to 3 attempts and exponential backoff.
+ * Backoff waits are capped and the last wait is at most 2000 ms.
+ *
+ * Rules:
+ * - HTTP 200 => return 1
+ * - HTTP 401/403 => return -1 (most certainly detected as a bot)
+ * - HTTP 404 => return 0
+ * - Other statuses or network errors => retry until attempts are exhausted
+ *
+ * @returns {Promise<Integer>} 1 if active, o if not active and -1 if detected as bot
+ */
+export default async function checkIfListingIsActive(link) {
+  await sleep(randomBetween(50, 100));
+
+  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
+    try {
+      const res = await fetch(link, {
+        headers: {
+          'User-Agent':
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36',
+          'Accept-Language': 'de-DE,de;q=0.9,en;q=0.8',
+        },
+      });
+
+      if (res.status === 200) {
+        return 1;
+      }
+      if (res.status === 401) return -1;
+      if (res.status === 403) return -1;
+      if (res.status === 404) return 0;
+
+      // For any other status, only retry if attempts remain
+      if (attempt < maxAttempts) {
+        await sleep(backoffDelay(attempt));
+        continue;
+      }
+
+      return 0;
+    } catch {
+      // Network error: retry if attempts remain
+      if (attempt < maxAttempts) {
+        await sleep(backoffDelay(attempt));
+        continue;
+      }
+      return 0;
+    }
+  }
+
+  return 0;
+}
+
+/**
+ * Exponential backoff delay with cap.
+ * attempt: 1 -> 500ms, 2 -> 1000ms, 3 -> 2000ms (cap)
+ * @param {number} attempt 1-based attempt index
+ * @returns {number} delay in ms
+ */
+function backoffDelay(attempt) {
+  const base = 500;
+  const cap = 2000;
+  return Math.min(base * 2 ** (attempt - 1), cap);
+}