feat(api): decouple api from curriculum (#40703)

api-server/src/server/models/donation.js

@@ -0,0 +1,77 @@
+import { Observable } from 'rx';
+import debug from 'debug';
+
+import { reportError } from '../middlewares/sentry-error-handler.js';
+import InMemoryCache from '../utils/in-memory-cache';
+
+const log = debug('fcc:boot:donate');
+const fiveMinutes = 1000 * 60 * 5;
+
+export default function(Donation) {
+  let activeDonationUpdateInterval = null;
+  const activeDonationCountCacheTTL = fiveMinutes;
+  const activeDonationCountCache = InMemoryCache(0, reportError);
+  const activeDonationsQuery$ = () =>
+    Donation.find$({
+      // eslint-disable-next-line no-undefined
+      where: { endDate: undefined }
+    }).map(instances => instances.length);
+  function cleanUp() {
+    if (activeDonationUpdateInterval) {
+      clearInterval(activeDonationUpdateInterval);
+    }
+    return;
+  }
+
+  process.on('exit', cleanUp);
+
+  Donation.on('dataSourceAttached', () => {
+    Donation.find$ = Observable.fromNodeCallback(Donation.find.bind(Donation));
+    Donation.findOne$ = Observable.fromNodeCallback(
+      Donation.findOne.bind(Donation)
+    );
+
+    seedTheCache()
+      .then(setupCacheUpdateInterval)
+      .catch(err => {
+        const errMsg = `Error caught seeding the cache: ${err.message}`;
+        err.message = errMsg;
+        reportError(err);
+      });
+  });
+
+  function seedTheCache() {
+    return new Promise((resolve, reject) =>
+      Observable.defer(activeDonationsQuery$).subscribe(count => {
+        log('activeDonor count: %d', count);
+        activeDonationCountCache.update(() => count);
+        return resolve();
+      }, reject)
+    );
+  }
+
+  function setupCacheUpdateInterval() {
+    activeDonationUpdateInterval = setInterval(
+      () =>
+        Observable.defer(activeDonationsQuery$).subscribe(
+          count => {
+            log('activeDonor count: %d', count);
+            return activeDonationCountCache.update(() => count);
+          },
+          err => {
+            const errMsg = `Error caught updating the cache: ${err.message}`;
+            err.message = errMsg;
+            reportError(err);
+          }
+        ),
+      activeDonationCountCacheTTL
+    );
+    return null;
+  }
+
+  function getCurrentActiveDonationCount$() {
+    return Observable.of(activeDonationCountCache.get());
+  }
+
+  Donation.getCurrentActiveDonationCount$ = getCurrentActiveDonationCount$;
+}