Finished auto increment firebase function

functions/package.json

@@ -15,7 +15,7 @@
     "@types/fs-extra": "^5.0.5",
     "@types/sharp": "^0.22.1",
     "firebase-admin": "~7.0.0",
-    "firebase-functions": "^2.2.0",
+    "firebase-functions": "^2.2.1",
     "fs-extra": "^7.0.1",
     "sharp": "^0.22.0"
   },

functions/src/generate_thumb.ts

@@ -9,6 +9,7 @@ import { join, dirname } from 'path';
 import * as sharp from 'sharp';
 import * as fs from 'fs-extra';
 
+/// Creates a thumbnail for every image that gets uploaded to the storage bucket.
 export const generateThumb: functions.CloudFunction<functions.storage.ObjectMetadata> = functions.storage.object().onFinalize(async object => {
     // Find the bucket where the uploaded file resides.
     const bucket = gcs.bucket(object.bucket);

functions/src/index.ts

@@ -1,5 +1,7 @@
 import * as functions from 'firebase-functions';
 
 import { generateThumb } from './generate_thumb';
+import { pendingTasksUpdater } from './pending_tasks_updater';
 
-export const generate_thumb: functions.CloudFunction<functions.storage.ObjectMetadata> = generateThumb;
+export const generate_thumb: functions.CloudFunction<functions.storage.ObjectMetadata> = generateThumb;
+export const pending_tasks_updater: functions.CloudFunction<functions.Change<FirebaseFirestore.DocumentSnapshot>> = pendingTasksUpdater;

functions/src/pending_tasks_updater.ts

@@ -0,0 +1,91 @@
+import * as functions from 'firebase-functions';
+import * as admin from 'firebase-admin';
+import { DocumentSnapshot } from 'firebase-functions/lib/providers/firestore';
+import { DocumentReference } from '@google-cloud/firestore';
+
+admin.initializeApp();
+
+
+const incrementValue = admin.firestore.FieldValue.increment(1);
+const decrementValue = admin.firestore.FieldValue.increment(-1);
+const db = admin.firestore();
+
+let getUserReference = async (taskSnapShot: DocumentSnapshot) => {
+    const querySnapshot = await db.collection('users').where('username', '==', taskSnapShot.get('ownerUsername')).get()
+    return querySnapshot.docs[0].ref;
+}
+
+let getEventReference = async (taskSnapshot: DocumentSnapshot, userReference: DocumentReference) => {
+    const querySnapshot = await userReference.collection('events').where('name', '==', taskSnapshot.get('event')).get();
+    return querySnapshot.docs[0].ref;
+}
+
+let incrementFromPriority = (
+    priority: number,
+    eventReference: DocumentReference,
+    userReference: DocumentReference,
+    value: FirebaseFirestore.FieldValue,
+) => {
+    let userFieldName: string = '';
+    let eventFieldName: string = '';
+
+    switch (priority) {
+        case 0:
+            userFieldName = 'pendingLow';
+            eventFieldName = 'lowPriority';
+            break;
+        case 1:
+            userFieldName = 'pendingMedium';
+            eventFieldName = 'mediumPriority';
+            break;
+        case 2:
+            userFieldName = 'pendingHigh';
+            eventFieldName = 'highPriority';
+            break;
+    }
+
+    eventReference.update({ [eventFieldName]: value });
+    userReference.update({ [userFieldName]: value });
+}
+
+export const pendingTasksUpdater: functions.CloudFunction<functions.Change<FirebaseFirestore.DocumentSnapshot>> = functions.firestore
+    .document('tasks/{taskId}')
+    .onWrite(async (change, _) => {
+        const before: DocumentSnapshot = change.before;
+        const after: DocumentSnapshot = change.after;
+        let action: string;
+        let userDocument: DocumentReference;
+        let eventDocument: DocumentReference;
+        let eventDocumentBefore: DocumentReference | null;
+
+        if (change.after.exists && change.before.exists) {
+            userDocument = await getUserReference(after);
+            eventDocumentBefore = await getEventReference(before, userDocument);
+            eventDocument = await getEventReference(after, userDocument);
+            action = 'update';
+        } else if (!change.before.exists) {
+            userDocument = await getUserReference(after);
+            eventDocument = await getEventReference(after, userDocument);
+            action = 'create';
+        } else {
+            userDocument = await getUserReference(before);
+            eventDocument = await getEventReference(before, userDocument);
+            action = 'delete';
+        }
+
+        switch (action) {
+            case 'create':
+                incrementFromPriority(after.get('priority'), eventDocument, userDocument, incrementValue);
+                break;
+            case 'delete':
+                incrementFromPriority(before.get('priority'), eventDocument, userDocument, decrementValue);
+                break;
+            case 'update':
+                incrementFromPriority(before.get('priority'), eventDocumentBefore!, userDocument, decrementValue);
+                incrementFromPriority(after.get('priority'), eventDocument, userDocument, incrementValue);
+                break;
+        }
+
+        console.log('Successfully updated user and event due to task update');
+        return true;
+    });