const functions = require('firebase-functions');

// The Firebase Admin SDK to access the Firebase Realtime Database.
const admin = require('firebase-admin');
admin.initializeApp();
const db = admin.firestore()

// // Create and Deploy Your First Cloud Functions
// // https://firebase.google.com/docs/functions/write-firebase-functions
//
// exports.helloWorld = functions.https.onRequest((request, response) => {
//  response.send("Hello from Firebase!");
// });

exports.addToFavorites = functions.firestore.document('users/{userId}/favorites/{favoriteId}')
    .onCreate((snap, context) =>
    {
        var favoritePost = snap.data();
        //Get current count and increase by 1
        var count = favoritePost.favoritesCount + 1;

        //Create new document in favoritesToUpdate
        var addDoc = db.collection('favoritesToUpdate').add({
          postId: favoritePost.docId,
          userId: context.userId,
          docId: context.favoriteId
        }).then(ref => {
          console.log('Added document to favoritesToUpdate with ID: ', ref.id);
        }).catch( error => console.log(error));

        //Get all documents where postId = favoritePost.postId
        var favoritesToUpdate = db.collection('favoritesToUpdate').where('postId', '==', favoritePost.postId);
        var userRef = db.collection('users');

        return db.runTransaction((transaction) => {
            return transaction.get(favoritesToUpdate).then((snapshot) => {
                for (let i = 0; i < snapshot.size; i++) { // Iterate through favoritesToUpdate
                    var data = snapshot.docs[i].data();

                    var userFavorites = userRef.doc(data.uid).collection('favorites').doc(data.docId);
                    transaction.get(userFavorites).then((userFavorite) => {
                        var updateObject = { favoritesCount: count };

                        transaction.update(userFavorite.ref, updateObject);
                    });

                    //console.log(${data.uid}); // Get uid for each update of post
                }
            });
        }).catch( error => console.log(error));
    });