prevent double follow/unfollow

src/socket.io/user.js

@@ -282,28 +282,24 @@ SocketUser.follow = function(socket, data, callback) {
 		return;
 	}
 
-	toggleFollow('follow', socket.uid, data.uid, function(err) {
-		if (err) {
-			return callback(err);
-		}
-
-		user.getUserFields(socket.uid, ['username', 'userslug'], function(err, userData) {
-			if (err) {
-				return callback(err);
-			}
-
+	async.waterfall([
+		function(next) {
+			toggleFollow('follow', socket.uid, data.uid, next);
+		},
+		function(next) {
+			user.getUserFields(socket.uid, ['username', 'userslug'], next);
+		},
+		function(userData, next) {
 			notifications.create({
 				bodyShort: '[[notifications:user_started_following_you, ' + userData.username + ']]',
 				nid: 'follow:' + data.uid + ':uid:' + socket.uid,
 				from: socket.uid
-			}, function(err, notification) {
-				if (!err && notification) {
-					notifications.push(notification, [data.uid]);
-				}
-				callback(err);
-			});
-		});
-	});
+			}, next);
+		},
+		function(notification, next) {
+			notifications.push(notification, [data.uid], next);
+		}
+	], callback);
 };
 
 SocketUser.unfollow = function(socket, data, callback) {

src/user/follow.js

@@ -23,22 +23,34 @@ module.exports = function(User) {
 			return callback(new Error('[[error:you-cant-follow-yourself]]'));
 		}
 
-		if (type === 'follow') {
-			var now = Date.now();
-			async.parallel([
-				async.apply(db.sortedSetAdd, 'following:' + uid, now, theiruid),
-				async.apply(db.sortedSetAdd, 'followers:' + theiruid, now, uid),
-				async.apply(User.incrementUserFieldBy, uid, 'followingCount', 1),
-				async.apply(User.incrementUserFieldBy, theiruid, 'followerCount', 1)
-			], callback);
-		} else {
-			async.parallel([
-				async.apply(db.sortedSetRemove, 'following:' + uid, theiruid),
-				async.apply(db.sortedSetRemove, 'followers:' + theiruid, uid),
-				async.apply(User.decrementUserFieldBy, uid, 'followingCount', 1),
-				async.apply(User.decrementUserFieldBy, theiruid, 'followerCount', 1)
-			], callback);
-		}
+		User.isFollowing(uid, theiruid, function(err, isFollowing) {
+			if (err) {
+				return callback(err);
+			}
+
+			if (type === 'follow') {
+				if (isFollowing) {
+					return callback(new Error('[[error:already-following]]'));
+				}
+				var now = Date.now();
+				async.parallel([
+					async.apply(db.sortedSetAdd, 'following:' + uid, now, theiruid),
+					async.apply(db.sortedSetAdd, 'followers:' + theiruid, now, uid),
+					async.apply(User.incrementUserFieldBy, uid, 'followingCount', 1),
+					async.apply(User.incrementUserFieldBy, theiruid, 'followerCount', 1)
+				], callback);
+			} else {
+				if (!isFollowing) {
+					return callback(new Error('[[error:not-following]]'));
+				}
+				async.parallel([
+					async.apply(db.sortedSetRemove, 'following:' + uid, theiruid),
+					async.apply(db.sortedSetRemove, 'followers:' + theiruid, uid),
+					async.apply(User.decrementUserFieldBy, uid, 'followingCount', 1),
+					async.apply(User.decrementUserFieldBy, theiruid, 'followerCount', 1)
+				], callback);
+			}
+		});
 	}
 
 	User.getFollowing = function(uid, start, end, callback) {