prevent overlapping classes

hourglass/server/main.js

@@ -175,6 +175,12 @@ Meteor.methods({
             schools.findOne({
                 name: input.school
             })) {
+            if (classes.find({
+                    status: true,
+                    privacy: false,
+                    teacher: input.teacher,
+                    hour: input.hour
+                }).fetch().length < 1) {
                 input.status = Roles.userIsInRole(Meteor.userId(), ['superadmin', 'admin']);
                 input.admin = Meteor.userId();
                 Meteor.call('genCode', function(error, result) {
@@ -190,6 +196,9 @@ Meteor.methods({
                 classes.insert(input, function(err, result) {
                     Meteor.call('joinClass', [result, input.code]);
                 });
+            } else {
+                throw new Meteor.Error("overlap", "This teacher is already teaching a class elsewhere!")
+            }
 
         } else {
             throw new Meteor.Error("unauthorized", "You are not authorized to complete this action.");