Add confirmation modal to admin group deletion

app/assets/javascripts/admin/controllers/admin_groups_controller.js

@@ -33,12 +33,16 @@ Discourse.AdminGroupsController = Ember.Controller.extend({
   },
 
   destroy: function(group){
-    var list = this.get("model");
-    if(group.get("id")){
-      group.destroy().then(function(){
-        list.removeObject(group);
-      });
-    }
+    var _this = this;
+    return bootbox.confirm(I18n.t("admin.groups.delete_confirm"), I18n.t("no_value"), I18n.t("yes_value"), function(result) {
+      if (result) {
+        group.destroy().then(function(deleted) {
+          if (deleted) {
+            _this.get("model").removeObject(group);
+          }
+        });
+      }
+    });
   }
 });
 

app/assets/javascripts/admin/models/group.js

@@ -36,12 +36,18 @@ Discourse.Group = Discourse.Model.extend({
   }.property('users'),
 
   destroy: function(){
+    if(!this.id) return;
+
     var group = this;
     group.set('disableSave', true);
 
-    return Discourse.ajax("/admin/groups/" + this.get("id"), {type: "DELETE"})
+    return Discourse.ajax("/admin/groups/" + group.id, {type: "DELETE"})
       .then(function(){
+        return true;
+      }, function(jqXHR, status, error) {
         group.set('disableSave', false);
+        bootbox.alert(I18n.t("admin.groups.delete_failed"));
+        return false;
       });
   },