always use a department if there is only one active

packages/rocketchat-livechat/app/client/lib/chatMessages.coffee

@@ -93,7 +93,7 @@ class @ChatMessages
 							showError error.reason
 
 			if not Meteor.userId()
-				Meteor.call 'registerGuest', visitor.getToken(), (error, result) ->
+				Meteor.call 'livechat:registerGuest', { token: visitor.getToken() }, (error, result) ->
 					if error?
 						return showError error.reason
 

packages/rocketchat-livechat/app/client/views/register.js

@@ -6,7 +6,7 @@ Template.register.helpers({
 		return "";
 	},
 	hasDepartments() {
-		return Department.find().count() > 0;
+		return Department.find().count() > 1;
 	},
 	departments() {
 		return Department.find();
@@ -22,11 +22,19 @@ Template.register.events({
 		if (!($name.val().trim() && $email.val().trim())) {
 			return instance.showError(TAPi18n.__('Please_fill_name_and_email'));
 		} else {
+			var departmentId = instance.$('select[name=department]').val();
+			if (!departmentId) {
+				var department = Department.findOne();
+				if (department) {
+					departmentId = department._id;
+				}
+			}
+
 			var guest = {
 				token: visitor.getToken(),
 				name: $name.val(),
 				email: $email.val(),
-				department: instance.$('select[name=department]').val()
+				department: departmentId
 			};
 			Meteor.call('livechat:registerGuest', guest, function(error, result) {
 				if (error != null) {

packages/rocketchat-livechat/server/methods/registerGuest.js

 Meteor.methods({
-	'livechat:registerGuest': function({ token, name, email, department }) {
+	'livechat:registerGuest': function({ token, name, email, department } = {}) {
 		var pass, qt, user, userData, userExists, userId, inc = 0;
 
 		check(token, String);

packages/rocketchat-livechat/server/methods/sendMessageLivechat.js

@@ -14,6 +14,15 @@ Meteor.methods({
 
 		room = RocketChat.models.Rooms.findOneById(message.rid);
 		if (room == null) {
+
+			// if no department selected verify if there is only one active and use it
+			if (!guest.department) {
+				var departments = RocketChat.models.LivechatDepartment.findEnabledWithAgents();
+				if (departments.count() === 1) {
+					guest.department = departments.fetch()[0]._id;
+				}
+			}
+
 			agent = getNextAgent(guest.department);
 			if (!agent) {
 				throw new Meteor.Error('no-agent-online', 'Sorry, no online agents');