Building a Time and Remoting work tracking application.

I am looking to build a simple time tracking and work monitoring desktop application for remote workers. Application must be workable on window and Mac as well as a mobile application with some basic features.

Application to consists of user log in, chat functions, shared calendar, report generating and do background monitoring.

Must have a master admin control which I am able to assign sub controls and unique log in to department supervisors for monitoring of remote working staff who is going to use this application.

Application must lastly be scalable for additional features add on later.