register attendance automatically

I want to create a mobile application to register attendance for employees automatically.
This application mainly depends on the network. This application should register attendance automatically when an employee enters his workplace by connecting his mobile to the local network of his workplace. All the data should be stored in a database. Also, there will be a web page for the administrator to print different kinds of reports about each employee individually and as a group of employees. By this web page administrator also could record attendance manually, new employees, and assign a new administrator.