Create a custom WordPress plugin with rest api communication

”CRM similar” WordPress plugin. The project scope is to develop a WordPress plugin for a web based employee handling system. The plugin should display information related to a specific company. The information is divided into separate parts. Organization and Employee information. It should be possible to edit departments and hierarchy. Departments are identified by a custom text, for example “Department B”. When select an employee a pop-up (in some way) displays more information regarding the person. It should be possible to edit which employees are working at the department. Department and employee handling should support add/remove/move. The plugin should use rest api functionality with json objects. For this project scope temporary calls can be used. Get/set for organization and Get/Set for employee.