Timesheet Soultion for SharePoint 2013

Dear All,

I am looking for a timesheet solution which works with sharepoint.

Requirement:

1. User works on multiple projects.

2. Approval of the timesheet is project based. The corresponding project managers will approve their repective timesheets.

3. Validation for the timesheets like Users will not be allowed to charge for more than his alloted standard working hours.

4. Default 

Thanks,

Alex