PHP / MYSQL Developer to Add 'Approval' to Anuko Time Tracker

I have a fully functioning version of Anuko Time Tracker that I'm using. Its coded in PHP and uses a MYSQL db - I'd like to add a feature to it. I can fill in hours, generate a report, and email them over - thats great. But I would like an "APPROVE" or "DECLINE" button on that email which the manager would click, then an email would come back to the submitter with the decision: "This timesheet has been approved/declined" - then once that is completed. I would like to be able to email the report/invoice (with approval noted) over to my agency to bill them for the hours. Versions: Anuko Time Tracker - 1.17.89.4270 PHP 7.1 IIS 8.5 (Installed on Windows Server 2012 R2) MYSQL Server 5.7 (Installed on Windows Server 2012 R2) Access will be granted to the server via FTP, your IP should be noted as it will only be granted from this address into the environment. Thanks