Timesheet integration with existing web based payroll

I need someone who is familiar with payroll development to develop a timesheet module and integrate with my existing payroll on oops PHP platform. It has to calculate the actual work hours, overtime hours, shift pay, be able to define different types of overtime with different overtime rate eg overtime rate on weekends and public holidays are different. I need someone who has an experience with this cos I need the project completed as soon as possible like in one week