Android application built on the google android calendar

I am looking for an android developer who knows google android calendar source code thoroughly . for him this job would be very quick and easy to accomplish. the app is a simple shifts manager for a workplace . the dates and hours input method is on the calendar weekly view , you have to change the way you set the dates : instead of the edit event activity i want to do that with two long clicks , one for the start and one for the end date . a dialog will appear with the hour grayed and the minutes to change . all the rest will be inherited . if you are a good android developer with years of experience , it should not be a problem for you to get it done very quickly . please state the time frame on your application . Thank you