Online Appointment Calendar

I am in need of a website calendar that allows several features. I need users to be able to register/login and see the current appointments available for any date. They need to be able to select the time with the person and book it online. I then need it to send confirmation to both the main person and the user that booked it. The main person(admin) needs to be able to add/delete available times as well. Admin login, logout Add availability for date, time slots from Mon-Sat starting with 9am. So 9, 11, 1, 3, 5, 7 Visitor registration -Fields --Name --Contact Number --Email Address anyone can register Visitor login, logout, change password Visitor view calendar with available dates On clicking a date can see available time slots Can book a time slot - mail will be sent to admin and to person booking