Calendar Application

We require an .ics application, which has the ability to interact with a database driven website that uses MySQL and WordPress and which is capable of the following actions and parameters. The purpose of this site is to display to a select audience, the availability of others within a similar sphere. The availability is stored in the database, which is then using the calendar as a way to display this information. We require a calendar which can be replicated for multiple users on the same site (using php), with each calendar having the ability to be edited by it's own individual user by clicking on the square (day) which requires editing. The calendar should appear to both the public (any user) and the individual (the individual user).