Calendar and Contact Migration tool for Google Apps

I require a C# library which is able to migrate all Calendar and Contact entries for a Google Apps user and move them to Exchange. The tool should: General 1. Use OAuth authentication to be able to do source system impersonation 2. Be written and be able to run outside of an ASP application Calendar 1. Maintain appointment accuracy 2. Deal with recurring appointment Contact 1. Maintain contact fidelity 2. Handle group memberships (new GA feature)