PHP functions for Oauth Authorization in FB,Twitter,Google

We need 3 PHP functions for user authorization in web page commenting system + comment form widget PHP script (not required, but is a plus - read below). For posting a comment user should authorize himself via Twitter, Facebook or Google. If user has authorized successfully, function should return user's Nick/Name, Avatar URL, profile URL. Example: [login to view URL] (see comments widget in the bottom or page) Example supports authorization via [login to view URL], FB, Twitter, Google, Tumblr We are creating the same thing for our website, but need only Twitter,FB,Google social networks support. If you can also develop a full commenting form widget script, it is the plus: requirements and cost can be discussed. But we mostly need help with social network authorization functions in this job. PHP code must be well structured and accurate for understanding and modifications that may be needed in future. If you have any examples of jobs where such authorization fucntions were used - please, post. If you need domain/hosting/anything else for development, this can be provided.