Integrate Twitter Post Functionality

Our users have Twitter accounts linked to their user accounts in our DB We want to add the ability for them to 'Tweet' an action when using our service. For example, when they make a selection, it posts an auto-tweet to their twitter account. The tweet will be pre-written and dynamic based on their selection. "I've just selected $item from Site Name at http://example.com. Check it Out" Also need to add the option to toggle this functionality on/off in their accounts (add a field to db for twitter_active ON / OFF) When they make a selection, check if twitter_active is ON If yes, then post the tweet to their @username (taken from profile)