Facebook developer

Im looking for a robot or automated system that can respond to comments made on your company's Facebook posts, as well as messages received through Messenger and DMs. The posts may feature a product for sale by your company, and followers are instructed to use a specific trigger word in their comments to initiate a purchase. If the correct trigger word is used, the system should respond by liking and commenting on the post, confirming the purchase for the buyer. Confirmation to customers via Messenger and DM should also be possible.