Implementing the chatbot

Now that we have the backend tasks ready, let's focus on the chatbot itself. In general, the chatbot will take the user's utterances as input and respond with utterances of its own. However, since we are building a chatbot for Facebook Messenger, our chatbot will mostly take input in the form of button presses and respond using both utterances and visually appealing cards.

Let's start by implementing the Chatbot.java class. We will begin by working out an algorithm to process and respond to users' utterances:

1. Process user input.
2. Update context.
3. Identify bot intent.
4. Generate bot utterance and output structure.
5. Respond.

This one is a very simple algorithm to start with. First, user input, in the form of utterances or button presses is processed. Then the context of the conversation is updated. In the next step, we identify what the bot needs to say. Once that is determined, we figure out how to say it and respond. Let us start by implementing the basic structure based on...