index.js

//...
firebase.initializeApp(functions.config().firebase);

exports.waterLog = functions.https.onRequest((request, response) => {
    //Initialise app dependencies
    const dialogflowApp = new DialogflowApp({request, response});
    const userManager = new UserManager(firebase);
    const waterLog = new WaterLog(firebase, userManager);
    const conversation = new Conversation(dialogflowApp, userManager, waterLog);

    //Define map of Dialogflow agent Intents
    let actionMap = new Map();
    actionMap.set(Actions.ACTION_WELCOME, () => conversation.actionWelcomeUser());
    actionMap.set(Actions.ACTION_LOG_WATER, () => conversation.actionLogWater());
    actionMap.set(Actions.ACTION_GET_LOGGED_WATER, () => conversation.actionGetLoggedWater());
    
    //Handle request from Dialogflow (will be dispatched into appropriate action defined above)
    dialogflowApp.handleRequest(actionMap);
});