app.js

var express = require("express");
var request = require("request");
var bodyParser = require("body-parser");

var mongoose = require("mongoose");

var db = mongoose.connect(process.env.MONGODB_URI);
var Movie = require("./models/movie");


var app = express();
app.use(bodyParser.urlencoded({extended: false}));
app.use(bodyParser.json());
app.listen((process.env.PORT || 5000));

// Server index page
app.get("/", function (req, res) {
  res.send("Deployed!");
});


// Facebook Webhook
// Used for verification
app.get("/webhook", function (req, res) {
	// hub.verify_token
  if (req.query["hub.verify_token"] === process.env.VARIFICATION_TOKEN) {
    console.log("Verified webhook");
    res.status(200).send(req.query["hub.challenge"]);
  } else {
    console.error("Verification failed. The tokens do not match.");
    res.sendStatus(403);
  }
});

// All callbacks for Messenger will be POST-ed here
app.post("/webhook", function (req, res) {
  // Make sure this is a page subscription
  if (req.body.object == "page") {
    // Iterate over each entry
    // There may be multiple entries if batched
    req.body.entry.forEach(function(entry) {
      // Iterate over each messaging event
      entry.messaging.forEach(function(event) {
        if (event.postback) {
          processPostback(event);
        } else if (event.message) {
          processMessage(event);
        }
      });
    });

    res.sendStatus(200);
  }
});

function processPostback(event) {
  var senderId = event.sender.id;
  var payload = event.postback.payload;

  if (payload === "Greeting") {
    // Get user's first name from the User Profile API
    // and include it in the greeting
    request({
      url: "https://graph.facebook.com/v2.6/" + senderId,
      qs: {
        access_token: process.env.PAGE_ACCESS_TOKEN,
        fields: "first_name"
      },
      method: "GET"
    }, function(error, response, body) {
      var greeting = "";
      if (error) {
        console.log("Error getting user's name: " +  error);
      } else {
        var bodyObj = JSON.parse(body);
        name = bodyObj.first_name;
        greeting = "Hi " + name + ". ";
      }
      var message = greeting + "Hi! I'm a robot that Malthe made. I can tell you various details regarding movies. What movie would you like to know about?";
      sendMessage(senderId, {text: message});
    });
  } else if (payload === "Correct") {
    sendMessage(senderId, {text: "Awesome! What would you like to find out? Enter 'plot', 'date', 'runtime', 'director', 'cast' or 'rating' for the various details."});
  } else if (payload === "Incorrect") {
    sendMessage(senderId, {text: "Oops! Sorry about that. Try using the exact title of the movie"});
  }
}


function processMessage(event) {
  // Make sure the message wasnt from our selves.
  if (!event.message.is_echo) {
    
    var message = event.message;
    var senderId = event.sender.id;

    console.log("Received message from senderId: " + senderId);
    console.log("Message is: " + JSON.stringify(message));

    // You may get a text or attachment but not both
    if (message.text) {
      var formattedMsg = message.text.toLowerCase().trim();

      // If we receive a text message, check to see if it matches any special
      // keywords and send back the corresponding movie detail.
      // Otherwise, search for new movie.
      switch (formattedMsg) {
        case "plot":
        case "date":
        case "runtime":
        case "director":
        case "cast":
        case "rating":
          getMovieDetail(senderId, formattedMsg);
          break;

        default:
          findMovie(senderId, formattedMsg);
      }
    } else if (message.attachments) {
      sendMessage(senderId, {text: "Sorry, I don't understand your request."});
    }
  }
}


function findMovie(userId, movieTitle) {
  request("http://www.omdbapi.com/?apikey=bd757374&type=movie&t=" + movieTitle, function (error, response, body) {
    if (!error && response.statusCode == 200) {
            var movieObj = JSON.parse(body);
            if (movieObj.Response === "True") {
                var query = {user_id: userId};
                var update = {
                    user_id: userId,
                    title: movieObj.Title,
                    plot: movieObj.Plot,
                    date: movieObj.Released,
                    runtime: movieObj.Runtime,
                    director: movieObj.Director,
                    cast: movieObj.Actors,
                    rating: movieObj.imdbRating,
                    poster_url:movieObj.Poster
                };
                var options = {upsert: true};
                Movie.findOneAndUpdate(query, update, options, function(err, mov) {
                    if (err) {
                        console.log("Database error: " + err);
                    } else {
                        message = {
                            attachment: {
                                type: "template",
                                payload: {
                                    template_type: "generic",
                                    elements: [{
                                        title: movieObj.Title,
                                        subtitle: "Is this the movie you are looking for?",
                                        image_url: movieObj.Poster === "N/A" ? "http://placehold.it/350x150" : movieObj.Poster,
                                        buttons: [{
                                            type: "postback",
                                            title: "Yes",
                                            payload: "Correct"
                                        }, {
                                            type: "postback",
                                            title: "No",
                                            payload: "Incorrect"
                                        }]
                                    }]
                                }
                            }
                        };
                        sendMessage(userId, message);
                    }
                });
            } else {
                console.log(movieObj.Error);
                sendMessage(userId, {text: movieObj.Error});
            }
        } else {
            sendMessage(userId, {text: "Something went wrong. Try again."});
        }
    });
}

function getMovieDetail(userId, field) {
  Movie.findOne({user_id: userId}, function(err, movie) {
    if(err) {
      sendMessage(userId, {text: "Something went wrong. Try again"});
    } else {
      sendMessage(userId, {text: movie[field]});
    }
  });
}

// sends message to user
function sendMessage(recipientId, message) {
  request({
    url: "https://graph.facebook.com/v2.6/me/messages",
    qs: {access_token: process.env.PAGE_ACCESS_TOKEN},
    method: "POST",
    json: {
      recipient: {id: recipientId},
      message: message,
    }
  }, function(error, response, body) {
    if (error) {
      console.log("Error sending message: " + response.error);
    }
  });
}