Merge pull request #59 from chokkyvista/alexa_timeout

Reprompt to keep session alive for long downloads

Author: dmhacker

src/index.js

@@ -12,21 +12,29 @@ var response_messages = require("./util/responses.js");
 // Create Alexa skill application
 var app = new alexa.app("youtube");
 
-// Set Heroku URL
-var heroku = process.env.HEROKU_APP_URL || "https://dmhacker-youtube.herokuapp.com";
+// Process environment variables 
+const heroku = process.env.HEROKU_APP_URL || "https://dmhacker-youtube.herokuapp.com";
+const interactive_wait = !(process.env.DISABLE_INTERACTIVE_WAIT === "true" || 
+                           process.env.DISABLE_INTERACTIVE_WAIT === true ||
+                           process.env.DISABLE_INTERACTIVE_WAIT === 1);
+const cache_polling_interval = parseInt(process.env.CACHE_POLLING_INTERVAL || "5000", 10);
+const ask_interval = parseInt(process.env.ASK_INTERVAL || "45000", 10);
 
-// Variables relating to videos waiting for user input 
-var buffer_search = {}; 
+// Variables relating to videos waiting for user input
+var buffer_search = {};
 
 // Variables relating to the last video searched
 var last_search = {};
 var last_token = {};
 var last_playback = {};
 
-// Variables for repetition of current song 
+// Variables for repetition of current song
 var repeat_infinitely = {};
 var repeat_once = {};
 
+// To track whether downloading is already in progress
+var downloading = false;
+
 /**
  * Generates a random UUID. Used for creating an audio stream token.
  *
@@ -103,7 +111,7 @@ function search_video(req, res, lang) {
   return new Promise((resolve, reject) => {
     var search = heroku + "/alexa/v3/search/" + new Buffer(query).toString("base64");
 
-    // Populate URL with correct language 
+    // Populate URL with correct language
     if (lang === "de-DE") {
       search += "?language=de";
     } else if (lang === "fr-FR") {
@@ -120,7 +128,7 @@ function search_video(req, res, lang) {
       } else {
         // Convert body text in response to JSON object
         var body_json = JSON.parse(body);
-        if (body_json.status === "error" && body_json.message === "No results found") {
+        if (body_json.state === "error" && body_json.message === "No results found") {
           // Query did not return any video
           resolve({
             message: response_messages[lang]["NO_RESULTS_FOUND"].formatUnicorn(query),
@@ -155,6 +163,7 @@ function search_video(req, res, lang) {
 
       // Set most recently searched for video
       buffer_search[userId] = metadata;
+      downloading = false;
 
       res.reprompt().shouldEndSession(false);
     }
@@ -167,8 +176,110 @@ function search_video(req, res, lang) {
   });
 }
 
+function make_download_video_request(id) {
+  return new Promise((resolve, reject) => {
+    request(heroku + "/alexa/v3/download/" + id, function(err, res, body) {
+      if (err) {
+        console.error(err.message);
+        reject(err.message);
+      } else {
+        var body_json = JSON.parse(body);
+        var url = heroku + body_json.link;
+        console.log("Requested download for ... " + url);
+        resolve(url);
+      }
+    });
+  });
+}
+
+function check_cache_ready(id, timeout) {
+  return new Promise((resolve, reject) => {
+      request(heroku + "/alexa/v3/cache/" + id, function(err, res, body) {
+      if (!err) {
+        var body_json = JSON.parse(body);
+        if (body_json.hasOwnProperty('downloaded') && body_json['downloaded'] != null) {
+          if (body_json.downloaded) {
+            downloading = false;
+
+            console.log(id + " has been cached. Ready to play!");
+
+            resolve();
+          }
+          else {
+            downloading = true;
+
+            console.log(id + " is being cached.");
+            if (timeout <= 0) {
+              resolve();
+              return;
+            }
+
+            var interval = Math.min(cache_polling_interval, timeout);
+            console.log("Checking again in " + interval + "ms (delay: " + timeout + "ms).");
+
+            resolve(new Promise((_resolve, _reject) => {
+              setTimeout(() => {
+                _resolve(check_cache_ready(id, timeout - cache_polling_interval).catch(_reject));
+              }, interval);
+            }).catch(reject));
+          }
+        }
+        else {
+          console.log(id + " will not be cached.");
+          reject("Video unavailable.");
+        }
+      }
+      else {
+        console.error(err.message);
+        reject(err.message);
+      }
+    });
+  });
+}
+
+function respond_play(req, res) {
+  var userId = req.userId;
+
+  // Final response to the user, indicating that their video will be playing
+  var speech = new ssml();
+  var title = buffer_search[userId].title;
+  var message = response_messages[req.data.request.locale]["NOW_PLAYING"].formatUnicorn(title);
+  speech.say(message);
+  res.say(speech.ssml(true));
+
+  console.log("Starting to play ... " + title);
+
+  // Start playing the video!
+  restart_video(req, res, 0);
+}
+
+function interactively_wait_for_video(req, res) {
+  var userId = req.userId;
+  var id = buffer_search[userId].id;
+  return check_cache_ready(id, ask_interval).then(() => {
+    if (!downloading) {
+      // Download finished ... notify user 
+      respond_play(req, res);
+    }
+    else {
+      console.log("Asking whether to continue waiting." );
+
+      // Download still in progress ... ask if the user wants to keep tracking 
+      var message = response_messages[req.data.request.locale]["ASK_TO_CONTINUE"];
+      var speech = new ssml();
+      speech.say(message);
+      res.say(speech.ssml(true));
+      res.reprompt(message).shouldEndSession(false);
+    }
+    return res.send();
+  }).catch(reason => {
+    console.error(reason);
+    return res.fail(reason);
+  });
+}
+
 /**
- * Downloads the mostly recent video the user requested. 
+ * Downloads the mostly recent video the user requested.
  *
  * @param  {Object} req  A request from an Alexa device
  * @param  {Object} res  A response that will be sent to the device
@@ -181,7 +292,7 @@ function download_video(req, res) {
   console.log("Requesting download ... " + id);
 
   return new Promise((resolve, reject) => {
-    var download = heroku + "/alexa/v3/download/" + id; 
+    var download = heroku + "/alexa/v3/download/" + id;
 
     // Make download request to server
     request(download, function(err, res, body) {
@@ -209,12 +320,7 @@ function download_video(req, res) {
     });
   }).then(function() {
     // Have Alexa tell the user that the video is finished downloading
-    var speech = new ssml();
-    speech.say(response_messages[req.data.request.locale]["NOW_PLAYING"].formatUnicorn(buffer_search[userId].title));
-    res.say(speech.ssml(true));
-
-    // Start playing the video!
-    restart_video(req, res, 0);
+    respond_play(req, res);
 
     // Send response to Alexa device
     res.send();
@@ -231,19 +337,17 @@ function download_video(req, res) {
  * @param  {Function} callback The function to execute about load completion
  */
 function wait_for_video(id, callback) {
-  setTimeout(function() {
-    request(heroku + "/alexa/v3/cache/" + id, function(err, res, body) {
-      if (!err) {
-        var body_json = JSON.parse(body);
-        if (body_json.downloaded) {
-          callback();
-        }
-        else {
-          wait_for_video(id, callback);
-        }
+  request(heroku + "/alexa/v3/cache/" + id, function(err, res, body) {
+    if (!err) {
+      var body_json = JSON.parse(body);
+      if (body_json.downloaded) {
+        callback();
       }
-    });
-  }, 2000);
+      else {
+        setTimeout(wait_for_video, cache_polling_interval, id, callback);
+      }
+    }
+  });
 }
 
 // Filter out bad requests (the client's ID is not the same as the server's)
@@ -260,6 +364,10 @@ app.pre = function(req, res, type) {
   }
 };
 
+app.error = function(exc, req, res) {
+  res.say("An error occured: " + exc);
+};
+
 // Looking up a video in English
 app.intent("GetVideoIntent", {
     "slots": {
@@ -339,9 +447,24 @@ app.intent("AMAZON.YesIntent", function(req, res) {
   if (!buffer_search.hasOwnProperty(userId) || buffer_search[userId] == null) {
     res.send();
   }
-  else {
+  else if (!interactive_wait) {
     return download_video(req, res);
   }
+  else {
+    var id = buffer_search[userId].id;
+    if (!downloading) {
+      return make_download_video_request(id)
+      .then(url => {
+        downloading = true;
+        last_search[userId] = url;
+        return interactively_wait_for_video(req, res);
+      })
+      .catch(reason => {
+        return res.fail(reason);
+      });
+    }
+    return interactively_wait_for_video(req, res);
+  }
 });
 
 app.intent("AMAZON.NoIntent", function(req, res) {
@@ -362,9 +485,9 @@ app.audioPlayer("PlaybackNearlyFinished", function(req, res) {
   var userId = req.userId;
 
   // Repeat is enabled, so begin next playback
-  if (has_video(userId) && 
-    ((repeat_infinitely.hasOwnProperty(userId) && repeat_infinitely[userId]) || 
-    (repeat_once.hasOwnProperty(userId) && repeat_once[userId]))) 
+  if (has_video(userId) &&
+    ((repeat_infinitely.hasOwnProperty(userId) && repeat_infinitely[userId]) ||
+    (repeat_once.hasOwnProperty(userId) && repeat_once[userId])))
   {
     // Generate new token for the stream
     var new_token = uuidv4();
@@ -473,7 +596,7 @@ app.intent("AMAZON.PauseIntent", {}, function(req, res) {
   res.send();
 });
 
-// User told Alexa to repeat audio once 
+// User told Alexa to repeat audio once
 app.intent("AMAZON.RepeatIntent", {}, function(req, res) {
   var userId = req.userId;