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Reprompt to keep session alive for long downloads #59

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Feb 9, 2019
Merged

Reprompt to keep session alive for long downloads #59

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4c2430a
Reprompt to keep session alive for long videos
chokkyvista Dec 30, 2018
5728ddb
Enable UK locale
chokkyvista Dec 30, 2018
d203be8
Minor fixes
chokkyvista Dec 30, 2018
22d89a9
Better error handling
chokkyvista Dec 30, 2018
81c97cb
Change package lock
dmhacker Feb 8, 2019
d661937
Revert return logic, add ASK_TO_CONTINUE locale-based message
dmhacker Feb 9, 2019
a8106eb
Update version to 3.0.1
dmhacker Feb 9, 2019
d96a5f7
Add package-lock
dmhacker Feb 9, 2019
04521c2
Decrease default ask interval
dmhacker Feb 9, 2019
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187 changes: 155 additions & 32 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -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.
*
Expand Down Expand Up @@ -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") {
Expand All @@ -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),
Expand Down Expand Up @@ -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);
}
Expand All @@ -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) {
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This will periodically (per CACHE_POLLING_INTERVAL) check if the cache is ready up until timeout, when Alexa has to reprompt the user to avoid being timed out.

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
Expand All @@ -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) {
Expand Down Expand Up @@ -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();
Expand All @@ -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) {
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I've changed it from "wait and check" to "check and wait" to save the few seconds in case the cache should be already ready (e.g. from previous searches).

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)
Expand All @@ -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": {
Expand Down Expand Up @@ -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) {
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interactive_wait defaults to false to make it backward compatible.

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) {
Expand All @@ -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();
Expand Down Expand Up @@ -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;

Expand Down
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