removing authentication when integrating google api to dialogflow webhook - php

Question

I'm creating an AI Assistant using Dialogflow and I need to use Google APIs (google calendar and gmail). The APIs were working perfectly (I used this as reference). However, when I integrated my code with the dialogflow webhook, it returns Webhook Call failed. Error: 500 Internal Server Error.
here is a code snippet:
$client = new Google_Client();
$client->addScope(Google_Service_Gmail::GMAIL_READONLY); //view your emails and settings
$client->addScope(Google_Service_Gmail::GMAIL_COMPOSE); //manage drafts and send emails
$client->addScope(Google_Service_Gmail::GMAIL_MODIFY);
$client->addScope(Google_Service_Gmail::GMAIL_SEND); //send email on your behalf
$client->addScope(Google_Service_Calendar::CALENDAR); //manage calendar
$client->setAuthConfig('client_secret.json');
$client->setAccessType('offline');
$client->setApprovalPrompt('auto');
if($_SERVER['REQUEST_METHOD'] == 'POST'){
if(isset($_SESSION['access_token']) && $_SESSION['access_token']){
$client->setAccessToken($_SESSION['access_token']);
$gmail = new Google_Service_Gmail($client);
$user = "emailaddress#gmail.com";
$calendar = new Google_Service_Calendar($client);
$intent = $json->queryResult->intent->displayName;
$location_any = $json->queryResult->parameters->location_any;
$text = $json->queryResult->parameters->text;
$name = $json->queryResult->parameters->name;
$choice = $json->queryResult->parameters->choice;
$subject = $json->queryResult->parameters->subject;
$location = $json->queryResult->parameters->location;
$description = $json->queryResult->parameters->description;
$startDateTime = $json->queryResult->parameters->startDateTime;
$endDateTime = $json->queryResult->parameters->endDateTime;
if($intent== "UnreadMessages"){
$unread = unReadMessages($gmail, $user);
$speech = "You have ".$unread." messages";
}
else if($intent == "GetSchedule"){
$events = get_event($calendar);
if($events){
$reply = "You have the following events coming up:";
foreach($events as $event){
$eventName = $event['eventName'];
$eventTime = $event['time'];
$reply .= $eventName."is at".$eventTime;
}
$speech = $reply;
}
else{
$speech = "You don't have any events coming up.";
}
}
}
I'm suspecting it may be because of the authentication process that's required everytime I try to run the app, since the error only starts popping up whenever I check for session tokens. My problem now is how do I remove this authentication process?

Answer 1

You have several serious issues with your approach here, but most of them result from you treating the interaction with the Google Assistant like it was a browser hitting your web page. Although Actions on Google uses HTTPS and a webhook, it is otherwise not really like a browser at all.
For example, you check $_SESSION to see if an access token has already been set. $_SESSION is typically implemented by setting a session ID in the browser with a session cookie. The Assistant doesn't use cookies at all. Although it has a userStorage object which can be used it similar ways, this is accessed very differently.
It isn't clear if this is what is causing the error, or if the problem is related here somewhere. If you do have error logs, this would be useful to include in the question.
There is a lot that remains unclear. Primarily - where does the auth token come from in the first place in your code.
In a purely web-based OAuth scheme, you'll direct the user to log in using Google Sign In and, as part of that process, request authorization to access their Drive and GMail. Google Sign In for the Assistant doesn't allow you to do that - all it gives you is an Identity Token.
You can use Account Linking to link the Assistant account to your system - but this requires you to have an OAuth server that generates the auth token that the Assistant will give back to you. This is your OAuth token - not one that comes from Google (unless you're proxying it).
If you have a web-based way to get authorization, you can leverage this to provide access through the Assistant as well using Google Sign In for the Assistant.