Currently this extension only really deals with logging in

You can find the repository here Installing and configuring is quite easy.

Make sure to follow this guide on Discourse and while setting up SSO, after getting the secret needed, configure your application like so:

    'discourseSso' => [
    	'class' => 'sammaye\discourse\Sso',
    	'secret' => "Some super secret, super awesome dupa secret key"
    ],

That is this extension installed. Now you just need to learn how to use it.

Your extension is accessible via Yii::$app->discourseSso. This is the location used throughout this readme.

The first step is to setup a action in your SiteController.php to actually do the logic of signing in someone:

public function actionDiscourseSso()
{
	$request = Yii::$app->getRequest();
	$sso = Yii::$app->discourseSso;
	
	$payload = $request->get('sso');
	$sig = $request->get('sig');

	if(!($sso->validate($payload, $sig))){
		// invaild, deny
		throw new ForbiddenHttpException('Bad SSO request');
	}
	
	$nonce = $sso->getNonce($payload);
	
	if(Yii::$app->getUser()->isGuest){
		// We add session variable to track it after we log the user in so we can redirect them back
		// This method works well with custom login methods like social networks
		Yii::$app->getSession()->set('sso', ['sso' => $payload, 'sig' => $sig]);
		return $this->redirect(['site/login']);
	}else{
		$user = Yii::$app->getuser()->getIdentity();
	}
	
	Yii::$app->getSession()->remove('sso');
	
	// We send over the data
	$userparams = [
    	"nonce" => $nonce,
    	"external_id" => (String)$user->_id,
    	"email" => $user->email,
    	
    	// Optional - feel free to delete these two
    	"username" => $user->username,
    	"name" => $user->username,
    	
    	//'avatar_url' => Url::to(['image/profile-image', 'id' => (String)$user->_id], 'http')
	];
	$q = $sso->buildLoginString($userparams);
	
	/// We redirect back
	header('Location: ' . Yii::getAlias('@discourse') . '/session/sso_login?' . $q);
}

and even though this goes 90% of the way it does not complete it. If you notice:

Yii::$app->getSession()->set('sso', ['sso' => $payload, 'sig' => $sig]);

We load the sig and payload into session so we can tell if we came from single sign-on so we can redirect back. This means that in our login functions (whether it be login() or some social login) we need to change it to (as an example for login):

public function actionLogin()
{
    if (!\Yii::$app->user->isGuest) {
        return $this->goHome();
    }

    $model = new LoginForm();
    if ($model->load(Yii::$app->request->post()) && $model->login()) {
    	
    	if($sso = Yii::$app->getSession()->get('sso')){
    		return $this->redirect([
    			'discourse-sso', 
    			'sso' => $sso['sso'], 
    			'sig' => $sso['sig']
			]);
    	}
    	
    	if($model->getUser()->profile_filled){
        	return $this->goBack();
    	}else{
    		return $this->redirect(['user/about-me']);
    	}
    } else {
        return $this->render('login', [
            'model' => $model,
        ]);
    }
}

Notice the if($sso = Yii::$app->getSession()->get('sso')){, that is where he magic happens, it detects our single sign-on and redirects back to our single sign-on function.

To customise this, just add:

    if($sso = Yii::$app->getSession()->get('sso')){
    	return $this->redirect([
    		'discourse-sso', 
    		'sso' => $sso['sso'], 
    		'sig' => $sso['sig']
		]);
    }
    

to the end of every authentication function you have.