This is SSO provider based on oauth2-server. At the moment this integration was tested with https://js.wiki

Implementation is based on example given there https://github.com/thephpleague/oauth2-server/tree/master/examples

Change domain where needed

Authorization Endpoint URL:

https://chat.example.com/site_admin/ssoprovider/authorize

Token Endpoint URL

https://chat.example.com/site_admin/ssoprovider/token

User Info Endpoint URL

https://chat.example.com/site_admin/ssoprovider/userinfo

ID Claim

id

Display Name Claim

displayName

Email Claim

email

• Clone repository and put it in extension/ssoprovider
• Modify main settings file lhc_web/settings/settings.ini.php and activate extensions

...
'extensions' =>
    array (   
    'ssoprovider'
    ),
...

• Make sure your main composer.json file contains https://github.com/LiveHelperChat/livehelperchat/blob/c42935aef767c3d7ab9ec87cd25bce7b270937e8/lhc_web/composer.json#L80-L81 and dependencies are installed.
• Copy extension/ssoprovider/settings/settings.ini.default.php to extension/ssoprovider/settings/settings.ini.php
• Generate private and public keys

openssl genrsa -out private.key 2048
openssl rsa -in private.key -pubout > public.key

• Put generated files content in private_key and public_key content.
• Put your preferred client_id, client_secret, client_name values.
• Modify url_login value. It's full login URL for third party.
• Modify redirect_url value. This value was taken from js.wiki back office.

At this moment goal of this extension was to have SSO login directly to https://js.wiki in Live Helper Chat. Configuration screenshot.