PLEASE NOTE: It is an hourly project, as the scope will be extended! I only pay 2€/hour, all above will be declined! AI generated bids will be declined! I need a PHP-based WordPress plugin that lets my site authenticate users against an external SaaS platform. The workflow is straightforward: a visitor clicks “Log in with <SaaS>,” is sent through that service’s OAuth flow, and on success is brought back to WordPress already signed in (new users created on the fly, existing ones matched by email). Key goals • Build the full OAuth handshake, token exchange, and refresh logic. • Create an admin settings page where I can drop in client ID, secret, scopes, and redirect URI without editing code. • Hook into the native wp_login / wp_logout actions so the experience feels like any other WordPress login. • Write clear installation & usage notes so I can move the plugin between staging and production with just new keys. You can leverage the WordPress Settings API, REST API, and standard best practices for secure credential storage. Clean, commented code is a must; no framework overlays—plain, modern PHP that passes WordPress coding standards will do. Once the .zip installs and authenticates successfully on my test site, the project is complete.