add an endpoint/functionality to an AI saas, in nextjs

Hello, I have a SaaS focused on generative AI, and it's almost ready. However, I need to add an endpoint with the functionality to write texts for blogs or emails using the OpenAI API and save them in the database. The rest is already done, such as authentication, integration with Stripe, etc. The technologies used in the app are Next.js, zod, zustand, Stripe, MySql, PlanetScale, and OpenAI. The developer needs to be familiar with these technologies. I have some references.