auth.config.ts

import Credentials from "next-auth/providers/credentials";
import bcrypt from "bcryptjs";
import { prisma } from "@/lib/prisma";
import type { NextAuthConfig } from "next-auth";

import { LoginSchema } from "./app/_lib/definitions";

// Notice this is only an object, not a full Auth.js instance
export default {
  providers: [
    Credentials({
      authorize: async (credentials) => {
        try {
          let user = null;

          // 1. Validate form fields
          const validatedFields = await LoginSchema.validate(credentials);

          // If any form fields are invalid, return early
          if (!validatedFields.username || !validatedFields.password) {
            return {
              errors: validatedFields,
            };
          }

          // 2. Prepare data for insertion into database
          const { username, password } = validatedFields;

          // 3. Insert the user into the database or verify if the user exists
          user = await prisma.user.findFirst({
            where: {
              OR: [
                {username},
                {email: username}
              ]
            },
          });

          if (!user) {
            throw new Error("Invalid credentials.");
          }

          const isPasswordValid = await bcrypt.compare(password, user.password);

          if (!isPasswordValid) {
            throw new Error("Invalid credentials.");
          }

          // return JSON object with the user data
          return user;
        } catch (error) {
          console.error("ERROR: ", error);
          return null;
        }
      },
    }),
  ],
} satisfies NextAuthConfig;