nextjs/dashboard-app-course/auth.ts

import NextAuth from 'next-auth';
import { authConfig } from './auth.config';
import Credentials from 'next-auth/providers/credentials';
import { z } from 'zod';
import type { User } from '@/app/lib/definitions';
import bcrypt from 'bcrypt';
import postgres from 'postgres';
 
const sql = postgres(process.env.POSTGRES_URL!, { ssl: 'require' });

async function getUser(email: string): Promise<User | undefined> {
    try{
        const user = await sql<User[]>`SELECT * FROM users WHERE email=${email}`;
        return user[0];
    } catch(error){
        console.error('Failed to fetch user:', error);
        throw new Error('Failed to fetch user.');
    }
}

export const { auth, signIn, signOut } = NextAuth({
  ...authConfig,
  providers: [Credentials({
    async authorize(credentials){
        const parsedCredentials = z
        .object({ email: z.string().email(), password: z.string().min(6)})
        .safeParse(credentials);

        if(parsedCredentials.success){
            const { email, password } = parsedCredentials.data;
            const user = await getUser(email);
            if(!user) return null;
            const passwordsMatch = await bcrypt.compare(password, user.password);

            if(passwordsMatch) return user;
        }
        
        console.log('Invalid credentials');
        return null;
    },
  })],
});