Chapter 15 - implement authentication

app/lib/actions.ts

@@ -4,6 +4,9 @@ import { z } from 'zod';
 import { sql } from '@vercel/postgres';
 import { revalidatePath } from 'next/cache';
 import {redirect} from "next/navigation";
+import { signIn } from '@/auth';
+import { AuthError } from 'next-auth';
+
 
 const FormSchema = z.object({
     id: z.string(),
@@ -97,4 +100,23 @@ export async function deleteInvoice(id: string) {
     } catch (error) {
         return { message: 'Database Error: Failed to Delete Invoice.' };
     }
+}
+
+export async function authenticate(
+    prevState: string | undefined,
+    formData: FormData,
+) {
+    try {
+        await signIn('credentials', formData);
+    } catch (error) {
+        if (error instanceof AuthError) {
+            switch (error.type) {
+                case 'CredentialsSignin':
+                    return 'Invalid credentials.';
+                default:
+                    return 'Something went wrong.';
+            }
+        }
+        throw error;
+    }
 }