implemented login

app/lib/loginActions.ts

@@ -0,0 +1,21 @@
+import { signIn } from '@/auth';
+import { AuthError } from 'next-auth';
+
+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;
+    }
+  }