fix: invalid username or password handle on login form

lib/src/providers/auth_provider.dart

@@ -49,6 +49,10 @@ class AuthProvider with ChangeNotifier {
     loanBookSuccess = value;
   }
 
+  void setInvalidUsernameOrPassword(bool value) {
+    invalidUsernameOrPassword = value;
+  }
+
   Future<void> signIn(
       BuildContext context, String username, String password) async {
     try {
@@ -65,16 +69,14 @@ class AuthProvider with ChangeNotifier {
         await storeAccessToken(token);
 
         isAuthenticated = true;
-        invalidUsernameOrPassword = false;
+        setInvalidUsernameOrPassword(false);
 
         debugPrint("Login successful $token");
-      } else if (response.statusCode == 401) {
-        invalidUsernameOrPassword = true;
-
+      } else if (response.statusCode == 400) {
+        setInvalidUsernameOrPassword(true);
         debugPrint("Login failed: ${response.statusCode} ${response.body}");
       } else {
-        final code = response.statusCode;
-        debugPrint("Login failed $code");
+        debugPrint("Login failed: ${response.statusCode} ${response.body}");
       }
 
       setLoading(false);

lib/src/widgets/forms/login_form.dart

@@ -39,7 +39,8 @@ class _LoginForm extends State<LoginForm> {
     const String formText = "Log In to continue";
 
     return Consumer<AuthProvider>(builder: (context, authProvider, child) {
-      final isInvalid = authProvider.invalidUsernameOrPassword;
+      final isInvalidUsernameOrPassword =
+          authProvider.invalidUsernameOrPassword;
 
       return Column(
         children: [
@@ -106,28 +107,21 @@ class _LoginForm extends State<LoginForm> {
                     },
                     keyboardType: TextInputType.visiblePassword,
                   ),
-                  Visibility(
-                    visible: isInvalid,
-                    child: Container(
-                      decoration: BoxDecoration(
-                        borderRadius: BorderRadius.circular(10),
-                        color: Theme.of(context).highlightColor,
-                      ),
-                      margin: const EdgeInsets.symmetric(vertical: 20.0),
-                      padding: const EdgeInsets.symmetric(
-                          horizontal: 10.0, vertical: 8.0),
-                      child: const Text("Invalid username or password"),
-                    ),
+                  Padding(
+                    padding: const EdgeInsets.symmetric(vertical: 20.0),
+                    child: Text(
+                      isInvalidUsernameOrPassword
+                          ? "Invalid username or password"
+                          : "",
+                      style: const TextStyle(color: Colors.red),
                     ),
-                  const SizedBox(
-                    height: 20.0,
                   ),
                   Column(
                     children: [
                       SizedBox(
                         width: double.infinity,
                         child: FilledButton(
-                          onPressed: () {
+                          onPressed: () async {
                             if (_formKey.currentState!.validate()) {}
                             authProvider.signIn(
                               context,

lib/src/widgets/forms/search_form.dart

@@ -24,7 +24,7 @@ class _SearchForm extends State<SearchForm> {
       width: queryData.size.width * 0.8,
       padding: const EdgeInsets.symmetric(vertical: 8.0),
       child: SearchBar(
-        hintText: "Enter keywords...",
+        hintText: "Enter book title...",
         elevation: WidgetStateProperty.all(0),
         onChanged: (value) {
           if (value.length >= 3) {