fix: Negative value handling

lib/features/portfolio/subfeatures/token/send_token/send_crypto/send_crypto_page.dart

@@ -53,8 +53,10 @@ class SendCryptoPage extends HookConsumerWidget {
               ? () {
                   FocusManager.instance.primaryFocus?.unfocus();
 
-                  if (!ref.watch(state).formKey.currentState!.validate())
+                  if (!ref.watch(state).formKey.currentState!.validate()) {
+                    ref.watch(presenter).onValidChange();
                     return;
+                  }
 
                   ref.read(presenter).transactionProcess();
                 }
@@ -108,11 +110,24 @@ class SendCryptoPage extends HookConsumerWidget {
                 controller: ref.read(presenter).amountController,
                 keyboardType: TextInputType.number,
                 action: TextInputAction.next,
-                validator: (v) => Validation.notEmpty(
-                    context,
-                    v,
-                    translate('x_not_empty')
-                        .replaceFirst('{0}', translate('amount'))),
+                validator: (v) {
+                  final res = Validation.notEmpty(
+                      context,
+                      v,
+                      translate('x_not_empty')
+                          .replaceFirst('{0}', translate('amount')));
+                  if (res != null) {
+                    return res;
+                  }
+                  try {
+                    if (int.parse(v!).isNegative) {
+                      return translate('invalid_format');
+                    }
+                    return null;
+                  } catch (e) {
+                    return translate('invalid_format');
+                  }
+                },
                 hint: 'e.g 100',
                 suffixText: token.symbol,
                 suffixButton: MxcTextFieldButton.text(
@@ -155,11 +170,14 @@ class SendCryptoPage extends HookConsumerWidget {
                 controller: ref.read(presenter).recipientController,
                 action: TextInputAction.done,
                 validator: (v) {
-                  Validation.notEmpty(
+                  final res = Validation.notEmpty(
                       context,
                       v,
                       translate('x_not_empty')
                           .replaceFirst('{0}', translate('recipient')));
+                  if (res != null) {
+                    return res;
+                  }
                   if (v!.startsWith('0x')) {
                     return Validation.checkEthereumAddress(context, v);
                   } else {

lib/features/portfolio/subfeatures/token/send_token/send_crypto/send_crypto_presenter.dart

@@ -71,8 +71,8 @@ class SendCryptoPresenter extends CompletePresenter<SendCryptoState> {
       }
     });
 
-    amountController.addListener(_onValidChange);
-    recipientController.addListener(_onValidChange);
+    amountController.addListener(onValidChange);
+    recipientController.addListener(onValidChange);
 
     recipientController.text = state.qrCode ?? '';
   }
@@ -86,7 +86,7 @@ class SendCryptoPresenter extends CompletePresenter<SendCryptoState> {
     notify(() => state.discount = value);
   }
 
-  void _onValidChange() {
+  void onValidChange() {
     final result = state.formKey.currentState!.validate();
     notify(() => state.valid = result);
   }
@@ -190,7 +190,7 @@ class SendCryptoPresenter extends CompletePresenter<SendCryptoState> {
   Future<void> dispose() async {
     super.dispose();
 
-    amountController.removeListener(_onValidChange);
-    recipientController.removeListener(_onValidChange);
+    amountController.removeListener(onValidChange);
+    recipientController.removeListener(onValidChange);
   }
 }