Add more guards to amounts being zero or infinity (#3612)

diff --git a/cw_core/test/amount/non_finite_amount_test.dart b/cw_core/test/amount/non_finite_amount_test.dart
new file mode 100644
index 00000000..4498e2f9
--- /dev/null
+++ b/cw_core/test/amount/non_finite_amount_test.dart
@@ -0,0 +1,127 @@
+import "package:cw_core/amount/money.dart";
+import "package:cw_core/amount/money_double.dart";
+import "package:cw_core/crypto_currency.dart";
+import "package:cw_core/parse_fixed.dart";
+import "package:flutter_test/flutter_test.dart";
+
+/// Every non-finite spelling that `double.tryParse` accepts.
+///
+/// These matter because a `double`-based amount guard cannot reject them:
+/// `Infinity <= 0` is false and *every* comparison against `NaN` is false, so a
+/// non-finite amount sails through an `if (amount <= 0) throw` check and then
+/// collapses to zero once it reaches Money/BigInt -- i.e. a zero-amount
+/// transaction that passed validation. The Money layer is the enforcement point
+/// for that invariant, so pin it here.
+const nonFiniteSpellings = <String>[
+  "Infinity",
+  "+Infinity",
+  "-Infinity",
+  "NaN",
+  "1e999", // overflows to Infinity as a double
+  "1E400",
+  "  Infinity ",
+];
+
+void main() {
+  group("non-finite amounts", () {
+    test("double.tryParse accepts them (this is why Money must reject them)", () {
+      for (final spelling in nonFiniteSpellings) {
+        final parsed = double.tryParse(spelling);
+        expect(parsed, isNotNull, reason: "double.tryParse rejected $spelling");
+        expect(parsed!.isFinite, isFalse, reason: "$spelling parsed as finite");
+        // The point of the whole exercise: a `<= 0` guard does not stop these.
+        if (!parsed.isNegative) {
+          expect(parsed <= 0, isFalse, reason: "$spelling was caught by a <= 0 guard");
+        }
+      }
+    });
+
+    test("Money.tryParse returns null for every non-finite spelling", () {
+      for (final spelling in nonFiniteSpellings) {
+        expect(
+          Money.tryParse(spelling, CryptoCurrency.btc),
+          isNull,
+          reason: "Money.tryParse accepted $spelling",
+        );
+        expect(
+          Money.tryParse(spelling, CryptoCurrency.btc, strictParsing: false),
+          isNull,
+          reason: "Money.tryParse(strictParsing: false) accepted $spelling",
+        );
+      }
+    });
+
+    test("Money.parse throws for every non-finite spelling", () {
+      for (final spelling in nonFiniteSpellings) {
+        expect(
+          () => Money.parse(spelling, CryptoCurrency.btc),
+          throwsA(isA<FormatException>()),
+          reason: "Money.parse accepted $spelling",
+        );
+      }
+    });
+
+    test("CryptoCurrency.tryParseAmount returns null, parseAmount throws", () {
+      for (final spelling in nonFiniteSpellings) {
+        expect(CryptoCurrency.btc.tryParseAmount(spelling), isNull, reason: spelling);
+        expect(
+          () => CryptoCurrency.btc.parseAmount(spelling),
+          throwsA(isA<FormatException>()),
+          reason: spelling,
+        );
+      }
+    });
+
+    test("tryParseFixed returns null / parseFixed throws (the underlying gate)", () {
+      for (final spelling in nonFiniteSpellings) {
+        expect(tryParseFixed(spelling, 8), isNull, reason: spelling);
+        expect(
+          () => parseFixed(spelling, 8),
+          throwsA(isA<FormatException>()),
+          reason: spelling,
+        );
+      }
+    });
+
+    test("double.tryToMoney returns null for non-finite doubles", () {
+      // Relied on by ExchangeViewModel.changeReceiveAmount/changeDepositAmount, which
+      // divide by `bestRate` and can produce Infinity when the rate is still 0.
+      expect(double.infinity.tryToMoney(CryptoCurrency.btc), isNull);
+      expect(double.negativeInfinity.tryToMoney(CryptoCurrency.btc), isNull);
+      expect(double.nan.tryToMoney(CryptoCurrency.btc), isNull);
+    });
+
+    test("a rejected amount funnels to Money.zero, which is the sweep-all sentinel", () {
+      // Why the cw_monero/cw_wownero guards exist. MONERO_Wallet_createTransaction:
+      //     Monero::optional<uint64_t> optAmount;
+      //     if (amount != 0) { optAmount = amount; }
+      // so amount == 0 means "no amount given" and wallet2 sweeps the whole account.
+      // Output.cryptoAmountMoney falls back to Money.zero on any parse failure, and a
+      // zero Money stringifies to an all-zeros decimal -- exactly the value the native
+      // layer reads as "send everything". Nothing between them may treat 0 as an amount.
+      for (final spelling in nonFiniteSpellings) {
+        final fallback =
+            CryptoCurrency.btc.tryParseAmount(spelling) ?? Money.zero(CryptoCurrency.xmr);
+        expect(fallback.amount, BigInt.zero, reason: spelling);
+      }
+
+      final zeroXmr = Money.zero(CryptoCurrency.xmr);
+      expect(zeroXmr.amount, BigInt.zero);
+      expect(double.tryParse(zeroXmr.toString()), 0.0,
+          reason: "a zero Money must stringify to a numeric zero, i.e. the sweep-all sentinel");
+      expect(RegExp(r"^0(\.0+)?$").hasMatch(zeroXmr.toString()), isTrue,
+          reason: "unexpected zero rendering: ${zeroXmr.toString()}");
+
+      // One piconero is NOT zero -- the guards must not reject genuine dust.
+      expect(Money(BigInt.one, CryptoCurrency.xmr).sign, 1);
+      expect(double.parse(Money(BigInt.one, CryptoCurrency.xmr).toString()) > 0, isTrue);
+    });
+
+    test("finite amounts still round-trip (guard did not over-reject)", () {
+      expect(Money.tryParse("0", CryptoCurrency.btc)!.amount, BigInt.zero);
+      expect(Money.tryParse("1", CryptoCurrency.btc)!.amount, BigInt.from(100000000));
+      expect(Money.tryParse("0.00000001", CryptoCurrency.btc)!.amount, BigInt.one);
+      expect(1.5.tryToMoney(CryptoCurrency.btc)!.amount, BigInt.from(150000000));
+    });
+  });
+}
diff --git a/cw_monero/lib/api/transaction_history.dart b/cw_monero/lib/api/transaction_history.dart
index c6d1c3cf..16bfa1e9 100644
--- a/cw_monero/lib/api/transaction_history.dart
+++ b/cw_monero/lib/api/transaction_history.dart
@@ -149,6 +149,11 @@ Future<PendingTransactionDescription> createTransactionSync(
     List<String> preferredInputs = const []}) async {
   final amt = amount == null ? 0 : currentWallet!.amountFromString(amount);
 
+  if (amount != null && amt == 0) {
+    throw MoneroTransactionCreationException(
+        'Refusing to create a transaction with a zero amount: 0 is the sweep-all ');
+  }
+
   final waddr = currentWallet!.ffiAddress();
 
   // force reconnection in case the os killed the connection?
diff --git a/cw_monero/lib/monero_wallet.dart b/cw_monero/lib/monero_wallet.dart
index afd9284b..98d9e9d5 100644
--- a/cw_monero/lib/monero_wallet.dart
+++ b/cw_monero/lib/monero_wallet.dart
@@ -476,6 +476,11 @@ abstract class MoneroWalletBase
     } else {
       final output = outputs.first;
       final address = output.isParsedAddress ? output.extractedAddress : output.address;
+
+      if (!output.sendAll && output.cryptoAmount.amount <= BigInt.zero) {
+        throw MoneroTransactionCreationException('Amount must be greater than 0.');
+      }
+
       final amount = output.sendAll ? null : output.cryptoAmount.toString();
 
       // if ((formattedAmount != null && unlockedBalance < formattedAmount) ||
diff --git a/lib/entities/calculate_fiat_amount.dart b/lib/entities/calculate_fiat_amount.dart
index ae1436e5..17fe60b6 100644
--- a/lib/entities/calculate_fiat_amount.dart
+++ b/lib/entities/calculate_fiat_amount.dart
@@ -8,8 +8,9 @@ String calculateFiatAmount({double? price, String? cryptoAmount, bool raw = fals
   cryptoAmount = cryptoAmount.sanitized();
 
   final _amount = double.tryParse(cryptoAmount);
-  if (_amount == null || _amount.isNaN) return '0.00';
+  if (_amount == null || !_amount.isFinite) return '0.00';
   final _result = price * _amount;
+  if (!_result.isFinite) return '0.00';
   final result = _result < 0 ? _result * -1 : _result;
 
   if (result == 0.0) {
diff --git a/lib/entities/calculate_fiat_amount_raw.dart b/lib/entities/calculate_fiat_amount_raw.dart
index 0156c703..9465b55b 100644
--- a/lib/entities/calculate_fiat_amount_raw.dart
+++ b/lib/entities/calculate_fiat_amount_raw.dart
@@ -7,6 +7,10 @@ String calculateFiatAmountRaw({required double cryptoAmount, double? price}) {
 
   final result = price * cryptoAmount;
 
+  if (!result.isFinite) {
+    return '0.00';
+  }
+
   if (result == 0.0) {
     return '0.00';
   }
diff --git a/lib/new-ui/widgets/send_page/send_confirm_sheet.dart b/lib/new-ui/widgets/send_page/send_confirm_sheet.dart
index 35f71020..2830aa32 100644
--- a/lib/new-ui/widgets/send_page/send_confirm_sheet.dart
+++ b/lib/new-ui/widgets/send_page/send_confirm_sheet.dart
@@ -214,7 +214,7 @@ class SendTransactionDetails extends StatelessWidget {
                         sendViewModel.balance, sendViewModel.selectedCryptoCurrency) ??
                     zero;
 
-              return sendViewModel.selectedCryptoCurrency.tryParseAmount(o.cryptoAmount) ?? zero;
+              return o.cryptoAmountMoney;
             }, sendViewModel.selectedCryptoCurrency))
           : sendViewModel.amountParsingProxy.asDisplayString(transaction.amount);
 
diff --git a/lib/new-ui/widgets/swap_page/swap_confirm_sheet.dart b/lib/new-ui/widgets/swap_page/swap_confirm_sheet.dart
index b5626056..db1cd6d0 100644
--- a/lib/new-ui/widgets/swap_page/swap_confirm_sheet.dart
+++ b/lib/new-ui/widgets/swap_page/swap_confirm_sheet.dart
@@ -14,6 +14,7 @@ import 'package:cake_wallet/src/widgets/new_list_row/new_list_section.dart';
 import 'package:cake_wallet/view_model/exchange/exchange_trade_view_model.dart';
 import 'package:cake_wallet/view_model/exchange/exchange_view_model.dart';
 import 'package:cake_wallet/view_model/send/send_view_model_state.dart';
+import 'package:cw_core/amount/amount_sanitizer.dart';
 import 'package:cw_core/amount/money.dart';
 import 'package:cw_core/crypto_amount_format.dart';
 import 'package:cw_core/crypto_currency.dart';
@@ -176,9 +177,11 @@ class SwapTransactionDetails extends StatelessWidget {
                         iconPath: exchangeViewModel.depositCurrency.iconPath ?? "",
                         badgeIconPath: _resolveChainBadgePath(exchangeViewModel.depositCurrency),
                         trailingText: exchangeViewModel.amountParsingProxy
-                            .asDisplayStringWithSymbol(exchangeViewModel.depositCurrency
-                                    .tryParseAmount(exchangeTradeViewModel.trade.amount) ??
-                                Money.zero(exchangeViewModel.depositCurrency)),
+                            .asDisplayStringWithSymbol(
+                                exchangeViewModel.depositCurrency.tryParseAmount(
+                                      exchangeTradeViewModel.trade.amount.sanitized(),
+                                    ) ??
+                                    Money.zero(exchangeViewModel.depositCurrency)),
                       ),
                       if (exchangeTradeViewModel.sendViewModel.pendingTransaction != null)
                         ListItemRegularRow(
diff --git a/lib/view_model/send/output.dart b/lib/view_model/send/output.dart
index 106dc7a8..618416b9 100644
--- a/lib/view_model/send/output.dart
+++ b/lib/view_model/send/output.dart
@@ -338,10 +338,21 @@ abstract class OutputBase with Store {
           ? CryptoCurrency.btc
           : cryptoCurrencyHandler();
 
+      final price = _fiatConversationStore.prices[cryptoCurrency];
+      if (price == null || !price.isFinite || price <= 0) {
+        printV('_updateCryptoAmount: invalid fiat rate $price for $cryptoCurrency');
+        cryptoAmount = '';
+        return;
+      }
+
       final decimals = min(20, cryptoCurrencyHandler().decimals);
-      final crypto = (double.parse(fiatAmount.replaceAll(',', '.')) /
-              _fiatConversationStore.prices[cryptoCurrency]!)
-          .toStringAsFixed(decimals);
+      final rawCrypto = double.parse(fiatAmount.replaceAll(',', '.')) / price;
+      if (!rawCrypto.isFinite) {
+        cryptoAmount = '';
+        return;
+      }
+
+      final crypto = rawCrypto.toStringAsFixed(decimals);
 
       if (cryptoAmount != crypto) cryptoAmount = crypto;
     } catch (e) {
diff --git a/lib/view_model/send/send_view_model.dart b/lib/view_model/send/send_view_model.dart
index 187c718c..3d32febf 100644
--- a/lib/view_model/send/send_view_model.dart
+++ b/lib/view_model/send/send_view_model.dart
@@ -54,6 +54,7 @@ import 'package:cake_wallet/view_model/unspent_coins/unspent_coins_list_view_mod
 import 'package:cake_wallet/wownero/wownero.dart';
 import 'package:cake_wallet/zano/zano.dart';
 import 'package:cake_wallet/zcash/zcash.dart';
+import 'package:cw_core/amount/amount_sanitizer.dart';
 import 'package:cw_core/amount/money.dart';
 import 'package:cw_core/crypto_currency.dart';
 import 'package:cw_core/currency_for_wallet_type.dart';
@@ -882,7 +883,11 @@ abstract class SendViewModelBase extends WalletChangeListenerViewModel with Stor
             final fee = actualFee > 0 ? actualFee : 0.0005;
 
             final fromCurrency = trade.from ?? CryptoCurrency.sol;
-            final amount = Money.tryParse(trade.amount, fromCurrency) ?? Money.zero(fromCurrency);
+            final amount = Money.tryParse(
+              trade.amount.sanitized(),
+              fromCurrency,
+              strictParsing: false,
+            ) ?? Money.zero(fromCurrency);
 
             pendingTransaction = await solana!.signAndPrepareJupiterSwapTransaction(
               wallet,
@@ -920,8 +925,15 @@ abstract class SendViewModelBase extends WalletChangeListenerViewModel with Stor
       final bool isTradeTx = trade != null && provider != null;
 
       if (isTradeTx) {
-        final tradeAmountDouble = double.tryParse(trade.amount) ?? 0.0;
-        if (tradeAmountDouble <= 0) throw Exception('Trade amount must be greater than 0');
+        final tradeAmountMoney = Money.tryParse(
+          trade.amount.sanitized(),
+          trade.from ?? selectedCryptoCurrency,
+          strictParsing: false,
+        );
+        if (tradeAmountMoney == null || tradeAmountMoney.sign <= 0) {
+          throw Exception('Trade amount must be greater than 0');
+        }
+        final tradeAmountDouble = double.tryParse(tradeAmountMoney.toString()) ?? 0.0;
 
         if (trade.isSendAll == true) {
           if (provider is NearIntentsExchangeProvider) {