CAKE-345 | added monero_output.dart to the app; fixed transaction_history.dart; renamed SendItem on Output; calculated formattedCryptoAmount in the output.dart; used outputs list instead sendItemList; fixed bitcoin_transaction_credentials.dart, electrum_wallet.dart, monero_transaction_creation_credentials.dart, monero_wallet.dart, exchange and send pages, view models

cw_monero/lib/monero_output.dart

@@ -0,0 +1,8 @@
+import 'package:flutter/foundation.dart';
+
+class MoneroOutput {
+  MoneroOutput({@required this.address, @required this.amount});
+
+  final String address;
+  final String amount;
+}

cw_monero/lib/transaction_history.dart

@@ -1,5 +1,6 @@
 import 'dart:ffi';
 import 'package:cw_monero/convert_utf8_to_string.dart';
+import 'package:cw_monero/monero_output.dart';
 import 'package:cw_monero/structs/ut8_box.dart';
 import 'package:ffi/ffi.dart';
 import 'package:flutter/foundation.dart';
@@ -107,21 +108,21 @@ PendingTransactionDescription createTransactionSync(
 }
 
 PendingTransactionDescription createTransactionMultDestSync(
-    {List<String> addresses,
+    {List<MoneroOutput> outputs,
       String paymentId,
-      List<String> amounts,
-      int size,
       int priorityRaw,
       int accountIndex = 0}) {
-  final List<Pointer<Utf8>> addressesPointers = addresses.map(Utf8.toUtf8).toList();
+  final int size = outputs.length;
+  final List<Pointer<Utf8>> addressesPointers = outputs.map((output) =>
+      Utf8.toUtf8(output.address)).toList();
   final Pointer<Pointer<Utf8>> addressesPointerPointer = allocate(count: size);
-
+  final List<Pointer<Utf8>> amountsPointers = outputs.map((output) =>
-  final List<Pointer<Utf8>> amountsPointers = amounts.map(Utf8.toUtf8).toList();
+      Utf8.toUtf8(output.amount)).toList();
   final Pointer<Pointer<Utf8>> amountsPointerPointer = allocate(count: size);
 
   for (int i = 0; i < size; i++) {
-    addressesPointerPointer[ i ] = addressesPointers[ i ];
+    addressesPointerPointer[i] = addressesPointers[i];
-    amountsPointerPointer[ i ] = amountsPointers[ i ];
+    amountsPointerPointer[i] = amountsPointers[i];
   }
 
   final paymentIdPointer = Utf8.toUtf8(paymentId);
@@ -190,18 +191,14 @@ PendingTransactionDescription _createTransactionSync(Map args) {
 }
 
 PendingTransactionDescription _createTransactionMultDestSync(Map args) {
-  final addresses = args['addresses'] as List<String>;
+  final outputs = args['outputs'] as List<MoneroOutput>;
   final paymentId = args['paymentId'] as String;
-  final amounts = args['amounts'] as List<String>;
-  final size = args['size'] as int;
   final priorityRaw = args['priorityRaw'] as int;
   final accountIndex = args['accountIndex'] as int;
 
   return createTransactionMultDestSync(
-      addresses: addresses,
+      outputs: outputs,
       paymentId: paymentId,
-      amounts: amounts,
-      size: size,
       priorityRaw: priorityRaw,
       accountIndex: accountIndex);
 }
@@ -221,17 +218,13 @@ Future<PendingTransactionDescription> createTransaction(
     });
 
 Future<PendingTransactionDescription> createTransactionMultDest(
-    {List<String> addresses,
+    {List<MoneroOutput> outputs,
       String paymentId,
-      List<String> amounts,
-      int size,
       int priorityRaw,
       int accountIndex = 0}) =>
     compute(_createTransactionMultDestSync, {
-      'addresses': addresses,
+      'outputs': outputs,
       'paymentId': paymentId,
-      'amounts': amounts,
-      'size': size,
       'priorityRaw': priorityRaw,
       'accountIndex': accountIndex
     });

lib/bitcoin/bitcoin_transaction_credentials.dart

@@ -1,9 +1,9 @@
 import 'package:cake_wallet/bitcoin/bitcoin_transaction_priority.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 
 class BitcoinTransactionCredentials {
-  BitcoinTransactionCredentials(this.sendItemList, this.priority);
+  BitcoinTransactionCredentials(this.outputs, this.priority);
 
-  final List<SendItem> sendItemList;
+  final List<Output> outputs;
   BitcoinTransactionPriority priority;
 }

lib/bitcoin/electrum_wallet.dart

@@ -158,7 +158,8 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
     const minAmount = 546;
     final transactionCredentials = credentials as BitcoinTransactionCredentials;
     final inputs = <BitcoinUnspent>[];
-    final sendItemList = transactionCredentials.sendItemList;
+    final outputs = transactionCredentials.outputs;
+    final hasMultiDestination = outputs.length > 1;
     var allInputsAmount = 0;
 
     if (unspentCoins.isEmpty) {
@@ -177,61 +178,54 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
     }
 
     final allAmountFee = feeAmountForPriority(
-        transactionCredentials.priority, inputs.length, sendItemList.length);
+        transactionCredentials.priority, inputs.length, outputs.length);
     final allAmount = allInputsAmount - allAmountFee;
 
     var credentialsAmount = 0;
     var amount = 0;
     var fee = 0;
 
-    if (sendItemList.length > 1) {
+    if (hasMultiDestination) {
-      final sendAllItems = sendItemList.where((item) => item.sendAll).toList();
+      final sendAllItems = outputs.where((item) => item.sendAll).toList();
 
       if (sendAllItems?.isNotEmpty ?? false) {
         throw BitcoinTransactionWrongBalanceException(currency);
       }
 
-      final nullAmountItems = sendItemList.where((item) =>
+      final nullAmountItems = outputs.where((item) =>
-      stringDoubleToBitcoinAmount(item.cryptoAmount.replaceAll(',', '.')) <= 0)
+          item.formattedCryptoAmount <= 0).toList();
-          .toList();
 
       if (nullAmountItems?.isNotEmpty ?? false) {
         throw BitcoinTransactionWrongBalanceException(currency);
       }
 
-      credentialsAmount = sendItemList.fold(0, (previousValue, element) =>
+      credentialsAmount = outputs.fold(0, (acc, value) =>
-      previousValue + stringDoubleToBitcoinAmount(
+          acc + value.formattedCryptoAmount);
-          element.cryptoAmount.replaceAll(',', '.')));
 
-      if (credentialsAmount > allAmount) {
+      if (allAmount - credentialsAmount < minAmount) {
         throw BitcoinTransactionWrongBalanceException(currency);
       }
 
-      amount = allAmount - credentialsAmount < minAmount
+      amount = credentialsAmount;
-          ? allAmount
-          : credentialsAmount;
 
-      fee = amount == allAmount
+      fee = calculateEstimatedFee(transactionCredentials.priority, amount,
-          ? allAmountFee
+          outputsCount: outputs.length + 1);
-          : calculateEstimatedFee(transactionCredentials.priority, amount,
-          outputsCount: sendItemList.length + 1);
     } else {
-      final sendItem = sendItemList.first;
+      final output = outputs.first;
 
-      credentialsAmount = !sendItem.sendAll
+      credentialsAmount = !output.sendAll
-          ? stringDoubleToBitcoinAmount(
+          ? output.formattedCryptoAmount
-          sendItem.cryptoAmount.replaceAll(',', '.'))
           : 0;
 
       if (credentialsAmount > allAmount) {
         throw BitcoinTransactionWrongBalanceException(currency);
       }
 
-      amount = sendItem.sendAll || allAmount - credentialsAmount < minAmount
+      amount = output.sendAll || allAmount - credentialsAmount < minAmount
           ? allAmount
           : credentialsAmount;
 
-      fee = sendItem.sendAll || amount == allAmount
+      fee = output.sendAll || amount == allAmount
           ? allAmountFee
           : calculateEstimatedFee(transactionCredentials.priority, amount);
     }
@@ -289,18 +283,18 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
       }
     });
 
-    sendItemList.forEach((item) {
+    outputs.forEach((item) {
-      final _amount = item.sendAll
+      final outputAmount = hasMultiDestination
-          ? amount
+          ? item.formattedCryptoAmount
-          : stringDoubleToBitcoinAmount(item.cryptoAmount.replaceAll(',', '.'));
+          : amount;
 
       txb.addOutput(
           addressToOutputScript(item.address, networkType),
-          _amount);
+          outputAmount);
     });
 
     final estimatedSize =
-      estimatedTransactionSize(inputs.length, sendItemList.length + 1);
+      estimatedTransactionSize(inputs.length, outputs.length + 1);
     final feeAmount = feeRate(transactionCredentials.priority) * estimatedSize;
     final changeValue = totalInputAmount - amount - feeAmount;
 

lib/monero/monero_transaction_creation_credentials.dart

@@ -1,11 +1,11 @@
 import 'package:cake_wallet/entities/transaction_creation_credentials.dart';
 import 'package:cake_wallet/entities/monero_transaction_priority.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 
 class MoneroTransactionCreationCredentials
     extends TransactionCreationCredentials {
-  MoneroTransactionCreationCredentials({this.sendItemList, this.priority});
+  MoneroTransactionCreationCredentials({this.outputs, this.priority});
 
-  final List<SendItem> sendItemList;
+  final List<Output> outputs;
   final MoneroTransactionPriority priority;
 }

lib/monero/monero_wallet.dart

@@ -13,6 +13,7 @@ import 'package:cw_monero/transaction_history.dart'
 import 'package:cw_monero/wallet.dart';
 import 'package:cw_monero/wallet.dart' as monero_wallet;
 import 'package:cw_monero/transaction_history.dart' as transaction_history;
+import 'package:cw_monero/monero_output.dart';
 import 'package:cake_wallet/monero/monero_transaction_creation_credentials.dart';
 import 'package:cake_wallet/monero/pending_monero_transaction.dart';
 import 'package:cake_wallet/monero/monero_wallet_keys.dart';
@@ -150,8 +151,8 @@ abstract class MoneroWalletBase extends WalletBase<MoneroBalance,
   @override
   Future<PendingTransaction> createTransaction(Object credentials) async {
     final _credentials = credentials as MoneroTransactionCreationCredentials;
-    final sendItemList = _credentials.sendItemList;
+    final outputs = _credentials.outputs;
-    final listSize = sendItemList.length;
+    final hasMultiDestination = outputs.length > 1;
     final unlockedBalance =
     monero_wallet.getUnlockedBalance(accountIndex: walletAddresses.account.id);
 
@@ -161,16 +162,15 @@ abstract class MoneroWalletBase extends WalletBase<MoneroBalance,
       throw MoneroTransactionCreationException('The wallet is not synced.');
     }
 
-    if (listSize > 1) {
+    if (hasMultiDestination) {
-      final sendAllItems = sendItemList.where((item) => item.sendAll).toList();
+      final sendAllItems = outputs.where((item) => item.sendAll).toList();
 
       if (sendAllItems?.isNotEmpty ?? false) {
         throw MoneroTransactionCreationException('Wrong balance. Not enough XMR on your balance.');
       }
 
-      final nullAmountItems = sendItemList.where((item) =>
+      final nullAmountItems = outputs.where((item) =>
-        moneroParseAmount(amount: item.cryptoAmount.replaceAll(',', '.')) <= 0)
+          item.formattedCryptoAmount <= 0).toList();
-        .toList();
 
       if (nullAmountItems?.isNotEmpty ?? false) {
         throw MoneroTransactionCreationException('Wrong balance. Not enough XMR on your balance.');
@@ -178,42 +178,41 @@ abstract class MoneroWalletBase extends WalletBase<MoneroBalance,
 
       var credentialsAmount = 0;
 
-      credentialsAmount = sendItemList.fold(0, (previousValue, element) =>
+      credentialsAmount = outputs.fold(0, (acc, value) =>
-      previousValue + moneroParseAmount(
+          acc + value.formattedCryptoAmount);
-          amount: element.cryptoAmount.replaceAll(',', '.')));
 
       if (unlockedBalance < credentialsAmount) {
         throw MoneroTransactionCreationException('Wrong balance. Not enough XMR on your balance.');
       }
 
-      final addresses = sendItemList.map((e) => e.address).toList();
+      final moneroOutputs = outputs.map((output) =>
-      final amounts = sendItemList.map((e) =>
+          MoneroOutput(
-          e.cryptoAmount.replaceAll(',', '.')).toList();
+              address: output.address,
+              amount: output.cryptoAmount.replaceAll(',', '.')))
+          .toList();
 
       pendingTransactionDescription =
       await transaction_history.createTransactionMultDest(
-          addresses: addresses,
+          outputs: moneroOutputs,
           paymentId: '',
-          amounts: amounts,
-          size: listSize,
           priorityRaw: _credentials.priority.serialize(),
           accountIndex: walletAddresses.account.id);
     } else {
-      final item = sendItemList.first;
+      final output = outputs.first;
-      final address = item.address;
+      final address = output.address;
-      final amount = item.sendAll
+      final amount = output.sendAll
           ? null
-          : item.cryptoAmount.replaceAll(',', '.');
+          : output.cryptoAmount.replaceAll(',', '.');
-      final formattedAmount = item.sendAll
+      final formattedAmount = output.sendAll
           ? null
-          : moneroParseAmount(amount: amount);
+          : output.formattedCryptoAmount;
 
       if ((formattedAmount != null && unlockedBalance < formattedAmount) ||
           (formattedAmount == null && unlockedBalance <= 0)) {
         final formattedBalance = moneroAmountToString(amount: unlockedBalance);
 
         throw MoneroTransactionCreationException(
-            'Incorrect unlocked balance. Unlocked: $formattedBalance. Transaction amount: ${item.cryptoAmount}.');
+            'Incorrect unlocked balance. Unlocked: $formattedBalance. Transaction amount: ${output.cryptoAmount}.');
       }
 
       pendingTransactionDescription =

lib/src/screens/exchange_trade/exchange_trade_page.dart

@@ -385,8 +385,8 @@ class ExchangeTradeState extends State<ExchangeTradeForm> {
                             .pendingTransactionFiatAmount +
                         ' ' +
                         widget.exchangeTradeViewModel.sendViewModel.fiat.title,
-                    sendItemList: widget.exchangeTradeViewModel.sendViewModel
+                    outputs: widget.exchangeTradeViewModel.sendViewModel
-                                 .sendItemList);
+                                 .outputs);
               });
         });
       }

lib/src/screens/send/send_page.dart

@@ -3,7 +3,7 @@ import 'package:cake_wallet/src/screens/send/widgets/parse_address_from_domain_a
 import 'package:cake_wallet/src/screens/send/widgets/send_card.dart';
 import 'package:cake_wallet/src/widgets/alert_with_two_actions.dart';
 import 'package:cake_wallet/src/widgets/template_tile.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_mobx/flutter_mobx.dart';
@@ -55,16 +55,16 @@ class SendPage extends BasePage {
         onPressed: () {
           var pageToJump = controller.page.round() - 1;
           pageToJump = pageToJump > 0 ? pageToJump : 0;
-          final item = _defineCurrentSendItem();
+          final output = _defineCurrentOutput();
-          sendViewModel.removeSendItem(item);
+          sendViewModel.removeOutput(output);
           controller.jumpToPage(pageToJump);
         })
         : TrailButton(
         caption: S.of(context).clear,
         onPressed: () {
-          final item = _defineCurrentSendItem();
+          final output = _defineCurrentOutput();
           _formKey.currentState.reset();
-          item.reset();
+          output.reset();
         });
   });
 
@@ -85,13 +85,13 @@ class SendPage extends BasePage {
                       return PageView.builder(
                           scrollDirection: Axis.horizontal,
                           controller: controller,
-                          itemCount: sendViewModel.sendItemList.length,
+                          itemCount: sendViewModel.outputs.length,
                           itemBuilder: (context, index) {
-                            final item = sendViewModel.sendItemList[index];
+                            final output = sendViewModel.outputs[index];
 
                             return SendCard(
-                              key: item.key,
+                              key: output.key,
-                              item: item,
+                              output: output,
                               sendViewModel: sendViewModel,
                             );
                           }
@@ -104,7 +104,7 @@ class SendPage extends BasePage {
                   child: Container(
                       height: 10,
                       child: Observer(builder: (_) {
-                        final count = sendViewModel.sendItemList.length;
+                        final count = sendViewModel.outputs.length;
 
                         return count > 1
                           ? SmoothPageIndicator(
@@ -211,11 +211,11 @@ class SendPage extends BasePage {
                                 amount: template.amount,
                                 from: template.cryptoCurrency,
                                 onTap: () async {
-                                  final item = _defineCurrentSendItem();
+                                  final output = _defineCurrentOutput();
-                                  item.address =
+                                  output.address =
                                       template.address;
-                                  item.setCryptoAmount(template.amount);
+                                  output.setCryptoAmount(template.amount);
-                                  final parsedAddress = await item
+                                  final parsedAddress = await output
                                       .applyOpenaliasOrUnstoppableDomains();
                                   showAddressAlert(context, parsedAddress);
                                 },
@@ -263,7 +263,7 @@ class SendPage extends BasePage {
                 padding: EdgeInsets.only(bottom: 12),
                 child: PrimaryButton(
                   onPressed: () {
-                    sendViewModel.addSendItem();
+                    sendViewModel.addOutput();
                   },
                   text: S.of(context).add_receiver,
                   color: Colors.green,
@@ -274,16 +274,16 @@ class SendPage extends BasePage {
                 return LoadingPrimaryButton(
                   onPressed: () async {
                     if (!_formKey.currentState.validate()) {
-                      if (sendViewModel.sendItemList.length > 1) {
+                      if (sendViewModel.outputs.length > 1) {
                         showErrorValidationAlert(context);
                       }
 
                       return;
                     }
 
-                    final notValidItems = sendViewModel.sendItemList
+                    final notValidItems = sendViewModel.outputs
                         .where((item) =>
-                    item.address.isEmpty || item.cryptoAmount.isEmpty)
+                        item.address.isEmpty || item.cryptoAmount.isEmpty)
                         .toList();
 
                     if (notValidItems?.isNotEmpty ?? false) {
@@ -343,7 +343,7 @@ class SendPage extends BasePage {
                     feeValue: sendViewModel.pendingTransaction.feeFormatted,
                     feeFiatAmount: sendViewModel.pendingTransactionFeeFiatAmount
                         +  ' ' + sendViewModel.fiat.title,
-                    sendItemList: sendViewModel.sendItemList,
+                    outputs: sendViewModel.outputs,
                     rightButtonText: S.of(context).ok,
                     leftButtonText: S.of(context).cancel,
                     actionRightButton: () {
@@ -381,7 +381,7 @@ class SendPage extends BasePage {
 
       if (state is TransactionCommitted) {
         WidgetsBinding.instance.addPostFrameCallback((_) {
-          sendViewModel.clearSendItemList();
+          sendViewModel.clearOutputs();
         });
       }
     });
@@ -389,9 +389,9 @@ class SendPage extends BasePage {
     _effectsInstalled = true;
   }
 
-  SendItem _defineCurrentSendItem() {
+  Output _defineCurrentOutput() {
     final itemCount = controller.page.round();
-    return sendViewModel.sendItemList[itemCount];
+    return sendViewModel.outputs[itemCount];
   }
 
   void showErrorValidationAlert(BuildContext context) async {

lib/src/screens/send/send_template_page.dart

@@ -14,7 +14,7 @@ import 'package:cake_wallet/src/widgets/scollable_with_bottom_section.dart';
 
 class SendTemplatePage extends BasePage {
   SendTemplatePage({@required this.sendTemplateViewModel}) {
-    sendTemplateViewModel.sendItem.reset();
+    sendTemplateViewModel.output.reset();
   }
 
   final SendTemplateViewModel sendTemplateViewModel;
@@ -258,21 +258,21 @@ class SendTemplatePage extends BasePage {
       return;
     }
 
-    final item = sendTemplateViewModel.sendItem;
+    final output = sendTemplateViewModel.output;
 
-    reaction((_) => item.fiatAmount, (String amount) {
+    reaction((_) => output.fiatAmount, (String amount) {
       if (amount != _fiatAmountController.text) {
         _fiatAmountController.text = amount;
       }
     });
 
-    reaction((_) => item.cryptoAmount, (String amount) {
+    reaction((_) => output.cryptoAmount, (String amount) {
       if (amount != _cryptoAmountController.text) {
         _cryptoAmountController.text = amount;
       }
     });
 
-    reaction((_) => item.address, (String address) {
+    reaction((_) => output.address, (String address) {
       if (address != _addressController.text) {
         _addressController.text = address;
       }
@@ -281,24 +281,24 @@ class SendTemplatePage extends BasePage {
     _cryptoAmountController.addListener(() {
       final amount = _cryptoAmountController.text;
 
-      if (amount != item.cryptoAmount) {
+      if (amount != output.cryptoAmount) {
-        item.setCryptoAmount(amount);
+        output.setCryptoAmount(amount);
       }
     });
 
     _fiatAmountController.addListener(() {
       final amount = _fiatAmountController.text;
 
-      if (amount != item.fiatAmount) {
+      if (amount != output.fiatAmount) {
-        item.setFiatAmount(amount);
+        output.setFiatAmount(amount);
       }
     });
 
     _addressController.addListener(() {
       final address = _addressController.text;
 
-      if (item.address != address) {
+      if (output.address != address) {
-        item.address = address;
+        output.address = address;
       }
     });
 

lib/src/screens/send/widgets/confirm_sending_alert.dart

@@ -1,5 +1,5 @@
 import 'package:cake_wallet/palette.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 import 'package:flutter/material.dart';
 import 'package:cake_wallet/src/widgets/base_alert_dialog.dart';
 import 'package:cake_wallet/generated/i18n.dart';
@@ -13,14 +13,14 @@ class ConfirmSendingAlert extends BaseAlertDialog {
     @required this.fee,
     @required this.feeValue,
     @required this.feeFiatAmount,
-    @required this.sendItemList,
+    @required this.outputs,
     @required this.leftButtonText,
     @required this.rightButtonText,
     @required this.actionLeftButton,
     @required this.actionRightButton,
     this.alertBarrierDismissible = true
   }) {
-    itemCount = sendItemList.length;
+    itemCount = outputs.length;
     recipientTitle = itemCount > 1
         ? S.current.transaction_details_recipient_address
         : S.current.recipient_address;
@@ -33,7 +33,7 @@ class ConfirmSendingAlert extends BaseAlertDialog {
   final String fee;
   final String feeValue;
   final String feeFiatAmount;
-  final List<SendItem> sendItemList;
+  final List<Output> outputs;
   final String leftButtonText;
   final String rightButtonText;
   final VoidCallback actionLeftButton;
@@ -179,10 +179,10 @@ class ConfirmSendingAlert extends BaseAlertDialog {
                       physics: NeverScrollableScrollPhysics(),
                       itemCount: itemCount,
                       itemBuilder: (context, index) {
-                        final item = sendItemList[index];
+                        final item = outputs[index];
                         final _address = item.address;
                         final _amount =
-                        item.cryptoAmount.replaceAll(',', '.');
+                          item.cryptoAmount.replaceAll(',', '.');
 
                         return Column(
                           children: [
@@ -225,7 +225,7 @@ class ConfirmSendingAlert extends BaseAlertDialog {
                     : Padding(
                     padding: EdgeInsets.only(top: 8),
                     child: Text(
-                      sendItemList.first.address,
+                      outputs.first.address,
                       style: TextStyle(
                         fontSize: 12,
                         fontWeight: FontWeight.w600,

lib/src/screens/send/widgets/send_card.dart

@@ -4,7 +4,7 @@ import 'package:cake_wallet/routes.dart';
 import 'package:cake_wallet/src/screens/send/widgets/parse_address_from_domain_alert.dart';
 import 'package:cake_wallet/src/widgets/keyboard_done_button.dart';
 import 'package:cake_wallet/src/widgets/picker.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 import 'package:cake_wallet/view_model/settings/settings_view_model.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
@@ -19,21 +19,21 @@ import 'package:cake_wallet/generated/i18n.dart';
 import 'package:cake_wallet/src/widgets/base_text_form_field.dart';
 
 class SendCard extends StatefulWidget {
-  SendCard({Key key, @required this.item, @required this.sendViewModel}) : super(key: key);
+  SendCard({Key key, @required this.output, @required this.sendViewModel}) : super(key: key);
 
-  final SendItem item;
+  final Output output;
   final SendViewModel sendViewModel;
 
   @override
   SendCardState createState() => SendCardState(
-    item: item,
+    output: output,
     sendViewModel: sendViewModel
   );
 }
 
 class SendCardState extends State<SendCard>
     with AutomaticKeepAliveClientMixin<SendCard> {
-  SendCardState({@required this.item, @required this.sendViewModel})
+  SendCardState({@required this.output, @required this.sendViewModel})
       : addressController = TextEditingController(),
         cryptoAmountController = TextEditingController(),
         fiatAmountController = TextEditingController(),
@@ -45,7 +45,7 @@ class SendCardState extends State<SendCard>
   static const prefixIconWidth = 34.0;
   static const prefixIconHeight = 34.0;
 
-  final SendItem item;
+  final Output output;
   final SendViewModel sendViewModel;
 
   final TextEditingController addressController;
@@ -143,7 +143,7 @@ class SendCardState extends State<SendCard>
                               .decorationColor),
                       onPushPasteButton: (context) async {
                         final parsedAddress =
-                          await item.applyOpenaliasOrUnstoppableDomains();
+                          await output.applyOpenaliasOrUnstoppableDomains();
                         showAddressAlert(context, parsedAddress);
                       },
                       validator: sendViewModel.addressValidator,
@@ -189,7 +189,7 @@ class SendCardState extends State<SendCard>
                                               .decorationColor,
                                           fontWeight: FontWeight.w500,
                                           fontSize: 14),
-                                      validator: item.sendAll
+                                      validator: output.sendAll
                                           ? sendViewModel.allAmountValidator
                                           : sendViewModel
                                           .amountValidator),
@@ -201,7 +201,7 @@ class SendCardState extends State<SendCard>
                                           height: prefixIconHeight,
                                           child: InkWell(
                                               onTap: () async =>
-                                                  item.setSendAll(),
+                                                  output.setSendAll(),
                                               child: Container(
                                                 decoration: BoxDecoration(
                                                     color: Theme.of(context)
@@ -349,7 +349,7 @@ class SendCardState extends State<SendCard>
                                         crossAxisAlignment: CrossAxisAlignment.end,
                                         children: [
                                           Text(
-                                              item
+                                              output
                                                   .estimatedFee
                                                   .toString() +
                                                   ' ' +
@@ -366,7 +366,7 @@ class SendCardState extends State<SendCard>
                                               padding:
                                               EdgeInsets.only(top: 5),
                                               child: Text(
-                                                  item
+                                                  output
                                                       .estimatedFeeFiatAmount
                                                       +  ' ' +
                                                       sendViewModel
@@ -435,10 +435,10 @@ class SendCardState extends State<SendCard>
   }
 
   void _setEffects(BuildContext context) {
-    addressController.text = item.address;
+    addressController.text = output.address;
-    cryptoAmountController.text = item.cryptoAmount;
+    cryptoAmountController.text = output.cryptoAmount;
-    fiatAmountController.text = item.fiatAmount;
+    fiatAmountController.text = output.fiatAmount;
-    noteController.text = item.note;
+    noteController.text = output.note;
 
     if (_effectsInstalled) {
       return;
@@ -447,48 +447,48 @@ class SendCardState extends State<SendCard>
     cryptoAmountController.addListener(() {
       final amount = cryptoAmountController.text;
 
-      if (item.sendAll && amount != S.current.all) {
+      if (output.sendAll && amount != S.current.all) {
-        item.sendAll = false;
+        output.sendAll = false;
       }
 
-      if (amount != item.cryptoAmount) {
+      if (amount != output.cryptoAmount) {
-        item.setCryptoAmount(amount);
+        output.setCryptoAmount(amount);
       }
     });
 
     fiatAmountController.addListener(() {
       final amount = fiatAmountController.text;
 
-      if (amount != item.fiatAmount) {
+      if (amount != output.fiatAmount) {
-        item.sendAll = false;
+        output.sendAll = false;
-        item.setFiatAmount(amount);
+        output.setFiatAmount(amount);
       }
     });
 
     noteController.addListener(() {
       final note = noteController.text ?? '';
 
-      if (note != item.note) {
+      if (note != output.note) {
-        item.note = note;
+        output.note = note;
       }
     });
 
-    reaction((_) => item.sendAll, (bool all) {
+    reaction((_) => output.sendAll, (bool all) {
       if (all) {
         cryptoAmountController.text = S.current.all;
         fiatAmountController.text = null;
       }
     });
 
-    reaction((_) => item.fiatAmount, (String amount) {
+    reaction((_) => output.fiatAmount, (String amount) {
       if (amount != fiatAmountController.text) {
         fiatAmountController.text = amount;
       }
     });
 
-    reaction((_) => item.cryptoAmount, (String amount) {
+    reaction((_) => output.cryptoAmount, (String amount) {
-      if (item.sendAll && amount != S.current.all) {
+      if (output.sendAll && amount != S.current.all) {
-        item.sendAll = false;
+        output.sendAll = false;
       }
 
       if (amount != cryptoAmountController.text) {
@@ -496,7 +496,7 @@ class SendCardState extends State<SendCard>
       }
     });
 
-    reaction((_) => item.address, (String address) {
+    reaction((_) => output.address, (String address) {
       if (address != addressController.text) {
         addressController.text = address;
       }
@@ -505,12 +505,12 @@ class SendCardState extends State<SendCard>
     addressController.addListener(() {
       final address = addressController.text;
 
-      if (item.address != address) {
+      if (output.address != address) {
-        item.address = address;
+        output.address = address;
       }
     });
 
-    reaction((_) => item.note, (String note) {
+    reaction((_) => output.note, (String note) {
       if (note != noteController.text) {
         noteController.text = note;
       }
@@ -518,7 +518,7 @@ class SendCardState extends State<SendCard>
 
     addressFocusNode.addListener(() async {
       if (!addressFocusNode.hasFocus && addressController.text.isNotEmpty) {
-        final parsedAddress = await item.applyOpenaliasOrUnstoppableDomains();
+        final parsedAddress = await output.applyOpenaliasOrUnstoppableDomains();
         showAddressAlert(context, parsedAddress);
       }
     });

lib/view_model/exchange/exchange_trade_view_model.dart

@@ -79,11 +79,11 @@ abstract class ExchangeTradeViewModelBase with Store {
       return;
     }
 
-    sendViewModel.clearSendItemList();
+    sendViewModel.clearOutputs();
-    final item = sendViewModel.sendItemList.first;
+    final output = sendViewModel.outputs.first;
 
-    item.address = trade.inputAddress;
+    output.address = trade.inputAddress;
-    item.setCryptoAmount(trade.amount);
+    output.setCryptoAmount(trade.amount);
     await sendViewModel.createTransaction();
   }
 

lib/view_model/send/output.dart

@@ -15,14 +15,14 @@ import 'package:cake_wallet/store/dashboard/fiat_conversion_store.dart';
 import 'package:cake_wallet/store/settings_store.dart';
 import 'package:cake_wallet/generated/i18n.dart';
 
-part 'send_item.g.dart';
+part 'output.g.dart';
 
 const String cryptoNumberPattern = '0.0';
 
-class SendItem = SendItemBase with _$SendItem;
+class Output = OutputBase with _$Output;
 
-abstract class SendItemBase with Store {
+abstract class OutputBase with Store {
-  SendItemBase(this._wallet, this._settingsStore, this._fiatConversationStore)
+  OutputBase(this._wallet, this._settingsStore, this._fiatConversationStore)
       :_cryptoNumberFormat = NumberFormat(cryptoNumberPattern) {
     reset();
     _setCryptoNumMaximumFractionDigits();
@@ -47,8 +47,8 @@ abstract class SendItemBase with Store {
   bool sendAll;
 
   @computed
-  double get estimatedFee {
+  int get formattedCryptoAmount {
-    int amount;
+    int amount = 0;
 
     try {
       if (cryptoAmount?.isNotEmpty ?? false) {
@@ -72,9 +72,18 @@ abstract class SendItemBase with Store {
           amount = _amount;
         }
       }
+    } catch(e) {
+      amount = 0;
+    }
 
+    return amount;
+  }
+
+  @computed
+  double get estimatedFee {
+    try {
       final fee = _wallet.calculateEstimatedFee(
-          _settingsStore.priority[_wallet.type], amount);
+          _settingsStore.priority[_wallet.type], formattedCryptoAmount);
 
       if (_wallet is ElectrumWallet) {
         return bitcoinAmountToDouble(amount: fee);

lib/view_model/send/send_template_view_model.dart

@@ -1,4 +1,4 @@
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 import 'package:mobx/mobx.dart';
 import 'package:cake_wallet/entities/template.dart';
 import 'package:cake_wallet/store/templates/send_template_store.dart';
@@ -21,10 +21,10 @@ abstract class SendTemplateViewModelBase with Store {
   SendTemplateViewModelBase(this._wallet, this._settingsStore,
       this._sendTemplateStore, this._fiatConversationStore) {
 
-    sendItem = SendItem(_wallet, _settingsStore, _fiatConversationStore);
+    output = Output(_wallet, _settingsStore, _fiatConversationStore);
   }
 
-  SendItem sendItem;
+  Output output;
 
   Validator get amountValidator => AmountValidator(type: _wallet.type);
 

lib/view_model/send/send_view_model.dart

@@ -2,7 +2,7 @@ import 'package:cake_wallet/bitcoin/bitcoin_transaction_priority.dart';
 import 'package:cake_wallet/bitcoin/electrum_wallet.dart';
 import 'package:cake_wallet/entities/transaction_description.dart';
 import 'package:cake_wallet/entities/transaction_priority.dart';
-import 'package:cake_wallet/view_model/send/send_item.dart';
+import 'package:cake_wallet/view_model/send/output.dart';
 import 'package:cake_wallet/view_model/send/send_template_view_model.dart';
 import 'package:cake_wallet/view_model/settings/settings_view_model.dart';
 import 'package:hive/hive.dart';
@@ -42,33 +42,33 @@ abstract class SendViewModelBase with Store {
       _settingsStore.priority[_wallet.type] = priorities.first;
     }
 
-    sendItemList = ObservableList<SendItem>()
+    outputs = ObservableList<Output>()
-      ..add(SendItem(_wallet, _settingsStore, _fiatConversationStore));
+      ..add(Output(_wallet, _settingsStore, _fiatConversationStore));
   }
 
   @observable
   ExecutionState state;
 
-  ObservableList<SendItem> sendItemList;
+  ObservableList<Output> outputs;
 
   @action
-  void addSendItem() {
+  void addOutput() {
-    sendItemList.add(SendItem(_wallet, _settingsStore, _fiatConversationStore));
+    outputs.add(Output(_wallet, _settingsStore, _fiatConversationStore));
   }
 
   @action
-  void removeSendItem(SendItem item) {
+  void removeOutput(Output output) {
-    sendItemList.remove(item);
+    outputs.remove(output);
   }
 
   @action
-  void clearSendItemList() {
+  void clearOutputs() {
-    sendItemList.clear();
+    outputs.clear();
-    addSendItem();
+    addOutput();
   }
 
   @computed
-  bool get isBatchSending => sendItemList.length > 1;
+  bool get isBatchSending => outputs.length > 1;
 
   @computed
   String get pendingTransactionFiatAmount {
@@ -150,14 +150,14 @@ abstract class SendViewModelBase with Store {
 
   @action
   Future<void> commitTransaction() async {
-    String address = sendItemList.fold('', (previousValue, item) {
+    String address = outputs.fold('', (acc, value) {
-      return previousValue + item.address + '\n';
+      return acc + value.address + '\n';
     });
 
     address = address.trim();
 
-    String note = sendItemList.fold('', (previousValue, item) {
+    String note = outputs.fold('', (acc, value) {
-      return previousValue + item.note + '\n';
+      return acc + value.note + '\n';
     });
 
     note = note.trim();
@@ -192,17 +192,17 @@ abstract class SendViewModelBase with Store {
         final priority = _settingsStore.priority[_wallet.type];
 
         return BitcoinTransactionCredentials(
-            sendItemList, priority as BitcoinTransactionPriority);
+            outputs, priority as BitcoinTransactionPriority);
       case WalletType.litecoin:
         final priority = _settingsStore.priority[_wallet.type];
 
         return BitcoinTransactionCredentials(
-            sendItemList, priority as BitcoinTransactionPriority);
+            outputs, priority as BitcoinTransactionPriority);
       case WalletType.monero:
         final priority = _settingsStore.priority[_wallet.type];
 
         return MoneroTransactionCreationCredentials(
-            sendItemList: sendItemList,
+            outputs: outputs,
             priority: priority as MoneroTransactionPriority);
       default:
         return null;