import 'dart:async'; import 'package:decimal/decimal.dart'; import 'package:flutter/material.dart'; import 'package:flutter_riverpod/flutter_riverpod.dart'; import 'package:flutter_svg/flutter_svg.dart'; import 'package:flutter_svg/svg.dart'; import 'package:intl/intl.dart'; import 'package:isar/isar.dart'; import 'package:stackwallet/models/exchange/aggregate_currency.dart'; import 'package:stackwallet/models/exchange/incomplete_exchange.dart'; import 'package:stackwallet/models/exchange/response_objects/estimate.dart'; import 'package:stackwallet/models/exchange/response_objects/range.dart'; import 'package:stackwallet/models/isar/exchange_cache/currency.dart'; import 'package:stackwallet/models/isar/exchange_cache/pair.dart'; import 'package:stackwallet/models/isar/models/ethereum/eth_contract.dart'; import 'package:stackwallet/pages/exchange_view/exchange_coin_selection/exchange_currency_selection_view.dart'; import 'package:stackwallet/pages/exchange_view/exchange_step_views/step_1_view.dart'; import 'package:stackwallet/pages/exchange_view/exchange_step_views/step_2_view.dart'; import 'package:stackwallet/pages/exchange_view/sub_widgets/exchange_provider_options.dart'; import 'package:stackwallet/pages/exchange_view/sub_widgets/rate_type_toggle.dart'; import 'package:stackwallet/pages_desktop_specific/desktop_exchange/exchange_steps/step_scaffold.dart'; import 'package:stackwallet/providers/providers.dart'; import 'package:stackwallet/services/exchange/change_now/change_now_exchange.dart'; import 'package:stackwallet/services/exchange/exchange_data_loading_service.dart'; import 'package:stackwallet/services/exchange/majestic_bank/majestic_bank_exchange.dart'; import 'package:stackwallet/services/exchange/trocador/trocador_exchange.dart'; import 'package:stackwallet/utilities/assets.dart'; import 'package:stackwallet/utilities/constants.dart'; import 'package:stackwallet/utilities/enums/coin_enum.dart'; import 'package:stackwallet/utilities/enums/exchange_rate_type_enum.dart'; import 'package:stackwallet/utilities/text_styles.dart'; import 'package:stackwallet/utilities/theme/stack_colors.dart'; import 'package:stackwallet/utilities/util.dart'; import 'package:stackwallet/widgets/conditional_parent.dart'; import 'package:stackwallet/widgets/custom_loading_overlay.dart'; import 'package:stackwallet/widgets/desktop/desktop_dialog.dart'; import 'package:stackwallet/widgets/desktop/desktop_dialog_close_button.dart'; import 'package:stackwallet/widgets/desktop/primary_button.dart'; import 'package:stackwallet/widgets/desktop/secondary_button.dart'; import 'package:stackwallet/widgets/rounded_container.dart'; import 'package:stackwallet/widgets/rounded_white_container.dart'; import 'package:stackwallet/widgets/stack_dialog.dart'; import 'package:stackwallet/widgets/textfields/exchange_textfield.dart'; import 'package:tuple/tuple.dart'; import 'package:uuid/uuid.dart'; import '../../services/exchange/exchange_response.dart'; class ExchangeForm extends ConsumerStatefulWidget { const ExchangeForm({ Key? key, this.walletId, this.coin, this.contract, }) : super(key: key); final String? walletId; final Coin? coin; final EthContract? contract; @override ConsumerState createState() => _ExchangeFormState(); } class _ExchangeFormState extends ConsumerState { late final String? walletId; late final Coin? coin; late final bool walletInitiated; final exchanges = [ MajesticBankExchange.instance, ChangeNowExchange.instance, TrocadorExchange.instance, ]; late final TextEditingController _sendController; late final TextEditingController _receiveController; final isDesktop = Util.isDesktop; final FocusNode _sendFocusNode = FocusNode(); final FocusNode _receiveFocusNode = FocusNode(); bool _swapLock = false; // todo: check and adjust this value? static const _valueCheckInterval = Duration(milliseconds: 1500); Future showUpdatingExchangeRate({ required Future whileFuture, }) async { unawaited( showDialog( context: context, barrierDismissible: false, builder: (_) => WillPopScope( onWillPop: () async => false, child: Container( color: Theme.of(context) .extension()! .overlay .withOpacity(0.6), child: const CustomLoadingOverlay( message: "Updating exchange rate", eventBus: null, ), ), ), ), ); final result = await whileFuture; if (mounted) { Navigator.of(context, rootNavigator: isDesktop).pop(); } return result; } Timer? _sendFieldOnChangedTimer; void sendFieldOnChanged(String value) { if (_sendFocusNode.hasFocus) { _sendFieldOnChangedTimer?.cancel(); _sendFieldOnChangedTimer = Timer(_valueCheckInterval, () async { final newFromAmount = _localizedStringToNum(value); ref.read(efSendAmountProvider.notifier).state = newFromAmount; if (!_swapLock && !ref.read(efReversedProvider)) { unawaited(update()); } }); } } Timer? _receiveFieldOnChangedTimer; void receiveFieldOnChanged(String value) async { _receiveFieldOnChangedTimer?.cancel(); _receiveFieldOnChangedTimer = Timer(_valueCheckInterval, () async { final newToAmount = _localizedStringToNum(value); ref.read(efReceiveAmountProvider.notifier).state = newToAmount; if (!_swapLock && ref.read(efReversedProvider)) { unawaited(update()); } }); } Decimal? _localizedStringToNum(String? value) { if (value == null) { return null; } try { final numFromLocalised = NumberFormat.decimalPattern( ref.read(localeServiceChangeNotifierProvider).locale) .parse(value); return Decimal.tryParse(numFromLocalised.toString()); } catch (_) { return null; } } Future _getAggregateCurrency(Currency currency) async { final rateType = ref.read(efRateTypeProvider); final currencies = await ExchangeDataLoadingService.instance.isar.currencies .filter() .group((q) => rateType == ExchangeRateType.fixed ? q .rateTypeEqualTo(SupportedRateType.both) .or() .rateTypeEqualTo(SupportedRateType.fixed) : q .rateTypeEqualTo(SupportedRateType.both) .or() .rateTypeEqualTo(SupportedRateType.estimated)) .and() .tickerEqualTo( currency.ticker, caseSensitive: false, ) .and() .tokenContractEqualTo(currency.tokenContract) .findAll(); final items = [Tuple2(currency.exchangeName, currency)]; for (final currency in currencies) { items.add(Tuple2(currency.exchangeName, currency)); } return AggregateCurrency(exchangeCurrencyPairs: items); } void selectSendCurrency() async { final type = ref.read(efRateTypeProvider); final fromTicker = ref.read(efCurrencyPairProvider).send?.ticker ?? ""; if (walletInitiated) { if (widget.contract != null && fromTicker.toLowerCase() == widget.contract!.symbol.toLowerCase()) { return; } if (fromTicker.toLowerCase() == coin!.ticker.toLowerCase()) { // do not allow changing away from wallet coin return; } } final selectedCurrency = await _showCurrencySelectionSheet( willChange: ref.read(efCurrencyPairProvider).send?.ticker, willChangeIsSend: true, paired: ref.read(efCurrencyPairProvider).receive?.ticker, isFixedRate: type == ExchangeRateType.fixed, ); if (selectedCurrency != null) { await showUpdatingExchangeRate( whileFuture: _getAggregateCurrency(selectedCurrency).then( (aggregateSelected) => ref.read(efCurrencyPairProvider).setSend( aggregateSelected, notifyListeners: true, ), ), ); } } void selectReceiveCurrency() async { final toTicker = ref.read(efCurrencyPairProvider).receive?.ticker ?? ""; if (walletInitiated && toTicker.toLowerCase() == coin!.ticker.toLowerCase()) { // do not allow changing away from wallet coin return; } final selectedCurrency = await _showCurrencySelectionSheet( willChange: ref.read(efCurrencyPairProvider).receive?.ticker, willChangeIsSend: false, paired: ref.read(efCurrencyPairProvider).send?.ticker, isFixedRate: ref.read(efRateTypeProvider) == ExchangeRateType.fixed, ); if (selectedCurrency != null) { await showUpdatingExchangeRate( whileFuture: _getAggregateCurrency(selectedCurrency).then( (aggregateSelected) => ref.read(efCurrencyPairProvider).setReceive( aggregateSelected, notifyListeners: true, ), ), ); } } Future _swap() async { _swapLock = true; _sendFocusNode.unfocus(); _receiveFocusNode.unfocus(); final temp = ref.read(efCurrencyPairProvider).send; ref.read(efCurrencyPairProvider).setSend( ref.read(efCurrencyPairProvider).receive, notifyListeners: true, ); ref.read(efCurrencyPairProvider).setReceive( temp, notifyListeners: true, ); // final reversed = ref.read(efReversedProvider); final amount = ref.read(efSendAmountProvider); ref.read(efSendAmountProvider.notifier).state = ref.read(efReceiveAmountProvider); ref.read(efReceiveAmountProvider.notifier).state = amount; unawaited(update()); _swapLock = false; } Future _showCurrencySelectionSheet({ required String? willChange, required String? paired, required bool isFixedRate, required bool willChangeIsSend, }) async { _sendFocusNode.unfocus(); _receiveFocusNode.unfocus(); final result = isDesktop ? await showDialog( context: context, builder: (context) { return DesktopDialog( maxHeight: 700, maxWidth: 580, child: Column( children: [ Row( mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Padding( padding: const EdgeInsets.only( left: 32, ), child: Text( "Choose a coin to exchange", style: STextStyles.desktopH3(context), ), ), const DesktopDialogCloseButton(), ], ), Expanded( child: Padding( padding: const EdgeInsets.only( left: 32, right: 32, bottom: 32, ), child: Row( children: [ Expanded( child: RoundedWhiteContainer( padding: const EdgeInsets.all(16), borderColor: Theme.of(context) .extension()! .background, child: ExchangeCurrencySelectionView( willChangeTicker: willChange, pairedTicker: paired, isFixedRate: isFixedRate, willChangeIsSend: willChangeIsSend, ), ), ), ], ), ), ), ], ), ); }) : await Navigator.of(context).push( MaterialPageRoute( builder: (_) => ExchangeCurrencySelectionView( willChangeTicker: willChange, pairedTicker: paired, isFixedRate: isFixedRate, willChangeIsSend: willChangeIsSend, ), ), ); if (mounted && result is Currency) { return result; } else { return null; } } void onRateTypeChanged(ExchangeRateType newType) { _receiveFocusNode.unfocus(); _sendFocusNode.unfocus(); ref.read(efRateTypeProvider.notifier).state = newType; update(); } void onExchangePressed() async { final rateType = ref.read(efRateTypeProvider); final fromTicker = ref.read(efCurrencyPairProvider).send?.ticker ?? ""; final toTicker = ref.read(efCurrencyPairProvider).receive?.ticker ?? ""; final estimate = ref.read(efEstimateProvider)!; final sendAmount = ref.read(efSendAmountProvider)!; if (rateType == ExchangeRateType.fixed && toTicker.toUpperCase() == "WOW") { await showDialog( context: context, builder: (context) => const StackOkDialog( title: "WOW error", message: "Wownero is temporarily disabled as a receiving currency for fixed rate trades due to network issues", ), ); return; } String rate; final amountToSend = estimate.reversed ? estimate.estimatedAmount : sendAmount; final amountToReceive = estimate.reversed ? ref.read(efReceiveAmountProvider)! : estimate.estimatedAmount; switch (rateType) { case ExchangeRateType.estimated: rate = "1 ${fromTicker.toUpperCase()} ~${(amountToReceive / sendAmount).toDecimal(scaleOnInfinitePrecision: 8).toStringAsFixed(8)} ${toTicker.toUpperCase()}"; break; case ExchangeRateType.fixed: bool? shouldCancel; if (estimate.warningMessage != null && estimate.warningMessage!.isNotEmpty) { shouldCancel = await showDialog( context: context, barrierDismissible: true, builder: (_) { if (isDesktop) { return DesktopDialog( maxWidth: 500, maxHeight: 300, child: Column( crossAxisAlignment: CrossAxisAlignment.start, children: [ Row( mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Text( "Failed to update trade estimate", style: STextStyles.desktopH3(context), ), const DesktopDialogCloseButton(), ], ), const Spacer(), Text( estimate.warningMessage!, style: STextStyles.desktopTextSmall(context), ), const Spacer(), Text( "Do you want to attempt trade anyways?", style: STextStyles.desktopTextSmall(context), ), const Spacer( flex: 2, ), Row( children: [ Expanded( child: SecondaryButton( label: "Cancel", buttonHeight: ButtonHeight.l, onPressed: () => Navigator.of( context, rootNavigator: true, ).pop(true), ), ), const SizedBox( width: 16, ), Expanded( child: PrimaryButton( label: "Attempt", buttonHeight: ButtonHeight.l, onPressed: () => Navigator.of( context, rootNavigator: true, ).pop(false), ), ), ], ) ], ), ); } else { return StackDialog( title: "Failed to update trade estimate", message: "${estimate.warningMessage!}\n\nDo you want to attempt trade anyways?", leftButton: TextButton( style: Theme.of(context) .extension()! .getSecondaryEnabledButtonStyle(context), child: Text( "Cancel", style: STextStyles.itemSubtitle12(context), ), onPressed: () { // notify return to cancel Navigator.of(context).pop(true); }, ), rightButton: TextButton( style: Theme.of(context) .extension()! .getPrimaryEnabledButtonStyle(context), child: Text( "Attempt", style: STextStyles.button(context), ), onPressed: () { // continue and try to attempt trade Navigator.of(context).pop(false); }, ), ); } }, ); } if (shouldCancel is bool && shouldCancel) { return; } rate = "1 ${fromTicker.toUpperCase()} ~${(amountToReceive / amountToSend).toDecimal( scaleOnInfinitePrecision: 12, ).toStringAsFixed(8)} ${toTicker.toUpperCase()}"; break; } final model = IncompleteExchangeModel( sendTicker: fromTicker.toUpperCase(), receiveTicker: toTicker.toUpperCase(), rateInfo: rate, sendAmount: amountToSend, receiveAmount: amountToReceive, rateType: rateType, estimate: estimate, reversed: estimate.reversed, walletInitiated: walletInitiated, ); if (mounted) { if (walletInitiated) { ref.read(exchangeSendFromWalletIdStateProvider.state).state = Tuple2(walletId!, coin!); if (isDesktop) { ref.read(ssss.state).state = model; await showDialog( context: context, barrierDismissible: false, builder: (context) { return const DesktopDialog( maxWidth: 720, maxHeight: double.infinity, child: StepScaffold( initialStep: 2, ), ); }, ); } else { unawaited( Navigator.of(context).pushNamed( Step2View.routeName, arguments: model, ), ); } } else { ref.read(exchangeSendFromWalletIdStateProvider.state).state = null; if (isDesktop) { ref.read(ssss.state).state = model; await showDialog( context: context, barrierDismissible: false, builder: (context) { return const DesktopDialog( maxWidth: 720, maxHeight: double.infinity, child: StepScaffold( initialStep: 1, ), ); }, ); } else { unawaited( Navigator.of(context).pushNamed( Step1View.routeName, arguments: model, ), ); } } } } bool isWalletCoin(Coin? coin, bool isSend) { if (coin == null) { return false; } String? ticker = isSend ? ref.read(efCurrencyPairProvider).send?.ticker : ref.read(efCurrencyPairProvider).receive?.ticker; if (ticker == null) { return false; } return coin.ticker.toUpperCase() == ticker.toUpperCase(); } Future update() async { final uuid = const Uuid().v1(); _latestUuid = uuid; _addUpdate(uuid); for (final exchange in exchanges) { ref.read(efEstimatesListProvider(exchange.name).notifier).state = null; } final reversed = ref.read(efReversedProvider); final amount = reversed ? ref.read(efReceiveAmountProvider) : ref.read(efSendAmountProvider); final pair = ref.read(efCurrencyPairProvider); if (amount == null || amount <= Decimal.zero || pair.send == null || pair.receive == null) { _removeUpdate(uuid); return; } final rateType = ref.read(efRateTypeProvider); final Map>, Range?>> results = {}; for (final exchange in exchanges) { final sendCurrency = pair.send?.forExchange(exchange.name); final receiveCurrency = pair.receive?.forExchange(exchange.name); if (sendCurrency != null && receiveCurrency != null) { final rangeResponse = await exchange.getRange( reversed ? receiveCurrency.ticker : sendCurrency.ticker, reversed ? sendCurrency.ticker : receiveCurrency.ticker, rateType == ExchangeRateType.fixed, ); final estimateResponse = await exchange.getEstimates( sendCurrency.ticker, receiveCurrency.ticker, amount, rateType == ExchangeRateType.fixed, reversed, ); results.addAll( { exchange.name: Tuple2( estimateResponse, rangeResponse.value, ), }, ); } } for (final exchange in exchanges) { if (uuid == _latestUuid) { ref.read(efEstimatesListProvider(exchange.name).notifier).state = results[exchange.name]; } } _removeUpdate(uuid); } String? _latestUuid; final Set _uuids = {}; void _addUpdate(String uuid) { _uuids.add(uuid); ref.read(efRefreshingProvider.notifier).state = true; } void _removeUpdate(String uuid) { _uuids.remove(uuid); if (_uuids.isEmpty) { WidgetsBinding.instance.addPostFrameCallback((_) { ref.read(efRefreshingProvider.notifier).state = false; }); } } void updateSend(Estimate? estimate) { ref.read(efSendAmountProvider.notifier).state = estimate?.estimatedAmount; } void updateReceive(Estimate? estimate) { ref.read(efReceiveAmountProvider.notifier).state = estimate?.estimatedAmount; } @override void initState() { _sendController = TextEditingController(); _receiveController = TextEditingController(); walletId = widget.walletId; coin = widget.coin; walletInitiated = walletId != null && coin != null; _sendFocusNode.addListener(() { if (_sendFocusNode.hasFocus) { final reversed = ref.read(efReversedProvider); WidgetsBinding.instance.addPostFrameCallback((_) { ref.read(efReversedProvider.notifier).state = false; if (reversed == true) { update(); } }); } }); _receiveFocusNode.addListener(() { if (_receiveFocusNode.hasFocus && ref.read(efExchangeProvider).name != ChangeNowExchange.exchangeName) { final reversed = ref.read(efReversedProvider); WidgetsBinding.instance.addPostFrameCallback((_) { ref.read(efReversedProvider.notifier).state = true; if (reversed != true) { update(); } }); } }); if (walletInitiated) { WidgetsBinding.instance.addPostFrameCallback((timeStamp) { ref.read(efSendAmountProvider.notifier).state = null; ref.read(efReceiveAmountProvider.notifier).state = null; ref.read(efReversedProvider.notifier).state = false; ref.read(efRefreshingProvider.notifier).state = false; ref.read(efCurrencyPairProvider).setSend(null, notifyListeners: true); ref .read(efCurrencyPairProvider) .setReceive(null, notifyListeners: true); ExchangeDataLoadingService.instance .getAggregateCurrency( widget.contract == null ? coin!.ticker : widget.contract!.symbol, ExchangeRateType.estimated, widget.contract == null ? null : widget.contract!.address, ) .then((value) { if (value != null) { ref.read(efCurrencyPairProvider).setSend( value, notifyListeners: true, ); } }); }); } else { WidgetsBinding.instance.addPostFrameCallback((timeStamp) { _sendController.text = ref.read(efSendAmountStringProvider); _receiveController.text = ref.read(efReceiveAmountStringProvider); }); } super.initState(); } @override void dispose() { _receiveController.dispose(); _sendController.dispose(); _receiveFocusNode.dispose(); _sendFocusNode.dispose(); super.dispose(); } @override Widget build(BuildContext context) { debugPrint("BUILD: $runtimeType"); final rateType = ref.watch(efRateTypeProvider); final isEstimated = rateType == ExchangeRateType.estimated; ref.listen(efReceiveAmountStringProvider, (previous, String next) { if (!_receiveFocusNode.hasFocus) { _receiveController.text = isEstimated && next.isEmpty ? "-" : next; // if (_swapLock) { _sendController.text = ref.read(efSendAmountStringProvider); // } } }); ref.listen(efSendAmountStringProvider, (previous, String next) { if (!_sendFocusNode.hasFocus) { _sendController.text = next; // if (_swapLock) { _receiveController.text = isEstimated && ref.read(efReceiveAmountStringProvider).isEmpty ? "-" : ref.read(efReceiveAmountStringProvider); // } } }); ref.listen(efEstimateProvider.notifier, (previous, next) { final estimate = (next as StateController).state; if (ref.read(efReversedProvider)) { updateSend(estimate); } else { updateReceive(estimate); } }); ref.listen(efCurrencyPairProvider, (previous, next) { if (!_swapLock) { update(); } }); return Column( mainAxisSize: MainAxisSize.min, crossAxisAlignment: CrossAxisAlignment.stretch, children: [ Text( "You will send", style: STextStyles.itemSubtitle(context).copyWith( color: Theme.of(context).extension()!.textDark3, ), ), SizedBox( height: isDesktop ? 10 : 4, ), ExchangeTextField( key: Key("exchangeTextFieldKeyFor_" "${Theme.of(context).extension()!.themeType.name}" "${ref.watch(efCurrencyPairProvider.select((value) => value.send?.ticker))}"), controller: _sendController, focusNode: _sendFocusNode, textStyle: STextStyles.smallMed14(context).copyWith( color: Theme.of(context).extension()!.textDark, ), buttonColor: Theme.of(context).extension()!.buttonBackSecondary, borderRadius: Constants.size.circularBorderRadius, background: Theme.of(context).extension()!.textFieldDefaultBG, onTap: () { if (_sendController.text == "-") { _sendController.text = ""; } }, onChanged: sendFieldOnChanged, onButtonTap: selectSendCurrency, isWalletCoin: isWalletCoin(coin, true), currency: ref.watch(efCurrencyPairProvider.select((value) => value.send)), ), SizedBox( height: isDesktop ? 10 : 4, ), SizedBox( height: isDesktop ? 10 : 4, ), Row( crossAxisAlignment: CrossAxisAlignment.end, mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Text( "You will receive", style: STextStyles.itemSubtitle(context).copyWith( color: Theme.of(context).extension()!.textDark3, ), ), ConditionalParent( condition: isDesktop, builder: (child) => MouseRegion( cursor: SystemMouseCursors.click, child: child, ), child: Semantics( label: "Swap Button. Reverse The Exchange Currencies.", excludeSemantics: true, child: RoundedContainer( padding: isDesktop ? const EdgeInsets.all(6) : const EdgeInsets.all(2), color: Theme.of(context) .extension()! .buttonBackSecondary, radiusMultiplier: 0.75, child: GestureDetector( onTap: () async { await _swap(); }, child: Padding( padding: const EdgeInsets.all(4), child: SvgPicture.asset( Assets.svg.swap, width: 20, height: 20, color: Theme.of(context) .extension()! .accentColorDark, ), ), ), ), ), ), ], ), SizedBox( height: isDesktop ? 10 : 7, ), ExchangeTextField( key: Key( "exchangeTextFieldKeyFor1_${Theme.of(context).extension()!.themeType.name}"), focusNode: _receiveFocusNode, controller: _receiveController, textStyle: STextStyles.smallMed14(context).copyWith( color: Theme.of(context).extension()!.textDark, ), buttonColor: Theme.of(context).extension()!.buttonBackSecondary, borderRadius: Constants.size.circularBorderRadius, background: Theme.of(context).extension()!.textFieldDefaultBG, onTap: rateType == ExchangeRateType.estimated && ref.watch(efExchangeProvider).name == ChangeNowExchange.exchangeName ? null : () { if (_sendController.text == "-") { _sendController.text = ""; } }, onChanged: receiveFieldOnChanged, onButtonTap: selectReceiveCurrency, isWalletCoin: isWalletCoin(coin, true), currency: ref .watch(efCurrencyPairProvider.select((value) => value.receive)), readOnly: rateType == ExchangeRateType.estimated && ref.watch(efExchangeProvider).name == ChangeNowExchange.exchangeName, ), SizedBox( height: isDesktop ? 20 : 12, ), SizedBox( height: isDesktop ? 60 : 40, child: RateTypeToggle( key: UniqueKey(), onChanged: onRateTypeChanged, ), ), Padding( padding: EdgeInsets.only(top: isDesktop ? 20 : 12), child: ExchangeProviderOptions( fixedRate: rateType == ExchangeRateType.fixed, reversed: ref.watch(efReversedProvider), ), ), SizedBox( height: isDesktop ? 20 : 12, ), PrimaryButton( buttonHeight: isDesktop ? ButtonHeight.l : null, enabled: ref.watch(efCanExchangeProvider), onPressed: onExchangePressed, label: "Swap", ) ], ); } }