replace get supportsTor with an exchangesWithTorSupport List<Exchange>

more convenient to use elsewhere

lib/pages/exchange_view/exchange_coin_selection/exchange_currency_selection_view.dart

@@ -24,6 +24,7 @@ import 'package:stackwallet/themes/stack_colors.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/prefs.dart';
 import 'package:stackwallet/utilities/text_styles.dart';
 import 'package:stackwallet/utilities/util.dart';
 import 'package:stackwallet/widgets/background.dart';
@@ -39,6 +40,8 @@ import 'package:stackwallet/widgets/stack_dialog.dart';
 import 'package:stackwallet/widgets/stack_text_field.dart';
 import 'package:stackwallet/widgets/textfield_icon_button.dart';
 
+import '../../../services/exchange/exchange.dart';
+
 class ExchangeCurrencySelectionView extends StatefulWidget {
   const ExchangeCurrencySelectionView({
     Key? key,
@@ -165,20 +168,25 @@ class _ExchangeCurrencySelectionViewState
                 .rateTypeEqualTo(SupportedRateType.both)
                 .or()
                 .rateTypeEqualTo(SupportedRateType.fixed)
-                .and()
-                .not()
-                .exchangeNameEqualTo(ChangeNowExchange.exchangeName)
             : q
                 .rateTypeEqualTo(SupportedRateType.both)
                 .or()
-                .rateTypeEqualTo(SupportedRateType.estimated)
-                .and()
-                .not()
-                .exchangeNameEqualTo(ChangeNowExchange.exchangeName))
+                .rateTypeEqualTo(SupportedRateType.estimated))
         .sortByIsStackCoin()
         .thenByName()
         .findAll();
 
+    // If using Tor, filter exchanges which do not support Tor.
+    if (Prefs.instance.useTor) {
+      if (Exchange.exchangesWithTorSupport.isNotEmpty) {
+        currencies
+            .removeWhere((element) => !Exchange.exchangesWithTorSupport.any(
+                  (e) => e.name == element.exchangeName,
+                ));
+        // Could have also filtered using the List<String> Exchange.exchangeNamesWithTorSupport.  But I didn't.  This is fancier.
+      }
+    }
+
     return _getDistinctCurrenciesFrom(currencies);
   }
 

lib/pages/exchange_view/exchange_form.dart

@@ -31,15 +31,19 @@ import 'package:stackwallet/pages/exchange_view/sub_widgets/rate_type_toggle.dar
 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.dart';
 import 'package:stackwallet/services/exchange/exchange_data_loading_service.dart';
+import 'package:stackwallet/services/exchange/exchange_response.dart';
 import 'package:stackwallet/services/exchange/majestic_bank/majestic_bank_exchange.dart';
 import 'package:stackwallet/services/exchange/trocador/trocador_exchange.dart';
+import 'package:stackwallet/services/tor_service.dart';
 import 'package:stackwallet/themes/stack_colors.dart';
 import 'package:stackwallet/utilities/amount/amount_unit.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/prefs.dart';
 import 'package:stackwallet/utilities/text_styles.dart';
 import 'package:stackwallet/utilities/util.dart';
 import 'package:stackwallet/widgets/conditional_parent.dart';
@@ -55,8 +59,6 @@ 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,
@@ -78,7 +80,7 @@ class _ExchangeFormState extends ConsumerState<ExchangeForm> {
   late final Coin? coin;
   late final bool walletInitiated;
 
-  final exchanges = [
+  var exchanges = [
     MajesticBankExchange.instance,
     ChangeNowExchange.instance,
     TrocadorExchange.instance,
@@ -773,6 +775,14 @@ class _ExchangeFormState extends ConsumerState<ExchangeForm> {
       });
     }
 
+    // Instantiate the Tor service.
+    torService = TorService.sharedInstance;
+
+    // Filter exchanges based on Tor support.
+    if (Prefs.instance.useTor) {
+      exchanges = Exchange.exchangesWithTorSupport;
+    }
+
     super.initState();
   }
 
@@ -1007,4 +1017,7 @@ class _ExchangeFormState extends ConsumerState<ExchangeForm> {
       ],
     );
   }
+
+  // TorService instance.
+  late TorService torService;
 }

lib/services/exchange/exchange.dart

@@ -91,6 +91,24 @@ abstract class Exchange {
     required bool reversed,
   });
 
-  // Flag to indicate that the exchange supports Tor.
-  bool get supportsTor => false;
+  /// List of exchanges which support Tor.
+  ///
+  /// Add to this list when adding a new exchange which supports Tor.
+  static List<Exchange> get exchangesWithTorSupport => [
+        MajesticBankExchange.instance,
+        TrocadorExchange.instance,
+      ];
+
+  /// List of exchange names which support Tor.
+  ///
+  /// Convenience method for when you just want to check for a String
+  /// .exchangeName instead of Exchange instances. Shouldn't need to be updated
+  /// as long as the above List is updated.
+  static List<String> get exchangeNamesWithTorSupport =>
+      exchangesWithTorSupport.map((exchange) => exchange.name).toList();
+  // Instead of using this, you can do like:
+  // currencies
+  //     .removeWhere((element) => !Exchange.exchangesWithTorSupport.any(
+  //             (e) => e.name == element.exchangeName,
+  //         ));
 }

lib/services/exchange/exchange_data_loading_service.dart

@@ -20,6 +20,7 @@ import 'package:stackwallet/services/exchange/majestic_bank/majestic_bank_exchan
 import 'package:stackwallet/services/exchange/trocador/trocador_exchange.dart';
 import 'package:stackwallet/utilities/enums/exchange_rate_type_enum.dart';
 import 'package:stackwallet/utilities/logger.dart';
+import 'package:stackwallet/utilities/prefs.dart';
 import 'package:stackwallet/utilities/stack_file_system.dart';
 import 'package:tuple/tuple.dart';
 
@@ -145,6 +146,7 @@ class ExchangeDataLoadingService {
       final start = DateTime.now();
       try {
         /*
+        // Old exchange data loading code.
         await Future.wait([
           _loadChangeNowCurrencies(),
           // _loadChangeNowFixedRatePairs(),
@@ -159,16 +161,19 @@ class ExchangeDataLoadingService {
         // await _loadChangeNowFixedRatePairs();
         // await _loadChangeNowEstimatedRatePairs();
          */
-        // Use the supportsTor flag to filter out unsupported exchanges.
-        if (ChangeNowExchange.instance.supportsTor) {
+
+        // If using Tor, don't load data for exchanges which don't support Tor.
+        //
+        // Add to this list when adding an exchange which doesn't supports Tor.
+        if (!Prefs.instance.useTor) {
           await _loadChangeNowCurrencies();
         }
-        if (MajesticBankExchange.instance.supportsTor) {
-          await loadMajesticBankCurrencies();
-        }
-        if (TrocadorExchange.instance.supportsTor) {
-          await loadTrocadorCurrencies();
-        }
+
+        // Exchanges which support Tor just get treated normally.
+        await Future.wait([
+          loadMajesticBankCurrencies(),
+          loadTrocadorCurrencies(),
+        ]);
 
         Logging.instance.log(
           "ExchangeDataLoadingService.loadAll finished in ${DateTime.now().difference(start).inSeconds} seconds",