use simple setState for toggling between buy with crypto/fiat and store current selected crypto/fiat values in state vars and update ui accordingly

lib/pages/buy_view/buy_form.dart

@@ -11,7 +11,6 @@ import 'package:stackwallet/models/buy/response_objects/quote.dart';
 import 'package:stackwallet/pages/address_book_views/address_book_view.dart';
 import 'package:stackwallet/pages/buy_view/buy_quote_preview.dart';
 import 'package:stackwallet/pages/buy_view/sub_widgets/crypto_selection_view.dart';
-import 'package:stackwallet/pages/buy_view/sub_widgets/fiat_crypto_toggle.dart';
 import 'package:stackwallet/pages/buy_view/sub_widgets/fiat_selection_view.dart';
 import 'package:stackwallet/pages/exchange_view/choose_from_stack_view.dart';
 import 'package:stackwallet/providers/providers.dart';
@@ -352,9 +351,6 @@ class _BuyFormState extends ConsumerState<BuyForm> {
   Widget build(BuildContext context) {
     debugPrint("BUILD: $runtimeType");
 
-    buyWithFiat = ref.watch(
-        prefsChangeNotifierProvider.select((value) => value.buyWithFiat));
-
     return ConditionalParent(
       condition: isDesktop,
       builder: (child) => SizedBox(
@@ -409,7 +405,8 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                           .textFieldDefaultBG,
                   child: Padding(
                     padding: const EdgeInsets.all(12),
-                    child: Row(children: <Widget>[
+                    child: Row(
+                      children: <Widget>[
                         SvgPicture.asset(
                           Assets.svg.iconFor(
                             coin: coinFromTickerCaseInsensitive("BTC"),
@@ -422,9 +419,10 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                         ),
                         Expanded(
                           child: Text(
-                        "BTC",
+                            selectedCrypto?.ticker ?? "ERR",
                             style: STextStyles.largeMedium14(context),
-                      )),
+                          ),
+                        ),
                         SvgPicture.asset(
                           Assets.svg.chevronDown,
                           color: Theme.of(context)
@@ -433,7 +431,8 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                           width: 10,
                           height: 5,
                         ),
-                    ]),
+                      ],
+                    ),
                   ),
                 ),
               ),
@@ -457,7 +456,6 @@ class _BuyFormState extends ConsumerState<BuyForm> {
             SizedBox(
               height: isDesktop ? 10 : 4,
             ),
-
             MouseRegion(
               cursor: SystemMouseCursors.click,
               onEnter: (_) => setState(() => _hovering2 = true),
@@ -479,7 +477,8 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                           .textFieldDefaultBG,
                   child: Padding(
                     padding: const EdgeInsets.all(12),
-                    child: Row(children: <Widget>[
+                    child: Row(
+                      children: <Widget>[
                         RoundedContainer(
                           radiusMultiplier: 0.5,
                           padding: const EdgeInsets.symmetric(
@@ -504,9 +503,10 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                         ),
                         Expanded(
                           child: Text(
-                        "USD",
+                            selectedFiat?.ticker ?? "ERR",
                             style: STextStyles.largeMedium14(context),
-                      )),
+                          ),
+                        ),
                         SvgPicture.asset(
                           Assets.svg.chevronDown,
                           color: Theme.of(context)
@@ -515,7 +515,8 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                           width: 10,
                           height: 5,
                         ),
-                    ]),
+                      ],
+                    ),
                   ),
                 ),
               ),
@@ -534,12 +535,16 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                         Theme.of(context).extension<StackColors>()!.textDark3,
                   ),
                 ),
-                const FiatCryptoToggle(),
+                BlueTextButton(
+                  text: buyWithFiat ? "Use crypto amount" : "Use fiat amount",
+                  onTap: () {
+                    setState(() {
+                      buyWithFiat = !buyWithFiat;
+                    });
+                  },
+                )
               ],
             ),
-            // // these reads should be watch
-            // if (ref.watch(buyFormStateProvider).fromAmount != null &&
-            //     ref.watch(buyFormStateProvider).fromAmount != Decimal.zero)
             SizedBox(
               height: isDesktop ? 10 : 4,
             ),
@@ -560,13 +565,20 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                     ),
               textAlign: TextAlign.right,
               inputFormatters: [
-                // TODO reactivate formatter
+                // regex to validate a crypto amount with 8 decimal places or
-                // regex to validate a crypto amount with 8 decimal places
+                // 2 if fiat
-                // TextInputFormatter.withFunction((oldValue, newValue) =>
+                TextInputFormatter.withFunction(
-                //     RegExp(r'^([0-9]*[,.]?[0-9]{0,8}|[,.][0-9]{0,8})$')
+                  (oldValue, newValue) {
-                //             .hasMatch(newValue.text)
+                    final regexString = buyWithFiat
-                //         ? newValue
+                        ? r'^([0-9]*[,.]?[0-9]{0,2}|[,.][0-9]{0,2})$'
-                //         : oldValue),
+                        : r'^([0-9]*[,.]?[0-9]{0,8}|[,.][0-9]{0,8})$';
+
+                    // return RegExp(r'^([0-9]*[,.]?[0-9]{0,8}|[,.][0-9]{0,8})$')
+                    return RegExp(regexString).hasMatch(newValue.text)
+                        ? newValue
+                        : oldValue;
+                  },
+                ),
               ],
               decoration: InputDecoration(
                 contentPadding: const EdgeInsets.only(
@@ -585,7 +597,9 @@ class _BuyFormState extends ConsumerState<BuyForm> {
                   child: Padding(
                     padding: const EdgeInsets.all(12),
                     child: Text(
-                      "BTC",
+                      buyWithFiat
+                          ? selectedFiat?.ticker ?? "ERR"
+                          : selectedCrypto?.ticker ?? "ERR",
                       style: STextStyles.smallMed14(context).copyWith(
                           color: Theme.of(context)
                               .extension<StackColors>()!

lib/pages/buy_view/sub_widgets/fiat_crypto_toggle.dart

@@ -1,28 +0,0 @@
-import 'package:flutter/material.dart';
-import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:stackwallet/providers/providers.dart';
-import 'package:stackwallet/widgets/custom_buttons/blue_text_button.dart';
-
-class FiatCryptoToggle extends ConsumerWidget {
-  const FiatCryptoToggle({
-    Key? key,
-  }) : super(key: key);
-
-  @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    debugPrint("BUILD: $runtimeType");
-
-    return BlueTextButton(
-      text: ref.watch(
-              prefsChangeNotifierProvider.select((value) => value.buyWithFiat))
-          ? "Use crypto amount"
-          : "Use fiat amount",
-      textSize: 14,
-      onTap: () {
-        final buyWithFiat = ref.read(prefsChangeNotifierProvider).buyWithFiat;
-        ref.read(prefsChangeNotifierProvider).buyWithFiat = !buyWithFiat;
-        // Navigator.of(context).pop();
-      },
-    );
-  }
-}

lib/utilities/prefs.dart

@@ -38,7 +38,6 @@ class Prefs extends ChangeNotifier {
       _startupWalletId = await _getStartupWalletId();
       _externalCalls = await _getHasExternalCalls();
       _familiarity = await _getHasFamiliarity();
-      _buyWithFiat = await _getBuyWithFiat();
 
       _initialized = true;
     }
@@ -351,25 +350,6 @@ class Prefs extends ChangeNotifier {
         0;
   }
 
-  // buy with fiat (default) or crypto
-  bool _buyWithFiat = true;
-  bool get buyWithFiat => _buyWithFiat;
-
-  set buyWithFiat(bool buyWithFiat) {
-    if (this.buyWithFiat != buyWithFiat) {
-      DB.instance.put<dynamic>(
-          boxName: DB.boxNamePrefs, key: "buyWithFiat", value: buyWithFiat);
-      _buyWithFiat = buyWithFiat;
-      notifyListeners();
-    }
-  }
-
-  Future<bool> _getBuyWithFiat() async {
-    return await DB.instance.get<dynamic>(
-            boxName: DB.boxNamePrefs, key: "buyWithFiat") as bool? ??
-        true;
-  }
-
   // show testnet coins
 
   bool _showTestNetCoins = false;