fiat amount string formatting and parsing and more WIP usages thereof

lib/pages/send_view/send_view.dart

@@ -10,7 +10,6 @@
 
 import 'dart:async';
 import 'dart:io';
-import 'dart:math';
 
 import 'package:bip47/bip47.dart';
 import 'package:cw_core/monero_transaction_priority.dart';
@@ -127,27 +126,13 @@ class _SendViewState extends ConsumerState<SendView> {
 
   void _cryptoAmountChanged() async {
     if (!_cryptoAmountChangeLock) {
-      String cryptoAmount = cryptoAmountController.text;
+      final cryptoAmount = ref.read(pAmountFormatter(coin)).tryParse(
-      if (cryptoAmount.isNotEmpty &&
+            cryptoAmountController.text,
-          cryptoAmount != "." &&
+            locale: ref.read(localeServiceChangeNotifierProvider).locale,
-          cryptoAmount != ",") {
+            coin: coin,
-        if (cryptoAmount.startsWith("~")) {
+          );
-          cryptoAmount = cryptoAmount.substring(1);
+      if (cryptoAmount != null) {
-        }
+        _amountToSend = cryptoAmount;
-        if (cryptoAmount.contains(" ")) {
-          cryptoAmount = cryptoAmount.split(" ").first;
-        }
-
-        // ensure we don't shift past minimum atomic value
-        final shift = min(ref.read(pAmountUnit(coin)).shift, coin.decimals);
-
-        _amountToSend = cryptoAmount.contains(",")
-            ? Decimal.parse(cryptoAmount.replaceFirst(",", "."))
-                .shift(0 - shift)
-                .toAmount(fractionDigits: coin.decimals)
-            : Decimal.parse(cryptoAmount)
-                .shift(0 - shift)
-                .toAmount(fractionDigits: coin.decimals);
         if (_cachedAmountToSend != null &&
             _cachedAmountToSend == _amountToSend) {
           return;
@@ -1623,17 +1608,11 @@ class _SendViewState extends ConsumerState<SendView> {
                                         : oldValue),
                               ],
                               onChanged: (baseAmountString) {
-                                if (baseAmountString.isNotEmpty &&
+                                final baseAmount = Amount.tryParseFiatString(
-                                    baseAmountString != "." &&
+                                  baseAmountString,
-                                    baseAmountString != ",") {
+                                  locale: locale,
-                                  final Amount baseAmount =
+                                );
-                                      baseAmountString.contains(",")
+                                if (baseAmount != null) {
-                                          ? Decimal.parse(baseAmountString
-                                                  .replaceFirst(",", "."))
-                                              .toAmount(fractionDigits: 2)
-                                          : Decimal.parse(baseAmountString)
-                                              .toAmount(fractionDigits: 2);
-
                                   final Decimal _price = ref
                                       .read(priceAnd24hChangeNotifierProvider)
                                       .getPrice(coin)

lib/pages/send_view/token_send_view.dart

@@ -218,16 +218,11 @@ class _TokenSendViewState extends ConsumerState<TokenSendView> {
   }
 
   void _onFiatAmountFieldChanged(String baseAmountString) {
-    if (baseAmountString.isNotEmpty &&
+    final baseAmount = Amount.tryParseFiatString(
-        baseAmountString != "." &&
+      baseAmountString,
-        baseAmountString != ",") {
+      locale: ref.read(localeServiceChangeNotifierProvider).locale,
-      final baseAmount = Amount.fromDecimal(
+    );
-        baseAmountString.contains(",")
+    if (baseAmount != null) {
-            ? Decimal.parse(baseAmountString.replaceFirst(",", "."))
-            : Decimal.parse(baseAmountString),
-        fractionDigits: tokenContract.decimals,
-      );
-
       final _price = ref
           .read(priceAnd24hChangeNotifierProvider)
           .getTokenPrice(tokenContract.address)
@@ -272,22 +267,14 @@ class _TokenSendViewState extends ConsumerState<TokenSendView> {
 
   void _cryptoAmountChanged() async {
     if (!_cryptoAmountChangeLock) {
-      String cryptoAmount = cryptoAmountController.text;
+      final cryptoAmount = ref.read(pAmountFormatter(coin)).tryParse(
-      if (cryptoAmount.isNotEmpty &&
+            cryptoAmountController.text,
-          cryptoAmount != "." &&
+            locale: ref.read(localeServiceChangeNotifierProvider).locale,
-          cryptoAmount != ",") {
+            coin: coin,
-        if (cryptoAmount.startsWith("~")) {
+            ethContract: tokenContract,
-          cryptoAmount = cryptoAmount.substring(1);
+          );
-        }
+      if (cryptoAmount != null) {
-        if (cryptoAmount.contains(" ")) {
+        _amountToSend = cryptoAmount;
-          cryptoAmount = cryptoAmount.split(" ").first;
-        }
-
-        _amountToSend = Amount.fromDecimal(
-            cryptoAmount.contains(",")
-                ? Decimal.parse(cryptoAmount.replaceFirst(",", "."))
-                : Decimal.parse(cryptoAmount),
-            fractionDigits: tokenContract.decimals);
         if (_cachedAmountToSend != null &&
             _cachedAmountToSend == _amountToSend) {
           return;
@@ -1185,7 +1172,7 @@ class _TokenSendViewState extends ConsumerState<TokenSendView> {
                                                       ConnectionState.done &&
                                                   snapshot.hasData) {
                                                 return Text(
-                                                  "~${snapshot.data! as String}",
+                                                  "~${snapshot.data!}",
                                                   style:
                                                       STextStyles.itemSubtitle(
                                                           context),

lib/utilities/amount/amount.dart

@@ -32,6 +32,39 @@ class Amount {
       : assert(fractionDigits >= 0),
         _value = amount.shift(fractionDigits).toBigInt();
 
+  static Amount? tryParseFiatString(
+    String value, {
+    required String locale,
+  }) {
+    final parts = value.split(" ");
+
+    if (parts.first.isEmpty) {
+      return null;
+    }
+
+    String str = parts.first;
+    if (str.startsWith(RegExp(r'[+-]'))) {
+      str = str.substring(1);
+    }
+
+    if (str.isEmpty) {
+      return null;
+    }
+
+    // get number symbols for decimal place and group separator
+    final numberSymbols = numberFormatSymbols[locale] as NumberSymbols? ??
+        numberFormatSymbols[locale.substring(0, 2)] as NumberSymbols?;
+
+    final groupSeparator = numberSymbols?.GROUP_SEP ?? ",";
+    final decimalSeparator = numberSymbols?.DECIMAL_SEP ?? ".";
+
+    str = str.replaceAll(groupSeparator, "");
+
+    final decimalString = str.replaceFirst(decimalSeparator, ".");
+
+    return Decimal.tryParse(decimalString)?.toAmount(fractionDigits: 2);
+  }
+
   // ===========================================================================
   // ======= Instance properties ===============================================
 
@@ -67,15 +100,23 @@ class Amount {
   }) {
     final wholeNumber = decimal.truncate();
 
-    final String separator =
+    // get number symbols for decimal place and group separator
-        (numberFormatSymbols[locale] as NumberSymbols?)?.DECIMAL_SEP ??
+    final numberSymbols = numberFormatSymbols[locale] as NumberSymbols? ??
-            (numberFormatSymbols[locale.substring(0, 2)] as NumberSymbols?)
+        numberFormatSymbols[locale.substring(0, 2)] as NumberSymbols?;
-                ?.DECIMAL_SEP ??
+
-            ".";
+    final String separator = numberSymbols?.DECIMAL_SEP ?? ".";
 
     final fraction = decimal - wholeNumber;
 
-    return "${wholeNumber.toStringAsFixed(0)}$separator${fraction.toStringAsFixed(2).substring(2)}";
+    String wholeNumberString = wholeNumber.toStringAsFixed(0);
+    // insert group separator
+    final regex = RegExp(r'\B(?=(\d{3})+(?!\d))');
+    wholeNumberString = wholeNumberString.replaceAllMapped(
+      regex,
+      (m) => "${m.group(0)}${numberSymbols?.GROUP_SEP ?? ","}",
+    );
+
+    return "$wholeNumberString$separator${fraction.toStringAsFixed(2).substring(2)}";
   }
   // String localizedStringAsFixed({
   //   required String locale,

lib/utilities/amount/amount_formatter.dart

@@ -64,7 +64,7 @@ class AmountFormatter {
     );
   }
 
-  Amount? amountFrom(
+  Amount? tryParse(
     String string, {
     required String locale,
     required Coin coin,