feat(l10n): add a replaceL10nPlaceholderWithWidget helper

lib/src/utils/l10n.dart

@@ -1,5 +1,6 @@
 import 'dart:ui' as ui;
 
+import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter/material.dart';
 import 'package:freezed_annotation/freezed_annotation.dart';
 import 'package:lichess_mobile/l10n/l10n.dart';
@@ -52,3 +53,50 @@ class _LocaleObserver extends WidgetsBindingObserver {
     _didChangeLocales(locales);
   }
 }
+
+/// Takes a localization function (from lib/l10n/l10n.dart) with a single placeholder
+/// and replaces the placeholder with the given widget, surrounded by Text widgets if necessary.
+///
+/// For example:
+///
+/// ```dart
+/// String translationFun(String name) {
+///   return 'Hello, ${name}!';
+/// }
+///
+/// // returns [Text('Hello, '), MyFancyWidget('Magnus'), Text('!')]
+/// replaceL10nPlaceholderWithWidget(translationFun, MyFancyWidget('Magnus'));
+/// ```
+///
+/// @param l10nWithReplacement The localization function corresponding to a localized string with a placeholder.
+/// @param widget The widget to replace the placeholder with.
+/// @param testStyle The style to apply to the Text widgets.
+///
+/// If the placeholder is not present in the localized string,
+/// will return a single Text widget with the localized string.
+/// If the placeholder is at the beginning or end of the localized string,
+/// will return a list with a single Text widget and the widget.
+/// Otherwise, will return a list with three Text widgets:
+/// the first with the text before the placeholder, the second with the widget,
+/// and the third with the text after the placeholder.
+IList<Widget> replaceL10nPlaceholderWithWidget<T extends Widget>(
+  String Function(String) l10nWithReplacement,
+  T widget, {
+  TextStyle? textStyle,
+}) {
+  final localizedStringWithPlaceholder = l10nWithReplacement('%s');
+
+  final parts = localizedStringWithPlaceholder.split('%s');
+
+  // Localized string did not actually contain the placeholder
+  if (parts[0] == localizedStringWithPlaceholder) {
+    return [Text(localizedStringWithPlaceholder)].lock;
+  }
+
+  return [
+    if (parts[0].isNotEmpty) Text(parts[0], style: textStyle),
+    if (parts[0] != localizedStringWithPlaceholder) widget,
+    if (parts.length > 1 && parts[1].isNotEmpty)
+      Text(parts[1], style: textStyle),
+  ].lock;
+}

lib/src/view/home/home_tab_screen.dart

@@ -13,6 +13,7 @@ import 'package:lichess_mobile/src/navigation.dart';
 import 'package:lichess_mobile/src/styles/styles.dart';
 import 'package:lichess_mobile/src/utils/chessground_compat.dart';
 import 'package:lichess_mobile/src/utils/connectivity.dart';
+import 'package:lichess_mobile/src/utils/l10n.dart';
 import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/utils/navigation.dart';
 import 'package:lichess_mobile/src/utils/screen.dart';
@@ -507,8 +508,6 @@ class _HelloWidget extends ConsumerWidget {
 
     final user = accountUser ?? session?.user;
 
-    final greetingParts = context.l10n.mobileGreeting.split('%s');
-
     return Padding(
       padding:
           Styles.horizontalBodyPadding.add(Styles.sectionBottomPadding).add(
@@ -530,11 +529,13 @@ class _HelloWidget extends ConsumerWidget {
               color: context.lichessColors.brag,
             ),
             const SizedBox(width: 5.0),
-            if (user != null && greetingParts.length == 2) ...[
-              Text(greetingParts[0], style: style),
-              UserFullNameWidget(user: user, style: style),
-              Text(greetingParts[1], style: style),
-            ] else
+            if (user != null)
+              ...replaceL10nPlaceholderWithWidget(
+                context.l10n.mobileGreeting,
+                UserFullNameWidget(user: user),
+                textStyle: style,
+              )
+            else
               Text(context.l10n.mobileGreetingWithoutName, style: style),
           ],
         ),

test/utils/l10n_test.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:lichess_mobile/src/utils/l10n.dart';
+
+void main() {
+  group('replaceL10nPlaceholderWithWidget', () {
+    const widget = Text('I am a widget');
+    test('placeholder in the middle', () {
+      final widgets = replaceL10nPlaceholderWithWidget(
+        (_) => 'foo %s bar',
+        widget,
+      );
+      expect(widgets.length, 3);
+      expect((widgets[0] as Text).data, 'foo ');
+      expect(widgets[1], widget);
+      expect((widgets[2] as Text).data, ' bar');
+    });
+
+    test('no placeholder', () {
+      final widgets = replaceL10nPlaceholderWithWidget(
+        (_) => 'foo bar',
+        widget,
+      );
+      expect(widgets.length, 1);
+      expect((widgets.first as Text).data, 'foo bar');
+    });
+
+    test('placeholder at the beginning', () {
+      final widgets = replaceL10nPlaceholderWithWidget(
+        (_) => '%s foo bar',
+        widget,
+      );
+      expect(widgets.length, 2);
+      expect(widgets[0], widget);
+      expect((widgets[1] as Text).data, ' foo bar');
+    });
+
+    test('placeholder at the end', () {
+      final widgets = replaceL10nPlaceholderWithWidget(
+        (_) => 'foo bar %s',
+        widget,
+      );
+      expect(widgets.length, 2);
+      expect((widgets[0] as Text).data, 'foo bar ');
+      expect(widgets[1], widget);
+    });
+
+    test('passes textStyle', () {
+      final widgets = replaceL10nPlaceholderWithWidget(
+        (_) => 'foo %s bar',
+        widget,
+        textStyle: const TextStyle(fontWeight: FontWeight.bold),
+      );
+      expect(widgets.length, 3);
+      expect((widgets[0] as Text).style?.fontWeight, FontWeight.bold);
+      expect(widgets[1], widget);
+      expect((widgets[2] as Text).style?.fontWeight, FontWeight.bold);
+    });
+  });
+}