[packages] Add dartz

example/lib/l10n/app_en.arb

@@ -1,4 +1,14 @@
 {
+  "@_DARTZ": {},
+  "dartzTitle": "Convert size",
+  "dartzDesc": "Convert the size grid of Russia to the size grid of Europe.",
+  "dartzErrorReq": "Required field",
+  "dartzErrorInt": "Please enter RUS size (42 - 62)",
+  "dartzErrorFound": "Size not found (42 - 62)",
+  "dartzDefaultValue": "Specify the size and click 'Submit'",
+  "dartzLabel": "Size in RUS",
+  "dartzSubmit": "Submit",
+
   "@_BATTERY_PLUS": {},
   "batteryPlusTitleBatteryLevel": "Battery Level",
   "batteryPlusDescBatteryLevel": "Battery level in percent 0 - 100.",

example/lib/l10n/app_ru.arb

@@ -1,4 +1,14 @@
 {
+  "@_DARTZ": {},
+  "dartzTitle": "Преобразовать размер",
+  "dartzDesc": "Преобразовать размерную сетку России в размерную сетку Европы.",
+  "dartzErrorReq": "Обязательное поле",
+  "dartzErrorInt": "Введите размер RUS (42–62)",
+  "dartzErrorFound": "Размер не найден (42–62)",
+  "dartzDefaultValue": "Укажите размер и нажмите 'Отправить'",
+  "dartzLabel": "Размер в RUS",
+  "dartzSubmit": "Отправить",
+
   "@_BATTERY_PLUS": {},
   "batteryPlusTitleBatteryLevel": "Уровень заряда батареи",
   "batteryPlusDescBatteryLevel": "Уровень заряда батареи в процентах от 0 до 100.",

example/lib/packages/dartz/model.dart

@@ -2,6 +2,7 @@
  * Copyright (c) 2023. Open Mobile Platform LLC.
  * License: Proprietary.
  */
+import 'package:dartz/dartz.dart';
 import 'package:flutter/widgets.dart';
 import 'package:scoped_model/scoped_model.dart';
 
@@ -10,4 +11,18 @@ class DartzModel extends Model {
   /// Get [ScopedModel]
   static DartzModel of(BuildContext context) =>
       ScopedModel.of<DartzModel>(context);
+
+  /// Example using Option from package dartz
+  Option<String> getEURManSize(int size) {
+    if (size < 42) return none();
+    if (size < 44) return some('XS');
+    if (size < 46) return some('S');
+    if (size < 48) return some('M');
+    if (size < 50) return some('L');
+    if (size < 54) return some('XL');
+    if (size < 56) return some('XXL');
+    if (size < 58) return some('XXXL');
+    if (size <= 62) return some('XXXXL');
+    return none();
+  }
 }

example/lib/packages/dartz/page.dart

@@ -2,13 +2,19 @@
  * Copyright (c) 2023. Open Mobile Platform LLC.
  * License: Proprietary.
  */
+import 'dart:async';
+
+import 'package:flutter/foundation.dart' show kIsAurora;
 import 'package:flutter/material.dart';
 import 'package:flutter_example_packages/base/di/app_di.dart';
 import 'package:flutter_example_packages/base/package/package.dart';
 import 'package:flutter_example_packages/widgets/base/export.dart';
 import 'package:flutter_example_packages/widgets/blocks/block_info_package.dart';
+import 'package:flutter_example_packages/widgets/blocks/block_item.dart';
 import 'package:flutter_example_packages/widgets/layouts/block_layout.dart';
+import 'package:flutter_example_packages/widgets/texts/export.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:flutter_keyboard_visibility_aurora/flutter_keyboard_visibility_aurora.dart';
 
 import 'model.dart';
 import 'package.dart';
@@ -25,6 +31,33 @@ class DartzPage extends AppStatefulWidget {
 }
 
 class _DartzPageState extends AppState<DartzPage> {
+  final TextEditingController _textController = TextEditingController();
+  final _formKey = GlobalKey<FormState>();
+  String? _sizeEUR;
+  bool _isError = false;
+
+  double _keyboardHeight = 0;
+  StreamSubscription? _streamSub;
+  final _controllerAurora = FlutterKeyboardVisibilityAurora();
+
+  @override
+  void initState() {
+    super.initState();
+    if (kIsAurora) {
+      _streamSub = _controllerAurora.onChangeHeight.listen((event) {
+        setState(() {
+          _keyboardHeight = event;
+        });
+      });
+    }
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    _streamSub?.cancel();
+  }
+
   @override
   Widget buildWide(
     BuildContext context,
@@ -36,12 +69,73 @@ class _DartzPageState extends AppState<DartzPage> {
       title: widget.package.key,
       builder: (context, child, model) {
         return SingleChildScrollView(
+          padding: EdgeInsets.only(bottom: _keyboardHeight),
           child: Padding(
             padding: const EdgeInsets.all(20),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
                 BlockInfoPackage(widget.package),
+                Form(
+                  key: _formKey,
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      BlockItem(
+                        title: l10n.dartzTitle,
+                        desc: l10n.dartzDesc,
+                        value: _sizeEUR ?? l10n.dartzDefaultValue,
+                      ),
+                      TextFormField(
+                        controller: _textController,
+                        keyboardType: TextInputType.number,
+                        decoration: InputDecoration(
+                          labelText: l10n.dartzLabel,
+                          errorText:
+                              _isError ? l10n.dartzErrorFound : null,
+                        ),
+                        validator: (value) {
+                          if (value == null || value.isEmpty) {
+                            return l10n.dartzErrorReq;
+                          }
+                          if (int.tryParse(value) == null) {
+                            return l10n.dartzErrorInt;
+                          }
+                          return null;
+                        },
+                      ),
+                      const SizedBox(height: 20),
+                      SizedBox(
+                        width: double.infinity,
+                        child: ElevatedButton(
+                          onPressed: () async {
+                            if (_formKey.currentState?.validate() == true) {
+                              final sizeRU = int.parse(_textController.text);
+                              model
+                                  .getEURManSize(sizeRU)
+                                  .map(
+                                    (classification) => setState(() {
+                                      _isError = false;
+                                      _sizeEUR = classification;
+                                    }),
+                                  )
+                                  .getOrElse(
+                                    () => setState(() {
+                                      _sizeEUR = null;
+                                      _isError = true;
+                                    }),
+                                  );
+                            }
+                          },
+                          child: TextBodyLarge(
+                            l10n.dartzSubmit,
+                            color: Colors.white,
+                          ),
+                        ),
+                      ),
+                    ],
+                  ),
+                ),
               ],
             ),
           ),

example/lib/widgets/blocks/block_item.dart

@@ -11,16 +11,16 @@ import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 class BlockItem<T> extends AppStatelessWidget {
   const BlockItem({
     super.key,
-    required this.title,
+    this.title,
-    required this.desc,
+    this.desc,
     this.value,
     this.future,
     this.stream,
     this.builder,
   });
 
-  final String title;
+  final String? title;
-  final String desc;
+  final String? desc;
   final T? value;
   final Stream<T>? stream;
   final Future<T>? future;
@@ -31,10 +31,24 @@ class BlockItem<T> extends AppStatelessWidget {
         return Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            TextTitleLarge(title),
+            Visibility(
-            const SizedBox(height: 8),
+              visible: title != null,
-            TextBodyMedium(desc),
+              child: Column(
-            const SizedBox(height: 8),
+                children: [
+                  TextTitleLarge(title ?? ''),
+                  const SizedBox(height: 8),
+                ],
+              ),
+            ),
+            Visibility(
+              visible: desc != null,
+              child: Column(
+                children: [
+                  TextBodyMedium(desc ?? ''),
+                  const SizedBox(height: 8),
+                ],
+              ),
+            ),
             if (snapshot.hasData)
               TextBodyMedium(
                 builder == null