feat: dialig for conectivity

lib/core/network/connectivity_service.dart

@@ -0,0 +1,65 @@
+import 'dart:async';
+
+import 'package:connectivity_plus/connectivity_plus.dart';
+import 'package:dio/dio.dart';
+import 'package:flutter/foundation.dart';
+
+import '../config.dart';
+
+/// وضعیتِ اینترنت را نگه می‌دارد: هم قطعِ رابطِ شبکه (وای‌فای/دیتا) و هم دسترسیِ
+/// واقعی به سرور (با پینگِ سبکِ /health). [online] برای نمایشِ اوورلیِ «اتصال نیست».
+class ConnectivityService {
+  ConnectivityService._();
+  static final ConnectivityService I = ConnectivityService._();
+
+  final ValueNotifier<bool> online = ValueNotifier<bool>(true);
+
+  final Connectivity _conn = Connectivity();
+  final Dio _dio = Dio(BaseOptions(
+    connectTimeout: const Duration(seconds: 4),
+    receiveTimeout: const Duration(seconds: 4),
+  ));
+  StreamSubscription? _sub;
+  bool _checking = false;
+
+  Future<void> init() async {
+    _sub = _conn.onConnectivityChanged.listen(_onChange);
+    await recheck();
+  }
+
+  void _onChange(List<ConnectivityResult> results) {
+    final hasInterface =
+        results.any((r) => r != ConnectivityResult.none);
+    if (!hasInterface) {
+      online.value = false; // بی‌درنگ: رابطِ شبکه قطع است
+    } else {
+      _verify(); // رابط هست؛ دسترسیِ واقعی را بررسی کن
+    }
+  }
+
+  /// بررسیِ دستیِ اتصال (دکمه‌ی «تلاش مجدد»).
+  Future<void> recheck() async {
+    final results = await _conn.checkConnectivity();
+    final hasInterface = results.any((r) => r != ConnectivityResult.none);
+    if (!hasInterface) {
+      online.value = false;
+      return;
+    }
+    await _verify();
+  }
+
+  Future<void> _verify() async {
+    if (_checking) return;
+    _checking = true;
+    try {
+      final res = await _dio.get('${AppConfig.baseUrl}/health');
+      online.value = res.statusCode == 200;
+    } catch (_) {
+      online.value = false;
+    } finally {
+      _checking = false;
+    }
+  }
+
+  void dispose() => _sub?.cancel();
+}

lib/core/widgets/offline_gate.dart

@@ -0,0 +1,124 @@
+import 'package:flutter/material.dart';
+
+import '../network/connectivity_service.dart';
+import '../theme/app_theme.dart';
+
+/// [child] را می‌پوشاند و هنگامِ قطعِ اینترنت یک اوورلیِ «اتصال برقرار نیست» با
+/// دکمه‌ی «تلاش مجدد» نشان می‌دهد. به‌محضِ برقراریِ اتصال، خودش کنار می‌رود.
+class OfflineGate extends StatelessWidget {
+  final Widget child;
+  const OfflineGate({super.key, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      children: [
+        child,
+        ValueListenableBuilder<bool>(
+          valueListenable: ConnectivityService.I.online,
+          builder: (context, online, _) =>
+              online ? const SizedBox.shrink() : const _OfflineOverlay(),
+        ),
+      ],
+    );
+  }
+}
+
+class _OfflineOverlay extends StatefulWidget {
+  const _OfflineOverlay();
+  @override
+  State<_OfflineOverlay> createState() => _OfflineOverlayState();
+}
+
+class _OfflineOverlayState extends State<_OfflineOverlay> {
+  bool _busy = false;
+
+  Future<void> _retry() async {
+    setState(() => _busy = true);
+    await ConnectivityService.I.recheck();
+    if (mounted) setState(() => _busy = false);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Positioned.fill(
+      child: Material(
+        color: Colors.black.withValues(alpha: 0.82),
+        child: Center(
+          child: Container(
+            margin: const EdgeInsets.symmetric(horizontal: 32),
+            padding: const EdgeInsets.fromLTRB(24, 28, 24, 22),
+            decoration: BoxDecoration(
+              gradient: const LinearGradient(
+                begin: Alignment.topCenter,
+                end: Alignment.bottomCenter,
+                colors: [AppColors.lapisMid, AppColors.lapisLo],
+              ),
+              borderRadius: BorderRadius.circular(20),
+              border: Border.all(color: AppColors.gold, width: 2),
+              boxShadow: const [
+                BoxShadow(color: Colors.black54, blurRadius: 20),
+              ],
+            ),
+            child: Column(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                Container(
+                  width: 72,
+                  height: 72,
+                  decoration: BoxDecoration(
+                    shape: BoxShape.circle,
+                    color: AppColors.bgDark,
+                    border: Border.all(color: AppColors.goldDark, width: 2),
+                  ),
+                  child: const Icon(Icons.wifi_off_rounded,
+                      color: AppColors.gold, size: 38),
+                ),
+                const SizedBox(height: 16),
+                const Text(
+                  'اتصال به اینترنت برقرار نیست',
+                  textAlign: TextAlign.center,
+                  style: TextStyle(
+                    color: AppColors.gold,
+                    fontSize: 18,
+                    fontWeight: FontWeight.bold,
+                  ),
+                ),
+                const SizedBox(height: 8),
+                const Text(
+                  'اینترنتِ دستگاهت را بررسی کن و دوباره تلاش کن.',
+                  textAlign: TextAlign.center,
+                  style: TextStyle(color: Colors.white70, fontSize: 13),
+                ),
+                const SizedBox(height: 22),
+                SizedBox(
+                  width: double.infinity,
+                  child: ElevatedButton.icon(
+                    onPressed: _busy ? null : _retry,
+                    style: ElevatedButton.styleFrom(
+                      backgroundColor: AppColors.gold,
+                      foregroundColor: AppColors.bg,
+                      padding: const EdgeInsets.symmetric(vertical: 12),
+                      shape: RoundedRectangleBorder(
+                        borderRadius: BorderRadius.circular(12),
+                      ),
+                    ),
+                    icon: _busy
+                        ? const SizedBox(
+                            width: 18,
+                            height: 18,
+                            child: CircularProgressIndicator(
+                                strokeWidth: 2, color: AppColors.bg),
+                          )
+                        : const Icon(Icons.refresh, size: 20),
+                    label: Text(_busy ? 'در حال بررسی…' : 'تلاش مجدد'),
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}