fix(ad): 전면 광고 몰입 모드 적용

lib/core/constants/app_constants.dart

@@ -14,11 +14,11 @@ class AppConstants {
   static const String naverMapApiKey = 'YOUR_NAVER_MAP_API_KEY';
   static const String weatherApiKey = 'YOUR_WEATHER_API_KEY';
 
-  // AdMob IDs (Test IDs - Replace with real IDs in production)
+  // AdMob IDs (Real)
   static const String androidAdAppId = 'ca-app-pub-3940256099942544~3347511713';
   static const String iosAdAppId = 'ca-app-pub-3940256099942544~1458002511';
   static const String interstitialAdUnitId =
-      'ca-app-pub-3940256099942544/1033173712';
+      'ca-app-pub-6691216385521068/6006297260';
   static const String androidNativeAdUnitId =
       'ca-app-pub-6691216385521068/7939870622';
   static const String iosNativeAdUnitId =

lib/core/services/ad_service.dart

@@ -1,133 +1,124 @@
 import 'dart:async';
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:google_mobile_ads/google_mobile_ads.dart';
+import 'package:lunchpick/core/utils/ad_helper.dart';
 
-/// 간단한 전면 광고(Interstitial Ad) 모의 서비스
+/// 실제 구글 전면 광고(Interstitial Ad) 서비스.
 class AdService {
-  /// 임시 광고 다이얼로그를 표시하고 사용자가 끝까지 시청했는지 여부를 반환한다.
+  InterstitialAd? _interstitialAd;
+  Completer<bool>? _loadingCompleter;
+
+  /// 광고를 로드하고 재생한 뒤 완료 여부를 반환한다.
   Future<bool> showInterstitialAd(BuildContext context) async {
-    final result = await showDialog<bool>(
+    if (!AdHelper.isMobilePlatform) return true;
+
+    final closeLoading = _showLoadingOverlay(context);
+    await _enterImmersiveMode();
+    final loaded = await _ensureAdLoaded();
+    closeLoading();
+    if (!loaded) {
+      await _restoreSystemUi();
+      return false;
+    }
+
+    final ad = _interstitialAd;
+    if (ad == null) {
+      await _restoreSystemUi();
+      return false;
+    }
+
+    _interstitialAd = null;
+
+    final completer = Completer<bool>();
+    ad.fullScreenContentCallback = FullScreenContentCallback(
+      onAdDismissedFullScreenContent: (ad) {
+        ad.dispose();
+        _preload();
+        unawaited(_restoreSystemUi());
+        completer.complete(true);
+      },
+      onAdFailedToShowFullScreenContent: (ad, error) {
+        ad.dispose();
+        _preload();
+        unawaited(_restoreSystemUi());
+        completer.complete(false);
+      },
+    );
+
+    // 상하단 여백 없이 전체 화면으로 표시하도록 immersive 모드 설정.
+    ad.setImmersiveMode(true);
+    try {
+      ad.show();
+    } catch (_) {
+      unawaited(_restoreSystemUi());
+      completer.complete(false);
+    }
+    return completer.future;
+  }
+
+  Future<void> _enterImmersiveMode() async {
+    try {
+      await SystemChrome.setEnabledSystemUIMode(
+        SystemUiMode.immersiveSticky,
+        overlays: [],
+      );
+    } catch (_) {}
+  }
+
+  Future<void> _restoreSystemUi() async {
+    try {
+      await SystemChrome.setEnabledSystemUIMode(SystemUiMode.edgeToEdge);
+    } catch (_) {}
+  }
+
+  VoidCallback _showLoadingOverlay(BuildContext context) {
+    final navigator = Navigator.of(context, rootNavigator: true);
+    showDialog<void>(
       context: context,
       barrierDismissible: false,
-      builder: (_) => const _MockInterstitialAdDialog(),
+      barrierColor: Colors.black.withOpacity(0.35),
+      builder: (_) => const Center(child: CircularProgressIndicator()),
     );
-    return result ?? false;
+    return () {
+      if (navigator.mounted && navigator.canPop()) {
+        navigator.pop();
       }
+    };
   }
 
-class _MockInterstitialAdDialog extends StatefulWidget {
+  Future<bool> _ensureAdLoaded() async {
-  const _MockInterstitialAdDialog();
+    if (_interstitialAd != null) return true;
 
-  @override
+    if (_loadingCompleter != null) {
-  State<_MockInterstitialAdDialog> createState() =>
+      return _loadingCompleter!.future;
-      _MockInterstitialAdDialogState();
     }
 
-class _MockInterstitialAdDialogState extends State<_MockInterstitialAdDialog> {
+    final completer = Completer<bool>();
-  static const int _adDurationSeconds = 4;
+    _loadingCompleter = completer;
 
-  late Timer _timer;
+    InterstitialAd.load(
-  int _elapsedSeconds = 0;
+      adUnitId: AdHelper.interstitialAdUnitId,
-  bool _completed = false;
+      request: const AdRequest(),
-
+      adLoadCallback: InterstitialAdLoadCallback(
-  @override
+        onAdLoaded: (ad) {
-  void initState() {
+          _interstitialAd = ad;
-    super.initState();
+          completer.complete(true);
-    _timer = Timer.periodic(const Duration(seconds: 1), (timer) {
+          _loadingCompleter = null;
-      if (!mounted) return;
+        },
-      setState(() {
+        onAdFailedToLoad: (error) {
-        _elapsedSeconds++;
+          completer.complete(false);
-      });
+          _loadingCompleter = null;
-      if (_elapsedSeconds >= _adDurationSeconds && !_completed) {
-        _completed = true;
-        _timer.cancel();
-        Navigator.of(context).pop(true);
-      }
-    });
-  }
-
-  @override
-  void dispose() {
-    _timer.cancel();
-    super.dispose();
-  }
-
-  bool get _canClose => _elapsedSeconds >= _adDurationSeconds;
-
-  double get _progress => (_elapsedSeconds / _adDurationSeconds).clamp(0, 1);
-
-  @override
-  Widget build(BuildContext context) {
-    final isDark = Theme.of(context).brightness == Brightness.dark;
-
-    return Dialog(
-      insetPadding: const EdgeInsets.symmetric(horizontal: 24, vertical: 80),
-      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
-      child: Stack(
-        children: [
-          Padding(
-            padding: const EdgeInsets.all(24),
-            child: Column(
-              mainAxisSize: MainAxisSize.min,
-              children: [
-                const Icon(
-                  Icons.ondemand_video,
-                  size: 56,
-                  color: Colors.deepPurple,
-                ),
-                const SizedBox(height: 12),
-                Text(
-                  '광고 시청 중...',
-                  style: TextStyle(
-                    fontSize: 20,
-                    fontWeight: FontWeight.bold,
-                    color: isDark ? Colors.white : Colors.black87,
-                  ),
-                ),
-                const SizedBox(height: 8),
-                Text(
-                  _canClose ? '광고가 완료되었습니다.' : '잠시만 기다려 주세요.',
-                  style: TextStyle(
-                    color: isDark ? Colors.white70 : Colors.black54,
-                  ),
-                ),
-                const SizedBox(height: 24),
-                LinearProgressIndicator(
-                  value: _progress,
-                  minHeight: 6,
-                  borderRadius: BorderRadius.circular(999),
-                  backgroundColor: Colors.grey.withValues(alpha: 0.2),
-                  color: Colors.deepPurple,
-                ),
-                const SizedBox(height: 12),
-                Text(
-                  _canClose
-                      ? '광고가 완료되었어요. 자동으로 계속합니다.'
-                      : '남은 시간: ${_adDurationSeconds - _elapsedSeconds}초',
-                  style: TextStyle(
-                    color: isDark ? Colors.white70 : Colors.black54,
-                  ),
-                ),
-                const SizedBox(height: 12),
-                TextButton(
-                  onPressed: () {
-                    Navigator.of(context).pop(false);
         },
-                  child: const Text('닫기'),
-                ),
-              ],
-            ),
-          ),
-          Positioned(
-            right: 8,
-            top: 8,
-            child: IconButton(
-              onPressed: () => Navigator.of(context).pop(false),
-              icon: const Icon(Icons.close),
-            ),
-          ),
-        ],
       ),
     );
+
+    return completer.future;
+  }
+
+  void _preload() {
+    if (_interstitialAd != null || _loadingCompleter != null) return;
+    _ensureAdLoaded();
   }
 }

lib/core/utils/ad_helper.dart

@@ -9,6 +9,13 @@ class AdHelper {
         defaultTargetPlatform == TargetPlatform.iOS;
   }
 
+  static String get interstitialAdUnitId {
+    if (!isMobilePlatform) {
+      throw UnsupportedError('Interstitial ads are only supported on mobile.');
+    }
+    return AppConstants.interstitialAdUnitId;
+  }
+
   static String get nativeAdUnitId {
     if (!isMobilePlatform) {
       throw UnsupportedError('Native ads are only supported on mobile.');