refactor(ads): make AdmobInlineAdWidget stateless to fix lifecycle crash

Converted `AdmobInlineAdWidget` from a `StatefulWidget` to a `StatelessWidget`.

This is the core fix for the "AdWidget requires Ad.load" crash. The stateful widget's `dispose` method was prematurely destroying the native AdMob ad object when it scrolled out of view. The `InlineAdCacheService` would then serve this "zombie" ad when the user scrolled back, causing the crash.

By making the widget stateless and removing all lifecycle management (including the `dispose` method), the responsibility for the ad's lifecycle is now correctly and solely managed by the `InlineAdCacheService`. The widget's only job is to render a valid, pre-loaded ad.

Author: fulleni

lib/ads/widgets/admob_inline_ad_widget.dart

@@ -7,19 +7,22 @@ import 'package:google_mobile_ads/google_mobile_ads.dart' as admob;
 import 'package:logging/logging.dart';
 
 /// {@template admob_inline_ad_widget}
-/// A widget that specifically renders an inline Google AdMob ad,
-/// supporting both native and banner ad formats.
+/// A stateless widget that renders a pre-loaded inline Google AdMob ad.
 ///
 /// This widget is responsible for taking a generic [InlineAd]
 /// and rendering it using the `AdWidget` from the `google_mobile_ads` package.
 /// It dynamically determines if the underlying `adObject` is an `admob.NativeAd`
 /// or an `admob.BannerAd` and adjusts its rendering and size accordingly.
 ///
-/// This is a [StatefulWidget] to properly manage the lifecycle of the AdMob
-/// ad object, ensuring it is disposed when the widget is removed from the tree
-/// or when the underlying ad object changes.
+/// **IMPORTANT:** This widget is intentionally stateless. It does **not** manage
+/// the lifecycle of the ad object (e.g., loading or disposing). Its sole
+/// responsibility is to render a valid, pre-loaded ad. The lifecycle, including
+/// caching and disposal, is managed by the [InlineAdCacheService] and the
+/// ad loader widgets ([FeedAdLoaderWidget], [InArticleAdLoaderWidget]). This
+/// prevents the ad from being destroyed when it scrolls out of view, which is
+/// the root cause of the "Ad.load to be called" error.
 /// {@endtemplate}
-class AdmobInlineAdWidget extends StatefulWidget {
+class AdmobInlineAdWidget extends StatelessWidget {
   /// {@macro admob_inline_ad_widget}
   const AdmobInlineAdWidget({
     required this.inlineAd,
@@ -28,131 +31,86 @@ class AdmobInlineAdWidget extends StatefulWidget {
     super.key,
   });
 
-  /// The generic inline ad model which contains the provider-specific AdMob ad object.
+  /// The generic inline ad model which contains the provider-specific AdMob ad
+  /// object. This ad is expected to be fully loaded and valid.
   final InlineAd inlineAd;
 
-  /// The user's preference for feed layout, used to determine the ad's visual size.
-  /// This is only relevant for native ads.
+  /// The user's preference for feed layout, used to determine the ad's visual
+  /// size. This is only relevant for native ads.
   final HeadlineImageStyle? headlineImageStyle;
 
   /// The preferred shape for banner ads, used for in-article banners.
   final BannerAdShape? bannerAdShape;
 
   @override
-  State<AdmobInlineAdWidget> createState() => _AdmobInlineAdWidgetState();
-}
-
-class _AdmobInlineAdWidgetState extends State<AdmobInlineAdWidget> {
-  admob.Ad? _ad;
-  final Logger _logger = Logger('AdmobInlineAdWidget');
-
-  @override
-  void initState() {
-    super.initState();
-    _setAd();
-  }
-
-  @override
-  void didUpdateWidget(covariant AdmobInlineAdWidget oldWidget) {
-    super.didUpdateWidget(oldWidget);
-    // If the inlineAd object reference itself has changed, dispose the old ad
-    // and set the new one. This is a more robust check than just comparing IDs,
-    // as a new InlineAd instance might be created for the same logical ad slot.
-    if (widget.inlineAd != oldWidget.inlineAd) {
-      _disposeCurrentAd();
-      _setAd();
-    }
-  }
-
-  @override
-  void dispose() {
-    // Dispose the AdMob ad object when the widget is removed from the tree.
-    // This is crucial to prevent "AdWidget is already in the Widget tree" errors
-    // and memory leaks, as each AdWidget instance should manage its own ad object.
-    _disposeCurrentAd();
-    _logger.info(
-      'AdmobInlineAdWidget disposed. Ad object explicitly disposed.',
-    );
-    super.dispose();
-  }
+  Widget build(BuildContext context) {
+    final logger = Logger('AdmobInlineAdWidget');
+    admob.Ad? ad;
 
-  /// Sets the internal [_ad] object from the widget's [inlineAd].
-  ///
-  /// This method ensures that the adObject is of the correct AdMob type
-  /// (NativeAd or BannerAd) and logs an error if it's not.
-  void _setAd() {
-    if (widget.inlineAd.adObject is admob.NativeAd) {
-      _ad = widget.inlineAd.adObject as admob.NativeAd;
-    } else if (widget.inlineAd.adObject is admob.BannerAd) {
-      _ad = widget.inlineAd.adObject as admob.BannerAd;
+    // Safely cast the generic adObject to a specific AdMob ad type.
+    if (inlineAd.adObject is admob.NativeAd) {
+      ad = inlineAd.adObject as admob.NativeAd;
+    } else if (inlineAd.adObject is admob.BannerAd) {
+      ad = inlineAd.adObject as admob.BannerAd;
     } else {
-      _ad = null;
-      _logger.severe(
+      ad = null;
+      logger.severe(
         'The provided ad object for AdMob inline ad is not of type '
         'admob.NativeAd or admob.BannerAd. Received: '
-        '${widget.inlineAd.adObject.runtimeType}. Ad will not be displayed.',
+        '${inlineAd.adObject.runtimeType}. Ad will not be displayed.',
       );
     }
-  }
-
-  /// Disposes the currently held [_ad] object if it's an [admob.Ad].
-  void _disposeCurrentAd() {
-    if (_ad is admob.Ad) {
-      _logger.info('Disposing AdMob ad object: ${_ad!.adUnitId}');
-      _ad!.dispose();
-      _ad = null;
-    }
-  }
 
-  @override
-  Widget build(BuildContext context) {
-    if (_ad == null) {
+    if (ad == null) {
       // Return an empty widget if the ad object is not of the correct type
       // or if it was explicitly set to null due to an error.
       return const SizedBox.shrink();
     }
 
     // Determine the height based on the actual ad type and headlineImageStyle.
     double adHeight;
-    if (widget.inlineAd is NativeAd) {
-      final nativeAd = widget.inlineAd as NativeAd;
+    if (inlineAd is NativeAd) {
+      final nativeAd = inlineAd as NativeAd;
       adHeight = switch (nativeAd.templateType) {
         NativeAdTemplateType.small => 120,
         NativeAdTemplateType.medium => 250,
       };
-    } else if (widget.inlineAd is BannerAd) {
+    } else if (inlineAd is BannerAd) {
       // For banner ads, prioritize bannerAdShape if provided (for in-article ads).
       // Otherwise, fall back to headlineImageStyle (for feed ads).
-      if (widget.bannerAdShape != null) {
-        adHeight = switch (widget.bannerAdShape) {
+      if (bannerAdShape != null) {
+        adHeight = switch (bannerAdShape) {
           BannerAdShape.square => 250,
           BannerAdShape.rectangle => 50,
           _ => 50,
         };
       } else {
-        adHeight =
-            widget.headlineImageStyle == HeadlineImageStyle.largeThumbnail
+        adHeight = headlineImageStyle == HeadlineImageStyle.largeThumbnail
             ? 250 // Assumes large thumbnail feed style wants a medium rectangle banner
             : 50;
       }
     } else {
       // Fallback height for unknown inline ad types.
+      logger.warning(
+        'Unknown InlineAd type: ${inlineAd.runtimeType}. '
+        'Defaulting to height 100.',
+      );
       adHeight = 100;
     }
 
     // The AdWidget from the google_mobile_ads package handles the rendering
     // of the pre-loaded AdMob ad.
     // We wrap it in a SizedBox to provide explicit height constraints,
-    // which is crucial for platform views (like native ads) within scrollable
-    // lists to prevent "unbounded height" errors.
+    // which is crucial for platform views (like native ads) within
+    // scrollable lists to prevent "unbounded height" errors.
     return SizedBox(
       height: adHeight,
       // Use a ValueKey derived from the adObject's hashCode to force Flutter
       // to create a new AdWidget instance if the underlying ad object changes.
       // This prevents the "AdWidget is already in the Widget tree" error.
       child: admob.AdWidget(
-        key: ValueKey(_ad!.hashCode),
-        ad: _ad! as admob.AdWithView,
+        key: ValueKey(ad.hashCode),
+        ad: ad as admob.AdWithView,
       ),
     );
   }