content: Implement inline video preview

Fixes: #356

assets/l10n/app_en.arb

@@ -381,6 +381,10 @@
       "httpStatus": {"type": "int", "example": "500"}
     }
   },
+  "errorVideoPlayerFailed": "Unable to play the video",
+  "@errorVideoPlayerFailed": {
+    "description": "Error message when a video fails to play."
+  },
   "serverUrlValidationErrorEmpty": "Please enter a URL.",
   "@serverUrlValidationErrorEmpty": {
     "description": "Error message when URL is empty"

lib/widgets/content.dart

@@ -99,13 +99,7 @@ class BlockContentList extends StatelessWidget {
           );
           return MessageImage(node: node);
         } else if (node is InlineVideoNode) {
-          return Text.rich(
-            TextSpan(children: [
-              const TextSpan(text: "(unimplemented:", style: errorStyle),
-              TextSpan(text: node.debugHtmlText, style: errorCodeStyle),
-              const TextSpan(text: ")", style: errorStyle),
-            ]),
-            style: errorStyle);
+          return MessageInlineVideo(node: node);
         } else if (node is EmbedVideoNode) {
           return MessageEmbedVideo(node: node);
         } else if (node is UnimplementedBlockContentNode) {
@@ -387,7 +381,10 @@ class MessageImage extends StatelessWidget {
     return MessageMediaContainer(
       onTap: resolvedSrc == null ? null : () { // TODO(log)
         Navigator.of(context).push(getLightboxRoute(
-          context: context, message: message, src: resolvedSrc));
+          context: context,
+          message: message,
+          src: resolvedSrc,
+          mediaType: MediaType.image));
       },
       child: resolvedSrc == null ? null : LightboxHero(
         message: message,
@@ -398,6 +395,37 @@ class MessageImage extends StatelessWidget {
   }
 }
 
+class MessageInlineVideo extends StatelessWidget {
+  const MessageInlineVideo({super.key, required this.node});
+
+  final InlineVideoNode node;
+
+  @override
+  Widget build(BuildContext context) {
+    final message = InheritedMessage.of(context);
+    final store = PerAccountStoreWidget.of(context);
+    final resolvedSrc = store.tryResolveUrl(node.srcUrl);
+
+    return MessageMediaContainer(
+      onTap: resolvedSrc == null ? null : () { // TODO(log)
+        Navigator.of(context).push(getLightboxRoute(
+          context: context,
+          message: message,
+          src: resolvedSrc,
+          mediaType: MediaType.video));
+      },
+      child: Container(
+        color: Colors.black,
+        alignment: Alignment.center,
+        // To avoid potentially confusing UX, do not show play icon as
+        // we also disable onTap above.
+        child: resolvedSrc == null ? null : const Icon( // TODO(log)
+          Icons.play_arrow_rounded,
+          color: Colors.white,
+          size: 32)));
+  }
+}
+
 class MessageEmbedVideo extends StatelessWidget {
   const MessageEmbedVideo({super.key, required this.node});
 

lib/widgets/dialog.dart

@@ -19,16 +19,19 @@ Future<void> showErrorDialog({
   required BuildContext context,
   required String title,
   String? message,
+  bool barrierDismissible = true,
+  VoidCallback? onContinue,
 }) {
   final zulipLocalizations = ZulipLocalizations.of(context);
   return showDialog(
     context: context,
+    barrierDismissible: barrierDismissible,
     builder: (BuildContext context) => AlertDialog(
       title: Text(title),
       content: message != null ? SingleChildScrollView(child: Text(message)) : null,
       actions: [
         TextButton(
-          onPressed: () => Navigator.pop(context),
+          onPressed: onContinue ?? () => Navigator.pop(context),
           child: _dialogActionText(zulipLocalizations.errorDialogContinue)),
       ]));
 }