action_sheet [nfc]: Rename pageContext field on button widgets

Most of the ways we use this field (specifically, all the ways we
use it other than in findMessageListPage) aren't related to it
being the message list in particular.

When we add action sheets other than the message action sheet,
they'll still need a page context.  So prepare the way for those
by giving this a name that can generalize.

Author: gnprice

lib/widgets/action_sheet.dart

@@ -47,15 +47,15 @@ void showMessageActionSheet({required BuildContext context, required Message mes
 
   final optionButtons = [
     if (!hasThumbsUpReactionVote)
-      AddThumbsUpButton(message: message, messageListContext: context),
-    StarButton(message: message, messageListContext: context),
+      AddThumbsUpButton(message: message, pageContext: context),
+    StarButton(message: message, pageContext: context),
     if (isComposeBoxOffered)
-      QuoteAndReplyButton(message: message, messageListContext: context),
+      QuoteAndReplyButton(message: message, pageContext: context),
     if (showMarkAsUnreadButton)
-      MarkAsUnreadButton(message: message, messageListContext: context, narrow: narrow),
-    CopyMessageTextButton(message: message, messageListContext: context),
-    CopyMessageLinkButton(message: message, messageListContext: context),
-    ShareButton(message: message, messageListContext: context),
+      MarkAsUnreadButton(message: message, pageContext: context, narrow: narrow),
+    CopyMessageTextButton(message: message, pageContext: context),
+    CopyMessageLinkButton(message: message, pageContext: context),
+    ShareButton(message: message, pageContext: context),
   ];
 
   showModalBottomSheet<void>(
@@ -94,24 +94,27 @@ abstract class MessageActionSheetMenuItemButton extends StatelessWidget {
   MessageActionSheetMenuItemButton({
     super.key,
     required this.message,
-    required this.messageListContext,
-  }) : assert(messageListContext.findAncestorWidgetOfExactType<MessageListPage>() != null);
+    required this.pageContext,
+  }) : assert(pageContext.findAncestorWidgetOfExactType<MessageListPage>() != null);
 
   IconData get icon;
   String label(ZulipLocalizations zulipLocalizations);
   void onPressed(BuildContext context);
 
   final Message message;
-  final BuildContext messageListContext;
+
+  /// A context within the [MessageListPage] this action sheet was
+  /// triggered from.
+  final BuildContext pageContext;
 
   /// The [MessageListPageState] this action sheet was triggered from.
   ///
   /// Uses the inefficient [BuildContext.findAncestorStateOfType];
   /// don't call this in a build method.
   MessageListPageState findMessageListPage() {
-    assert(messageListContext.mounted,
-      'findMessageListPage should be called only when messageListContext is known to still be mounted');
-    return MessageListPage.ancestorOf(messageListContext);
+    assert(pageContext.mounted,
+      'findMessageListPage should be called only when pageContext is known to still be mounted');
+    return MessageListPage.ancestorOf(pageContext);
   }
 
   @override
@@ -166,7 +169,7 @@ class AddThumbsUpButton extends MessageActionSheetMenuItemButton {
   AddThumbsUpButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override IconData get icon => ZulipIcons.smile;
@@ -180,14 +183,14 @@ class AddThumbsUpButton extends MessageActionSheetMenuItemButton {
     Navigator.of(context).pop();
     String? errorMessage;
     try {
-      await addReaction(PerAccountStoreWidget.of(messageListContext).connection,
+      await addReaction(PerAccountStoreWidget.of(pageContext).connection,
         messageId: message.id,
         reactionType: ReactionType.unicodeEmoji,
         emojiCode: '1f44d',
         emojiName: '+1',
       );
     } catch (e) {
-      if (!messageListContext.mounted) return;
+      if (!pageContext.mounted) return;
 
       switch (e) {
         case ZulipApiException():
@@ -207,7 +210,7 @@ class StarButton extends MessageActionSheetMenuItemButton {
   StarButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override IconData get icon => _isStarred ? ZulipIcons.star_filled : ZulipIcons.star;
@@ -223,17 +226,17 @@ class StarButton extends MessageActionSheetMenuItemButton {
 
   @override void onPressed(BuildContext context) async {
     Navigator.of(context).pop();
-    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
     final op = message.flags.contains(MessageFlag.starred)
       ? UpdateMessageFlagsOp.remove
       : UpdateMessageFlagsOp.add;
 
     try {
-      final connection = PerAccountStoreWidget.of(messageListContext).connection;
+      final connection = PerAccountStoreWidget.of(pageContext).connection;
       await updateMessageFlags(connection, messages: [message.id],
         op: op, flag: MessageFlag.starred);
     } catch (e) {
-      if (!messageListContext.mounted) return;
+      if (!pageContext.mounted) return;
 
       String? errorMessage;
       switch (e) {
@@ -244,7 +247,7 @@ class StarButton extends MessageActionSheetMenuItemButton {
         default:
       }
 
-      showErrorDialog(context: messageListContext,
+      showErrorDialog(context: pageContext,
         title: switch(op) {
           UpdateMessageFlagsOp.remove => zulipLocalizations.errorUnstarMessageFailedTitle,
           UpdateMessageFlagsOp.add    => zulipLocalizations.errorStarMessageFailedTitle,
@@ -305,7 +308,7 @@ class QuoteAndReplyButton extends MessageActionSheetMenuItemButton {
   QuoteAndReplyButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override IconData get icon => ZulipIcons.format_quote;
@@ -319,7 +322,7 @@ class QuoteAndReplyButton extends MessageActionSheetMenuItemButton {
     // Close the message action sheet. We'll show the request progress
     // in the compose-box content input with a "[Quoting…]" placeholder.
     Navigator.of(context).pop();
-    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
 
     // This will be null only if the compose box disappeared after the
     // message action sheet opened, and before "Quote and reply" was pressed.
@@ -334,24 +337,24 @@ class QuoteAndReplyButton extends MessageActionSheetMenuItemButton {
       topicController.value = TextEditingValue(text: message.topic);
     }
     final tag = composeBoxController.contentController
-      .registerQuoteAndReplyStart(PerAccountStoreWidget.of(messageListContext),
+      .registerQuoteAndReplyStart(PerAccountStoreWidget.of(pageContext),
         message: message,
       );
 
     final rawContent = await fetchRawContentWithFeedback(
-      context: messageListContext,
+      context: pageContext,
       messageId: message.id,
       errorDialogTitle: zulipLocalizations.errorQuotationFailed,
     );
 
-    if (!messageListContext.mounted) return;
+    if (!pageContext.mounted) return;
 
     // This will be null only if the compose box disappeared during the
     // quotation request. Currently a compose box can't ever disappear,
     // so this is impossible.
     composeBoxController = findMessageListPage().composeBoxController!;
     composeBoxController.contentController
-      .registerQuoteAndReplyEnd(PerAccountStoreWidget.of(messageListContext), tag,
+      .registerQuoteAndReplyEnd(PerAccountStoreWidget.of(pageContext), tag,
         message: message,
         rawContent: rawContent,
       );
@@ -365,7 +368,7 @@ class MarkAsUnreadButton extends MessageActionSheetMenuItemButton {
   MarkAsUnreadButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
     required this.narrow,
   });
 
@@ -380,15 +383,15 @@ class MarkAsUnreadButton extends MessageActionSheetMenuItemButton {
 
   @override void onPressed(BuildContext context) async {
     Navigator.of(context).pop();
-    unawaited(markNarrowAsUnreadFromMessage(messageListContext, message, narrow));
+    unawaited(markNarrowAsUnreadFromMessage(pageContext, message, narrow));
   }
 }
 
 class CopyMessageTextButton extends MessageActionSheetMenuItemButton {
   CopyMessageTextButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override IconData get icon => ZulipIcons.copy;
@@ -403,19 +406,19 @@ class CopyMessageTextButton extends MessageActionSheetMenuItemButton {
     // but hopefully it won't take long at all, and
     // fetchRawContentWithFeedback has a TODO for giving feedback if it does.
     Navigator.of(context).pop();
-    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
 
     final rawContent = await fetchRawContentWithFeedback(
-      context: messageListContext,
+      context: pageContext,
       messageId: message.id,
       errorDialogTitle: zulipLocalizations.errorCopyingFailed,
     );
 
     if (rawContent == null) return;
 
-    if (!messageListContext.mounted) return;
+    if (!pageContext.mounted) return;
 
-    copyWithPopup(context: messageListContext,
+    copyWithPopup(context: pageContext,
       successContent: Text(zulipLocalizations.successMessageTextCopied),
       data: ClipboardData(text: rawContent));
   }
@@ -425,7 +428,7 @@ class CopyMessageLinkButton extends MessageActionSheetMenuItemButton {
   CopyMessageLinkButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override IconData get icon => Icons.link;
@@ -437,16 +440,16 @@ class CopyMessageLinkButton extends MessageActionSheetMenuItemButton {
 
   @override void onPressed(BuildContext context) {
     Navigator.of(context).pop();
-    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
 
-    final store = PerAccountStoreWidget.of(messageListContext);
+    final store = PerAccountStoreWidget.of(pageContext);
     final messageLink = narrowLink(
       store,
       SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
       nearMessageId: message.id,
     );
 
-    copyWithPopup(context: messageListContext,
+    copyWithPopup(context: pageContext,
       successContent: Text(zulipLocalizations.successMessageLinkCopied),
       data: ClipboardData(text: messageLink.toString()));
   }
@@ -456,7 +459,7 @@ class ShareButton extends MessageActionSheetMenuItemButton {
   ShareButton({
     super.key,
     required super.message,
-    required super.messageListContext,
+    required super.pageContext,
   });
 
   @override
@@ -479,17 +482,17 @@ class ShareButton extends MessageActionSheetMenuItemButton {
     //   `showMessageActionSheet` call) and cover a large part of the
     //   share sheet.
     Navigator.of(context).pop();
-    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+    final zulipLocalizations = ZulipLocalizations.of(pageContext);
 
     final rawContent = await fetchRawContentWithFeedback(
-      context: messageListContext,
+      context: pageContext,
       messageId: message.id,
       errorDialogTitle: zulipLocalizations.errorSharingFailed,
     );
 
     if (rawContent == null) return;
 
-    if (!messageListContext.mounted) return;
+    if (!pageContext.mounted) return;
 
     // TODO: to support iPads, we're asked to give a
     //   `sharePositionOrigin` param, or risk crashing / hanging:
@@ -502,8 +505,8 @@ class ShareButton extends MessageActionSheetMenuItemButton {
       // The plugin isn't very helpful: "The status can not be determined".
       // Until we learn otherwise, assume something wrong happened.
       case ShareResultStatus.unavailable:
-        if (!messageListContext.mounted) return;
-        showErrorDialog(context: messageListContext,
+        if (!pageContext.mounted) return;
+        showErrorDialog(context: pageContext,
           title: zulipLocalizations.errorSharingFailed);
       case ShareResultStatus.success:
       case ShareResultStatus.dismissed: