compose_box [nfc]: Name error banner helper more specifically

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/widgets/compose_box.dart

@@ -1269,13 +1269,15 @@ class StreamComposeBoxController extends ComposeBoxController {
 class FixedDestinationComposeBoxController extends ComposeBoxController {}
 
 class _ErrorBanner extends StatelessWidget {
-  const _ErrorBanner({required this.label});
+  const _ErrorBanner({required this.label, this.onDismiss});
 
   final String label;
+  final void Function()? onDismiss;
 
   @override
   Widget build(BuildContext context) {
     final designVariables = DesignVariables.of(context);
+    final iconButtonTheme = IconButtonTheme.of(context);
     final labelTextStyle = TextStyle(
       fontSize: 17,
       height: 22 / 17,
@@ -1297,8 +1299,14 @@ class _ErrorBanner extends StatelessWidget {
                 child: Text(style: labelTextStyle,
                   label))),
             const SizedBox(width: 8),
-            // TODO(#720) "x" button goes here.
-            //   24px square with 8px touchable padding in all directions?
+            if (onDismiss != null)
+              IconButton(
+                icon: Icon(
+                  ZulipIcons.remove, color: designVariables.btnLabelAttLowIntDanger),
+                style: iconButtonTheme.style!.copyWith(
+                  shape: const WidgetStatePropertyAll(ContinuousRectangleBorder(
+                    borderRadius: BorderRadius.all(Radius.circular(4))))),
+                onPressed: onDismiss),
           ])));
   }
 }
@@ -1358,7 +1366,7 @@ class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
     super.dispose();
   }
 
-  Widget? _errorBanner(BuildContext context) {
+  Widget? _canPostInNarrowErrorBanner(BuildContext context) {
     final store = PerAccountStoreWidget.of(context);
     final selfUser = store.users[store.selfUserId]!;
     switch (widget.narrow) {
@@ -1385,13 +1393,28 @@ class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
     return null;
   }
 
+  Widget _sendMessageErrorErrorBanner(BuildContext context) {
+    final designVariables = DesignVariables.of(context);
+    return ValueListenableBuilder(
+      valueListenable: controller._sendMessageError,
+      builder: (context, sendMessageError, child) {
+        if (sendMessageError == null) return const SizedBox.shrink();
+        return _ErrorBanner(
+          label: sendMessageError,
+          onDismiss: () => controller._sendMessageError.value = null);
+      },
+      child: IconButton(icon: Icon(ZulipIcons.remove,
+        color: designVariables.btnLabelAttLowIntDanger),
+        onPressed: () => controller._sendMessageError.value = null));
+  }
+
   @override
   Widget build(BuildContext context) {
     final Widget? body;
 
-    final errorBanner = _errorBanner(context);
-    if (errorBanner != null) {
-      return _ComposeBoxContainer(body: null, errorBanner: errorBanner);
+    final canPostInNarrowErrorBanner = _canPostInNarrowErrorBanner(context);
+    if (canPostInNarrowErrorBanner != null) {
+      return _ComposeBoxContainer(body: null, errorBanner: canPostInNarrowErrorBanner);
     }
 
     final narrow = widget.narrow;
@@ -1406,11 +1429,7 @@ class _ComposeBoxState extends State<ComposeBox> implements ComposeBoxState {
       }
     }
 
-    // TODO(#720) dismissable message-send error, maybe something like:
-    //     if (controller.sendMessageError.value != null) {
-    //       errorBanner = _ErrorBanner(label:
-    //         ZulipLocalizations.of(context).errorSendMessageTimeout);
-    //     }
-    return _ComposeBoxContainer(body: body, errorBanner: null);
+    return _ComposeBoxContainer(
+      body: body, errorBanner: _sendMessageErrorErrorBanner(context));
   }
 }