action-sheet: Add "Copy message link" button

Fixes: #673

Author: sm-sayedi

assets/l10n/app_en.arb

@@ -47,6 +47,10 @@
   "@actionSheetOptionCopyMessageText":  {
     "description": "Label for copy message text button on action sheet."
   },
+  "actionSheetOptionCopyMessageLink": "Copy link to message",
+  "@actionSheetOptionCopyMessageLink": {
+    "description": "Label for copy message link button on action sheet."
+  },
   "actionSheetOptionShare": "Share",
   "@actionSheetOptionShare":  {
     "description": "Label for share button on action sheet."

lib/widgets/action_sheet.dart

@@ -6,6 +6,8 @@ import 'package:share_plus/share_plus.dart';
 import '../api/exception.dart';
 import '../api/model/model.dart';
 import '../api/route/messages.dart';
+import '../model/internal_link.dart';
+import '../model/narrow.dart';
 import 'clipboard.dart';
 import 'compose_box.dart';
 import 'dialog.dart';
@@ -44,6 +46,7 @@ void showMessageActionSheet({required BuildContext context, required Message mes
           messageListContext: context,
         ),
         CopyMessageTextButton(message: message, messageListContext: context),
+        CopyMessageLinkButton(message: message, messageListContext: context),
         ShareButton(message: message, messageListContext: context),
       ]);
     });
@@ -310,6 +313,37 @@ class CopyMessageTextButton extends MessageActionSheetMenuItemButton {
   }
 }
 
+class CopyMessageLinkButton extends MessageActionSheetMenuItemButton {
+  CopyMessageLinkButton({
+    super.key,
+    required super.message,
+    required super.messageListContext,
+  });
+
+  @override IconData get icon => Icons.link;
+
+  @override
+  String label(ZulipLocalizations zulipLocalizations) {
+    return zulipLocalizations.actionSheetOptionCopyMessageLink;
+  }
+
+  @override void onPressed(BuildContext context) {
+    Navigator.of(context).pop();
+    final zulipLocalizations = ZulipLocalizations.of(messageListContext);
+
+    final store = PerAccountStoreWidget.of(messageListContext);
+    final messageLink = narrowLink(
+      store,
+      SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
+      nearMessageId: message.id,
+    );
+
+    copyWithPopup(context: messageListContext,
+        successContent: Text(zulipLocalizations.successLinkCopied),
+        data: ClipboardData(text: messageLink.toString()));
+  }
+}
+
 class ShareButton extends MessageActionSheetMenuItemButton {
   ShareButton({
     super.key,

test/widgets/action_sheet_test.dart

@@ -9,6 +9,7 @@ import 'package:http/http.dart' as http;
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/messages.dart';
 import 'package:zulip/model/compose.dart';
+import 'package:zulip/model/internal_link.dart';
 import 'package:zulip/model/localizations.dart';
 import 'package:zulip/model/narrow.dart';
 import 'package:zulip/model/store.dart';
@@ -490,4 +491,31 @@ void main() {
       check(await Clipboard.getData('text/plain')).isNull();
     });
   });
+
+  group('CopyMessageLinkButton', () {
+    setUp(() async {
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+        SystemChannels.platform,
+        MockClipboard().handleMethodCall,
+      );
+    });
+
+    Future<void> tapCopyMessageLinkButton(WidgetTester tester) async {
+      await tester.ensureVisible(find.byIcon(Icons.link, skipOffstage: false));
+      await tester.tap(find.byIcon(Icons.link));
+      await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
+    }
+
+    testWidgets('copies message link to clipboard', (tester) async {
+      final message = eg.streamMessage();
+      final narrow = TopicNarrow.ofMessage(message);
+      await setupToMessageActionSheet(tester, message: message, narrow: narrow);
+      final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+
+      final expectedLink = narrowLink(store, narrow, nearMessageId: message.id).toString();
+      await tapCopyMessageLinkButton(tester);
+      await tester.pump(Duration.zero);
+      check(await Clipboard.getData('text/plain')).isNotNull().text.equals(expectedLink);
+    });
+  });
 }