From bf6de8162cf274fa6454bce9101ceae1aefe6d27 Mon Sep 17 00:00:00 2001
From: Aaron Madlon-Kay <aaron@madlon-kay.com>
Date: Sat, 14 Sep 2024 22:14:54 +0900
Subject: [PATCH] Refactor cancelable task logic

---
 lib/src/components/dialogs.dart        | 42 ++++++++++++++++++++++++++
 lib/src/pages/document/encryption.dart | 28 +++++------------
 lib/src/pages/document/links.dart      | 38 ++++++++---------------
 3 files changed, 62 insertions(+), 46 deletions(-)

diff --git a/lib/src/components/dialogs.dart b/lib/src/components/dialogs.dart
index d1de507..f1f7ff6 100644
--- a/lib/src/components/dialogs.dart
+++ b/lib/src/components/dialogs.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 import 'package:org_flutter/org_flutter.dart';
+import 'package:orgro/src/debug.dart';
 import 'package:orgro/src/preferences.dart';
 import 'package:orgro/src/serialization.dart';
 import 'package:share_plus/share_plus.dart';
@@ -164,6 +165,47 @@ class InputPasswordDialog extends StatelessWidget {
   }
 }
 
+Future<({bool succeeded, T? result})> cancelableProgressTask<T>(
+  BuildContext context, {
+  required Future<T> task,
+  required String dialogTitle,
+}) async {
+  var canceled = false;
+
+  final dialogFuture = showDialog<(T, Object?)>(
+    context: context,
+    builder: (context) => ProgressIndicatorDialog(
+      title: dialogTitle,
+      dismissable: true,
+    ),
+  );
+
+  task.then((result) {
+    if (!canceled && context.mounted) Navigator.pop(context, (result, null));
+  }).onError((error, stackTrace) {
+    if (context.mounted) showErrorSnackBar(context, error);
+    logError(error, stackTrace);
+    if (!canceled && context.mounted) Navigator.pop(context, (null, error));
+  });
+
+  // Popped will be one of:
+  // - null if the user closed the dialog by tapping outside or using the back
+  //   button/gesture
+  // - (task result, null) if completed normally
+  // - (null, error) if completed with error
+  final popped = await dialogFuture;
+
+  if (popped == null) {
+    canceled = true;
+    return (succeeded: false, result: null);
+  }
+
+  final (result, error) = popped;
+  return error == null
+      ? (succeeded: true, result: result)
+      : (succeeded: false, result: null);
+}
+
 class ProgressIndicatorDialog extends StatelessWidget {
   const ProgressIndicatorDialog({
     required this.title,
diff --git a/lib/src/pages/document/encryption.dart b/lib/src/pages/document/encryption.dart
index b47adcc..8bf8d4b 100644
--- a/lib/src/pages/document/encryption.dart
+++ b/lib/src/pages/document/encryption.dart
@@ -24,28 +24,14 @@ extension EncryptionHandler on DocumentPageState {
     );
     if (password == null) return;
     if (!mounted) return;
-    var canceled = false;
-    time('decrypt', () => compute(decrypt, (blocks, password)))
-        .then((decrypted) {
-      if (!canceled && mounted) Navigator.pop(context, decrypted);
-    }).onError((error, stackTrace) {
-      if (mounted) showErrorSnackBar(context, error);
-      logError(error, stackTrace);
-      if (!canceled && mounted) Navigator.pop(context);
-    });
-    final result = await showDialog<List<String?>>(
-      context: context,
-      builder: (context) => ProgressIndicatorDialog(
-        title: AppLocalizations.of(context)!.decryptingProgressDialogTitle,
-        dismissable: true,
-      ),
+
+    final (succeeded: succeeded, result: result) = await cancelableProgressTask(
+      context,
+      task: time('decrypt', () => compute(decrypt, (blocks, password))),
+      dialogTitle: AppLocalizations.of(context)!.decryptingProgressDialogTitle,
     );
-    if (!mounted) return;
-    if (result == null) {
-      // Canceled
-      canceled = true;
-      return;
-    }
+    if (!succeeded || result == null) return;
+
     OrgTree newDoc = doc;
     final toRemember = <OrgroPassword>[];
     for (final (i, cleartext) in result.indexed) {
diff --git a/lib/src/pages/document/links.dart b/lib/src/pages/document/links.dart
index c8f4035..9b3b351 100644
--- a/lib/src/pages/document/links.dart
+++ b/lib/src/pages/document/links.dart
@@ -61,39 +61,27 @@ extension LinkHandler on DocumentPageState {
     final targetId = parseOrgIdUrl(url);
     final requestId = Object().hashCode.toString();
 
-    var canceled = false;
-    time(
-      'find file with ID',
-      () => findFileForId(
-        requestId: requestId,
-        orgId: targetId,
-        dirIdentifier: dataSource.rootDirIdentifier!,
-      ),
-    ).then((found) {
-      if (!canceled && mounted) Navigator.pop(context, (found, true));
-    }).onError((error, stackTrace) {
-      if (mounted) showErrorSnackBar(context, error);
-      logError(error, stackTrace);
-      if (!canceled && mounted) Navigator.pop(context);
-    });
-
-    final result = await showDialog<(NativeDataSource?, bool)>(
-      context: context,
-      builder: (context) => ProgressIndicatorDialog(
-        title: AppLocalizations.of(context)!.searchingProgressDialogTitle,
-        dismissable: true,
+    final (succeeded: succeeded, result: foundFile) =
+        await cancelableProgressTask(
+      context,
+      task: time(
+        'find file with ID',
+        () => findFileForId(
+          requestId: requestId,
+          orgId: targetId,
+          dirIdentifier: dataSource.rootDirIdentifier!,
+        ),
       ),
+      dialogTitle: AppLocalizations.of(context)!.searchingProgressDialogTitle,
     );
 
-    if (result == null) {
-      canceled = true;
+    if (!succeeded) {
       cancelFindFileForId(requestId: requestId);
       return false;
     }
+
     if (!mounted) return false;
 
-    final (foundFile, searchCompleted) = result;
-    assert(searchCompleted);
     if (foundFile == null) {
       showErrorSnackBar(context,
           AppLocalizations.of(context)!.errorExternalIdNotFound(targetId));