first implementation finished

app/lib/features/web_view/utils/download_helper.dart

@@ -0,0 +1,39 @@
+//https://stackoverflow.com/a/67994693/20878798
+
+import 'package:universal_io/io.dart';
+
+final _utf8FilenameRegex = RegExp(
+  r"filename\*=UTF-8''([\w%\-\.]+)(?:; ?|$)",
+  caseSensitive: false,
+);
+
+final _asciiFilenameRegex = RegExp(
+  r"""^filename=(["']?)(.*?[^\\])\1(?:; ?|$)""",
+  caseSensitive: false,
+);
+
+String? getDispositionFileName(String contentDisposition) {
+  if (_utf8FilenameRegex.hasMatch(contentDisposition)) {
+    final file = Uri.decodeComponent(
+      _utf8FilenameRegex.firstMatch(contentDisposition)!.group(1)!,
+    );
+
+    return File(file).uri.pathSegments.last;
+  } else {
+    // Prevent ReDos attacks by anchoring the ascii regex to string start and
+    // slicing off everything before 'filename='
+    final filenameStart = contentDisposition.toLowerCase().indexOf('filename=');
+    if (filenameStart >= 0) {
+      final partialDisposition = contentDisposition.substring(filenameStart);
+      final matches = _asciiFilenameRegex.firstMatch(partialDisposition);
+      if (matches != null && matches.group(2) != null) {
+        final file = matches.group(2);
+        if (file != null) {
+          return File(file).uri.pathSegments.last;
+        }
+      }
+    }
+  }
+
+  return null;
+}

app/lib/features/web_view/utils/favicon_helper.dart

@@ -0,0 +1,23 @@
+import 'package:flutter_inappwebview/flutter_inappwebview.dart';
+
+Favicon? choseFavicon(Iterable<Favicon>? favicons, [Favicon? currentIcon]) {
+  var selectedIcon = currentIcon;
+
+  if (favicons != null) {
+    for (final icon in favicons) {
+      if (selectedIcon == null) {
+        selectedIcon = icon;
+      } else {
+        if ((selectedIcon.width == null &&
+                !selectedIcon.url.toString().endsWith("favicon.ico")) ||
+            (icon.width != null &&
+                selectedIcon.width != null &&
+                icon.width! > selectedIcon.width!)) {
+          selectedIcon = icon;
+        }
+      }
+    }
+  }
+
+  return selectedIcon;
+}