Access to fragment in router state on page refresh (flutter#131123)

This PR fixes the issue flutter#108614 
Particularly this behaviour flutter#108614 (comment)

Author: vasilich6107

packages/flutter_web_plugins/lib/src/navigation/url_strategy.dart

@@ -46,6 +46,7 @@ class PathUrlStrategy extends ui_web.HashUrlStrategy {
   /// interactions.
   PathUrlStrategy([
     super.platformLocation,
+    this.includeHash = false,
   ])  : _platformLocation = platformLocation,
         _basePath = stripTrailingSlash(extractPathname(checkBaseHref(
           platformLocation.getBaseHref(),
@@ -54,9 +55,20 @@ class PathUrlStrategy extends ui_web.HashUrlStrategy {
   final ui_web.PlatformLocation _platformLocation;
   final String _basePath;
 
+  /// There were an issue with url #hash which disappears from URL on first start of the web application
+  /// This flag allows to preserve that hash and was introduced mainly to preserve backward compatibility
+  /// with existing applications that rely on a full match on the path. If someone navigates to
+  /// /profile or /profile#foo, they both will work without this flag otherwise /profile#foo won't match
+  /// with the /profile route name anymore because the hash became part of the path.
+  ///
+  /// This flag solves the edge cases when using auth provider which redirects back to the app with
+  /// token in redirect URL as /#access_token=bla_bla_bla
+  final bool includeHash;
+
   @override
   String getPath() {
-    final String path = _platformLocation.pathname + _platformLocation.search;
+    final String? hash = includeHash ? _platformLocation.hash : null;
+    final String path = _platformLocation.pathname + _platformLocation.search + (hash ?? '');
     if (_basePath.isNotEmpty && path.startsWith(_basePath)) {
       return ensureLeadingSlash(path.substring(_basePath.length));
     }

packages/flutter_web_plugins/lib/src/navigation_non_web/url_strategy.dart

@@ -129,5 +129,5 @@ class PathUrlStrategy extends HashUrlStrategy {
   ///
   /// The [PlatformLocation] parameter is useful for testing to mock out browser
   /// integrations.
-  const PathUrlStrategy([PlatformLocation? _]);
+  const PathUrlStrategy([PlatformLocation? _, bool __ = false,]);
 }

packages/flutter_web_plugins/test/navigation/url_strategy_test.dart

@@ -80,17 +80,34 @@ void main() {
       expect(strategy.getPath(), '/bar');
     });
 
-    test('gets path correctly in the presence of query params', () {
+    test('gets path correctly in the presence of query params and omits fragment if no flag specified', () {
       location.baseHref = 'https://example.com/foo/';
       location.pathname = '/foo/bar';
       final PathUrlStrategy strategy = PathUrlStrategy(location);
 
+      location.search = '?q=1';
+      expect(strategy.getPath(), '/bar?q=1');
+
+      location.search = '?q=1&t=r';
+      expect(strategy.getPath(), '/bar?q=1&t=r');
+
+      location.hash = '#fragment=1';
+      expect(strategy.getPath(), '/bar?q=1&t=r');
+    });
+
+    test('gets path correctly in the presence of query params and fragment', () {
+      location.baseHref = 'https://example.com/foo/';
+      location.pathname = '/foo/bar';
+      final PathUrlStrategy strategy = PathUrlStrategy(location, true);
 
       location.search = '?q=1';
       expect(strategy.getPath(), '/bar?q=1');
 
       location.search = '?q=1&t=r';
       expect(strategy.getPath(), '/bar?q=1&t=r');
+
+      location.hash = '#fragment=1';
+      expect(strategy.getPath(), '/bar?q=1&t=r#fragment=1');
     });
 
     test('empty route name is ok', () {