// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:collection/collection.dart';
import 'package:flutter/widgets.dart';

import 'configuration.dart';
import 'pages/custom_transition_page.dart';
import 'path_utils.dart';
import 'typedefs.dart';

/// The base class for [GoRoute] and [ShellRoute].
///
/// Routes are defined in a tree such that parent routes must match the
/// current location for their child route to be considered a match. For
/// example the location "/home/user/12" matches with parent route "/home" and
/// child route "user/:userId".
///
/// To create sub-routes for a route, provide them as a [GoRoute] list
/// with the sub routes.
///
/// For example these routes:
/// ```
/// /         => HomePage()
///   family/f1 => FamilyPage('f1')
///     person/p2 => PersonPage('f1', 'p2') ← showing this page, Back pops ↑
/// ```
///
/// Can be represented as:
///
/// ```
/// final GoRouter _router = GoRouter(
///   routes: <GoRoute>[
///     GoRoute(
///       path: '/',
///       pageBuilder: (BuildContext context, GoRouterState state) => MaterialPage<void>(
///         key: state.pageKey,
///         child: HomePage(families: Families.data),
///       ),
///       routes: <GoRoute>[
///         GoRoute(
///           path: 'family/:fid',
///           pageBuilder: (BuildContext context, GoRouterState state) {
///             final Family family = Families.family(state.params['fid']!);
///             return MaterialPage<void>(
///               key: state.pageKey,
///               child: FamilyPage(family: family),
///             );
///           },
///           routes: <GoRoute>[
///             GoRoute(
///               path: 'person/:pid',
///               pageBuilder: (BuildContext context, GoRouterState state) {
///                 final Family family = Families.family(state.params['fid']!);
///                 final Person person = family.person(state.params['pid']!);
///                 return MaterialPage<void>(
///                   key: state.pageKey,
///                   child: PersonPage(family: family, person: person),
///                 );
///               },
///             ),
///           ],
///         ),
///       ],
///     ),
///   ],
/// );
///
/// If there are multiple routes that match the location, the first match is used.
/// To make predefined routes to take precedence over dynamic routes eg. '/:id'
/// consider adding the dynamic route at the end of the routes
/// For example:
/// ```
/// final GoRouter _router = GoRouter(
///   routes: <GoRoute>[
///     GoRoute(
///       path: '/',
///       redirect: (_) => '/family/${Families.data[0].id}',
///     ),
///     GoRoute(
///       path: '/family',
///       pageBuilder: (BuildContext context, GoRouterState state) => ...,
///     ),
///     GoRoute(
///       path: '/:username',
///       pageBuilder: (BuildContext context, GoRouterState state) => ...,
///     ),
///   ],
/// );
/// ```
/// In the above example, if /family route is matched, it will be used.
/// else /:username route will be used.
///
/// See [Sub-routes](https://github.com/flutter/packages/blob/main/packages/go_router/example/lib/sub_routes.dart)
/// for a complete runnable example.
@immutable
abstract class RouteBase {
  const RouteBase._({
    this.routes = const <RouteBase>[],
  });

  /// The list of child routes associated with this route.
  final List<RouteBase> routes;
}

/// A route that is displayed visually above the matching parent route using the
/// [Navigator].
///
/// The widget returned by [builder] is wrapped in [Page] and provided to the
/// root Navigator, the nearest ShellRoute ancestor's Navigator, or the
/// Navigator with a matching [parentNavigatorKey].
///
/// The Page depends on the application type: [MaterialPage] for
/// [MaterialApp], [CupertinoPage] for [CupertinoApp], or
/// [NoTransitionPage] for [WidgetsApp].
class GoRoute extends RouteBase {
  /// Constructs a [GoRoute].
  /// - [path] and [name] cannot be empty strings.
  /// - One of either [builder] or [pageBuilder] must be provided.
  GoRoute({
    required this.path,
    this.name,
    this.builder,
    this.pageBuilder,
    this.parentNavigatorKey,
    this.redirect = _emptyRedirect,
    List<RouteBase> routes = const <RouteBase>[],
  })  : assert(path.isNotEmpty, 'GoRoute path cannot be empty'),
        assert(name == null || name.isNotEmpty, 'GoRoute name cannot be empty'),
        assert(!(builder == null && pageBuilder == null),
            'builder or pageBuilder must be provided'),
        assert(
            pageBuilder != null ||
                builder != _invalidBuilder ||
                redirect != _noRedirection,
            'GoRoute builder parameter not set\n'),
        super._(
          routes: routes,
        ) {
    // cache the path regexp and parameters
    _pathRE = patternToRegExp(path, _pathParams);
    assert(() {
      // check path params
      final Map<String, List<String>> groupedParams =
          _pathParams.groupListsBy<String>((String p) => p);
      final Map<String, List<String>> dupParams =
          Map<String, List<String>>.fromEntries(
        groupedParams.entries
            .where((MapEntry<String, List<String>> e) => e.value.length > 1),
      );
      assert(dupParams.isEmpty,
          'duplicate path params: ${dupParams.keys.join(', ')}');

      // check sub-routes
      for (final RouteBase route in routes) {
        // check paths
        if (route is GoRoute) {
          assert(
              route.path == '/' ||
                  (!route.path.startsWith('/') && !route.path.endsWith('/')),
              'sub-route path may not start or end with /: ${route.path}');
        }
      }
      return true;
    }());
  }

  /// Optional name of the route.
  ///
  /// If used, a unique string name must be provided and it can not be empty.
  ///
  /// This is used in [GoRouter.namedLocation] and its related API. This
  /// property can be used to navigate to this route without knowing exact the
  /// URI of it.
  ///
  /// {@tool snippet}
  /// Typical usage is as follows:
  ///
  /// ```dart
  /// GoRoute(
  ///   name: 'home',
  ///   path: '/',
  ///   builder: (BuildContext context, GoRouterState state) =>
  ///       HomeScreen(),
  ///   routes: <GoRoute>[
  ///     GoRoute(
  ///       name: 'family',
  ///       path: 'family/:fid',
  ///       builder: (BuildContext context, GoRouterState state) =>
  ///           FamilyScreen(),
  ///     ),
  ///   ],
  /// );
  ///
  /// context.go(
  ///   context.namedLocation('family'),
  ///   params: <String, String>{'fid': 123},
  ///   queryParams: <String, String>{'qid': 'quid'},
  /// );
  /// ```
  ///
  /// See the [named routes example](https://github.com/flutter/packages/blob/main/packages/go_router/example/lib/named_routes.dart)
  /// for a complete runnable app.
  final String? name;

  /// The path of this go route.
  ///
  /// For example:
  /// ```
  /// GoRoute(
  ///   path: '/',
  ///   pageBuilder: (BuildContext context, GoRouterState state) => MaterialPage<void>(
  ///     key: state.pageKey,
  ///     child: HomePage(families: Families.data),
  ///   ),
  /// ),
  /// ```
  ///
  /// The path also support path parameters. For a path: `/family/:fid`, it
  /// matches all URIs start with `/family/...`, e.g. `/family/123`,
  /// `/family/456` and etc. The parameter values are stored in [GoRouterState]
  /// that are passed into [pageBuilder] and [builder].
  ///
  /// The query parameter are also capture during the route parsing and stored
  /// in [GoRouterState].
  ///
  /// See [Query parameters and path parameters](https://github.com/flutter/packages/blob/main/packages/go_router/example/lib/sub_routes.dart)
  /// to learn more about parameters.
  final String path;

  /// A page builder for this route.
  ///
  /// Typically a MaterialPage, as in:
  /// ```
  /// GoRoute(
  ///   path: '/',
  ///   pageBuilder: (BuildContext context, GoRouterState state) => MaterialPage<void>(
  ///     key: state.pageKey,
  ///     child: HomePage(families: Families.data),
  ///   ),
  /// ),
  /// ```
  ///
  /// You can also use CupertinoPage, and for a custom page builder to use
  /// custom page transitions, you can use [CustomTransitionPage].
  final GoRouterPageBuilder? pageBuilder;

  /// A custom builder for this route.
  ///
  /// For example:
  /// ```
  /// GoRoute(
  ///   path: '/',
  ///   builder: (BuildContext context, GoRouterState state) => FamilyPage(
  ///     families: Families.family(
  ///       state.params['id'],
  ///     ),
  ///   ),
  /// ),
  /// ```
  ///
  final GoRouterWidgetBuilder? builder;

  /// An optional redirect function for this route.
  ///
  /// In the case that you like to make a redirection decision for a specific
  /// route (or sub-route), consider doing so by passing a redirect function to
  /// the GoRoute constructor.
  ///
  /// For example:
  /// ```
  /// final GoRouter _router = GoRouter(
  ///   routes: <GoRoute>[
  ///     GoRoute(
  ///       path: '/',
  ///       redirect: (_) => '/family/${Families.data[0].id}',
  ///     ),
  ///     GoRoute(
  ///       path: '/family/:fid',
  ///       pageBuilder: (BuildContext context, GoRouterState state) => ...,
  ///     ),
  ///   ],
  /// );
  /// ```
  ///
  /// Redirect can also be used for conditionally preventing users from visiting
  /// routes, also known as route guards. One canonical example is user
  /// authentication. See [Redirection](https://github.com/flutter/packages/blob/main/packages/go_router/example/lib/redirection.dart)
  /// for a complete runnable example.
  final GoRouterRedirect redirect;

  /// An optional key specifying which Navigator to display this route's screen
  /// onto.
  ///
  /// Specifying the root Navigator will stack this route onto that
  /// Navigator instead of the nearest ShellRoute ancestor.
  final GlobalKey<NavigatorState>? parentNavigatorKey;

  /// Match this route against a location.
  RegExpMatch? matchPatternAsPrefix(String loc) =>
      _pathRE.matchAsPrefix(loc) as RegExpMatch?;

  /// Extract the path parameters from a match.
  Map<String, String> extractPathParams(RegExpMatch match) =>
      extractPathParameters(_pathParams, match);

  static String? _emptyRedirect(GoRouterState state) => null;

  final List<String> _pathParams = <String>[];

  late final RegExp _pathRE;

  static String? _noRedirection(GoRouterState state) => null;

  static Widget _invalidBuilder(
    BuildContext context,
    GoRouterState state,
  ) =>
      const SizedBox.shrink();
}

/// A route that displays a UI shell around the matching child route.
///
/// When a ShellRoute is added to the list of routes on GoRouter or GoRoute, a
/// new Navigator that is used to display any matching sub-routes, instead of
/// placing them on the root Navigator.
///
/// To display a child route on a different Navigator, provide it with a
/// [parentNavigatorKey] that matches the key provided to either the [GoRouter]
/// or [ShellRoute] constructor. In this example, the _rootNavigator key is
/// passed to the /b/details route so that it displays on the root Navigator
/// instead of the ShellRoute's Navigator:
///
/// ```
/// final GlobalKey<NavigatorState> _rootNavigatorKey =
//     GlobalKey<NavigatorState>();
///
///   final GoRouter _router = GoRouter(
///     navigatorKey: _rootNavigatorKey,
///     initialLocation: '/a',
///     routes: [
///       ShellRoute(
///         navigatorKey: _shellNavigatorKey,
///         builder: (context, state, child) {
///           return ScaffoldWithNavBar(child: child);
///         },
///         routes: [
///           // This screen is displayed on the ShellRoute's Navigator.
///           GoRoute(
///             path: '/a',
///             builder: (context, state) {
///               return const ScreenA();
///             },
///             routes: <RouteBase>[
///               // This screen is displayed on the ShellRoute's Navigator.
///               GoRoute(
///                 path: 'details',
///                 builder: (BuildContext context, GoRouterState state) {
///                   return const DetailsScreen(label: 'A');
///                 },
///               ),
///             ],
///           ),
///           // Displayed ShellRoute's Navigator.
///           GoRoute(
///             path: '/b',
///             builder: (BuildContext context, GoRouterState state) {
///               return const ScreenB();
///             },
///             routes: <RouteBase>[
///               // Displayed on the root Navigator by specifying the
///               // [parentNavigatorKey].
///               GoRoute(
///                 path: 'details',
///                 parentNavigatorKey: _rootNavigatorKey,
///                 builder: (BuildContext context, GoRouterState state) {
///                   return const DetailsScreen(label: 'B');
///                 },
///               ),
///             ],
///           ),
///         ],
///       ),
///     ],
///   );
/// ```
///
/// The widget built by the matching sub-route becomes the child parameter
/// of the [builder].
///
/// For example:
///
/// ```
/// ShellRoute(
///   path: '/',
///   builder: (BuildContext context, GoRouterState state, Widget child) {
///     return Scaffold(
///       appBar: AppBar(
///         title: Text('App Shell')
///       ),
///       body: Center(
///         child: child,
///       ),
///     );
///   },
///   routes: [
///     GoRoute(
///       path: 'a'
///       builder: (BuildContext context, GoRouterState state) {
///         return Text('Child Route "/a"');
///       }
///     ),
///   ],
/// ),
/// ```
///
class ShellRoute extends RouteBase {
  /// Constructs a [ShellRoute].
  ShellRoute({
    this.builder,
    this.pageBuilder,
    super.routes,
    GlobalKey<NavigatorState>? navigatorKey,
  })  : assert(routes.isNotEmpty),
        navigatorKey = navigatorKey ?? GlobalKey<NavigatorState>(),
        super._() {
    for (final RouteBase route in routes) {
      assert(route is GoRoute);
      assert((route as GoRoute).parentNavigatorKey == null);
    }
  }

  /// The widget builder for a shell route.
  ///
  /// Similar to GoRoute builder, but with an additional child parameter. This
  /// child parameter is the Widget built by calling the matching sub-route's
  /// builder.
  final ShellRouteBuilder? builder;

  /// The page builder for a shell route.
  ///
  /// Similar to GoRoute pageBuilder, but with an additional child parameter.
  /// This child parameter is the Widget built by calling the matching
  /// sub-route's builder.
  final ShellRoutePageBuilder? pageBuilder;

  /// The [GlobalKey] to be used by the [Navigator] built for this route.
  /// All ShellRoutes build a Navigator by default. Child GoRoutes
  /// are placed onto this Navigator instead of the root Navigator.
  final GlobalKey<NavigatorState> navigatorKey;
}