import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class GetRoute<T> extends PageRoute<T> {
  /// The values of [builder], [maintainState], and [fullScreenDialog] must not
  /// be null.
  GetRoute({
    @required this.builder,
    RouteSettings settings,
    this.opaque = false,
    this.maintainState = true,
    bool fullscreenDialog = false,
  }) : assert(builder != null),
        assert(maintainState != null),
        assert(fullscreenDialog != null),
        assert(opaque != null),
        super(settings: settings, fullscreenDialog: fullscreenDialog);

  /// Builds the primary contents of the route.
  final WidgetBuilder builder;

  @override
  final bool maintainState;

  /// Allows you to set opaque to false to prevent route reconstruction.
  @override
  final bool opaque;

  @override
  Duration get transitionDuration => const Duration(milliseconds: 300);

  @override
  Color get barrierColor => null;

  @override
  String get barrierLabel => null;

  @override
  bool canTransitionFrom(TransitionRoute<dynamic> previousRoute) {
    return previousRoute is GetRoute || previousRoute is CupertinoPageRoute;
  }

  @override
  bool canTransitionTo(TransitionRoute<dynamic> nextRoute) {
    // Don't perform outgoing animation if the next route is a fullscreen dialog.
    return (nextRoute is GetRoute && !nextRoute.fullscreenDialog)
        || (nextRoute is CupertinoPageRoute && !nextRoute.fullscreenDialog);
  }

  @override
  Widget buildPage(
      BuildContext context,
      Animation<double> animation,
      Animation<double> secondaryAnimation,
      ) {
    final Widget result = builder(context);
    assert(() {
      if (result == null) {
        throw FlutterError.fromParts(<DiagnosticsNode>[
          ErrorSummary('The builder for route "${settings.name}" returned null.'),
          ErrorDescription('Route builders must never return null.')
        ]);
      }
      return true;
    }());
    return Semantics(
      scopesRoute: true,
      explicitChildNodes: true,
      child: result,
    );
  }

  @override
  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
    final PageTransitionsTheme theme = Theme.of(context).pageTransitionsTheme;
    return theme.buildTransitions<T>(this, context, animation, secondaryAnimation, child);
  }

  @override
  String get debugLabel => '${super.debugLabel}(${settings.name})';
}