using System;
using System.Collections.Generic;
using Unity.UIWidgets.animation;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;

namespace UIWidgetsSample
{
    public static class ModalPage
    {
        public static void popup(
            BuildContext context,
            Widget child,
            Widget overlay = null,
            VoidCallback onPop = null,
            bool justFade = false
        )
        {
            PopupRoute route;
            if (justFade)
            {
                route = new _FadePopupRoute(
                    cxt => child,
                    overlay == null
                        ? (WidgetBuilder) null
                        : ctx => overlay,
                    "Dismiss"
                );
            }
            else
            {
                route = new _ModalPopupRoute(
                    cxt => child,
                    overlay == null
                        ? (WidgetBuilder) null
                        : ctx => overlay,
                    "Dismiss"
                );
            }
            Navigator.push<object>(context, route).then_(_ => onPop?.Invoke());
        }

        public static void dismiss(BuildContext context)
        {
            // if (Navigator.canPop(context))
            {
                Navigator.pop(context);
            }
        }
    }

    internal class _ModalPopupRoute : PopupRoute
    {
        public _ModalPopupRoute(
            WidgetBuilder builder = null,
            WidgetBuilder overlayBuilder = null,
            string barrierLabel = "",
            RouteSettings settings = null
        ) : base(settings)
        {
            this.builder = builder;
            this.barrierLabel = barrierLabel;
            this.overlayBuilder = overlayBuilder;
        }

        private readonly WidgetBuilder builder;

        private readonly WidgetBuilder overlayBuilder;

        public string barrierLabel { get; }

        public override Color barrierColor => new Color(0x6604040F);

        public override bool barrierDismissible => true;

        public override TimeSpan transitionDuration => TimeSpan.FromMilliseconds(335);

        private AnimationController _animationController;

        private Animation<float> _animation;

        private Tween<Offset> _offsetTween;

        private Tween<float> _opacityTween;

        public override Animation<float> createAnimation()
        {
            D.assert(_animation == null);
            _animation = new CurvedAnimation(
                base.createAnimation(),
                Curves.linearToEaseOut,
                Curves.linearToEaseOut.flipped
            );
            _offsetTween = new OffsetTween(
                new Offset(0, 1),
                new Offset(0, 0)
            );
            _opacityTween = new FloatTween(0, 1);
            return _animation;
        }

        public override Widget buildPage(BuildContext context, Animation<float> animation,
            Animation<float> secondaryAnimation)
        {
            return builder(context);
        }

        public override Widget buildTransitions(BuildContext context, Animation<float> animation,
            Animation<float> secondaryAnimation, Widget child)
        {
            Widget result = new Align(
                alignment: Alignment.bottomCenter,
                child: new FractionalTranslation(
                    translation: _offsetTween.evaluate(_animation),
                    child: child
                )
            );

            if (overlayBuilder != null)
            {
                result = new Stack(
                    children: new List<Widget>
                    {
                        Positioned.fill(
                            new Opacity(
                                opacity: _opacityTween.evaluate(_animation),
                                child: overlayBuilder(context)
                            )
                        ),
                        result
                    });
            }

            return result;
        }
    }
    
    internal class _FadePopupRoute : PopupRoute
    {
        public _FadePopupRoute(
            WidgetBuilder builder = null,
            WidgetBuilder overlayBuilder = null,
            string barrierLabel = "",
            RouteSettings settings = null
        ) : base(settings)
        {
            this.builder = builder;
            this.barrierLabel = barrierLabel;
            this.overlayBuilder = overlayBuilder;
        }

        private readonly WidgetBuilder builder;

        private readonly WidgetBuilder overlayBuilder;

        public string barrierLabel { get; }

        public override Color barrierColor => new Color(0x6604040F);

        public override bool barrierDismissible => true;

        public override TimeSpan transitionDuration => TimeSpan.FromMilliseconds(335);

        private AnimationController _animationController;

        private Animation<float> _animation;
        
        private Tween<float> _opacityTween;

        public override Animation<float> createAnimation()
        {
            D.assert(_animation == null);
            _animation = new CurvedAnimation(
                base.createAnimation(),
                Curves.linearToEaseOut,
                Curves.linearToEaseOut.flipped
            );
            _opacityTween = new FloatTween(0, 1);
            return _animation;
        }

        public override Widget buildPage(BuildContext context, Animation<float> animation,
            Animation<float> secondaryAnimation)
        {
            return builder(context);
        }

        public override Widget buildTransitions(BuildContext context, Animation<float> animation,
            Animation<float> secondaryAnimation, Widget child)
        {
            Widget result = new Align(
                alignment: Alignment.bottomCenter,
                child: new Opacity(
                    opacity: _opacityTween.evaluate(_animation),
                    child: child
                )
            );

            if (overlayBuilder != null)
            {
                result = new Stack(
                    children: new List<Widget>
                    {
                        Positioned.fill(
                            new Opacity(
                                opacity: _opacityTween.evaluate(_animation),
                                child: overlayBuilder(context)
                            )
                        ),
                        result
                    });
            }

            return result;
        }
    }
}