using System.Threading;
using KitsuneCafe.System;
using KitsuneCafe.System.Attributes;
using R3;
using UnityEngine;
using UnityEngine.UIElements;

namespace KitsuneCafe.UI
{
    [CreateAssetMenu(menuName = KitsuneCafeMenu.UiEffect + "Fade")]
    public class FadeEffect : BaseUiEffect
    {
        [SerializeField]
        private bool addTransition = false;

        [SerializeField, ShowIf("addTransition")]
        private string propertyName = "opacity";

        [SerializeField, ShowIf("addTransition")]
        private SerializableDuration duration;

        [SerializeField, ShowIf("addTransition")]
        private EasingMode easing;

        [SerializeField, ShowIf("addTransition")]
        private SerializableDuration delay;

        [SerializeField, Range(0f, 1f)]
        private float from;

        [SerializeField, Range(0f, 1f)]
        private float to;

        public override IUiEffect Instantiate()
        {
            var fade = new FadeEffectInstance(from, to);

            if (addTransition)
            {
                return new AddTransitionEffect(propertyName, duration, easing, delay, fade);
            }

            return fade;
        }
    }

    public readonly struct FadeEffectInstance : IUiEffect
    {
        public readonly float From;
        public readonly float To;

        public FadeEffectInstance(float from, float to)
        {
            From = from;
            To = to;
        }

        private void DoTransition(VisualElement target)
        {
            target.style.opacity = From;
            target.style.opacity = To;
        }


        public Observable<R3.Unit> Execute(VisualElement target, CancellationToken token)
        {
            target.style.opacity = From;

            var to = To;
            return Observable.NextFrame(cancellationToken: token)
               .Do(_ =>
               {
                   target.style.opacity = to;
               })
               .AsUnitObservable();
        }

    }
}