Syntriax.Engine/Engine.Systems/Tween/TweenManager.cs

using System.Collections;

using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;

namespace Syntriax.Engine.Systems.Tween;

public class TweenManager : HierarchyObject
{
    private CoroutineManager coroutineManager = null!;

    private readonly Dictionary<ITween, IEnumerator> runningCoroutines = [];

    public ITween StartTween(float duration, TweenSetCallback? setCallback = null)
    {
        Tween tween = new(duration);
        tween.OnUpdated += tween => setCallback?.Invoke(tween.Value);
        runningCoroutines.Add(tween, coroutineManager.StartCoroutine(RunTween(tween)));
        return tween;
    }

    private IEnumerator RunTween(Tween tween)
    {
        tween.State = TweenState.Playing;
        yield return null;

        while (true)
        {
            if (tween.State.CheckFlag(TweenState.Cancelled | TweenState.Completed))
                break;

            if (tween.State.CheckFlag(TweenState.Paused))
            {
                yield return null;
                continue;
            }

            tween.Counter += GameManager.Time.DeltaTime;
            yield return null;
        }

        runningCoroutines.Remove(tween);
    }

    public void CancelTween(ITween tween)
    {
        if (!runningCoroutines.TryGetValue(tween, out IEnumerator? runningCoroutine))
            return;

        tween.State = TweenState.Cancelled;
        coroutineManager.StopCoroutine(runningCoroutine);
        runningCoroutines.Remove(tween);
    }

    protected override void OnEnteringHierarchy(IGameManager gameManager)
    {
        coroutineManager = gameManager.FindHierarchyObject<CoroutineManager>() ?? throw new($"No {nameof(CoroutineManager)} was found in the game manager");
    }

    protected override void OnExitingHierarchy(IGameManager gameManager)
    {
        coroutineManager = null!;
    }

    public delegate void TweenSetCallback(float t);
}