using System.Collections.Generic;
using Syntriax.Engine.Core;

namespace Syntriax.Engine.Systems.Tween;

public static class TweenShape2DExtensions
{
    public static ITween TweenShape2D(this Shape2D shape, ITweenManager tweenManager, float duration, Shape2D targetShape2D)
    {
        List<Vector2D> initialVertices = new(shape.Vertices);
        List<Vector2D> shapeVertices = new(shape.Vertices);

        return tweenManager.StartTween(duration,
                t =>
                {
                    shapeVertices.Clear();
                    int maxCount = initialVertices.Count.Max(targetShape2D.Vertices.Count);
                    for (int i = 0; i < maxCount; i++)
                    {
                        int initialIndex = (i * (initialVertices.Count / (float)maxCount)).RoundToInt(Math.RoundMode.Floor);
                        int targetIndex = (i * (targetShape2D.Vertices.Count / (float)maxCount)).RoundToInt(Math.RoundMode.Floor);
                        shapeVertices.Add(targetShape2D.Vertices[targetIndex].Lerp(initialVertices[initialIndex], 1f - t));
                    }
                    shape.Vertices = shapeVertices;
                }
            ).OnComplete(() =>
            {
                shapeVertices.Clear();
                for (int i = 0; i < targetShape2D.Vertices.Count; i++)
                    shapeVertices.Add(targetShape2D.Vertices[i]);
                shape.Vertices = shapeVertices;
            });
    }
}