using System.Collections.Generic;

using Engine.Core;

namespace Engine.Integration.MonoGame;

public class SpriteBatcher : BehaviourBase, IFirstFrameUpdate, IDraw
{
    private static Comparer<int> SortByPriority() => Comparer<int>.Create((x, y) => y.CompareTo(x));
    private static System.Func<IBehaviour, int> GetPriority() => (b) => b.Priority;

    private ISpriteBatch spriteBatch = null!;
    private MonoGameCamera2D camera2D = null!;

    private readonly ActiveBehaviourCollectorOrdered<int, IDrawableSprite> drawableSprites = new(GetPriority(), SortByPriority());

    public void FirstActiveFrame()
    {
        MonoGameWindowContainer windowContainer = Universe.FindRequiredBehaviour<MonoGameWindowContainer>();
        camera2D = Universe.FindRequiredBehaviour<MonoGameCamera2D>();

        spriteBatch = new SpriteBatchWrapper(windowContainer.Window.GraphicsDevice);
        drawableSprites.Unassign();
        drawableSprites.Assign(Universe);
    }

    public void Draw()
    {
        spriteBatch.Begin(transformMatrix: camera2D.MatrixTransform);
        for (int i = 0; i < drawableSprites.Count; i++)
            drawableSprites[i].Draw(spriteBatch);
        spriteBatch.End();
    }
}