using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace Kav
{
    public class DirectionalShadowMapData
    {
        public static readonly int MAX_SHADOW_CASCADES = 4;

        public RenderTarget2D[] ShadowMaps { get; }

        public Matrix[] LightSpaceViews { get; }
        public Matrix[] LightSpaceProjections { get; }

        public float[] CascadeFarPlanes { get; }

        public int ShadowMapSize { get; }
        public int NumShadowCascades { get; }

        internal DirectionalShadowMapData(
            GraphicsDevice graphicsDevice,
            int shadowMapSize,
            int numCascades
        ) {
            ShadowMapSize = shadowMapSize;
            NumShadowCascades = (int)MathHelper.Clamp(numCascades, 1, MAX_SHADOW_CASCADES);

            LightSpaceViews = new Matrix[4];
            LightSpaceProjections = new Matrix[4];

            ShadowMaps = new RenderTarget2D[NumShadowCascades];

            for (var i = 0; i < NumShadowCascades; i++)
            {
                ShadowMaps[i] = new RenderTarget2D(
                    graphicsDevice,
                    shadowMapSize,
                    shadowMapSize,
                    false,
                    SurfaceFormat.Single,
                    DepthFormat.Depth24,
                    0,
                    RenderTargetUsage.PreserveContents
                );
            }

            CascadeFarPlanes = new float[MAX_SHADOW_CASCADES];
        }

        public void Clear(GraphicsDevice graphicsDevice)
        {
            foreach (var shadowMap in ShadowMaps)
            {
                graphicsDevice.SetRenderTarget(shadowMap);
                graphicsDevice.Clear(Color.White);
            }
        }
    }
}