using Amphora;
using Annulus;
using Azimuth;
using Blacklight.Core;
using Glass.Blacklight;
using System;

namespace Glass.Testbed
{
    /// <summary>
    /// Text whose tint texture slides along by age, drawn with the tint transform a render callback sets.
    /// </summary>
    public record ScrollingTintText : BakedTextMaterial
    {
        public ScrollingTintText(TextMaterialStyle style, StringView text, Scalar pixelsPerSecond,
            Scalar textureWidth) : base(style, text)
        {
            PixelsPerSecond = pixelsPerSecond;
            TextureWidth = textureWidth;
        }

        public Scalar PixelsPerSecond { get; }

        /// <summary>
        /// Gets the distance after which the tint texture repeats, which keeps the slide from growing without bound.
        /// </summary>
        public Scalar TextureWidth { get; }

        public static void Render(Renderer<Cel> renderer, Cel context, ScrollingTintText material, Rect rect,
            in DrawState drawState)
        {
            if (rect.Width == 0 || rect.Height == 0 || material.Style.Font == null)
            {
                return;
            }

            double slide = drawState.Age.TotalSeconds * material.PixelsPerSecond;
            double width = material.TextureWidth;

            DrawState scrolled = drawState;
            scrolled.TintTransform = new AffineMatrix(0, new Vector(slide - Math.Floor(slide / width) * width, 0));

            var blacklightRenderer = (BlacklightRenderer)renderer;
            blacklightRenderer.FontRendererFor(material.Style.Font).Render(context, material, rect, in scrolled);
        }
    }
}