using Robust.Client.Graphics.Drawing;
using Robust.Client.Interfaces.GameObjects.Components;
using Robust.Client.Interfaces.Graphics;
using Robust.Shared.Maths;
using System;

namespace Robust.Client.UserInterface.Controls
{
    public class CooldownGraphic : Control
    {
        public float Fraction { get; set; }

        protected override void Draw(DrawingHandleScreen handle)
        {
            const int maxSegments = 64;
            const float segment = MathHelper.TwoPi / maxSegments;

            var segments = (int)Math.Max(2, Math.Ceiling(maxSegments * Fraction)); // ensure that we always have at least 3 vertices
            var max = MathHelper.TwoPi * Fraction;
            var radius = (Math.Min(SizeBox.Height, SizeBox.Width) / 2) * 0.875f; // 28/32 = 0.875 - 2 pixels inwards from the edge
            var ring_radius = (Math.Min(SizeBox.Height, SizeBox.Width) / 2) * 0.5625f;

            Span <Vector2> vertices = stackalloc Vector2[segments * 2];
            var center = PixelPosition + SizeBox.Center;
            for (int i = 0; i < segments; i++)
            {
                var angle = MathHelper.Pi + Math.Min(max, segment * i);
                vertices[2*i] = center + new Vector2((float) Math.Sin(angle) * radius, (float) Math.Cos(angle) * radius);
                vertices[2*i + 1] = center + new Vector2((float) Math.Sin(angle) * ring_radius, (float) Math.Cos(angle) * ring_radius);
            }

            handle.DrawPrimitives(DrawPrimitiveTopology.TriangleStrip, vertices, new Color(0.3f, 0.3f, 0.4f, 0.75f));
        }
    }
}