using System;
using Robust.Client.Graphics;
using Robust.Client.UserInterface;
using Robust.Shared.IoC;
using Robust.Shared.Maths;
using Robust.Shared.Prototypes;
using Robust.Shared.Timing;

namespace Content.Client.DoAfter.UI
{
    public sealed class DoAfterBar : Control
    {
        private IGameTiming _gameTiming = default!;

        private readonly ShaderInstance _shader;

        /// <summary>
        ///     Set from 0.0f to 1.0f to reflect bar progress
        /// </summary>
        public float Ratio
        {
            get => _ratio;
            set => _ratio = value;
        }

        private float _ratio = 1.0f;

        /// <summary>
        ///     Flash red until removed
        /// </summary>
        public bool Cancelled
        {
            get => _cancelled;
            set
            {
                if (_cancelled == value)
                {
                    return;
                }

                _cancelled = value;
                if (_cancelled)
                {
                    _gameTiming = IoCManager.Resolve<IGameTiming>();
                    _lastFlash = _gameTiming.CurTime;
                }
            }
        }

        private bool _cancelled;

        /// <summary>
        ///     Is the cancellation bar red?
        /// </summary>
        private bool _flash = true;

        /// <summary>
        ///     Last time we swapped the flash.
        /// </summary>
        private TimeSpan _lastFlash;

        /// <summary>
        ///     How long each cancellation bar flash lasts in seconds.
        /// </summary>
        private const float FlashTime = 0.125f;

        private const int XPixelDiff = 20 * DoAfterBarScale;

        public const byte DoAfterBarScale = 2;

        public DoAfterBar()
        {
            IoCManager.InjectDependencies(this);
            _shader = IoCManager.Resolve<IPrototypeManager>().Index<ShaderPrototype>("unshaded").Instance();
        }

        protected override void FrameUpdate(FrameEventArgs args)
        {
            base.FrameUpdate(args);
            if (Cancelled)
            {
                if ((_gameTiming.CurTime - _lastFlash).TotalSeconds > FlashTime)
                {
                    _lastFlash = _gameTiming.CurTime;
                    _flash = !_flash;
                }
            }
        }

        protected override void Draw(DrawingHandleScreen handle)
        {
            base.Draw(handle);

            Color color;

            if (Cancelled)
            {
                if ((_gameTiming.CurTime - _lastFlash).TotalSeconds > FlashTime)
                {
                    _lastFlash = _gameTiming.CurTime;
                    _flash = !_flash;
                }

                color = new Color(1.0f, 0.0f, 0.0f, _flash ? 1.0f : 0.0f);
			}
            else
            {
                color = DoAfterHelpers.GetProgressColor(Ratio);
            }

            handle.UseShader(_shader);
            // If you want to make this less hard-coded be my guest
            var leftOffset = 2 * DoAfterBarScale;
            var box = new UIBox2i(
                leftOffset,
                -2 + 2 * DoAfterBarScale,
            leftOffset + (int) (XPixelDiff * Ratio * UIScale),
            -2);
            handle.DrawRect(box, color);
        }
    }

    public static class DoAfterHelpers
    {
        public static Color GetProgressColor(float progress)
        {
            if (progress >= 1.0f)
            {
                return new Color(0f, 1f, 0f);
            }
            // lerp
            var hue = (5f / 18f) * progress;
            return Color.FromHsv((hue, 1f, 0.75f, 1f));
        }
    }
}