// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System;
using osu.Framework.Allocation;
using osu.Framework.Extensions.Color4Extensions;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Graphics.Effects;
using osu.Game.Graphics;
using osuTK;
using osuTK.Graphics;
using osu.Framework.Graphics.Shapes;
using osu.Framework.Utils;
using osu.Game.Skinning;

namespace osu.Game.Screens.Play.HUD
{
    public partial class DefaultHealthDisplay : HealthDisplay, IHasAccentColour, ISerialisableDrawable
    {
        /// <summary>
        /// The base opacity of the glow.
        /// </summary>
        private const float base_glow_opacity = 0.6f;

        /// <summary>
        /// The number of sequential hits required within <see cref="glow_fade_delay"/> to reach the maximum glow opacity.
        /// </summary>
        private const int glow_max_hits = 8;

        /// <summary>
        /// The amount of time to delay before fading the glow opacity back to <see cref="base_glow_opacity"/>.
        /// <para>
        /// This is calculated to require a stream snapped to 1/4 at 150bpm to reach the maximum glow opacity with <see cref="glow_max_hits"/> hits.
        /// </para>
        /// </summary>
        private const float glow_fade_delay = 100;

        /// <summary>
        /// The amount of time to fade the glow to <see cref="base_glow_opacity"/> after <see cref="glow_fade_delay"/>.
        /// </summary>
        private const double glow_fade_time = 500;

        private readonly Container fill;

        public Color4 AccentColour
        {
            get => fill.Colour;
            set => fill.Colour = value;
        }

        private Color4 glowColour;

        public Color4 GlowColour
        {
            get => glowColour;
            set
            {
                if (glowColour == value)
                    return;

                glowColour = value;

                fill.EdgeEffect = new EdgeEffectParameters
                {
                    Colour = glowColour.Opacity(base_glow_opacity),
                    Radius = 8,
                    Roundness = 4,
                    Type = EdgeEffectType.Glow,
                };
            }
        }

        public bool UsesFixedAnchor { get; set; }

        public DefaultHealthDisplay()
        {
            const float padding = 20;
            const float bar_height = 5;

            Size = new Vector2(1, bar_height + padding * 2);
            RelativeSizeAxes = Axes.X;

            InternalChild = new Container
            {
                Padding = new MarginPadding { Vertical = padding },
                Anchor = Anchor.CentreLeft,
                Origin = Anchor.CentreLeft,
                RelativeSizeAxes = Axes.Both,
                Children = new Drawable[]
                {
                    new Box
                    {
                        RelativeSizeAxes = Axes.Both,
                        Colour = Color4.Black,
                    },
                    fill = new Container
                    {
                        RelativeSizeAxes = Axes.Both,
                        Size = new Vector2(0, 1),
                        Masking = true,
                        Children = new[]
                        {
                            new Box
                            {
                                RelativeSizeAxes = Axes.Both,
                            }
                        }
                    },
                }
            };
        }

        protected override void Flash()
        {
            fill.FadeEdgeEffectTo(Math.Min(1, fill.EdgeEffect.Colour.Linear.A + (1f - base_glow_opacity) / glow_max_hits), 50, Easing.OutQuint)
                .Delay(glow_fade_delay)
                .FadeEdgeEffectTo(base_glow_opacity, glow_fade_time, Easing.OutQuint);
        }

        [BackgroundDependencyLoader]
        private void load(OsuColour colours)
        {
            AccentColour = colours.BlueLighter;
            GlowColour = colours.BlueDarker;
        }

        protected override void Update()
        {
            base.Update();

            fill.Width = Interpolation.ValueAt(
                Math.Clamp(Clock.ElapsedFrameTime, 0, 200),
                fill.Width, (float)Current.Value, 0, 200, Easing.OutQuint);
        }
    }
}