// 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 System.Globalization;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Extensions.Color4Extensions;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Graphics.Effects;
using osu.Framework.Graphics.Shapes;
using osu.Framework.Graphics.UserInterface;
using osu.Framework.Input.Bindings;
using osu.Framework.Input.Events;
using osu.Framework.Threading;
using osu.Framework.Utils;
using osu.Game.Graphics;
using osu.Game.Graphics.Sprites;
using osu.Game.Input.Bindings;
using osuTK;
using osuTK.Graphics;

namespace osu.Game.Overlays.Volume
{
    public class VolumeMeter : Container, IKeyBindingHandler<GlobalAction>
    {
        private CircularProgress volumeCircle;
        private CircularProgress volumeCircleGlow;

        public BindableDouble Bindable { get; } = new BindableDouble { MinValue = 0, MaxValue = 1, Precision = 0.01 };
        private readonly float circleSize;
        private readonly Color4 meterColour;
        private readonly string name;

        private OsuSpriteText text;
        private BufferedContainer maxGlow;

        public VolumeMeter(string name, float circleSize, Color4 meterColour)
        {
            this.circleSize = circleSize;
            this.meterColour = meterColour;
            this.name = name;

            AutoSizeAxes = Axes.Both;
        }

        [BackgroundDependencyLoader]
        private void load(OsuColour colours)
        {
            Color4 backgroundColour = colours.Gray1;

            CircularProgress bgProgress;

            const float progress_start_radius = 0.75f;
            const float progress_size = 0.03f;
            const float progress_end_radius = progress_start_radius + progress_size;

            const float blur_amount = 5;

            Children = new Drawable[]
            {
                new Container
                {
                    Size = new Vector2(circleSize),
                    Children = new Drawable[]
                    {
                        new BufferedContainer
                        {
                            Alpha = 0.9f,
                            RelativeSizeAxes = Axes.Both,
                            Children = new Drawable[]
                            {
                                new Circle
                                {
                                    RelativeSizeAxes = Axes.Both,
                                    Colour = backgroundColour,
                                },
                                new CircularContainer
                                {
                                    Masking = true,
                                    Anchor = Anchor.Centre,
                                    Origin = Anchor.Centre,
                                    RelativeSizeAxes = Axes.Both,
                                    Size = new Vector2(progress_end_radius),
                                    Children = new Drawable[]
                                    {
                                        bgProgress = new CircularProgress
                                        {
                                            Anchor = Anchor.Centre,
                                            Origin = Anchor.Centre,
                                            RelativeSizeAxes = Axes.Both,
                                            Rotation = 180,
                                            Colour = backgroundColour,
                                        },
                                        new Container
                                        {
                                            Anchor = Anchor.Centre,
                                            Origin = Anchor.Centre,
                                            Name = "Progress under covers for smoothing",
                                            RelativeSizeAxes = Axes.Both,
                                            Rotation = 180,
                                            Child = volumeCircle = new CircularProgress
                                            {
                                                RelativeSizeAxes = Axes.Both,
                                            }
                                        },
                                    }
                                },
                                new Circle
                                {
                                    Name = "Inner Cover",
                                    Anchor = Anchor.Centre,
                                    Origin = Anchor.Centre,
                                    RelativeSizeAxes = Axes.Both,
                                    Colour = backgroundColour,
                                    Size = new Vector2(progress_start_radius),
                                },
                                new Container
                                {
                                    Name = "Progress overlay for glow",
                                    Anchor = Anchor.Centre,
                                    Origin = Anchor.Centre,
                                    RelativeSizeAxes = Axes.Both,
                                    Size = new Vector2(progress_start_radius + progress_size / 1.5f),
                                    Rotation = 180,
                                    Padding = new MarginPadding(-Blur.KernelSize(blur_amount)),
                                    Child = (volumeCircleGlow = new CircularProgress
                                    {
                                        RelativeSizeAxes = Axes.Both,
                                        InnerRadius = progress_size * 0.8f,
                                    }).WithEffect(new GlowEffect
                                    {
                                        Colour = meterColour,
                                        BlurSigma = new Vector2(blur_amount),
                                        Strength = 5,
                                        PadExtent = true
                                    }),
                                },
                            },
                        },
                        maxGlow = (text = new OsuSpriteText
                        {
                            Anchor = Anchor.Centre,
                            Origin = Anchor.Centre,
                            Font = OsuFont.Numeric.With(size: 0.16f * circleSize)
                        }).WithEffect(new GlowEffect
                        {
                            Colour = Color4.Transparent,
                            PadExtent = true,
                        })
                    }
                },
                new Container
                {
                    Size = new Vector2(120, 20),
                    CornerRadius = 10,
                    Masking = true,
                    Margin = new MarginPadding { Left = circleSize + 10 },
                    Origin = Anchor.CentreLeft,
                    Anchor = Anchor.CentreLeft,
                    Children = new Drawable[]
                    {
                        new Box
                        {
                            Alpha = 0.9f,
                            RelativeSizeAxes = Axes.Both,
                            Colour = backgroundColour,
                        },
                        new OsuSpriteText
                        {
                            Anchor = Anchor.Centre,
                            Origin = Anchor.Centre,
                            Font = OsuFont.GetFont(weight: FontWeight.Bold),
                            Text = name
                        }
                    }
                }
            };

            Bindable.ValueChanged += volume =>
            {
                this.TransformTo("DisplayVolume",
                    volume.NewValue,
                    400,
                    Easing.OutQuint);
            };

            bgProgress.Current.Value = 0.75f;
        }

        protected override void LoadComplete()
        {
            base.LoadComplete();
            Bindable.TriggerChange();
        }

        private double displayVolume;

        protected double DisplayVolume
        {
            get => displayVolume;
            set
            {
                displayVolume = value;

                if (displayVolume > 0.99f)
                {
                    text.Text = "MAX";
                    maxGlow.EffectColour = meterColour.Opacity(2f);
                }
                else
                {
                    maxGlow.EffectColour = Color4.Transparent;
                    text.Text = Math.Round(displayVolume * 100).ToString(CultureInfo.CurrentCulture);
                }

                volumeCircle.Current.Value = displayVolume * 0.75f;
                volumeCircleGlow.Current.Value = displayVolume * 0.75f;
            }
        }

        public double Volume
        {
            get => Bindable.Value;
            private set => Bindable.Value = value;
        }

        private const double adjust_step = 0.01;

        public void Increase(double amount = 1, bool isPrecise = false) => adjust(amount, isPrecise);
        public void Decrease(double amount = 1, bool isPrecise = false) => adjust(-amount, isPrecise);

        // because volume precision is set to 0.01, this local is required to keep track of more precise adjustments and only apply when possible.
        private double scrollAccumulation;

        private double accelerationModifier = 1;

        private const double max_acceleration = 5;
        private const double acceleration_multiplier = 1.8;

        private ScheduledDelegate accelerationDebounce;

        private void resetAcceleration() => accelerationModifier = 1;

        private void adjust(double delta, bool isPrecise)
        {
            if (delta == 0)
                return;

            // every adjust increment increases the rate at which adjustments happen up to a cutoff.
            // this debounce will reset on inactivity.
            accelerationDebounce?.Cancel();
            accelerationDebounce = Scheduler.AddDelayed(resetAcceleration, 150);

            delta *= accelerationModifier;
            accelerationModifier = Math.Min(max_acceleration, accelerationModifier * acceleration_multiplier);

            var precision = Bindable.Precision;

            if (isPrecise)
            {
                scrollAccumulation += delta * adjust_step * 0.1;

                while (Precision.AlmostBigger(Math.Abs(scrollAccumulation), precision))
                {
                    Volume += Math.Sign(scrollAccumulation) * precision;
                    scrollAccumulation = scrollAccumulation < 0 ? Math.Min(0, scrollAccumulation + precision) : Math.Max(0, scrollAccumulation - precision);
                }
            }
            else
            {
                Volume += Math.Sign(delta) * Math.Max(precision, Math.Abs(delta * adjust_step));
            }
        }

        protected override bool OnScroll(ScrollEvent e)
        {
            adjust(e.ScrollDelta.Y, e.IsPrecise);
            return true;
        }

        private const float transition_length = 500;

        protected override bool OnHover(HoverEvent e)
        {
            this.ScaleTo(1.04f, transition_length, Easing.OutExpo);
            return false;
        }

        protected override void OnHoverLost(HoverLostEvent e)
        {
            this.ScaleTo(1f, transition_length, Easing.OutExpo);
        }

        public bool OnPressed(GlobalAction action)
        {
            if (!IsHovered)
                return false;

            switch (action)
            {
                case GlobalAction.SelectPrevious:
                    adjust(1, false);
                    return true;

                case GlobalAction.SelectNext:
                    adjust(-1, false);
                    return true;
            }

            return false;
        }

        public void OnReleased(GlobalAction action)
        {
        }
    }
}