// 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.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Graphics.Pooling;
using osu.Game.Beatmaps;
using osu.Game.Beatmaps.Drawables;
using osu.Game.Graphics;
using osu.Game.Graphics.Containers;
using osu.Game.Graphics.Sprites;
using osu.Game.Graphics.UserInterface;
using osu.Game.Overlays;
using osu.Game.Resources.Localisation.Web;
using osu.Game.Rulesets;
using osu.Game.Rulesets.Mods;
using osuTK;

namespace osu.Game.Screens.SelectV2
{
    public partial class BeatmapPanel : PoolableDrawable, ICarouselPanel
    {
        public const float HEIGHT = CarouselItem.DEFAULT_HEIGHT;

        // todo: this should be replaced with information from CarouselItem about how deep is BeatmapPanel in the carousel
        // (i.e. whether it's under a beatmap set that's under a group, or just under a top-level beatmap set).
        private const float difficulty_x_offset = 100f; // constant X offset for beatmap difficulty panels specifically.

        private const float duration = 500;

        private CarouselPanelPiece panel = null!;
        private StarCounter starCounter = null!;
        private ConstrainedIconContainer difficultyIcon = null!;
        private OsuSpriteText keyCountText = null!;
        private StarRatingDisplay starRatingDisplay = null!;
        private TopLocalRankV2 difficultyRank = null!;
        private OsuSpriteText difficultyText = null!;
        private OsuSpriteText authorText = null!;

        private IBindable<StarDifficulty?>? starDifficultyBindable;
        private CancellationTokenSource? starDifficultyCancellationSource;

        [Resolved]
        private OverlayColourProvider colourProvider { get; set; } = null!;

        [Resolved]
        private OsuColour colours { get; set; } = null!;

        [Resolved]
        private BeatmapDifficultyCache difficultyCache { get; set; } = null!;

        [Resolved]
        private BeatmapCarousel? carousel { get; set; }

        [Resolved]
        private IBindable<RulesetInfo> ruleset { get; set; } = null!;

        [Resolved]
        private IBindable<IReadOnlyList<Mod>> mods { get; set; } = null!;

        [BackgroundDependencyLoader]
        private void load(OverlayColourProvider colourProvider)
        {
            Anchor = Anchor.TopRight;
            Origin = Anchor.TopRight;

            RelativeSizeAxes = Axes.X;
            Width = 1f;
            Height = HEIGHT;

            InternalChild = panel = new CarouselPanelPiece(difficulty_x_offset)
            {
                Action = onAction,
                Icon = difficultyIcon = new ConstrainedIconContainer
                {
                    Size = new Vector2(20),
                    Margin = new MarginPadding { Horizontal = 5f },
                    Colour = colourProvider.Background5,
                },
                Children = new[]
                {
                    new FillFlowContainer
                    {
                        Anchor = Anchor.CentreLeft,
                        Origin = Anchor.CentreLeft,
                        Padding = new MarginPadding { Left = 10f },
                        Direction = FillDirection.Vertical,
                        AutoSizeAxes = Axes.Both,
                        Children = new Drawable[]
                        {
                            new FillFlowContainer
                            {
                                Direction = FillDirection.Horizontal,
                                Spacing = new Vector2(3, 0),
                                AutoSizeAxes = Axes.Both,
                                Children = new Drawable[]
                                {
                                    starRatingDisplay = new StarRatingDisplay(default, StarRatingDisplaySize.Small)
                                    {
                                        Anchor = Anchor.CentreLeft,
                                        Origin = Anchor.CentreLeft,
                                    },
                                    difficultyRank = new TopLocalRankV2
                                    {
                                        Anchor = Anchor.CentreLeft,
                                        Origin = Anchor.CentreLeft,
                                        Scale = new Vector2(0.75f)
                                    },
                                    starCounter = new StarCounter
                                    {
                                        Anchor = Anchor.CentreLeft,
                                        Origin = Anchor.CentreLeft,
                                        Scale = new Vector2(0.4f)
                                    }
                                }
                            },
                            new FillFlowContainer
                            {
                                Direction = FillDirection.Horizontal,
                                AutoSizeAxes = Axes.Both,
                                Children = new[]
                                {
                                    keyCountText = new OsuSpriteText
                                    {
                                        Font = OsuFont.GetFont(size: 18, weight: FontWeight.SemiBold),
                                        Anchor = Anchor.BottomLeft,
                                        Origin = Anchor.BottomLeft,
                                        Alpha = 0,
                                    },
                                    difficultyText = new OsuSpriteText
                                    {
                                        Font = OsuFont.GetFont(size: 18, weight: FontWeight.SemiBold),
                                        Anchor = Anchor.BottomLeft,
                                        Origin = Anchor.BottomLeft,
                                        Margin = new MarginPadding { Right = 8f },
                                    },
                                    authorText = new OsuSpriteText
                                    {
                                        Colour = colourProvider.Content2,
                                        Font = OsuFont.GetFont(weight: FontWeight.SemiBold),
                                        Anchor = Anchor.BottomLeft,
                                        Origin = Anchor.BottomLeft
                                    }
                                }
                            }
                        }
                    },
                }
            };
        }

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

            ruleset.BindValueChanged(_ =>
            {
                computeStarRating();
                updateKeyCount();
            });

            mods.BindValueChanged(_ =>
            {
                computeStarRating();
                updateKeyCount();
            }, true);

            Selected.BindValueChanged(s => panel.Active.Value = s.NewValue, true);
            KeyboardSelected.BindValueChanged(k => panel.KeyboardActive.Value = k.NewValue, true);
        }

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

            Debug.Assert(Item != null);
            var beatmap = (BeatmapInfo)Item.Model;

            difficultyIcon.Icon = beatmap.Ruleset.CreateInstance().CreateIcon();

            difficultyRank.Beatmap = beatmap;
            difficultyText.Text = beatmap.DifficultyName;
            authorText.Text = BeatmapsetsStrings.ShowDetailsMappedBy(beatmap.Metadata.Author.Username);

            computeStarRating();
            updateKeyCount();

            FinishTransforms(true);
            this.FadeInFromZero(duration, Easing.OutQuint);
        }

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

            difficultyRank.Beatmap = null;
            starDifficultyBindable = null;
        }

        private void computeStarRating()
        {
            starDifficultyCancellationSource?.Cancel();
            starDifficultyCancellationSource = new CancellationTokenSource();

            if (Item == null)
                return;

            var beatmap = (BeatmapInfo)Item.Model;

            starDifficultyBindable = difficultyCache.GetBindableDifficulty(beatmap, starDifficultyCancellationSource.Token);
            starDifficultyBindable.BindValueChanged(_ => updateDisplay(), true);
        }

        private void updateKeyCount()
        {
            if (Item == null)
                return;

            var beatmap = (BeatmapInfo)Item.Model;

            if (ruleset.Value.OnlineID == 3)
            {
                // Account for mania differences locally for now.
                // Eventually this should be handled in a more modular way, allowing rulesets to add more information to the panel.
                ILegacyRuleset legacyRuleset = (ILegacyRuleset)ruleset.Value.CreateInstance();
                int keyCount = legacyRuleset.GetKeyCount(beatmap, mods.Value);

                keyCountText.Alpha = 1;
                keyCountText.Text = $"[{keyCount}K] ";
            }
            else
                keyCountText.Alpha = 0;
        }

        private void updateDisplay()
        {
            var starDifficulty = starDifficultyBindable?.Value ?? default;

            starRatingDisplay.Current.Value = starDifficulty;
            starCounter.Current = (float)starDifficulty.Stars;

            difficultyIcon.FadeColour(starDifficulty.Stars > 6.5f ? colours.Orange1 : colourProvider.Background5, duration, Easing.OutQuint);

            var starRatingColour = colours.ForStarDifficulty(starDifficulty.Stars);
            starCounter.FadeColour(starRatingColour, duration, Easing.OutQuint);
            panel.AccentColour = starRatingColour;
        }

        private void onAction()
        {
            if (carousel == null)
                return;

            if (carousel.CurrentSelection != Item!.Model)
                carousel.CurrentSelection = Item!.Model;
            else
                carousel.TryActivateSelection();
        }

        #region ICarouselPanel

        public CarouselItem? Item { get; set; }
        public BindableBool Selected { get; } = new BindableBool();
        public BindableBool Expanded { get; } = new BindableBool();
        public BindableBool KeyboardSelected { get; } = new BindableBool();

        public double DrawYPosition { get; set; }

        public void Activated()
        {
            panel.Flash();
        }

        #endregion
    }
}