// 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.Linq;
using osu.Framework.Allocation;
using osu.Framework.Audio.Track;
using osu.Framework.Bindables;
using osu.Framework.Extensions.IEnumerableExtensions;
using osu.Framework.Extensions.ObjectExtensions;
using osu.Framework.Graphics;
using osu.Framework.Input;
using osu.Framework.Threading;
using osu.Game.Beatmaps;
using osu.Game.Beatmaps.ControlPoints;
using osu.Game.Input.Handlers;
using osu.Game.Replays;
using osu.Game.Rulesets.Mania.Beatmaps;
using osu.Game.Rulesets.Mania.Configuration;
using osu.Game.Rulesets.Mania.Objects;
using osu.Game.Rulesets.Mania.Replays;
using osu.Game.Rulesets.Mania.Skinning;
using osu.Game.Rulesets.Mods;
using osu.Game.Rulesets.Objects;
using osu.Game.Rulesets.Objects.Drawables;
using osu.Game.Rulesets.UI;
using osu.Game.Rulesets.UI.Scrolling;
using osu.Game.Scoring;
using osu.Game.Skinning;

namespace osu.Game.Rulesets.Mania.UI
{
    public partial class DrawableManiaRuleset : DrawableScrollingRuleset<ManiaHitObject>
    {
        /// <summary>
        /// The minimum time range. This occurs at a <see cref="ManiaRulesetSetting.ScrollSpeed"/> of 40.
        /// </summary>
        public const double MIN_TIME_RANGE = 290;

        /// <summary>
        /// The maximum time range. This occurs with a <see cref="ManiaRulesetSetting.ScrollSpeed"/> of 1.
        /// </summary>
        public const double MAX_TIME_RANGE = 11485;

        protected new ManiaPlayfield Playfield => (ManiaPlayfield)base.Playfield;

        public new ManiaBeatmap Beatmap => (ManiaBeatmap)base.Beatmap;

        public IEnumerable<BarLine> BarLines;

        protected override bool RelativeScaleBeatLengths => true;

        protected new ManiaRulesetConfigManager Config => (ManiaRulesetConfigManager)base.Config;

        private readonly Bindable<ManiaScrollingDirection> configDirection = new Bindable<ManiaScrollingDirection>();
        private readonly BindableInt configScrollSpeed = new BindableInt();
        private double smoothTimeRange;

        // Stores the current speed adjustment active in gameplay.
        private readonly Track speedAdjustmentTrack = new TrackVirtual(0);

        private ISkinSource currentSkin = null!;

        public DrawableManiaRuleset(Ruleset ruleset, IBeatmap beatmap, IReadOnlyList<Mod>? mods = null)
            : base(ruleset, beatmap, mods)
        {
            BarLines = new BarLineGenerator<BarLine>(Beatmap).BarLines;

            TimeRange.MinValue = 1;
            TimeRange.MaxValue = MAX_TIME_RANGE;
        }

        [BackgroundDependencyLoader]
        private void load(ISkinSource source)
        {
            currentSkin = source;
            currentSkin.SourceChanged += onSkinChange;
            skinChanged();

            foreach (var mod in Mods.OfType<IApplicableToTrack>())
                mod.ApplyToTrack(speedAdjustmentTrack);

            bool isForCurrentRuleset = Beatmap.BeatmapInfo.Ruleset.Equals(Ruleset.RulesetInfo);

            foreach (var p in ControlPoints)
            {
                // Mania doesn't care about global velocity
                p.Velocity = 1;
                p.BaseBeatLength *= Beatmap.Difficulty.SliderMultiplier;

                // For non-mania beatmap, speed changes should only happen through timing points
                if (!isForCurrentRuleset)
                    p.EffectPoint = new EffectControlPoint();
            }

            BarLines.ForEach(Playfield.Add);

            Config.BindWith(ManiaRulesetSetting.ScrollDirection, configDirection);
            configDirection.BindValueChanged(direction => Direction.Value = (ScrollingDirection)direction.NewValue, true);

            Config.BindWith(ManiaRulesetSetting.ScrollSpeed, configScrollSpeed);
            configScrollSpeed.BindValueChanged(speed => this.TransformTo(nameof(smoothTimeRange), ComputeScrollTime(speed.NewValue), 200, Easing.OutQuint));

            TimeRange.Value = smoothTimeRange = ComputeScrollTime(configScrollSpeed.Value);
        }

        protected override void AdjustScrollSpeed(int amount) => configScrollSpeed.Value += amount;

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

        private ScheduledDelegate? pendingSkinChange;
        private float hitPosition;

        private void onSkinChange()
        {
            // schedule required to avoid calls after disposed.
            // note that this has the side-effect of components only performing a skin change when they are alive.
            pendingSkinChange?.Cancel();
            pendingSkinChange = Scheduler.Add(skinChanged);
        }

        private void skinChanged()
        {
            hitPosition = currentSkin.GetConfig<ManiaSkinConfigurationLookup, float>(
                              new ManiaSkinConfigurationLookup(LegacyManiaSkinConfigurationLookups.HitPosition))?.Value
                          ?? Stage.HIT_TARGET_POSITION;

            pendingSkinChange = null;
        }

        private void updateTimeRange()
        {
            const float length_to_default_hit_position = 768 - LegacyManiaSkinConfiguration.DEFAULT_HIT_POSITION;
            float lengthToHitPosition = 768 - hitPosition;

            // This scaling factor preserves the scroll speed as the scroll length varies from changes to the hit position.
            float scale = lengthToHitPosition / length_to_default_hit_position;

            TimeRange.Value = smoothTimeRange * speedAdjustmentTrack.AggregateTempo.Value * speedAdjustmentTrack.AggregateFrequency.Value * scale;
        }

        /// <summary>
        /// Computes a scroll time (in milliseconds) from a scroll speed in the range of 1-40.
        /// </summary>
        /// <param name="scrollSpeed">The scroll speed.</param>
        /// <returns>The scroll time.</returns>
        public static double ComputeScrollTime(int scrollSpeed) => MAX_TIME_RANGE / scrollSpeed;

        public override PlayfieldAdjustmentContainer CreatePlayfieldAdjustmentContainer() => new ManiaPlayfieldAdjustmentContainer();

        protected override Playfield CreatePlayfield() => new ManiaPlayfield(Beatmap.Stages);

        public override int Variant => (int)(Beatmap.Stages.Count == 1 ? PlayfieldType.Single : PlayfieldType.Dual) + Beatmap.TotalColumns;

        protected override PassThroughInputManager CreateInputManager() => new ManiaInputManager(Ruleset.RulesetInfo, Variant);

        public override DrawableHitObject<ManiaHitObject>? CreateDrawableRepresentation(ManiaHitObject h) => null;

        protected override ReplayInputHandler CreateReplayInputHandler(Replay replay) => new ManiaFramedReplayInputHandler(replay);

        protected override ReplayRecorder CreateReplayRecorder(Score score) => new ManiaReplayRecorder(score);

        protected override void Dispose(bool isDisposing)
        {
            base.Dispose(isDisposing);

            if (currentSkin.IsNotNull())
                currentSkin.SourceChanged -= onSkinChange;
        }
    }
}