// 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.Bindables;
using osu.Framework.Graphics;
using osu.Game.Skinning;
using osuTK;

namespace osu.Game.Rulesets.Osu.Skinning
{
    public class OsuLegacySkinTransformer : LegacySkinTransformer
    {
        private Lazy<bool> hasHitCircle;

        /// <summary>
        /// On osu-stable, hitcircles have 5 pixels of transparent padding on each side to allow for shadows etc.
        /// Their hittable area is 128px, but the actual circle portion is 118px.
        /// We must account for some gameplay elements such as slider bodies, where this padding is not present.
        /// </summary>
        public const float LEGACY_CIRCLE_RADIUS = 64 - 5;

        public OsuLegacySkinTransformer(ISkinSource source)
            : base(source)
        {
            Source.SourceChanged += sourceChanged;
            sourceChanged();
        }

        private void sourceChanged()
        {
            hasHitCircle = new Lazy<bool>(() => Source.GetTexture("hitcircle") != null);
        }

        public override Drawable GetDrawableComponent(ISkinComponent component)
        {
            if (!(component is OsuSkinComponent osuComponent))
                return null;

            switch (osuComponent.Component)
            {
                case OsuSkinComponents.FollowPoint:
                    return this.GetAnimation(component.LookupName, true, false, true, startAtCurrentTime: false);

                case OsuSkinComponents.SliderFollowCircle:
                    var followCircle = this.GetAnimation("sliderfollowcircle", true, true, true);
                    if (followCircle != null)
                        // follow circles are 2x the hitcircle resolution in legacy skins (since they are scaled down from >1x
                        followCircle.Scale *= 0.5f;
                    return followCircle;

                case OsuSkinComponents.SliderBall:
                    var sliderBallContent = this.GetAnimation("sliderb", true, true, animationSeparator: "");

                    // todo: slider ball has a custom frame delay based on velocity
                    // Math.Max((150 / Velocity) * GameBase.SIXTY_FRAME_TIME, GameBase.SIXTY_FRAME_TIME);

                    if (sliderBallContent != null)
                        return new LegacySliderBall(sliderBallContent);

                    return null;

                case OsuSkinComponents.SliderBody:
                    if (hasHitCircle.Value)
                        return new LegacySliderBody();

                    return null;

                case OsuSkinComponents.SliderHeadHitCircle:
                    if (hasHitCircle.Value)
                        return new LegacyMainCirclePiece("sliderstartcircle");

                    return null;

                case OsuSkinComponents.HitCircle:
                    if (hasHitCircle.Value)
                        return new LegacyMainCirclePiece();

                    return null;

                case OsuSkinComponents.Cursor:
                    if (Source.GetTexture("cursor") != null)
                        return new LegacyCursor();

                    return null;

                case OsuSkinComponents.CursorTrail:
                    if (Source.GetTexture("cursortrail") != null)
                        return new LegacyCursorTrail();

                    return null;

                case OsuSkinComponents.HitCircleText:
                    var font = GetConfig<OsuSkinConfiguration, string>(OsuSkinConfiguration.HitCirclePrefix)?.Value ?? "default";
                    var overlap = GetConfig<OsuSkinConfiguration, float>(OsuSkinConfiguration.HitCircleOverlap)?.Value ?? -2;

                    return !hasFont(font)
                        ? null
                        : new LegacySpriteText(Source, font)
                        {
                            // stable applies a blanket 0.8x scale to hitcircle fonts
                            Scale = new Vector2(0.8f),
                            Spacing = new Vector2(-overlap, 0)
                        };

                case OsuSkinComponents.SpinnerBody:
                    bool hasBackground = Source.GetTexture("spinner-background") != null;

                    if (Source.GetTexture("spinner-top") != null && !hasBackground)
                        return new LegacyNewStyleSpinner();
                    else if (hasBackground)
                        return new LegacyOldStyleSpinner();

                    return null;
            }

            return null;
        }

        public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
        {
            switch (lookup)
            {
                case OsuSkinColour colour:
                    return Source.GetConfig<SkinCustomColourLookup, TValue>(new SkinCustomColourLookup(colour));

                case OsuSkinConfiguration osuLookup:
                    switch (osuLookup)
                    {
                        case OsuSkinConfiguration.SliderPathRadius:
                            if (hasHitCircle.Value)
                                return SkinUtils.As<TValue>(new BindableFloat(LEGACY_CIRCLE_RADIUS));

                            break;

                        case OsuSkinConfiguration.HitCircleOverlayAboveNumber:
                            // See https://osu.ppy.sh/help/wiki/Skinning/skin.ini#%5Bgeneral%5D
                            // HitCircleOverlayAboveNumer (with typo) should still be supported for now.
                            return Source.GetConfig<OsuSkinConfiguration, TValue>(OsuSkinConfiguration.HitCircleOverlayAboveNumber) ??
                                   Source.GetConfig<OsuSkinConfiguration, TValue>(OsuSkinConfiguration.HitCircleOverlayAboveNumer);
                    }

                    break;
            }

            return Source.GetConfig<TLookup, TValue>(lookup);
        }

        private bool hasFont(string fontName) => Source.GetTexture($"{fontName}-0") != null;
    }
}