// 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.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using osu.Framework.Allocation;
using osu.Framework.Audio;
using osu.Framework.Audio.Sample;
using osu.Framework.Bindables;
using osu.Framework.Extensions.ObjectExtensions;
using osu.Framework.Graphics.Rendering;
using osu.Framework.Graphics.Shaders;
using osu.Framework.Graphics.Textures;
using osu.Framework.IO.Stores;
using osu.Framework.Platform;
using osu.Game.Rulesets.Configuration;

namespace osu.Game.Rulesets.UI
{
    public class DrawableRulesetDependencies : DependencyContainer, IDisposable
    {
        /// <summary>
        /// The texture store to be used for the ruleset.
        /// </summary>
        /// <remarks>
        /// Reads textures from the "Textures" folder in ruleset resources.
        /// If not available locally, lookups will fallback to the global texture store.
        /// </remarks>
        public TextureStore TextureStore { get; }

        /// <summary>
        /// The sample store to be used for the ruleset.
        /// </summary>
        /// <remarks>
        /// Reads samples from the "Samples" folder in ruleset resources.
        /// If not available locally, lookups will fallback to the global sample store.
        /// </remarks>
        public ISampleStore SampleStore { get; }

        /// <summary>
        /// The shader manager to be used for the ruleset.
        /// </summary>
        /// <remarks>
        /// Reads shaders from the "Shaders" folder in ruleset resources.
        /// If not available locally, lookups will fallback to the global shader manager.
        /// </remarks>
        public ShaderManager ShaderManager { get; }

        /// <summary>
        /// The ruleset config manager. May be null if ruleset does not expose a configuration manager.
        /// </summary>
        public IRulesetConfigManager? RulesetConfigManager { get; }

        public DrawableRulesetDependencies(Ruleset ruleset, IReadOnlyDependencyContainer parent)
            : base(parent)
        {
            var resources = ruleset.CreateResourceStore();

            var host = parent.Get<GameHost>();

            TextureStore = new TextureStore(host.Renderer, parent.Get<GameHost>().CreateTextureLoaderStore(new NamespacedResourceStore<byte[]>(resources, @"Textures")));
            CacheAs(TextureStore = new FallbackTextureStore(host.Renderer, TextureStore, parent.Get<TextureStore>()));

            SampleStore = parent.Get<AudioManager>().GetSampleStore(new NamespacedResourceStore<byte[]>(resources, @"Samples"));
            SampleStore.PlaybackConcurrency = OsuGameBase.SAMPLE_CONCURRENCY;
            CacheAs(SampleStore = new FallbackSampleStore(SampleStore, parent.Get<ISampleStore>()));

            CacheAs(ShaderManager = new RulesetShaderManager(host.Renderer, new NamespacedResourceStore<byte[]>(resources, @"Shaders"), parent.Get<ShaderManager>()));

            RulesetConfigManager = parent.Get<IRulesetConfigCache>().GetConfigFor(ruleset);
            if (RulesetConfigManager != null)
                Cache(RulesetConfigManager);
        }

        #region Disposal

        ~DrawableRulesetDependencies()
        {
            // required to potentially clean up sample store from audio hierarchy.
            Dispose(false);
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        private bool isDisposed;

        protected void Dispose(bool disposing)
        {
            if (isDisposed)
                return;

            isDisposed = true;

            if (SampleStore.IsNotNull()) SampleStore.Dispose();
            if (TextureStore.IsNotNull()) TextureStore.Dispose();
            if (ShaderManager.IsNotNull()) ShaderManager.Dispose();
        }

        #endregion

        /// <summary>
        /// A sample store which adds a fallback source and prevents disposal of the fallback source.
        /// </summary>
        private class FallbackSampleStore : ISampleStore
        {
            private readonly ISampleStore primary;
            private readonly ISampleStore fallback;

            public FallbackSampleStore(ISampleStore primary, ISampleStore fallback)
            {
                this.primary = primary;
                this.fallback = fallback;
            }

            public Sample Get(string name) => primary.Get(name) ?? fallback.Get(name);

            public async Task<Sample> GetAsync(string name, CancellationToken cancellationToken = default)
            {
                return await primary.GetAsync(name, cancellationToken).ConfigureAwait(false)
                       ?? await fallback.GetAsync(name, cancellationToken).ConfigureAwait(false);
            }

            public Stream GetStream(string name) => primary.GetStream(name) ?? fallback.GetStream(name);

            public IEnumerable<string> GetAvailableResources() => throw new NotSupportedException();

            public void AddAdjustment(AdjustableProperty type, IBindable<double> adjustBindable) => throw new NotSupportedException();

            public void RemoveAdjustment(AdjustableProperty type, IBindable<double> adjustBindable) => throw new NotSupportedException();

            public void RemoveAllAdjustments(AdjustableProperty type) => throw new NotSupportedException();

            public void BindAdjustments(IAggregateAudioAdjustment component) => throw new NotImplementedException();

            public void UnbindAdjustments(IAggregateAudioAdjustment component) => throw new NotImplementedException();

            public BindableNumber<double> Volume => throw new NotSupportedException();

            public BindableNumber<double> Balance => throw new NotSupportedException();

            public BindableNumber<double> Frequency => throw new NotSupportedException();

            public BindableNumber<double> Tempo => throw new NotSupportedException();

            public IBindable<double> AggregateVolume => throw new NotSupportedException();

            public IBindable<double> AggregateBalance => throw new NotSupportedException();

            public IBindable<double> AggregateFrequency => throw new NotSupportedException();

            public IBindable<double> AggregateTempo => throw new NotSupportedException();

            public int PlaybackConcurrency
            {
                get => throw new NotSupportedException();
                set => throw new NotSupportedException();
            }

            public void AddExtension(string extension) => throw new NotSupportedException();

            public void Dispose()
            {
                if (primary.IsNotNull()) primary.Dispose();
            }
        }

        /// <summary>
        /// A texture store which adds a fallback source and prevents disposal of the fallback source.
        /// </summary>
        private class FallbackTextureStore : TextureStore
        {
            private readonly TextureStore primary;
            private readonly TextureStore fallback;

            public FallbackTextureStore(IRenderer renderer, TextureStore primary, TextureStore fallback)
                : base(renderer)
            {
                this.primary = primary;
                this.fallback = fallback;
            }

            public override Texture Get(string name, WrapMode wrapModeS, WrapMode wrapModeT)
                => primary.Get(name, wrapModeS, wrapModeT) ?? fallback.Get(name, wrapModeS, wrapModeT);

            protected override void Dispose(bool disposing)
            {
                base.Dispose(disposing);
                if (primary.IsNotNull()) primary.Dispose();
            }
        }

        private class RulesetShaderManager : ShaderManager
        {
            private readonly ShaderManager parent;

            public RulesetShaderManager(IRenderer renderer, NamespacedResourceStore<byte[]> rulesetResources, ShaderManager parent)
                : base(renderer, rulesetResources)
            {
                this.parent = parent;
            }

            // When the debugger is attached, exceptions are expensive.
            // Manually work around this by caching failed lookups and falling back straight to parent.
            private readonly HashSet<(string, string)> failedLookups = new HashSet<(string, string)>();

            public override IShader Load(string vertex, string fragment)
            {
                if (!failedLookups.Contains((vertex, fragment)))
                {
                    try
                    {
                        return base.Load(vertex, fragment);
                    }
                    catch
                    {
                        // Shader lookup is very non-standard. Rather than returning null on missing shaders, exceptions are thrown.
                        failedLookups.Add((vertex, fragment));
                    }
                }

                return parent.Load(vertex, fragment);
            }
        }
    }
}