AnimationRegistry.cs

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Text;
 
namespace NeuroAccessMaui.Animations
{
    public interface IAnimationRegistry
    {
        bool TryCreateViewAnimation(AnimationKey Key, IAnimationContext Context, out IViewAnimation Animation);
 
        bool TryCreateTransition(AnimationKey Key, IAnimationContext Context, out ITransitionAnimation Animation);
 
        void Register(ViewAnimationDescriptor Descriptor, string? Platform = null, string? Theme = null);
 
        void Register(TransitionAnimationDescriptor Descriptor, string? Platform = null, string? Theme = null);
    }
 
    public sealed class AnimationRegistry : IAnimationRegistry
    {
        private readonly ConcurrentDictionary<string, ViewAnimationDescriptor> viewDescriptors = new(StringComparer.Ordinal);
        private readonly ConcurrentDictionary<string, TransitionAnimationDescriptor> transitionDescriptors = new(StringComparer.Ordinal);
 
        public bool TryCreateViewAnimation(AnimationKey Key, IAnimationContext Context, out IViewAnimation Animation)
        {
            ArgumentNullException.ThrowIfNull(Context);
 
            ViewAnimationDescriptor? Descriptor = ResolveDescriptor(this.viewDescriptors, Key, Context);
            if (Descriptor is null)
            {
                Animation = default!;
                return false;
            }
 
            Animation = Descriptor.CreateExecutor(Context);
            return true;
        }
 
        public bool TryCreateTransition(AnimationKey Key, IAnimationContext Context, out ITransitionAnimation Animation)
        {
            ArgumentNullException.ThrowIfNull(Context);
 
            TransitionAnimationDescriptor? Descriptor = ResolveDescriptor(this.transitionDescriptors, Key, Context);
            if (Descriptor is null)
            {
                Animation = default!;
                return false;
            }
 
            Animation = Descriptor.CreateExecutor(Context);
            return true;
        }
 
        public void Register(ViewAnimationDescriptor Descriptor, string? Platform = null, string? Theme = null)
        {
            ArgumentNullException.ThrowIfNull(Descriptor);
            string Key = ComposeKey(Descriptor.Key, Platform, Theme);
            this.viewDescriptors[Key] = Descriptor;
        }
 
        public void Register(TransitionAnimationDescriptor Descriptor, string? Platform = null, string? Theme = null)
        {
            ArgumentNullException.ThrowIfNull(Descriptor);
            string Key = ComposeKey(Descriptor.Key, Platform, Theme);
            this.transitionDescriptors[Key] = Descriptor;
        }
 
        private static TDescriptor? ResolveDescriptor<TDescriptor>(ConcurrentDictionary<string, TDescriptor> Descriptors, AnimationKey Key, IAnimationContext Context)
            where TDescriptor : AnimationDescriptor
        {
            string BaseKey = Key.Value;
            string PlatformKey = string.IsNullOrWhiteSpace(Context.Platform) ? string.Empty : Context.Platform;
            string? ThemeKey = Context.Theme;
 
            List<string> Candidates = new List<string>();
 
            if (!string.IsNullOrWhiteSpace(PlatformKey) && !string.IsNullOrWhiteSpace(ThemeKey))
                Candidates.Add(ComposeKey(BaseKey, PlatformKey, ThemeKey));
 
            if (!string.IsNullOrWhiteSpace(PlatformKey))
                Candidates.Add(ComposeKey(BaseKey, PlatformKey, null));
 
            if (!string.IsNullOrWhiteSpace(ThemeKey))
                Candidates.Add(ComposeKey(BaseKey, null, ThemeKey));
 
            Candidates.Add(BaseKey);
 
            foreach (string Candidate in Candidates)
            {
                if (Descriptors.TryGetValue(Candidate, out TDescriptor Descriptor))
                    return Descriptor;
            }
 
            return null;
        }
 
        private static string ComposeKey(AnimationKey Key, string? Platform, string? Theme)
        {
            return ComposeKey(Key.Value, Platform, Theme);
        }
 
        private static string ComposeKey(string BaseKey, string? Platform, string? Theme)
        {
            StringBuilder Builder = new StringBuilder(BaseKey);
            if (!string.IsNullOrWhiteSpace(Platform))
            {
                Builder.Append('.');
                Builder.Append(Platform);
            }
 
            if (!string.IsNullOrWhiteSpace(Theme))
            {
                Builder.Append('.');
                Builder.Append(Theme);
            }
 
            return Builder.ToString();
        }
    }
}