inabox/InABox.Core/Postable/PosterEngine.cs

using InABox.Configuration;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InABox.Core
{
    public interface IPosterEngine<TPostable>
        where TPostable : Entity, IPostable
    {
        bool Process(IEnumerable<TPostable> posts);
    }

    public abstract class PosterEngine<TPostable, TPoster, TSettings> : IPosterEngine<TPostable>
        where TPostable : Entity, IPostable
        where TPoster : IPoster<TPostable, TSettings>
        where TSettings : PosterSettings<TPostable>, new()
    {
        protected static TPoster Poster = GetPoster();

        private static Type[]? _posters;

        private static TPoster GetPoster()
        {
            _posters ??= CoreUtils.TypeList(
                AppDomain.CurrentDomain.GetAssemblies(),
                x => x.IsClass
                    && !x.IsAbstract
                    && !x.IsGenericType
                    && x.HasInterface(typeof(IPoster<,>))
            ).ToArray();

            var type = _posters.Where(x => typeof(TPoster).IsAssignableFrom(x)).FirstOrDefault()
                ?? throw new Exception($"No poster of type {typeof(TPoster)}.");
            return (TPoster)Activator.CreateInstance(type);
        }

        protected static TSettings GetSettings()
        {
            return new GlobalConfiguration<TSettings>(typeof(TPostable).Name).Load();
        }

        protected static string? GetScript()
        {
            return GetSettings().Script;
        }

        public abstract bool Process(IEnumerable<TPostable> posts);
    }
}