wabbajack/Wabbajack.DTOs/Extensions/DependencyInjectionExtensions.cs

using System;
using Microsoft.Extensions.DependencyInjection;

namespace Wabbajack.DTOs
{
    public static class DependencyInjectionExtensions
    {
        
        public static IServiceCollection AddAllSingleton<T1, TBase>(this IServiceCollection services, 
            Func<IServiceProvider, TBase>? ctor = null)
            where TBase : class, T1
            where T1 : class
        {
            if (ctor == null)
                services.AddSingleton<TBase>();
            else
                services.AddSingleton(ctor);

            services.AddSingleton<T1, TBase>(s => s.GetService<TBase>()!);
            return services;
        }
        public static IServiceCollection AddAllSingleton<T1, T2, TBase>(this IServiceCollection services, 
            Func<IServiceProvider, TBase>? ctor = null)
            where TBase : class, T1, T2
            where T1 : class
            where T2 : class
        {
            if (ctor == null)
                services.AddSingleton<TBase>();
            else
                services.AddSingleton(ctor);

            services.AddSingleton<T1, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T2, TBase>(s => s.GetService<TBase>()!);
            return services;
        }
        
        public static IServiceCollection AddAllSingleton<T1, T2, T3, TBase>(this IServiceCollection services, 
            Func<IServiceProvider, TBase>? ctor = null)
            where TBase : class, T1, T2, T3
            where T1 : class
            where T2 : class
            where T3 : class
        {
            if (ctor == null)
                services.AddSingleton<TBase>();
            else
                services.AddSingleton(ctor);

            services.AddSingleton<T1, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T2, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T3, TBase>(s => s.GetService<TBase>()!);
            return services;
        }
        
        public static IServiceCollection AddAllSingleton<T1, T2, T3, T4, TBase>(this IServiceCollection services, 
            Func<IServiceProvider, TBase>? ctor = null)
            where TBase : class, T1, T2, T3, T4
            where T1 : class
            where T2 : class
            where T3 : class
            where T4 : class
        {
            if (ctor == null)
                services.AddSingleton<TBase>();
            else
                services.AddSingleton(ctor);

            services.AddSingleton<T1, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T2, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T3, TBase>(s => s.GetService<TBase>()!);
            services.AddSingleton<T4, TBase>(s => s.GetService<TBase>()!);
            return services;
        }
    }
}