FlowScope/Packages/com.flowscope.gamecore/Runtime/Container/ReflectionFactoryBuilder.cs

using System;
using System.Linq;
using System.Reflection;

namespace FlowScope.Container
{
    public static class ReflectionFactoryBuilder
    {
        public static void RegisterType<TImplementation>(Container container)
        {
            if (container == null)
            {
                throw new ArgumentNullException(nameof(container));
            }

            container.RegisterFactory(typeof(TImplementation), BuildFactory(typeof(TImplementation)));
        }

        public static void RegisterType<TInterface, TImplementation>(Container container)
            where TImplementation : TInterface
        {
            if (container == null)
            {
                throw new ArgumentNullException(nameof(container));
            }

            container.RegisterFactory(typeof(TInterface), BuildFactory(typeof(TImplementation)));
        }

        public static Func<Container, object> BuildFactory(Type implementationType)
        {
            if (implementationType == null)
            {
                throw new ArgumentNullException(nameof(implementationType));
            }

            if (!Attribute.IsDefined(implementationType, typeof(InjectableAttribute)))
            {
                throw new InvalidOperationException($"{FormatType(implementationType)} must be marked with InjectableAttribute for reflection registration.");
            }

            var constructors = implementationType.GetConstructors(BindingFlags.Public | BindingFlags.Instance);
            if (constructors.Length != 1)
            {
                throw new InvalidOperationException($"{FormatType(implementationType)} must declare exactly one public constructor.");
            }

            var constructor = constructors[0];
            var parameters = constructor.GetParameters();

            return container =>
            {
                var arguments = parameters
                    .Select(parameter => container.Resolve(parameter.ParameterType))
                    .ToArray();
                return constructor.Invoke(arguments);
            };
        }

        private static string FormatType(Type type) => type.FullName ?? type.Name;
    }
}