using JetBrains.Annotations;
using System;
using System.Collections.Generic;
using System.Reflection;

namespace NEG.Utils
{
    public class KeyBasedFactory<T1, T2>
    {
        [PublicAPI]
        protected Dictionary<T1, Type> data;

        public KeyBasedFactory()
        {
            data = new Dictionary<T1, Type>();
        }

        public void FireRegistration()
        {
            ScanAssembly(typeof(T2).Assembly);
            
            if(typeof(T2).Assembly.GetType().Assembly == typeof(T2).Assembly)
                return;
            
            ScanAssembly(typeof(T2).Assembly.GetType().Assembly);
        }

        private static void ScanAssembly(Assembly assembly)
        {
            foreach (var type in assembly.GetTypes())
            {
                var methodFields =
                    type.GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic);
                for (int i = 0; i < methodFields.Length; i++)
                {
                    if (Attribute.GetCustomAttribute(methodFields[i], typeof(FactoryRegistration)) != null)
                    {
                        methodFields[i].Invoke(null, Array.Empty<object>());
                    }
                }
            }
        }

        public void Register(T1 key, Type type) => data.Add(key, type);

        public T2 CreateInstance(T1 key, params object[] args) => (T2)Activator.CreateInstance(data[key], args);
    }

    [AttributeUsage(AttributeTargets.Method)]
    public class FactoryRegistration : Attribute
    {
        public FactoryRegistration() { }
    }
}