using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using xCommons.Extensions;

namespace xCommons.Helpers
{
    public static class XGenericHelper
    {
        /// <summary>
        /// Invoke a Generic Method of Specified Type ...
        /// </summary>
        /// <param name="source"></param>
        /// <param name="methodName"></param>
        /// <param name="runtimeType"></param>
        /// <param name="args"></param>
        public static void InvokeGenericMethod(
            this Type source,
            string methodName,
            Type runtimeType,
            params object[] args
        )
        {
            //
            var overLoads = source.GetGenericMethodInfo(
                methodName: methodName
            );
            if (!overLoads.HasChild())
            {
                return;
            }

            //
            var method = overLoads.ElementAt(0);
            MethodInfo genericMethod = method.MakeGenericMethod(runtimeType);

            //
            genericMethod.Invoke(null, args);
        }

        /// <summary>
        /// Invoke a Generic Method of Specified Type ...
        /// </summary>
        /// <param name="source"></param>
        /// <param name="methodName"></param>
        /// <param name="runtimeTypes"></param>
        /// <param name="args"></param>
        public static void InvokeGenericMethod(
            this Type source,
            string methodName,
            Type[] runtimeTypes,
            params object[] args
        )
        {
            //
            var overLoads = source.GetGenericMethodInfo(
                methodName: methodName
            );
            if (!overLoads.HasChild())
            {
                return;
            }

            //
            // Detect a Method by Generic Types ...
            // var method = overLoads.ElementAt(0);
            var method = overLoads.First(m => m.GetGenericArguments().Length == runtimeTypes.Length);
            MethodInfo genericMethod = method.MakeGenericMethod(runtimeTypes);

            //
            genericMethod.Invoke(null, args);
        }

        /// <summary>
        /// Extract a Generic Method's Overloads ...
        /// </summary>
        /// <param name="source"></param>
        /// <param name="methodName"></param>
        /// <returns></returns>
        public static List<MethodInfo> GetGenericMethodInfo(
            this Type source,
            string methodName
        )
        {
            //
            var methods = source
                .GetMethods();

            //
            var result = methods
                .Where(mi =>
                    mi.Name == methodName &&
                    mi.IsGenericMethodDefinition)
                .ToList();

            //
            return result;
        }
    }
}