using System.Reflection;
using System.Threading.Tasks;

namespace AMWD.Common.Extensions
{
	/// <summary>
	/// Extension methods for <see cref="System.Reflection"/>.
	/// </summary>
	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
	public static class ReflectionExtensions
	{
		/// <summary>
		/// Calls a method from it's reflection asynchronously without result.
		/// </summary>
		/// <param name="methodInfo">The <see cref="MethodInfo"/> to call on an object.</param>
		/// <param name="obj">The reflected instance to call the method on.</param>
		/// <param name="parameters">The parameters of the called method.</param>
		/// <returns>An awaitable <see cref="Task"/>.</returns>
		public static async Task CallAsync(this MethodInfo methodInfo, object obj, params object[] parameters)
		{
			var task = (Task)methodInfo.Invoke(obj, parameters);
			await task.ConfigureAwait(false);
		}

		/// <summary>
		/// Invokes a method from it's reflection asynchronously with a result.
		/// </summary>
		/// <typeparam name="TResult">The result type, that is expected (and casted to).</typeparam>
		/// <param name="methodInfo">The <see cref="MethodInfo"/> to invoke on an object.</param>
		/// <param name="obj">The reflected instance to invoke the method on.</param>
		/// <param name="parameters">The parameters of the called method.</param>
		/// <returns>An awaitable <see cref="Task"/> with result.</returns>
		public static async Task<TResult> InvokeAsync<TResult>(this MethodInfo methodInfo, object obj, params object[] parameters)
		{
			var task = (Task)methodInfo.Invoke(obj, parameters);
			await task.ConfigureAwait(false);

			var resultPropertyInfo = task.GetType().GetProperty("Result");
			return (TResult)resultPropertyInfo.GetValue(task);
		}
	}
}