using System;
using System.Collections.Generic;
using System.Runtime.InteropServices.ComTypes;
using Vanara.InteropServices;

namespace Vanara.Extensions
{
	/// <summary>Extensions for types in System.Runtime.InteropServices.ComTypes.</summary>
	public static class ComTypeExtensions
	{
		/// <summary>Enumerates the strings from an <see cref="IEnumString"/> instance.</summary>
		/// <param name="iEnumString">The <see cref="IEnumString"/> instance.</param>
		/// <returns>A list of strings.</returns>
		/// <exception cref="ArgumentNullException">iEnumString</exception>
		public static IEnumerable<string> Enum(this IEnumString iEnumString)
		{
			if (iEnumString is null) yield break;
			using SafeCoTaskMemStruct<uint> ret = new();
			var items = new string[1];
			while (iEnumString.Next(1, items, ret) == 0 && ret.Value == 1)
				yield return items[0];
		}
	}
}