using System;
using System.Runtime.InteropServices;

namespace Ink_Canvas.Helpers
{
    /// <summary>
    /// .NET Core / 5+ 未提供 <see cref="Marshal.GetActiveObject"/>，通过 OLE 实现等效行为。
    /// </summary>
    internal static class OleActiveObject
    {
        [DllImport("ole32.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
        private static extern int CLSIDFromProgID(string lpszProgId, out Guid lpclsid);

        [DllImport("oleaut32.dll", PreserveSig = true)]
        private static extern int GetActiveObject(ref Guid rclsid, IntPtr pvReserved, [MarshalAs(UnmanagedType.IUnknown)] out object ppunk);

        public static object GetActiveObject(string progId)
        {
            int hr = CLSIDFromProgID(progId, out Guid clsid);
            Marshal.ThrowExceptionForHR(hr);
            hr = GetActiveObject(ref clsid, IntPtr.Zero, out object obj);
            Marshal.ThrowExceptionForHR(hr);
            return obj;
        }
    }
}