using System.Runtime.InteropServices;

namespace CursorLang.Interop;

/// <summary>
/// Input details of the active application: which window holds keyboard focus
/// and where the caret is.
/// </summary>
internal static class ForegroundInputNative
{
    [StructLayout(LayoutKind.Sequential)]
    internal struct GuiThreadInfo
    {
        public int cbSize;
        public uint flags;
        public IntPtr hwndActive;
        public IntPtr hwndFocus;
        public IntPtr hwndCapture;
        public IntPtr hwndMenuOwner;
        public IntPtr hwndMoveSize;
        public IntPtr hwndCaret;
        public PopupWindowNative.Rect rcCaret;
    }

    [DllImport("user32.dll")]
    private static extern bool GetGUIThreadInfo(uint idThread, ref GuiThreadInfo lpgui);

    /// <summary>
    /// The input state of the foreground thread.
    /// </summary>
    /// <remarks>
    /// The zero thread identifier is not accidental: in modern applications the
    /// top-level window and the input window live in different threads, and the
    /// question has to be about the foreground as a whole.
    /// </remarks>
    internal static bool TryGetInfo(out GuiThreadInfo info)
    {
        info = new GuiThreadInfo { cbSize = Marshal.SizeOf<GuiThreadInfo>() };
        return GetGUIThreadInfo(0, ref info);
    }
}