using System.Runtime.InteropServices;

namespace CursorLang.Settings.Interop;

/// <summary>
/// Window frame styling by the system: the title bar is drawn by Windows,
/// and in the dark theme it has to be switched separately from the window content.
/// </summary>
internal static class WindowThemeNative
{
    [DllImport("dwmapi.dll")]
    private static extern int DwmSetWindowAttribute(IntPtr hWnd, int attribute, ref int value, int size);

    private const int DWMWA_USE_IMMERSIVE_DARK_MODE = 20;

    /// <summary>
    /// Recolours the window title bar. On Windows 10 builds before 2004 the attribute
    /// is not supported — the title bar simply stays light.
    /// </summary>
    internal static void SetDarkTitleBar(IntPtr hWnd, bool isDark)
    {
        if (hWnd == IntPtr.Zero)
        {
            return;
        }

        int value = isDark ? 1 : 0;
        DwmSetWindowAttribute(hWnd, DWMWA_USE_IMMERSIVE_DARK_MODE, ref value, sizeof(int));
    }
}