namespace OcrDaemon;

using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

static class ScreenCapture
{
    [DllImport("user32.dll")]
    private static extern bool SetProcessDPIAware();

    [DllImport("user32.dll")]
    private static extern int GetSystemMetrics(int nIndex);

    public static void InitDpiAwareness() => SetProcessDPIAware();

    /// <summary>
    /// Capture from screen, or load from file if specified.
    /// When file is set, loads the image and crops to region.
    /// </summary>
    public static Bitmap CaptureOrLoad(string? file, RegionRect? region)
    {
        if (!string.IsNullOrEmpty(file))
        {
            var fullBmp = new Bitmap(file);
            if (region != null)
            {
                int cx = Math.Max(0, region.X);
                int cy = Math.Max(0, region.Y);
                int cw = Math.Min(region.Width, fullBmp.Width - cx);
                int ch = Math.Min(region.Height, fullBmp.Height - cy);
                var cropped = fullBmp.Clone(new Rectangle(cx, cy, cw, ch), PixelFormat.Format32bppArgb);
                fullBmp.Dispose();
                return cropped;
            }
            return fullBmp;
        }
        return CaptureScreen(region);
    }

    public static Bitmap CaptureScreen(RegionRect? region)
    {
        int x, y, w, h;
        if (region != null)
        {
            x = region.X;
            y = region.Y;
            w = region.Width;
            h = region.Height;
        }
        else
        {
            // Primary monitor only (0,0 origin, SM_CXSCREEN / SM_CYSCREEN)
            x = 0;
            y = 0;
            w = GetSystemMetrics(0);   // SM_CXSCREEN
            h = GetSystemMetrics(1);   // SM_CYSCREEN
        }

        var bitmap = new Bitmap(w, h, PixelFormat.Format32bppArgb);
        using var g = Graphics.FromImage(bitmap);
        g.CopyFromScreen(x, y, 0, 0, new System.Drawing.Size(w, h), CopyPixelOperation.SourceCopy);
        return bitmap;
    }
}