using anjianjingling.Native;

namespace anjianjingling.Vision
{
    /// <summary>
    /// 屏幕/区域/窗口截图（GDI BitBlt）。
    /// </summary>
    public sealed class ScreenCapture
    {
        /// <summary>截取整个虚拟屏幕（所有显示器）。</summary>
        public Bitmap CaptureScreen()
        {
            int x = Win32.GetSystemMetrics(Win32.SM_XVIRTUALSCREEN);
            int y = Win32.GetSystemMetrics(Win32.SM_YVIRTUALSCREEN);
            int w = Win32.GetSystemMetrics(Win32.SM_CXVIRTUALSCREEN);
            int h = Win32.GetSystemMetrics(Win32.SM_CYVIRTUALSCREEN);
            return CaptureRegion(x, y, w, h);
        }

        /// <summary>截取指定屏幕区域。</summary>
        public Bitmap CaptureRegion(int x, int y, int width, int height)
        {
            if (width <= 0 || height <= 0)
                throw new ArgumentException($"截图区域非法：({x},{y},{width},{height})");

            var bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            using (var g = Graphics.FromImage(bmp))
            {
                g.CopyFromScreen(x, y, 0, 0, new Size(width, height), CopyPixelOperation.SourceCopy);
            }
            return bmp;
        }

        /// <summary>
        /// 截取指定窗口（含被遮挡部分，依赖 PrintWindow；部分程序不支持则返回 null）。
        /// </summary>
        public Bitmap? CaptureWindow(IntPtr hWnd)
        {
            if (!Win32.GetClientRect(hWnd, out var rc) || rc.Width <= 0 || rc.Height <= 0)
                return null;

            var bmp = new Bitmap(rc.Width, rc.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            using (var g = Graphics.FromImage(bmp))
            {
                IntPtr hdc = g.GetHdc();
                bool ok = Win32.PrintWindow(hWnd, hdc, Win32.PW_RENDERFULLCONTENT);
                g.ReleaseHdc(hdc);
                if (!ok)
                {
                    bmp.Dispose();
                    return null;
                }
            }
            return bmp;
        }

        /// <summary>截图并保存到文件。</summary>
        public string SaveRegion(int x, int y, int width, int height, string path)
        {
            using var bmp = CaptureRegion(x, y, width, height);
            Directory.CreateDirectory(Path.GetDirectoryName(Path.GetFullPath(path))!);
            bmp.Save(path, System.Drawing.Imaging.ImageFormat.Png);
            return Path.GetFullPath(path);
        }
    }
}