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

namespace DeviceAgent.Services;

/// <summary>
/// 屏幕截图服务
/// </summary>
public class ScreenCaptureService
{
    private readonly ILogger<ScreenCaptureService> _logger;

    public ScreenCaptureService(ILogger<ScreenCaptureService> logger)
    {
        _logger = logger;
    }

    /// <summary>
    /// 截取屏幕并返回 JPEG 字节数组
    /// </summary>
    /// <param name="quality">JPEG 质量 (1-100)</param>
    /// <param name="maxWidth">最大宽度（用于缩略图）</param>
    public byte[] CaptureScreen(int quality = 50, int maxWidth = 800)
    {
        try
        {
            // 获取主屏幕尺寸
            var screenWidth = GetSystemMetrics(SM_CXSCREEN);
            var screenHeight = GetSystemMetrics(SM_CYSCREEN);

            using var bitmap = new Bitmap(screenWidth, screenHeight, PixelFormat.Format24bppRgb);
            using var graphics = Graphics.FromImage(bitmap);
            
            // 截取整个屏幕
            graphics.CopyFromScreen(0, 0, 0, 0, new Size(screenWidth, screenHeight));

            // 计算缩放后的尺寸
            var scale = Math.Min(1.0, (double)maxWidth / screenWidth);
            var newWidth = (int)(screenWidth * scale);
            var newHeight = (int)(screenHeight * scale);

            // 缩放图片
            using var resized = new Bitmap(newWidth, newHeight);
            using var resizeGraphics = Graphics.FromImage(resized);
            resizeGraphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
            resizeGraphics.DrawImage(bitmap, 0, 0, newWidth, newHeight);

            // 转换为 JPEG
            using var ms = new MemoryStream();
            var encoder = GetEncoder(ImageFormat.Jpeg);
            var encoderParams = new EncoderParameters(1);
            encoderParams.Param[0] = new EncoderParameter(Encoder.Quality, (long)quality);
            resized.Save(ms, encoder, encoderParams);
            
            return ms.ToArray();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "屏幕截图失败");
            return Array.Empty<byte>();
        }
    }

    /// <summary>
    /// 截取屏幕并返回 Base64 字符串
    /// </summary>
    public string CaptureScreenBase64(int quality = 50, int maxWidth = 800)
    {
        var bytes = CaptureScreen(quality, maxWidth);
        return bytes.Length > 0 ? Convert.ToBase64String(bytes) : string.Empty;
    }

    private static ImageCodecInfo GetEncoder(ImageFormat format)
    {
        var codecs = ImageCodecInfo.GetImageEncoders();
        return codecs.First(c => c.FormatID == format.Guid);
    }

    // Windows API
    private const int SM_CXSCREEN = 0;
    private const int SM_CYSCREEN = 1;

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