using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Media.Imaging;

namespace AutoFocusTool.Imaging
{
    /// <summary>
    /// 图像转换工具：把相机的 24bpp BGR 原始字节转成可显示/可保存的位图。
    /// 相机原始数据上下颠倒，统一在这里做 FlipY，保证显示、存图、算分用的是同一朝向。
    /// </summary>
    public static class ImageConverter
    {
        /// <summary>
        /// 24bpp BGR 字节数组 → System.Drawing.Bitmap（已 FlipY 翻正）。
        /// 调用方负责 Dispose。
        /// </summary>
        public static Bitmap ToBitmap(byte[] bgr24, int width, int height)
        {
            var bmp = new Bitmap(width, height, PixelFormat.Format24bppRgb);
            BitmapData data = bmp.LockBits(
                new Rectangle(0, 0, width, height),
                ImageLockMode.WriteOnly, bmp.PixelFormat);

            // 注意 stride 可能 > width*3（行对齐），逐行拷贝避免错位
            int rowBytes = width * 3;
            if (data.Stride == rowBytes)
            {
                Marshal.Copy(bgr24, 0, data.Scan0, Math.Min(bgr24.Length, rowBytes * height));
            }
            else
            {
                for (int y = 0; y < height; y++)
                {
                    Marshal.Copy(bgr24, y * rowBytes, data.Scan0 + y * data.Stride, rowBytes);
                }
            }
            bmp.UnlockBits(data);

            // 相机数据上下颠倒，翻正
            bmp.RotateFlip(RotateFlipType.RotateNoneFlipY);
            return bmp;
        }

        /// <summary>
        /// 24bpp BGR 字节 → WPF BitmapSource（冻结，可跨线程绑定到 Image.Source）。
        /// </summary>
        public static BitmapSource ToBitmapSource(byte[] bgr24, int width, int height)
        {
            using (var bmp = ToBitmap(bgr24, width, height))
            using (var ms = new MemoryStream())
            {
                bmp.Save(ms, ImageFormat.Bmp);
                ms.Position = 0;
                var bi = new BitmapImage();
                bi.BeginInit();
                bi.StreamSource = ms;
                bi.CacheOption = BitmapCacheOption.OnLoad;
                bi.EndInit();
                bi.Freeze();
                return bi;
            }
        }

        /// <summary>保存当前帧为 BMP（已翻正）。</summary>
        public static void SaveBmp(byte[] bgr24, int width, int height, string path)
        {
            using (var bmp = ToBitmap(bgr24, width, height))
            {
                bmp.Save(path, ImageFormat.Bmp);
            }
        }
    }
}