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

namespace anjianjingling.Vision
{
    /// <summary>
    /// 找色：LockBits 锁内存逐像素扫描，支持容差。
    /// </summary>
    public sealed class ColorFinder
    {
        /// <summary>解析 "RRGGBB" 或 "#RRGGBB" 颜色。</summary>
        public static Color ParseHex(string hex)
        {
            hex = hex.Trim().TrimStart('#');
            if (hex.Length != 6) throw new ArgumentException($"颜色格式非法：{hex}（应为 RRGGBB）");
            int r = Convert.ToInt32(hex[0..2], 16);
            int g = Convert.ToInt32(hex[2..4], 16);
            int b = Convert.ToInt32(hex[4..6], 16);
            return Color.FromArgb(r, g, b);
        }

        /// <summary>
        /// 在 bmp 的指定区域内找颜色，返回第一个匹配点的 bmp 内坐标；未找到返回 (-1,-1)。
        /// </summary>
        public Point FindColor(Bitmap bmp, int x1, int y1, int x2, int y2, Color target, int tolerance = 0)
        {
            // 裁剪到合法范围
            x1 = Math.Clamp(x1, 0, bmp.Width - 1);
            x2 = Math.Clamp(x2, 0, bmp.Width - 1);
            y1 = Math.Clamp(y1, 0, bmp.Height - 1);
            y2 = Math.Clamp(y2, 0, bmp.Height - 1);
            if (x1 > x2 || y1 > y2) return new Point(-1, -1);

            var rect = new Rectangle(x1, y1, x2 - x1 + 1, y2 - y1 + 1);
            using var fast = new LockedBitmap(bmp, rect);
            for (int y = 0; y < rect.Height; y++)
            {
                for (int x = 0; x < rect.Width; x++)
                {
                    var c = fast.GetPixel(x, y);
                    if (Math.Abs(c.R - target.R) <= tolerance &&
                        Math.Abs(c.G - target.G) <= tolerance &&
                        Math.Abs(c.B - target.B) <= tolerance)
                    {
                        return new Point(rect.X + x, rect.Y + y);
                    }
                }
            }
            return new Point(-1, -1);
        }

        /// <summary>LockBits 包装，按 Format24bpp/32bpp 通用读取 BGR。</summary>
        private sealed class LockedBitmap : IDisposable
        {
            private readonly BitmapData _data;
            private readonly Bitmap _bmp;
            private readonly int _stride;
            private readonly byte[] _buf;
            private readonly int _bytesPerPixel;

            public LockedBitmap(Bitmap bmp, Rectangle rect)
            {
                _bmp = bmp;
                _bytesPerPixel = Image.GetPixelFormatSize(bmp.PixelFormat) / 8;
                if (_bytesPerPixel < 3) _bytesPerPixel = 3;
                _data = bmp.LockBits(rect, ImageLockMode.ReadOnly,
                    _bytesPerPixel == 3 ? PixelFormat.Format24bppRgb : PixelFormat.Format32bppArgb);
                _stride = Math.Abs(_data.Stride);
                _buf = new byte[_stride * rect.Height];
                Marshal.Copy(_data.Scan0, _buf, 0, _buf.Length);
            }

            public Color GetPixel(int x, int y)
            {
                int i = y * _stride + x * _bytesPerPixel;
                return Color.FromArgb(_buf[i + 2], _buf[i + 1], _buf[i]);
            }

            public void Dispose()
            {
                _bmp.UnlockBits(_data);
            }
        }
    }
}