using System.Drawing;
using Emgu.CV;
using Emgu.CV.CvEnum;

namespace XP.Calibration.Core;

/// <summary>
/// RAW 投影数据读取器 | RAW projection data reader
/// </summary>
public static class RawReader
{
    /// <summary>
    /// 从 RAW 文件读取 float32 投影序列
    /// </summary>
    /// <param name="path">文件路径</param>
    /// <param name="width">图像宽度</param>
    /// <param name="height">图像高度</param>
    /// <param name="count">投影帧数</param>
    /// <returns>Mat 列表 (CV_32F)</returns>
    public static List<Mat> ReadFloat32(string path, int width, int height, int count)
    {
        var projections = new List<Mat>(count);
        int frameBytes = width * height * sizeof(float);

        using var stream = new FileStream(path, FileMode.Open, FileAccess.Read);
        byte[] buffer = new byte[frameBytes];

        for (int i = 0; i < count; i++)
        {
            int bytesRead = stream.Read(buffer, 0, frameBytes);
            if (bytesRead < frameBytes)
                throw new EndOfStreamException(
                    $"帧 {i} 数据不足: 期望 {frameBytes} 字节, 实际 {bytesRead} 字节");

            var mat = new Mat(height, width, DepthType.Cv32F, 1);
            System.Runtime.InteropServices.Marshal.Copy(buffer, 0, mat.DataPointer, frameBytes);
            projections.Add(mat);
        }

        return projections;
    }

    /// <summary>
    /// 读取单张 TIFF 图像, 返回 CV_32F 灰度 Mat
    /// </summary>
    /// <param name="path">TIFF 文件路径</param>
    /// <returns>Mat (CV_32F, 单通道)</returns>
    public static Mat ReadTiff(string path)
    {
        if (!File.Exists(path))
            throw new FileNotFoundException($"TIFF 文件不存在: {path}");

        // 以原始深度读取 (支持 8/16/32bit TIFF)
        var src = CvInvoke.Imread(path, ImreadModes.AnyDepth | ImreadModes.Grayscale);
        if (src.IsEmpty)
            throw new InvalidOperationException($"无法读取 TIFF: {path}");

        // 统一转为 CV_32F
        if (src.Depth != DepthType.Cv32F)
        {
            var dst = new Mat();
            src.ConvertTo(dst, DepthType.Cv32F);
            src.Dispose();
            return dst;
        }

        return src;
    }

    /// <summary>
    /// 批量读取多张 TIFF 图像 (按文件名排序)
    /// </summary>
    /// <param name="directory">TIFF 文件所在目录</param>
    /// <param name="pattern">搜索模式, 默认 "*.tif"</param>
    /// <returns>Mat 列表 (CV_32F)</returns>
    public static List<Mat> ReadTiffSequence(string directory, string pattern = "*.tif")
    {
        if (!Directory.Exists(directory))
            throw new DirectoryNotFoundException($"目录不存在: {directory}");

        var files = Directory.GetFiles(directory, pattern)
            .Concat(Directory.GetFiles(directory, pattern + "f")) // 同时匹配 .tif 和 .tiff
            .Distinct()
            .OrderBy(f => f)
            .ToList();

        if (files.Count == 0)
            throw new FileNotFoundException($"目录中未找到 TIFF 文件: {directory}");

        return files.Select(ReadTiff).ToList();
    }
}