// ============================================================================
// Copyright © 2026 Hexagon Technology Center GmbH. All Rights Reserved.
// 文件名: FilmEffectProcessor.cs
// 描述: 电子胶片效果算子，模拟传统X射线胶片的显示效果
// 功能:
//   - 窗宽窗位（Window/Level）调整
//   - 胶片反转（正片/负片）
//   - 多种胶片特性曲线（线性、S曲线、对数、指数）
//   - 边缘增强（模拟胶片锐化效果）
//   - 使用查找表（LUT）加速处理
// 算法: 窗宽窗位映射 + 特性曲线变换
// 作者: 李伟 wei.lw.li@hexagon.com
// ============================================================================

using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using XP.ImageProcessing.Core;
using Serilog;

namespace XP.ImageProcessing.Processors;

/// <summary>
/// 电子胶片效果算子
/// </summary>
public class FilmEffectProcessor : ImageProcessorBase
{
    private static readonly ILogger _logger = Log.ForContext<FilmEffectProcessor>();
    private byte[] _lut = new byte[256];

    public FilmEffectProcessor()
    {
        Name = LocalizationHelper.GetString("FilmEffectProcessor_Name");
        Description = LocalizationHelper.GetString("FilmEffectProcessor_Description");
    }

    protected override void InitializeParameters()
    {
        Parameters.Add("WindowCenter", new ProcessorParameter(
            "WindowCenter",
            LocalizationHelper.GetString("FilmEffectProcessor_WindowCenter"),
            typeof(int),
            128,
            0,
            255,
            LocalizationHelper.GetString("FilmEffectProcessor_WindowCenter_Desc")));

        Parameters.Add("WindowWidth", new ProcessorParameter(
            "WindowWidth",
            LocalizationHelper.GetString("FilmEffectProcessor_WindowWidth"),
            typeof(int),
            255,
            1,
            255,
            LocalizationHelper.GetString("FilmEffectProcessor_WindowWidth_Desc")));

        Parameters.Add("Invert", new ProcessorParameter(
            "Invert",
            LocalizationHelper.GetString("FilmEffectProcessor_Invert"),
            typeof(bool),
            false,
            null,
            null,
            LocalizationHelper.GetString("FilmEffectProcessor_Invert_Desc")));

        Parameters.Add("Curve", new ProcessorParameter(
            "Curve",
            LocalizationHelper.GetString("FilmEffectProcessor_Curve"),
            typeof(string),
            "Linear",
            null,
            null,
            LocalizationHelper.GetString("FilmEffectProcessor_Curve_Desc"),
            new string[] { "Linear", "Sigmoid", "Logarithmic", "Exponential" }));

        Parameters.Add("CurveStrength", new ProcessorParameter(
            "CurveStrength",
            LocalizationHelper.GetString("FilmEffectProcessor_CurveStrength"),
            typeof(double),
            1.0,
            0.1,
            5.0,
            LocalizationHelper.GetString("FilmEffectProcessor_CurveStrength_Desc")));

        Parameters.Add("EdgeEnhance", new ProcessorParameter(
            "EdgeEnhance",
            LocalizationHelper.GetString("FilmEffectProcessor_EdgeEnhance"),
            typeof(double),
            0.0,
            0.0,
            3.0,
            LocalizationHelper.GetString("FilmEffectProcessor_EdgeEnhance_Desc")));

        _logger.Debug("InitializeParameters");
    }

    public override Image<Gray, byte> Process(Image<Gray, byte> inputImage)
    {
        int windowCenter = GetParameter<int>("WindowCenter");
        int windowWidth = GetParameter<int>("WindowWidth");
        bool invert = GetParameter<bool>("Invert");
        string curve = GetParameter<string>("Curve");
        double curveStrength = GetParameter<double>("CurveStrength");
        double edgeEnhance = GetParameter<double>("EdgeEnhance");

        // 构建查找表
        BuildLUT(windowCenter, windowWidth, invert, curve, curveStrength);

        // 应用 LUT
        var result = inputImage.Clone();
        int width = result.Width;
        int height = result.Height;

        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                result.Data[y, x, 0] = _lut[result.Data[y, x, 0]];
            }
        }

        // 边缘增强（模拟胶片锐化）
        if (edgeEnhance > 0.01)
        {
            using var blurred = inputImage.SmoothGaussian(3);
            using var detail = new Image<Gray, float>(width, height);

            for (int y = 0; y < height; y++)
            {
                for (int x = 0; x < width; x++)
                {
                    float diff = inputImage.Data[y, x, 0] - blurred.Data[y, x, 0];
                    float enhanced = result.Data[y, x, 0] + (float)(diff * edgeEnhance);
                    result.Data[y, x, 0] = (byte)Math.Clamp((int)enhanced, 0, 255);
                }
            }
        }

        _logger.Debug("Process: WC={WC}, WW={WW}, Invert={Inv}, Curve={Curve}, Strength={Str}, Edge={Edge}",
            windowCenter, windowWidth, invert, curve, curveStrength, edgeEnhance);

        return result;
    }

    private void BuildLUT(int wc, int ww, bool invert, string curve, double strength)
    {
        double halfW = ww / 2.0;
        double low = wc - halfW;
        double high = wc + halfW;

        for (int i = 0; i < 256; i++)
        {
            // 窗宽窗位映射到 [0, 1]
            double normalized;
            if (ww <= 1)
                normalized = i >= wc ? 1.0 : 0.0;
            else
                normalized = Math.Clamp((i - low) / (high - low), 0.0, 1.0);

            // 应用特性曲线
            double mapped = curve switch
            {
                "Sigmoid" => ApplySigmoid(normalized, strength),
                "Logarithmic" => ApplyLogarithmic(normalized, strength),
                "Exponential" => ApplyExponential(normalized, strength),
                _ => normalized // Linear
            };

            // 反转（负片效果）
            if (invert)
                mapped = 1.0 - mapped;

            _lut[i] = (byte)Math.Clamp((int)(mapped * 255.0), 0, 255);
        }
    }

    /// <summary>S曲线（Sigmoid）：增强中间调对比度</summary>
    private static double ApplySigmoid(double x, double strength)
    {
        double k = strength * 10.0;
        return 1.0 / (1.0 + Math.Exp(-k * (x - 0.5)));
    }

    /// <summary>对数曲线：提亮暗部，压缩亮部</summary>
    private static double ApplyLogarithmic(double x, double strength)
    {
        double c = strength;
        return Math.Log(1.0 + c * x) / Math.Log(1.0 + c);
    }

    /// <summary>指数曲线：压缩暗部，增强亮部</summary>
    private static double ApplyExponential(double x, double strength)
    {
        double c = strength;
        return (Math.Exp(c * x) - 1.0) / (Math.Exp(c) - 1.0);
    }
}