// ============================================================================
// 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（支持 8 位和 16 位灰度图像）
/// 16 位模式下窗宽窗位参数范围扩展到 0-65535，LUT 升级为 ushort[65536]
/// </summary>
public class FilmEffectProcessor<TDepth> : ImageProcessorBase<TDepth>
    where TDepth : struct, IComparable
{
    private static readonly ILogger _logger = Log.ForContext<FilmEffectProcessor<TDepth>>();
    private byte[] _lut8 = new byte[256];
    private ushort[] _lut16 = new ushort[65536];

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

    protected override void InitializeParameters()
    {
        // 窗宽窗位默认值适配：8 位用 0-255，16 位用 0-65535
        // 运行时通过 MaxPixelValue 动态决定，参数范围设为最大（65535）
        Parameters.Add("WindowCenter", new ProcessorParameter(
            "WindowCenter",
            LocalizationHelper.GetString("FilmEffectProcessor_WindowCenter"),
            typeof(int), 32768, 0, 65535,
            LocalizationHelper.GetString("FilmEffectProcessor_WindowCenter_Desc")));

        Parameters.Add("WindowWidth", new ProcessorParameter(
            "WindowWidth",
            LocalizationHelper.GetString("FilmEffectProcessor_WindowWidth"),
            typeof(int), 65535, 1, 65535,
            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, TDepth> Process(Image<Gray, TDepth> 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");

        bool is16 = typeof(TDepth) == typeof(ushort);

        if (is16)
        {
            BuildLUT16(windowCenter, windowWidth, invert, curve, curveStrength);
            var img16 = new Image<Gray, ushort>(inputImage.Width, inputImage.Height);
            var ushortData = inputImage.Data as ushort[,,];
            int h = inputImage.Height, w = inputImage.Width;
            Parallel.For(0, h, y =>
            {
                for (int x = 0; x < w; x++)
                    img16.Data[y, x, 0] = _lut16[ushortData![y, x, 0]];
            });

            if (edgeEnhance > 0.01)
            {
                using var blurred = new Image<Gray, ushort>(w, h);
                CvInvoke.GaussianBlur(inputImage, blurred, new System.Drawing.Size(3, 3), 0);
                Parallel.For(0, h, y =>
                {
                    for (int x = 0; x < w; x++)
                    {
                        int diff = ushortData![y, x, 0] - blurred.Data[y, x, 0];
                        int enhanced = img16.Data[y, x, 0] + (int)(diff * edgeEnhance);
                        img16.Data[y, x, 0] = (ushort)Math.Clamp(enhanced, 0, 65535);
                    }
                });
            }

            _logger.Debug("Process(16bit): WC={WC}, WW={WW}", windowCenter, windowWidth);
            return (img16 as Image<Gray, TDepth>)!;
        }
        else
        {
            BuildLUT8(
                Math.Clamp(windowCenter, 0, 255),
                Math.Clamp(windowWidth, 1, 255),
                invert, curve, curveStrength);

            var byteInput = inputImage as Image<Gray, byte>;
            var resultImg = byteInput!.Clone();
            int h = inputImage.Height, w = inputImage.Width;

            for (int y = 0; y < h; y++)
                for (int x = 0; x < w; x++)
                    resultImg.Data[y, x, 0] = _lut8[resultImg.Data[y, x, 0]];

            if (edgeEnhance > 0.01)
            {
                using var blurred = byteInput.SmoothGaussian(3);
                for (int y = 0; y < h; y++)
                    for (int x = 0; x < w; x++)
                    {
                        float diff = byteInput.Data[y, x, 0] - blurred.Data[y, x, 0];
                        int enhanced = resultImg.Data[y, x, 0] + (int)(diff * edgeEnhance);
                        resultImg.Data[y, x, 0] = (byte)Math.Clamp(enhanced, 0, 255);
                    }
            }

            _logger.Debug("Process(8bit): WC={WC}, WW={WW}", windowCenter, windowWidth);
            return (resultImg as Image<Gray, TDepth>)!;
        }
    }

    private void BuildLUT8(int wc, int ww, bool invert, string curve, double strength)
    {
        double halfW = ww / 2.0;
        double low = wc - halfW, high = wc + halfW;
        for (int i = 0; i < 256; i++)
        {
            double normalized = ww <= 1 ? (i >= wc ? 1.0 : 0.0)
                : Math.Clamp((i - low) / (high - low), 0.0, 1.0);
            double mapped = ApplyCurve(normalized, curve, strength);
            if (invert) mapped = 1.0 - mapped;
            _lut8[i] = (byte)Math.Clamp((int)(mapped * 255.0), 0, 255);
        }
    }

    private void BuildLUT16(int wc, int ww, bool invert, string curve, double strength)
    {
        double halfW = ww / 2.0;
        double low = wc - halfW, high = wc + halfW;
        for (int i = 0; i < 65536; i++)
        {
            double normalized = ww <= 1 ? (i >= wc ? 1.0 : 0.0)
                : Math.Clamp((i - low) / (high - low), 0.0, 1.0);
            double mapped = ApplyCurve(normalized, curve, strength);
            if (invert) mapped = 1.0 - mapped;
            _lut16[i] = (ushort)Math.Clamp((int)(mapped * 65535.0), 0, 65535);
        }
    }

    private static double ApplyCurve(double x, string curve, double strength)
        => curve switch
        {
            "Sigmoid" => ApplySigmoid(x, strength),
            "Logarithmic" => ApplyLogarithmic(x, strength),
            "Exponential" => ApplyExponential(x, strength),
            _ => x
        };

    /// <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);
    }
}