// ============================================================================
// Copyright © 2026 Hexagon Technology Center GmbH. All Rights Reserved.
// 文件名: GammaProcessor.cs
// 描述: Gamma校正算子，用于调整图像亮度和对比度
// 功能:
//   - Gamma非线性校正
//   - 增益调整
//   - 使用查找表（LUT）加速处理
//   - 适用于图像显示和亮度调整
// 算法: Gamma校正公式 output = (input^(1/gamma)) * gain
// 作者: 李伟 wei.lw.li@hexagon.com
// ============================================================================

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

namespace XP.ImageProcessing.Processors;

/// <summary>
/// Gamma校正算子
/// </summary>
public class GammaProcessor : ImageProcessorBase
{
    private byte[] _lookupTable;
    private static readonly ILogger _logger = Log.ForContext<GammaProcessor>();

    public GammaProcessor()
    {
        Name = LocalizationHelper.GetString("GammaProcessor_Name");
        Description = LocalizationHelper.GetString("GammaProcessor_Description");
        _lookupTable = new byte[256];
    }

    protected override void InitializeParameters()
    {
        Parameters.Add("Gamma", new ProcessorParameter(
            "Gamma",
            LocalizationHelper.GetString("GammaProcessor_Gamma"),
            typeof(double),
            1.0,
            0.1,
            5.0,
            LocalizationHelper.GetString("GammaProcessor_Gamma_Desc")));

        Parameters.Add("Gain", new ProcessorParameter(
            "Gain",
            LocalizationHelper.GetString("GammaProcessor_Gain"),
            typeof(double),
            1.0,
            0.1,
            3.0,
            LocalizationHelper.GetString("GammaProcessor_Gain_Desc")));
        _logger.Debug("InitializeParameters");
    }

    public override Image<Gray, byte> Process(Image<Gray, byte> inputImage)
    {
        double gamma = GetParameter<double>("Gamma");
        double gain = GetParameter<double>("Gain");

        BuildLookupTable(gamma, gain);

        var result = inputImage.Clone();
        ApplyLookupTable(result);
        _logger.Debug("Process:Gamma = {0}, Gain = {1}", gamma, gain);
        return result;
    }

    private void BuildLookupTable(double gamma, double gain)
    {
        double invGamma = 1.0 / gamma;

        for (int i = 0; i < 256; i++)
        {
            double normalized = i / 255.0;
            double corrected = Math.Pow(normalized, invGamma) * gain;
            int value = (int)(corrected * 255.0);

            _lookupTable[i] = (byte)Math.Max(0, Math.Min(255, value));
        }
        _logger.Debug("Gamma and gain values recorded: gamma = {Gamma}, gain = {Gain}", gamma, gain);
    }

    private void ApplyLookupTable(Image<Gray, byte> image)
    {
        int width = image.Width;
        int height = image.Height;

        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                byte pixelValue = image.Data[y, x, 0];
                image.Data[y, x, 0] = _lookupTable[pixelValue];
            }
        }
    }
}