// ============================================================================
// Copyright © 2026 Hexagon Technology Center GmbH. All Rights Reserved.
// 文件名: DifferenceProcessor.cs
// 描述: 差分运算算子，用于边缘检测和变化检测
// 功能:
//   - 对图像进行差分运算
//   - 支持水平、垂直和对角线差分
//   - 可用于边缘检测
//   - 可选归一化输出
// 算法: 像素级差分运算
// 作者: 李伟 wei.lw.li@hexagon.com
// ============================================================================

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

namespace XP.ImageProcessing.Processors;

/// <summary>
/// 差分运算算子
/// </summary>
public class DifferenceProcessor : ImageProcessorBase
{
    private static readonly ILogger _logger = Log.ForContext<DifferenceProcessor>();

    public DifferenceProcessor()
    {
        Name = LocalizationHelper.GetString("DifferenceProcessor_Name");
        Description = LocalizationHelper.GetString("DifferenceProcessor_Description");
    }

    protected override void InitializeParameters()
    {
        Parameters.Add("Direction", new ProcessorParameter(
            "Direction",
            LocalizationHelper.GetString("DifferenceProcessor_Direction"),
            typeof(string),
            "Horizontal",
            null,
            null,
            LocalizationHelper.GetString("DifferenceProcessor_Direction_Desc"),
            new string[] { "Horizontal", "Vertical", "Both" }));

        Parameters.Add("Normalize", new ProcessorParameter(
            "Normalize",
            LocalizationHelper.GetString("DifferenceProcessor_Normalize"),
            typeof(bool),
            true,
            null,
            null,
            LocalizationHelper.GetString("DifferenceProcessor_Normalize_Desc")));

        _logger.Debug("InitializeParameters");
    }

    public override Image<Gray, byte> Process(Image<Gray, byte> inputImage)
    {
        string direction = GetParameter<string>("Direction");
        bool normalize = GetParameter<bool>("Normalize");

        int width = inputImage.Width;
        int height = inputImage.Height;

        var floatImage = inputImage.Convert<Gray, float>();
        var result = new Image<Gray, float>(width, height);

        if (direction == "Horizontal")
        {
            // 水平差分: I(x+1,y) - I(x,y)
            for (int y = 0; y < height; y++)
            {
                for (int x = 0; x < width - 1; x++)
                {
                    result.Data[y, x, 0] = floatImage.Data[y, x + 1, 0] - floatImage.Data[y, x, 0];
                }
                result.Data[y, width - 1, 0] = 0;
            }
        }
        else if (direction == "Vertical")
        {
            // 垂直差分: I(x,y+1) - I(x,y)
            for (int y = 0; y < height - 1; y++)
            {
                for (int x = 0; x < width; x++)
                {
                    result.Data[y, x, 0] = floatImage.Data[y + 1, x, 0] - floatImage.Data[y, x, 0];
                }
            }
            for (int x = 0; x < width; x++)
            {
                result.Data[height - 1, x, 0] = 0;
            }
        }
        else // Both
        {
            // 梯度幅值: sqrt((dx)^2 + (dy)^2)
            for (int y = 0; y < height - 1; y++)
            {
                for (int x = 0; x < width - 1; x++)
                {
                    float dx = floatImage.Data[y, x + 1, 0] - floatImage.Data[y, x, 0];
                    float dy = floatImage.Data[y + 1, x, 0] - floatImage.Data[y, x, 0];
                    result.Data[y, x, 0] = (float)Math.Sqrt(dx * dx + dy * dy);
                }
            }
        }

        if (normalize)
        {
            double minVal = 0, maxVal = 0;
            Point minLoc = new Point();
            Point maxLoc = new Point();
            CvInvoke.MinMaxLoc(result, ref minVal, ref maxVal, ref minLoc, ref maxLoc);

            if (maxVal > minVal)
            {
                result = (result - minVal) * (255.0 / (maxVal - minVal));
            }
        }

        floatImage.Dispose();
        _logger.Debug("Process: Direction = {Direction}, Normalize = {Normalize}", direction, normalize);
        return result.Convert<Gray, byte>();
    }
}