// ============================================================================
// Copyright © 2016-2025 Hexagon Technology Center GmbH. All Rights Reserved.
// 文件名: SubPixelZoomProcessor.cs
// 描述: 亚像素放大算子，通过高质量插值实现图像的亚像素级放大
// 功能:
//   - 支持任意倍率放大（含小数倍率如 1.5x、2.3x）
//   - 多种插值方法（最近邻、双线性、双三次、Lanczos）
//   - 可选锐化补偿（抵消插值模糊）
//   - 可选指定输出尺寸
// 算法: 基于 OpenCV Resize 的高质量插值放大
// 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;
using System.Drawing;

namespace XP.ImageProcessing.Processors;

/// <summary>
/// 亚像素放大算子
/// </summary>
public class SubPixelZoomProcessor : ImageProcessorBase
{
    private static readonly ILogger _logger = Log.ForContext<SubPixelZoomProcessor>();

    public SubPixelZoomProcessor()
    {
        Name = LocalizationHelper.GetString("SubPixelZoomProcessor_Name");
        Description = LocalizationHelper.GetString("SubPixelZoomProcessor_Description");
    }

    protected override void InitializeParameters()
    {
        Parameters.Add("ScaleFactor", new ProcessorParameter(
            "ScaleFactor",
            LocalizationHelper.GetString("SubPixelZoomProcessor_ScaleFactor"),
            typeof(double),
            2.0,
            1.0,
            16.0,
            LocalizationHelper.GetString("SubPixelZoomProcessor_ScaleFactor_Desc")));

        Parameters.Add("Interpolation", new ProcessorParameter(
            "Interpolation",
            LocalizationHelper.GetString("SubPixelZoomProcessor_Interpolation"),
            typeof(string),
            "Lanczos",
            null,
            null,
            LocalizationHelper.GetString("SubPixelZoomProcessor_Interpolation_Desc"),
            new string[] { "Nearest", "Bilinear", "Bicubic", "Lanczos" }));

        Parameters.Add("SharpenAfter", new ProcessorParameter(
            "SharpenAfter",
            LocalizationHelper.GetString("SubPixelZoomProcessor_SharpenAfter"),
            typeof(bool),
            false,
            null,
            null,
            LocalizationHelper.GetString("SubPixelZoomProcessor_SharpenAfter_Desc")));

        Parameters.Add("SharpenStrength", new ProcessorParameter(
            "SharpenStrength",
            LocalizationHelper.GetString("SubPixelZoomProcessor_SharpenStrength"),
            typeof(double),
            0.5,
            0.1,
            3.0,
            LocalizationHelper.GetString("SubPixelZoomProcessor_SharpenStrength_Desc")));

        _logger.Debug("InitializeParameters");
    }

    public override Image<Gray, byte> Process(Image<Gray, byte> inputImage)
    {
        double scaleFactor = GetParameter<double>("ScaleFactor");
        string interpolation = GetParameter<string>("Interpolation");
        bool sharpenAfter = GetParameter<bool>("SharpenAfter");
        double sharpenStrength = GetParameter<double>("SharpenStrength");

        Inter interMethod = interpolation switch
        {
            "Nearest" => Inter.Nearest,
            "Bilinear" => Inter.Linear,
            "Bicubic" => Inter.Cubic,
            _ => Inter.Lanczos4
        };

        int newWidth = (int)Math.Round(inputImage.Width * scaleFactor);
        int newHeight = (int)Math.Round(inputImage.Height * scaleFactor);

        // 确保最小尺寸为 1
        newWidth = Math.Max(1, newWidth);
        newHeight = Math.Max(1, newHeight);

        var result = new Image<Gray, byte>(newWidth, newHeight);
        CvInvoke.Resize(inputImage, result, new Size(newWidth, newHeight), 0, 0, interMethod);

        // 锐化补偿
        if (sharpenAfter)
        {
            // Unsharp Masking: result = result + strength * (result - blur)
            int ksize = Math.Max(3, (int)(scaleFactor * 2) | 1); // 奇数核
            using var blurred = result.SmoothGaussian(ksize);

            for (int y = 0; y < newHeight; y++)
            {
                for (int x = 0; x < newWidth; x++)
                {
                    float val = result.Data[y, x, 0];
                    float blur = blurred.Data[y, x, 0];
                    float sharpened = val + (float)(sharpenStrength * (val - blur));
                    result.Data[y, x, 0] = (byte)Math.Clamp((int)sharpened, 0, 255);
                }
            }
        }

        _logger.Debug("Process: Scale={Scale}, Interp={Interp}, Size={W}x{H}, Sharpen={Sharpen}",
            scaleFactor, interpolation, newWidth, newHeight, sharpenAfter);

        return result;
    }
}