using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Media.Imaging;

namespace DSPS_Lab3;

public static class Ex
{
    public static float[,] GenerateSpatialKernel(int size, float sigma)
    {
        var kernel = new float[size, size];
        float sum = 0;
        var half = size / 2;

        // Use <= half to ensure the full kernel is covered
        for (var y = -half; y <= half; y++)
        {
            for (var x = -half; x <= half; x++)
            {
                // Optional: Bounds check for odd/even sizes
                if (y + half >= size || x + half >= size) continue;

                var val = (float)Math.Exp(-(x * x + y * y) / (2 * sigma * sigma));
                kernel[y + half, x + half] = val;
                sum += val;
            }
        }

        for (var y = 0; y < size; y++)
            for (var x = 0; x < size; x++)
                kernel[y, x] /= sum;

        return kernel;
    }

    public static float[,] PadAndShiftKernel(float[,] smallKernel, int imgWidth, int imgHeight)
    {
        var fullKernel = new float[imgHeight, imgWidth];
        int kHeight = smallKernel.GetLength(0);
        int kWidth = smallKernel.GetLength(1);
        int radY = kHeight / 2;
        int radX = kWidth / 2;

        for (int y = 0; y < kHeight; y++)
        {
            for (int x = 0; x < kWidth; x++)
            {
                // Circular shift: maps kernel center to (0,0)
                int targetY = (y - radY + imgHeight) % imgHeight;
                int targetX = (x - radX + imgWidth) % imgWidth;
                fullKernel[targetY, targetX] = smallKernel[y, x];
            }
        }
        return fullKernel;
    }
}