import java.lang.Math.*;
import java.awt.*;

/**
 * Class containing method to apply a frequency filter to an image.
 *
 * @author Simon Horne.
 */
public class FreqFilter
{

    /**
     * Method to apply a high or low pass filter to an image.
     *
     * @param input TwoDArray representing the image.
     * @param h boolean true - highpass, false - lowpass.
     * @return TwoDArray representing new image.
     */
    public static TwoDArray filter(TwoDArray input, boolean lowpass, double r)
    {
        TwoDArray output = new TwoDArray(input.values, input.size, input.size);

        int i2, j2;
        double r2 = r * r;
        if (lowpass)
        {//if low pass filter
            for (int j = 0; j < input.size; ++j)
            {
                for (int i = 0; i < input.size; ++i)
                {
                    if (i >= input.size / 2)
                    {
                        i2 = i - input.size;
                    } else
                    {
                        i2 = i;
                    }
                    if (j >= input.size / 2)
                    {
                        j2 = j - input.size;
                    } else
                    {
                        j2 = j;
                    }
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 > r2)
                    {
                        output.values[i][j] = new ComplexNumber(0, 0);
                    } else
                    {
                        output.values[i][j] = input.values[i][j];
                    }
                }
            }
        } else
        {//else high pass filter
            for (int j = 0; j < input.size; ++j)
            {
                for (int i = 0; i < input.size; ++i)
                {
                    if (i >= input.size / 2)
                    {
                        i2 = i - input.size;
                    } else
                    {
                        i2 = i;
                    }
                    if (j >= input.size / 2)
                    {
                        j2 = j - input.size;
                    } else
                    {
                        j2 = j;
                    }
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 > r2)
                    {
                        output.values[i][j] = input.values[i][j];
                    } else
                    {
                        output.values[i][j] = new ComplexNumber(0, 0);
                    }
                }
            }
        }
        return output;
    }
    

    /**
     * Method to apply a high or low pass filter to an image.
     */
    public static void filterCorners(double[] io, int size, boolean lowpass, double radius)
    {
        int i2, j2;
        double r2 = radius * radius;
        if (lowpass)
        {//if low pass filter
            for (int j = 0; j < size; ++j)
            {
                for (int i = 0; i < size; ++i)
                {
                    i2 = i;
                    if (i2 >= size / 2)
                    {
                        i2 -= size;
                    }
                    
                    j2 = j;
                    if (j2 >= size / 2)
                    {
                        j2 -= size;
                    }
                    
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 > r2)
                    {
                        io[j*size + i] = 0;
                    }
                }
            }
        } else
        {//else high pass filter
            for (int j = 0; j < size; ++j)
            {
                for (int i = 0; i < size; ++i)
                {
                    i2 = i;
                    if (i2 >= size / 2)
                    {
                        i2 -= size;
                    }
                    
                    j2 = j;
                    if (j2 >= size / 2)
                    {
                        j2 -= size;
                    }
                    
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 <= r2)
                    {
                        io[j*size + i] = 0;
                    }
                }
            }
        }
    }
    
    /**
     * Method to apply a high or low pass filter to an image.
     */
    public static void filterCenter(double[] io, int size, boolean lowpass, double radius)
    {
        int i2, j2;
        double r2 = radius * radius;
        if (lowpass)
        {//if low pass filter
            for (int j = 0; j < size; ++j)
            {
                for (int i = 0; i < size; ++i)
                {
                    i2 = i - size/2;
                    j2 = j - size/2;
                    
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 > r2)
                    {
                        io[j*size + i] = 0;
                    }
                }
            }
        } else
        {//else high pass filter
            for (int j = 0; j < size; ++j)
            {
                for (int i = 0; i < size; ++i)
                {
                    i2 = i - size/2;
                    j2 = j - size/2;
                    
                    double d2 = i2 * i2 + j2 * j2;
                    if (d2 <= r2)
                    {
                        io[j*size + i] = 0;
                    }
                }
            }
        }
    }
}