#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <complex.h>

void Fourier(unsigned char *registro, int size, double complex *coeficientes)
{
    // N é o total de observacoes
    // M_PI é uma macro que define o valor do PI (math.h)
    int i, j;
    for (i = 0; i < size; i++)
        for (j = 0; j < size; j++)
            coeficientes[i] = coeficientes[i] + registro[j] * cexp( ( -2.0 * M_PI * ( ((j+1) * i * 1.0) / ( size * 1.0 ) ) ) * _Complex_I );
}

void Calculo_Magnitude(double complex *coeficientes, int size, double complex *magnitude)
{
    double parte_real;
    double parte_imaginaria;
    double mag;
    int i ;

    for (i = 0; i < size; i++)
    {
        parte_real = __real__ coeficientes[i];
        parte_imaginaria = __imag__ coeficientes[i];
        mag = sqrt(pow(parte_real, 2) + pow(parte_imaginaria, 2));
        magnitude[i] = mag;
    }
}

void Ordenacao(double complex *magnitude, double complex *auxiliar, int size)
{
    int i, j;

    for (i = 0; i < size; i++)
        auxiliar[i] = magnitude[i];


    for (j = size-2; j >= 0; j--)
    {
    // chave atual de comparacao
    int ckey = auxiliar[j];
    // compara com os valores abaixo
    // e tenta encontrar a posicao correta de ckey anterior
    i = j+1;
    while ((i < size) && ((int)auxiliar[i] > ckey))
    {
        auxiliar[i-1] = auxiliar[i];
        i++;
    }
    // o que significa o valor de i ???
    auxiliar[i-1] = ckey;
    }
}

void inverseFourier(double complex *coefficients, int N, unsigned char *audio8ubits)
{
    // N é o total de coeficientes
    // M_PI é uma macro que define o valor do PI (math.h)
    double complex *audio = (double complex *) calloc(N, sizeof(double complex));
    int n, k;
    for (n = 0; n < N; n++)
    {
        for (k = 0; k < N; k++)
        {
            audio[n] = audio[n] + coefficients[k] * cexp( ( 2.0 * M_PI * ( ((k+1) * n * 1.0) / ( N * 1.0 ) ) ) * _Complex_I );
        }
        audio[n] = audio[n] / ( N * 1.0);
        audio8ubits[n] = (int) __real__ audio[n];
    }
    free(audio);
}

int main(int argc, char* argv[])
{
    char filename[30];
    FILE *arq_bin;
    int t, size;
    int i = 0;
    unsigned char *registro;
    double complex *coeficientes;

    scanf ("%s", filename);
    scanf ("%d", &t);

    arq_bin = fopen(filename, "rb");
    if (arq_bin == NULL) {
        fprintf(stderr,"Erro ao abrir arquivo %s\n\n", argv[1]);
        return 2;
    }

    /*fseek(arq_bin, 0, SEEK_END);
    size = ftell(arq_bin)/sizeof(unsigned char);
    rewind (arq_bin);
    registro = (unsigned char*) malloc(size*sizeof(unsigned char));

    rewind (arq_bin);
    do
    {
        fread(&registro[i], sizeof(unsigned char), 1, arq_bin);
        i++;
    } while (!feof(arq_bin));*/

    unsigned char c;

    while((fread(&c, 1, 1, arq_bin)) > 0)
       i++;

    size = i;
    registro = (unsigned char*) malloc(size*sizeof(unsigned char));

    i = 0;
    while((fread(&c, 1, 1, arq_bin)) > 0)
    {
        registro[i] = (int) c;
        i++;
    }

    /*
    for (i = 0; i < size; i++)
        printf ("%d ", registro[i]);
    */

    coeficientes = (double complex*) calloc(size, sizeof(double complex));
    Fourier(registro, size, coeficientes);
    double complex *magnitude;
    magnitude = (double complex*) calloc (size, sizeof(double complex));
    Calculo_Magnitude(coeficientes, size, magnitude);
    double complex *auxiliar;
    auxiliar = (double complex*) calloc(size, sizeof(double complex));
    Ordenacao(magnitude, auxiliar, size);

    for (i = 0; i < size; i++)
        if ((int)auxiliar[t] > (int)magnitude[i])
            coeficientes[i] = 0;

    unsigned char *audio8ubits;
    audio8ubits = (unsigned char *) calloc(size, sizeof(unsigned char));
    inverseFourier(coeficientes, size, audio8ubits);


    FILE *arq_saida;
    arq_saida = fopen("saida.raw", "wb");
    if (arq_bin == NULL) {
        fprintf(stderr,"Erro ao abrir arquivo arquivo de saida\n\n");
        return 3;
    }

    for (i = 0; i < size; i++)
        fwrite (&audio8ubits[i], sizeof(unsigned char), 1, arq_saida);

    printf ("%d\n", size);
    int total = 0;
    for ( i = 0; i < size; i++)
        if (__real__ (coeficientes[i]) < 0.0 && __imag__ (coeficientes[i]) < 0.0 )
            total++;

    printf ("%d\n", total);
    for (i = 0; i <= t; i++)
            printf ("%d ", (int)auxiliar[i]);
    printf ("\n");

    free(magnitude);
    free(audio8ubits);
    free(auxiliar);
    free(coeficientes);
    free(registro);
    fclose(arq_bin);
    fclose(arq_saida);

    return 0;
}