// fft_wav.java     fft_wav  ok.wav junk.wav
//                  uses  read_wave.java
//                  uses  Cxfft.java

public class fft_wav
{
  public fft_wav(String file_in, String file_out)
  {
    double amin, amax, aavg;
    int m; // next power of 2

    read_wav R = new read_wav(file_in, file_out, false);
    // wav_read(file_in);  done by constructor
    int n = R.outix;  // number of sound samples
    for(m=64; m<2500000; m*=2) if(m>2*n) break;
    System.out.println("power of 2 m="+m);

    System.out.println("have "+n+" points for FFT");
    double A[] = new double[m];
    double B[] = new double[m];
    for(int i=0; i<2*n; i+=2) A[i] = (double)R.A[i/2]; // real
    for(int i=1; i<2*n; i+=2) A[i] = 0.0;              // imag
    amin = A[0];
    amax = A[0];
    aavg = 0.0;
    for(int i=0; i<2*n; i+=2)
    {
      amin = Math.min(amin, A[i]);
      amax = Math.max(amax, A[i]);
      aavg += A[i];
    }
    aavg = aavg/(double)n;
    System.out.println("input min="+amin+", max="+amax+", avg="+aavg);
    for(int i=2*n; i<m; i++) A[i] = 0.0; // zero to power of 2

    B = Cxfft.fft(A,1.0);

    // change frequency bins, some B[i], put code here for HW5
    // not just add/sub/mul/div all bins


    A = Cxfft.fft(B,-1.0);
    amin = A[0];
    amax = A[0];
    aavg = 0.0;
    for(int i=0; i<2*n; i+=2)
    {
      amin = Math.min(amin, A[i]);
      amax = Math.max(amax, A[i]);
      aavg += A[i];
    }
    aavg = aavg/(double)n;
    System.out.println("output min="+amin+", max="+amax+", avg="+aavg);
    // should normalize

    for(int i=0; i<2*n; i+=2) R.A[i/2] = (int)(0.99*A[i]);
    for(int i=0; i<n; i++)
    {
      if(R.A[i]>127)  R.A[i]= 127;
      if(R.A[i]<-127) R.A[i]=-127;
    }
    R.wav_write(file_out);
  }

  public static void main (String[] args)
  {
    String file_in = "ok.wav";
    if(args.length>0)
    {
      file_in = args[0];
    }
    String file_out = "junk.wav";
    if(args.length>1)
    {
      file_out = args[1];
    }
    new fft_wav(file_in, file_out);
  } // end main
} // end class fft_wav of fft_wav.java