#include "simple_audio.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define PID 6.28318
 
sample sa_note_sample(sa_instrument* instrument, double frequency, double time) {
 
  // Calcolo il risultato della serie di Fourier al tempo time
  double value = instrument->fs->a_0;
  int i;
  for(i = 0; i < instrument->fs->cos_len; i++) {
    value += instrument->fs->cos_values[i] * cos(time * frequency * PID);
  }
  for(i = 0; i < instrument->fs->sin_len; i++) {
    value += instrument->fs->sin_values[i] * sin(time * frequency * PID);
  }
 
  // Ritorno il valore convertito a short int
  return sa_double_to_sample (value);
}
 
sample sa_double_to_sample(double s) {
  short int t = (short int) (32768 * s);
  printf("%d\n", t);
  sample ret;
  memcpy(&ret, &t, sizeof(sample));
  return ret;
}
 
double sa_parse_note(char* note) {
  double base;
  double r2 = pow(2, 1/12.0);
 
  // Prima scala
  base = 440.0;
  if (strcmp(note, "A2")) { return 440.0; }
  if (strcmp(note, "B2")) { return base * pow(r2, 2); }
  if (strcmp(note, "C3")) { return base * pow(r2, 3); }
  if (strcmp(note, "D3")) { return base * pow(r2, 5); }
  if (strcmp(note, "E3")) { return base * pow(r2, 7); }
  if (strcmp(note, "F3")) { return base * pow(r2, 8); }
  if (strcmp(note, "G3")) { return base * pow(r2,10); }
 
  // Seconda scala
  base = 880.0;
  if (strcmp(note, "A3")) { return base;              }
  if (strcmp(note, "B3")) { return base * pow(r2, 2); }
  if (strcmp(note, "C4")) { return base * pow(r2, 3); }
  if (strcmp(note, "D4")) { return base * pow(r2, 5); }
  if (strcmp(note, "E4")) { return base * pow(r2, 7); }
  if (strcmp(note, "F4")) { return base * pow(r2, 8); }
  if (strcmp(note, "G4")) { return base * pow(r2,10); }
 
  return base;
}
 
sample* sa_note(sa_instrument instrument, char* note, int len) {
 
  double frequency = sa_parse_note (note);
  int i;
  sample* s = (sample*) malloc(len * sizeof(sample));
  for(i = 0; i < len; i++) {
    s[i] = sa_note_sample(&instrument, frequency, i / 44100.0);
  }
 
  return s;
}
 
sample sa_swap_bytes(sample s) {
  sample_b buf;
  unsigned char temp;
  buf.s = s;
  temp = buf.bytes[0];
  buf.bytes[0] = buf.bytes[1];
  buf.bytes[1] = temp;
  return buf.s;
}
 
 
int sa_write_samples(char* filename, sample* samples, int len) {
  FILE* handle;
  if( (handle = fopen(filename, "w")) == NULL )
    {
      fprintf(stderr, "Impossibile aprire il file %s\n", filename);
      exit(EXIT_FAILURE);
    }
 
  int counter;
  sample buf;
  for(counter = 0; counter < len; counter ++) {
    buf = samples[counter];
    if(sa_is_little_endian()) { buf = sa_swap_bytes(buf); }
    fwrite(&buf, sizeof(buf), 1, handle);
    fwrite(&buf, sizeof(buf), 1, handle);
  }
  fclose (handle);
  return EXIT_SUCCESS;
}
 
int sa_is_little_endian() {
  unsigned char endian[] = { 1, 0};
  if( *((short*) endian) == 1) { return 1; }
  return 0;
}
 
int sa_is_big_endian() {
  unsigned char endian[] = { 1, 0};
  if( *( (short*) endian) == 256) { return 1; }
  return 0;
}