#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>


#define SIZE 20

typedef struct sensor_reading {
  long ts;
  int  temp;
} Reading;


// --------------------------------------------------
// Initialize array with some random values
void init(Reading array_samples[], int nb_samples, int delta_time) {

  int i;
  int time = 0;
  for (i = 0 ; i < nb_samples; i++) {
    Reading r;
    r.ts = time;
    time += delta_time;
    if ( (i % 2) ) {
      r.temp = 68;
    } else {
      r.temp = 67;
    }

    // Important. The following statement makes copy of whole structure!
    array_samples[i] = r;

  }

}

// --------------------------------------------------
// Just prints the content of the array
void print(Reading array_samples[], int nb_samples) {

  int i;
  printf("[");
  for (i = 0 ; i < nb_samples; i++) {
    printf("(%ld,%d)", array_samples[i].ts, array_samples[i].temp);
  }
  printf("]\n");

}


// --------------------------------------------------
// Arguments should be: nb samples and delta time
int main(int argc, char** argv) {

  if ( argc <= 2 ) {
    fprintf(stderr,"Usage: %s nb_samples delta_time\n", argv[0]);
    return 1;
  }

  int nb_samples = atoi(argv[1]);
  int delta_time = atoi(argv[2]);

  Reading *array_samples = (Reading *)malloc( nb_samples * sizeof(Reading));

  init(array_samples,nb_samples,delta_time);
  print(array_samples,nb_samples);

  int capacity = nb_samples;

  while ( true ) {

    // Read next sample
    Reading r;
    printf("Enter next sample: ");
    scanf(" %ld %d",&(r.ts),&(r.temp));


    // If out-of-space, double the capacity
    if ( nb_samples >= capacity ) {
      
      printf("\nOut of space, doubling the size...\n");

      capacity = 2*capacity;

      Reading *old = array_samples;

      // Allocate a bigger array
      array_samples = (Reading *)malloc( capacity * sizeof(Reading));

      if ( ! array_samples ) {
	fprintf(stderr,"Out of memory\n");
	return 1;
      }

      // Copy old array into new location
      // memcpy is general utility to copy chunks of memory
      memcpy(array_samples,old,(nb_samples*sizeof(Reading)));

      // Deallocate old array
      free(old);

      // Note that we could do all this in one step by using realloc
    }

    array_samples[nb_samples] = r;
    nb_samples++;

    print(array_samples,nb_samples);

  }

  return 0;
}