#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "utils.h"
#include "log.h"

/**
 * @brief get a substring of a string
 *
 * @param s string
 * @param pos first pos
 * @param l length
 * @return the substring
 */
char
*get_substring(char *s, int pos, int l)
{
  int i = 0;
  char *out;

  if (l <= 0) {
    return NULL;
  }

  out = malloc((l + 1) * sizeof(char));
  if (out == NULL) {
    log_fatal("failed to get substring malloc: %s", strerror(errno));
    exit(1);
  }

  /* Copy substring into ss */
  while (i < l) {
    out[i] = s[pos + i];
    i++;
  }

  /* Null terminate the substring */
  out[i] = '\0';

  return out;
}

/**
 * @brief concatinate two strings
 *
 * @param s1 first
 * @param s2 second
 * @return the concatinated string
 */
char
*concat(const char *s1, const char *s2)
{
  int len1, len2;
  char *result;

  len1 = strlen(s1);
  len2 = strlen(s2);

  /* attempt to allocate size for the new string */
  result = malloc(len1 + len2 + 1);
  if (result == NULL) {
    log_fatal("malloc: %s", strerror(errno));
    exit(1);
  }

  memcpy(result, s1, len1);
  memcpy(result + len1, s2, len2 + 1);
                              // + 1 copies the null terminator

  return result;
}