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

#include "string.h"

char*
easycsv_set_charp_to_value(const char *rowstr,
			   unsigned int col)
{
  /* Get first occurance of comma in str, the first value is ommited but not the comma */
  char *pch = (char*) rowstr;
  /* Repeat until desired col is found */
  for (unsigned int i = 1; i < col; i++) {
    pch = strpbrk(pch + 1, ",");
  }

  return pch;
}

char*
easycsv_insert_string_row(const char* val,
			  const char* rowstr,
			  unsigned int col,
			  unsigned int col_max)
{
  size_t rowstrst = strlen(rowstr);
  size_t st = 0;
  size_t commas = 0;
  char *pch = NULL;
  char *newstr = NULL;

  /* column is within limit */
  if (1 <= col && col <= col_max) {

    /* Set pch to start of value in rowstr */
    pch = easycsv_set_charp_to_value(rowstr, col);

    /* Calculate size of existing value */
    st = strcspn(pch, ",");
    
    newstr = malloc(rowstrst - st + strlen(val) + 1);

    /* Copy char to newstr before value (pch) */
    strncpy(newstr, rowstr, pch - rowstr);

    strcat(newstr, val);

    /* Set pch to after value */
    pch = strchr(rowstr, ',');

    /* Calculate length of rest of string */
    st = strlen(pch);

    /* Concentate rest of string including NULL char */
    strcat(newstr, pch);
  }
  else {
    commas = col - col_max;
    // csv->cols = col;
    newstr = malloc(rowstrst + commas + strlen(val) + 1);
    strncpy(newstr, rowstr, rowstrst);
    for (size_t i = 0; i < commas; i++)
      strncat(newstr, ",", 1);
    strcat(newstr, val); // append \0
  }
  return newstr;
}