#include "inttoeng.h"
#include "string.h"

const char *digit_array[] = {
  "zero",
  "one",
  "two",
  "three",
  "four",
  "five",
  "six",
  "seven",
  "eight",
  "nine",
  "ten",
  "eleven",
  "twelve",
  "thirteen",
  "fourteen",
  "fifteen",
  "sixteen",
  "seventeen",
  "eighteen",
  "nineteen"
};

const char *tens_array[] = {
  "",
  "",
  "twenty",
  "thirty",
  "fourty",
  "fifty",
  "sixty",
  "seventy",
  "eighty",
  "ninety"
};

int intToEnglish(int i, char buf[]) 
{
  if(i < 0 || i > 9999) return 0;

  buf[0] = '\0';
  char spacer[2];     // by using this array, we can make sure not to add
                      // unnecessary whitespace by always prepending it to
                      // each word, and turning it from the empty string to 
                      // the string containing a space after the first word
  spacer[0] = '\0';
  spacer[1] = '\0';

  int t = i/1000;
  if(t) {
    strcat(buf, digit_array[t]);
    strcat(buf, " thousand");
    spacer[0] = ' ';
  }
  
  int h = (i%1000)/100;
  if(h) {
    strcat(buf, spacer);
    strcat(buf, digit_array[h]);
    strcat(buf, " hundred");
    spacer[0] = ' ';
  }
  
  int to = (i%100);
  if(to == 0) { // no-op
  }
  else if(to < 20) {
    strcat(buf, spacer);
    strcat(buf, digit_array[to]);
  } else {
    int tens = to/10;  // tens is at least 2 because to >= 20
    strcat(buf, spacer);
    strcat(buf, tens_array[tens]);
    
    int o = to%10;
    if(o) {
      strcat(buf, "-");
      strcat(buf, digit_array[o]);
    }
  }

  if(i == 0) strcat (buf, "zero");

  return 1;
}