package com.jclark.xsl.conv;

class AlphabetNumberFormat implements NumberFormat {
  private String letters;

  AlphabetNumberFormat(String letters) {
    this.letters = letters;
  }

  public String format(int n) {
    if (n == 0)
      return "0";
    StringBuffer result = new StringBuffer();
    do {
      n--;
      int r = n % letters.length();
      n -= r;
      n /= 26;
      result.append(letters.charAt(r));
    } while (n > 0);
    return result.reverse().toString();
  }
}