'use strict';

var letterScores = {
  'a': 1, 'e': 1, 'i': 1, 'o': 1,
  'u': 1, 'l': 1, 'n': 1, 'r': 1,
  's': 1, 't': 1, 'd': 2, 'g': 2,
  'b': 3, 'c': 3, 'm': 3, 'p': 3,
  'f': 4, 'h': 4, 'v': 4, 'w': 4,
  'y': 4, 'k': 5, 'j': 8, 'x': 8,
  'q': 10, 'z': 10
};

function letterScore(letter) {
  return letterScores[letter] || 0;
}

module.exports = function (word) {
  word || (word = '');
  word = word.toLowerCase();

  var sum = 0;
  var idx = -1;
  var end = word.length;

  while (++idx < end) {
    sum += letterScore(word[idx]);
  }

  return sum;
};