/**
   * _s.prune: a more elegant version of truncate
   * prune extra chars, never leaving a half-chopped word.
   * @author github.com/rwz
   */
  var makeString = require('./helper/makeString');
  var rtrim = require('./rtrim');
  
  module.exports = function prune(str, length, pruneStr) {
    str = makeString(str);
    length = ~~length;
    pruneStr = pruneStr != null ? String(pruneStr) : '...';
  
    if (str.length <= length) return str;
  
    var tmpl = function(c) {
        return c.toUpperCase() !== c.toLowerCase() ? 'A' : ' ';
      },
      template = str.slice(0, length + 1).replace(/.(?=\W*\w*$)/g, tmpl); // 'Hello, world' -> 'HellAA AAAAA'
  
    if (template.slice(template.length - 2).match(/\w\w/))
      template = template.replace(/\s*\S+$/, '');
    else
      template = rtrim(template.slice(0, template.length - 1));
  
    return (template + pruneStr).length > str.length ? str : str.slice(0, template.length) + pruneStr;
  };