/**
 * lodash 3.1.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.2 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseToString = require('lodash._basetostring'),
    createPadding = require('lodash._createpadding');

/** Native method references. */
var ceil = Math.ceil,
    floor = Math.floor;

/* Native method references for those with the same name as other `lodash` methods. */
var nativeIsFinite = global.isFinite;

/**
 * Pads `string` on the left and right sides if it is shorter than `length`.
 * Padding characters are truncated if they can't be evenly divided by `length`.
 *
 * @static
 * @memberOf _
 * @category String
 * @param {string} [string=''] The string to pad.
 * @param {number} [length=0] The padding length.
 * @param {string} [chars=' '] The string used as padding.
 * @returns {string} Returns the padded string.
 * @example
 *
 * _.pad('abc', 8);
 * // => '  abc   '
 *
 * _.pad('abc', 8, '_-');
 * // => '_-abc_-_'
 *
 * _.pad('abc', 3);
 * // => 'abc'
 */
function pad(string, length, chars) {
  string = baseToString(string);
  length = +length;

  var strLength = string.length;
  if (strLength >= length || !nativeIsFinite(length)) {
    return string;
  }
  var mid = (length - strLength) / 2,
      leftLength = floor(mid),
      rightLength = ceil(mid);

  chars = createPadding('', rightLength, chars);
  return chars.slice(0, leftLength) + string + chars;
}

module.exports = pad;
