var createPadding = require('./_createPadding'),
      stringSize = require('./_stringSize'),
      toInteger = require('./toInteger'),
      toString = require('./toString');
  
  /* Built-in method references for those with the same name as other `lodash` methods. */
  var nativeCeil = Math.ceil,
      nativeFloor = Math.floor;
  
  /**
   * Pads `string` on the left and right sides if it's shorter than `length`.
   * Padding characters are truncated if they can't be evenly divided by `length`.
   *
   * @static
   * @memberOf _
   * @since 3.0.0
   * @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 = toString(string);
    length = toInteger(length);
  
    var strLength = length ? stringSize(string) : 0;
    if (!length || strLength >= length) {
      return string;
    }
    var mid = (length - strLength) / 2;
    return (
      createPadding(nativeFloor(mid), chars) +
      string +
      createPadding(nativeCeil(mid), chars)
    );
  }
  
  module.exports = pad;