var baseToString = require('./_baseToString'),

castSlice = require('./_castSlice'),
charsEndIndex = require('./_charsEndIndex'),
charsStartIndex = require('./_charsStartIndex'),
stringToArray = require('./_stringToArray'),
toString = require('./toString');

/** Used to match leading and trailing whitespace. */ var reTrim = /^s+|s+$/g;

/**

* Removes leading and trailing whitespace or specified characters from `string`.
*
* @static
* @memberOf _
* @since 3.0.0
* @category String
* @param {string} [string=''] The string to trim.
* @param {string} [chars=whitespace] The characters to trim.
* @param- {Object} [guard] Enables use as an iteratee for methods like `_.map`.
* @returns {string} Returns the trimmed string.
* @example
*
* _.trim('  abc  ');
* // => 'abc'
*
* _.trim('-_-abc-_-', '_-');
* // => 'abc'
*
* _.map(['  foo  ', '  bar  '], _.trim);
* // => ['foo', 'bar']
*/

function trim(string, chars, guard) {

string = toString(string);
if (string && (guard || chars === undefined)) {
  return string.replace(reTrim, '');
}
if (!string || !(chars = baseToString(chars))) {
  return string;
}
var strSymbols = stringToArray(string),
    chrSymbols = stringToArray(chars),
    start = charsStartIndex(strSymbols, chrSymbols),
    end = charsEndIndex(strSymbols, chrSymbols) + 1;

return castSlice(strSymbols, start, end).join('');

}

module.exports = trim;