'use strict';

var trimStart = require('string.prototype.trimleft');
var trimEnd = require('string.prototype.trimright');

var GetIntrinsic = require('../GetIntrinsic');

var $TypeError = GetIntrinsic('%TypeError%');

var RequireObjectCoercible = require('./RequireObjectCoercible');
var ToString = require('./ToString');

// https://ecma-international.org/ecma-262/10.0/#sec-trimstring

module.exports = function TrimString(string, where) {
	var str = RequireObjectCoercible(string);
	var S = ToString(str);
	var T;
	if (where === 'start') {
		T = trimStart(S);
	} else if (where === 'end') {
		T = trimEnd(S);
	} else if (where === 'start+end') {
		T = trimStart(trimEnd(S));
	} else {
		throw new $TypeError('Assertion failed: invalid `where` value; must be "start", "end", or "start+end"');
	}
	return T;
};