/**
 * lodash 4.0.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var toString = require('lodash.tostring');

/** Used to match HTML entities and HTML characters. */
var reEscapedHtml = /&(?:amp|lt|gt|quot|#39|#96);/g,
    reHasEscapedHtml = RegExp(reEscapedHtml.source);

/** Used to map HTML entities to characters. */
var htmlUnescapes = {
  '&amp;': '&',
  '&lt;': '<',
  '&gt;': '>',
  '&quot;': '"',
  '&#39;': "'",
  '&#96;': '`'
};

/**
 * Used by `_.unescape` to convert HTML entities to characters.
 *
 * @private
 * @param {string} chr The matched character to unescape.
 * @returns {string} Returns the unescaped character.
 */
function unescapeHtmlChar(chr) {
  return htmlUnescapes[chr];
}

/**
 * The inverse of `_.escape`; this method converts the HTML entities
 * `&amp;`, `&lt;`, `&gt;`, `&quot;`, `&#39;`, and `&#96;` in `string` to
 * their corresponding characters.
 *
 * **Note:** No other HTML entities are unescaped. To unescape additional
 * HTML entities use a third-party library like [_he_](https://mths.be/he).
 *
 * @static
 * @memberOf _
 * @since 0.6.0
 * @category String
 * @param {string} [string=''] The string to unescape.
 * @returns {string} Returns the unescaped string.
 * @example
 *
 * _.unescape('fred, barney, &amp; pebbles');
 * // => 'fred, barney, & pebbles'
 */
function unescape(string) {
  string = toString(string);
  return (string && reHasEscapedHtml.test(string))
    ? string.replace(reEscapedHtml, unescapeHtmlChar)
    : string;
}

module.exports = unescape;