/**
 * showdownjs helper functions
 */

if (!showdown.hasOwnProperty('helper')) {
  showdown.helper = {};
}

/**
 * Check if var is string
 * @static
 * @param {string} a
 * @returns {boolean}
 */
showdown.helper.isString = function isString(a) {
  'use strict';
  return (typeof a === 'string' || a instanceof String);
};

/**
 * ForEach helper function
 * @static
 * @param {*} obj
 * @param {function} callback
 */
showdown.helper.forEach = function forEach(obj, callback) {
  'use strict';
  if (typeof obj.forEach === 'function') {
    obj.forEach(callback);
  } else {
    for (var i = 0; i < obj.length; i++) {
      callback(obj[i], i, obj);
    }
  }
};

/**
 * isArray helper function
 * @static
 * @param {*} a
 * @returns {boolean}
 */
showdown.helper.isArray = function isArray(a) {
  'use strict';
  return a.constructor === Array;
};

/**
 * Check if value is undefined
 * @static
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is `undefined`, else `false`.
 */
showdown.helper.isUndefined = function isUndefined(value) {
  'use strict';
  return typeof value === 'undefined';
};

/**
 * Standardidize extension name
 * @static
 * @param {string} s extension name
 * @returns {string}
 */
showdown.helper.stdExtName = function (s) {
  'use strict';
  return s.replace(/[_-]||\s/g, '').toLowerCase();
};

function escapeCharactersCallback(wholeMatch, m1) {
  'use strict';
  var charCodeToEscape = m1.charCodeAt(0);
  return '~E' + charCodeToEscape + 'E';
}

/**
 * Callback used to escape characters when passing through String.replace
 * @static
 * @param {string} wholeMatch
 * @param {string} m1
 * @returns {string}
 */
showdown.helper.escapeCharactersCallback = escapeCharactersCallback;

/**
 * Escape characters in a string
 * @static
 * @param {string} text
 * @param {string} charsToEscape
 * @param {boolean} afterBackslash
 * @returns {XML|string|void|*}
 */
showdown.helper.escapeCharacters = function escapeCharacters(text, charsToEscape, afterBackslash) {
  'use strict';
  // First we have to escape the escape characters so that
  // we can build a character class out of them
  var regexString = '([' + charsToEscape.replace(/([\[\]\\])/g, '\\$1') + '])';

  if (afterBackslash) {
    regexString = '\\\\' + regexString;
  }

  var regex = new RegExp(regexString, 'g');
  text = text.replace(regex, escapeCharactersCallback);

  return text;
};

/**
 * POLYFILLS
 */
if (showdown.helper.isUndefined(console)) {
  console = {
    warn: function (msg) {
      'use strict';
      alert(msg);
    },
    log: function (msg) {
      'use strict';
      alert(msg);
    }
  };
}