'use strict';

var chars = {}, unesc, temp;

function reverse(object, prepender) {
  return Object.keys(object).reduce(function(reversed, key) {
    var newKey = prepender ? prepender + key : key; // Optionally prepend a string to key.
    reversed[object[key]] = newKey; // Swap key and value.
    return reversed; // Return the result.
  }, {});
}

/**
 * Regex for common characters
 */

chars.escapeRegex = {
  '?': /\?/g,
  '@': /\@/g,
  '!': /\!/g,
  '+': /\+/g,
  '*': /\*/g,
  '(': /\(/g,
  ')': /\)/g,
  '[': /\[/g,
  ']': /\]/g,
};

/**
 * Escape characters
 */

chars.ESC = {
  '?': '__UNESC_QMRK__',
  '@': '__UNESC_AMPE__',
  '!': '__UNESC_EXCL__',
  '+': '__UNESC_PLUS__',
  '*': '__UNESC_STAR__',
  ',': '__UNESC_COMMA__',
  '(': '__UNESC_LTPAREN__',
  ')': '__UNESC_RTPAREN__',
  '[': '__UNESC_LTBRACK__',
  ']': '__UNESC_RTBRACK__',
};

/**
 * Unescape characters
 */

chars.UNESC = unesc || (unesc = reverse(chars.ESC, '\\'));

chars.ESC_TEMP = {
  '?': '__TEMP_QMRK__',
  '@': '__TEMP_AMPE__',
  '!': '__TEMP_EXCL__',
  '*': '__TEMP_STAR__',
  '+': '__TEMP_PLUS__',
  ',': '__TEMP_COMMA__',
  '(': '__TEMP_LTPAREN__',
  ')': '__TEMP_RTPAREN__',
  '[': '__TEMP_LTBRACK__',
  ']': '__TEMP_RTBRACK__',
};

chars.TEMP = temp || (temp = reverse(chars.ESC_TEMP));

module.exports = chars;
