/*
 * EJS Embedded JavaScript templates
 * Copyright 2112 Matthew Eernisse (mde@fleegix.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
*/

/**
 * Private utility functions
 * @module utils
 * @private
 */

'use strict';

var regExpChars = /[|\\{}()[\]^$+*?.]/g;

/**
 * Escape characters reserved in regular expressions.
 *
 * If `string` is `undefined` or `null`, the empty string is returned.
 *
 * @param {String} string Input string
 * @return {String} Escaped string
 * @static
 * @private
 */
exports.escapeRegExpChars = function (string) {
  // istanbul ignore if
  if (!string) {
    return '';
  }
  return String(string).replace(regExpChars, '\\$&');
};

var _ENCODE_HTML_RULES = {
      '&': '&'
    , '<': '&lt;'
    , '>': '&gt;'
    , '"': '&#34;'
    , "'": '&#39;'
    }
  , _MATCH_HTML = /[&<>\'"]/g;

/**
 * Stringified version of constants used by {@link module:utils.escapeXML}.
 *
 * It is used in the process of generating {@link ClientFunction}s.
 *
 * @readonly
 * @type {String}
 */

var escapeFuncStr =
  'var _ENCODE_HTML_RULES = {\n'
+ '      "&": "&amp;"\n'
+ '    , "<": "&lt;"\n'
+ '    , ">": "&gt;"\n'
+ '    , \'"\': "&#34;"\n'
+ '    , "\'": "&#39;"\n'
+ '    }\n'
+ '  , _MATCH_HTML = /[&<>\'"]/g;\n';

/**
 * Escape characters reserved in XML.
 *
 * If `markup` is `undefined` or `null`, the empty string is returned.
 *
 * @implements {EscapeCallback}
 * @param {String} markup Input string
 * @return {String} Escaped string
 * @static
 * @private
 */
exports.escapeXML = function (markup) {
  return markup == undefined
    ? ''
    : String(markup)
        .replace(_MATCH_HTML, function(m) {
          return _ENCODE_HTML_RULES[m] || m;
        });
};
exports.escapeXML.toString = function () {
  return Function.prototype.toString.call(this) + ';\n' + escapeFuncStr
};

/**
 * Copy all properties from one object to another, in a shallow fashion.
 *
 * @param  {Object} to   Destination object
 * @param  {Object} from Source object
 * @return {Object}      Destination object
 * @static
 * @private
 */
exports.shallowCopy = function (to, from) {
  from = from || {};
  for (var p in from) {
    to[p] = from[p];
  }
  return to;
};

/**
 * Simple in-process cache implementation. Does not implement limits of any
 * sort.
 *
 * @implements Cache
 * @static
 * @private
 */
exports.cache = {
  _data: {},
  set: function (key, val) {
    this._data[key] = val;
  },
  get: function (key) {
    return this._data[key];
  },
  reset: function () {
    this._data = {};
  }
};