'use strict';

/**
 * @description
 * Private service to sanitize uris for links and images. Used by $compile and $sanitize.
 */
function $$SanitizeUriProvider() {
  var aHrefSanitizationWhitelist = /^\s*(https?|ftp|mailto|tel|file):/,
    imgSrcSanitizationWhitelist = /^\s*(https?|ftp|file):|data:image\//;

  /**
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during a[href] sanitization.
   *
   * The sanitization is a security measure aimed at prevent XSS attacks via html links.
   *
   * Any url about to be assigned to a[href] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `aHrefSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$compileProvider} Current RegExp if called without value or self for
   *    chaining otherwise.
   */
  this.aHrefSanitizationWhitelist = function(regexp) {
    if (isDefined(regexp)) {
      aHrefSanitizationWhitelist = regexp;
      return this;
    }
    return aHrefSanitizationWhitelist;
  };


  /**
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during img[src] sanitization.
   *
   * The sanitization is a security measure aimed at prevent XSS attacks via html links.
   *
   * Any url about to be assigned to img[src] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `imgSrcSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$compileProvider} Current RegExp if called without value or self for
   *    chaining otherwise.
   */
  this.imgSrcSanitizationWhitelist = function(regexp) {
    if (isDefined(regexp)) {
      imgSrcSanitizationWhitelist = regexp;
      return this;
    }
    return imgSrcSanitizationWhitelist;
  };

  this.$get = function() {
    return function sanitizeUri(uri, isImage) {
      var regex = isImage ? imgSrcSanitizationWhitelist : aHrefSanitizationWhitelist;
      var normalizedVal;
      // NOTE: urlResolve() doesn't support IE < 8 so we don't sanitize for that case.
      if (!msie || msie >= 8 ) {
        normalizedVal = urlResolve(uri).href;
        if (normalizedVal !== '' && !normalizedVal.match(regex)) {
          return 'unsafe:'+normalizedVal;
        }
      }
      return uri;
    };
  };
}