index.js

const fs = require("fs"),
  url = require("url"),
  querystring = require("querystring"),
  path = require("path");
module.exports = Referer;

const dataFile = require("./data/referers.json");

var REFERERS = loadReferers(dataFile);

function loadReferers(source) {
  var referers_dict = {};

  for (var medium in source) {
    var conf_list = source[medium];

    for (var referer_name in conf_list) {
      var config = conf_list[referer_name];
      var params = null;

      if (config.parameters) {
        params = config.parameters.map(function (p) {
          return p.toLowerCase();
        });
      }
      config.domains.forEach(function (domain) {
        referers_dict[domain] = {
          name: referer_name,
          medium: medium,
        };
        if (params) {
          referers_dict[domain]["params"] = params;
        }
      });
    }
  }
  return referers_dict;
}

function Referer(referer_url, current_url, referers) {
  this.known = false;
  this.referer = null;
  this.medium = "unknown";
  this.search_parameter = null;
  this.search_term = null;
  this.referers = referers || REFERERS;

  var ref_uri = url.parse(referer_url);
  var ref_host = ref_uri.hostname;
  this.known = Boolean(~["http:", "https:"].indexOf(ref_uri.protocol));
  this.uri = ref_uri;

  if (!this.known) return;

  if (current_url) {
    var curr_uri = url.parse(current_url);
    var curr_host = curr_uri.hostname;

    if (curr_host == ref_host) {
      this.medium = "internal";
      return;
    }
  }

  var referer = this._lookup_referer(ref_host, ref_uri.pathname, true);
  if (!referer) {
    referer = this._lookup_referer(ref_host, ref_uri.pathname, false);
    if (!referer) {
      this.medium = "unknown";
      return;
    }
  }

  this.referer = referer["name"];
  this.medium = referer["medium"];

  if (referer["medium"] == "search") {
    if (!referer["params"]) return;

    var pqs = querystring.parse(ref_uri.query);

    for (var param in pqs) {
      var val = pqs[param];

      if (referer["params"].indexOf(param.toLowerCase()) !== -1) {
        this.search_parameter = param;
        this.search_term = val;
      }
    }
  }
}

Referer.prototype._lookup_referer = function (
  ref_host,
  ref_path,
  include_path,
) {
  // console.log(ref_host, ref_path, include_path)
  var referer = null;

  if (include_path) referer = this.referers[ref_host + ref_path];
  else referer = this.referers[ref_host];
  if (!referer) {
    if (include_path) {
      var path_parts = ref_path.split("/");
      if (path_parts.length > 1) {
        try {
          referer = this.referers[ref_host + "/" + path_parts[1]];
        } catch (e) {}
      }
    }
  }

  if (!referer) {
    try {
      var idx = ref_host.indexOf(".");
      if (idx === -1) return null;

      var slicedHost = ref_host.slice(idx + 1);
      return this._lookup_referer(slicedHost, ref_path, include_path);
    } catch (e) {
      return null;
    }
  } else return referer;
};

// var r = new Referer("http://www.google.com/search?q=gateway+oracle+cards+denise+linn&hl=en&client=safari")
// console.log(r.uri)