const XMLHttpRequest = require("xmlhttprequest-ssl");
const XHR = require("./polling-xhr");
const JSONP = require("./polling-jsonp");
const websocket = require("./websocket");

exports.polling = polling;
exports.websocket = websocket;

/**
 * Polling transport polymorphic constructor.
 * Decides on xhr vs jsonp based on feature detection.
 *
 * @api private
 */

function polling(opts) {
  let xhr;
  let xd = false;
  let xs = false;
  const jsonp = false !== opts.jsonp;

  if (typeof location !== "undefined") {
    const isSSL = "https:" === location.protocol;
    let port = location.port;

    // some user agents have empty `location.port`
    if (!port) {
      port = isSSL ? 443 : 80;
    }

    xd = opts.hostname !== location.hostname || port !== opts.port;
    xs = opts.secure !== isSSL;
  }

  opts.xdomain = xd;
  opts.xscheme = xs;
  xhr = new XMLHttpRequest(opts);

  if ("open" in xhr && !opts.forceJSONP) {
    return new XHR(opts);
  } else {
    if (!jsonp) throw new Error("JSONP disabled");
    return new JSONP(opts);
  }
}