// origin url parameter name
var ORIGIN_PAR = 'ORIGIN';

// url address of page that invoked this login dialog
var ORIGIN_URL_BASE64 = gup(ORIGIN_PAR);

// true if the origin parameter is given
var ORIGIN_GIVEN = ORIGIN_URL_BASE64 !== '' ? true : false;

// send POST to GEN=TOKEN
function fetchToken() {

    var data = JSON.stringify({
        username: document.getElementById("usr").value,
        password: document.getElementById("psw").value
    });

    var xhr = new XMLHttpRequest();
    xhr.withCredentials = true;

    xhr.addEventListener("readystatechange", function () {

      if (this.readyState === 4) {
        var response = JSON.parse(this.responseText);

        if (typeof response.Token === 'string') {

            callOriginPage(
                document.getElementById("usr").value,
                response.Token
            );
        }
        else {
            alert('Špatné přihlašovací údaje.');
        }

      }
    });

    xhr.open("POST", "https://webmap.dppcr.cz/dpp_cr/editor.dll?GEN=TOKEN&FORMAT=json");
    xhr.setRequestHeader("Content-Type", "application/json");
    xhr.setRequestHeader("cache-control", "no-cache");

    xhr.send(data);
    return false;

}

function callOriginPage(usr, token) {

    if (!ORIGIN_GIVEN) {
        console.log('ORIGIN URL NOT GIVEN!');
        window.location.href = "https://webmap.dppcr.cz/dpp_cr/editor.dll";
    }
    else {
        var originUrl = window.atob(ORIGIN_URL_BASE64);
        originUrl += originUrl.indexOf('?') > -1 ? '&' : '?';
        originUrl += 'USERNAME=' + usr + '&TOKEN=' + token;
        window.location.href = originUrl;
    }

}

// get url parameter
function gup (name) {

    name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");

    var regexS = "[\\?&]" + name + "=([^&#]*)";
    var regex = new RegExp(regexS);
    var results = regex.exec(window.location.href);

    if (results == null) { return ""; }
    else { return results[1].replace(/\+/g, ' '); }

};