function httpGetAsync(url, data, callback) {
    const xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function () {
        if (this.readyState === 4) {
            callback(xmlHttp.responseText, xmlHttp.status);
        }
    }

    xmlHttp.open("GET", url, true);
    xmlHttp.setRequestHeader('Authorization', 'Basic ' + sessionStorage.getItem('authorization'));
    xmlHttp.send(null);
}

function saveFile(url, filename, mimetype) {
    const xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function () {
        if (this.readyState === 4) {
            if (xmlHttp.status === 200) {
                let element = document.createElement('a');
                element.setAttribute('href', 'data:' + mimetype + ',' + encodeURIComponent(xmlHttp.responseText));
                element.setAttribute('download', filename);

                element.style.display = 'none';
                document.body.appendChild(element);
                element.click();
                document.body.removeChild(element);
            } else {
                create_error_view("Error " + xmlHttp.status);
            }
        }
    }

    xmlHttp.open("GET", url, true);
    xmlHttp.setRequestHeader('Authorization', 'Basic ' + sessionStorage.getItem('authorization'));
    xmlHttp.send(null);
}

function httpPostAsync(url, data, callback) {
    const xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function () {
        if (this.readyState === 4) {
            callback(xmlHttp.responseText, xmlHttp.status);
        }
    }

    xmlHttp.open("POST", url, true);
    xmlHttp.setRequestHeader('Authorization', 'Basic ' + sessionStorage.getItem('authorization'));
    xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    xmlHttp.send('content=' + btoa(data));
}

function httpDeleteAsync(url, data, callback) {
    const xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function () {
        if (this.readyState === 4) {
            callback(xmlHttp.responseText, xmlHttp.status);
        }
    }

    xmlHttp.open("DELETE", url, true);
    xmlHttp.setRequestHeader('Authorization', 'Basic ' + sessionStorage.getItem('authorization'));
    xmlHttp.send();
}

function findGetParameter(parameterName) {
    let result = null,
        tmp = [];
    location.search
        .substr(1)
        .split("&")
        .forEach(function (item) {
            tmp = item.split("=");
            if (tmp[0] === parameterName) result = decodeURIComponent(tmp[1]);
        });
    return result;
}