onmessage = function (event) {
    handleMessage(event.data);
}

// message = {type: '', task_id: '', [key: string]: any}
function handleMessage(message) {
    // console.log("new task from master " + JSON.stringify(message));
    let type = message['type'];

    if(type === 'fetch'){
        fetchUrl(message.url).then(function (res) {
            postMessage({
                type: 'fetch',
                task_id: message.task_id,
                info: JSON.parse(res),
            })
        });

        return;
    }
}

function processDelay(timeout) {
    setTimeout(function () {
        postMessage({
            type: 'delay',
            info: 'Its done! ' + timeout,
        })
    }, timeout)
}


function fetchUrl(request_url) {
    return new Promise(function (resolve, reject) {
        let xhr = new XMLHttpRequest();
        xhr.open('GET', request_url, true);
        xhr.onload = function () {
            if (xhr.status >= 200 && xhr.status < 300) {
                resolve(xhr.response);
            } else {
                reject('error');
            }
        };
        xhr.onerror = function () {
            reject('error');
        };
        xhr.send();
    });
}