export function mk(tag_selector, ...children) {
    let [tag, ...classes] = tag_selector.split('.');
    let el = document.createElement(tag);
    el.classList = classes.join(' ');
    if (children.length > 0) {
        if (!(children[0] instanceof Node) && children[0] !== undefined && typeof(children[0]) !== "string" && typeof(children[0]) !== "number") {
            let [attrs] = children.splice(0, 1);
            for (let [key, value] of Object.entries(attrs)) {
                el.setAttribute(key, value);
            }
        }
        el.append(...children);
    }
    return el;
}

export function promise_event(element, success_event, failure_event) {
    let resolve, reject;
    let promise = new Promise((res, rej) => {
        resolve = res;
        reject = rej;
    });

    let success_handler = e => {
        element.removeEventListener(success_event, success_handler);
        if (failure_event) {
            element.removeEventListener(failure_event, failure_handler);
        }

        resolve(e);
    };
    let failure_handler = e => {
        element.removeEventListener(success_event, success_handler);
        if (failure_event) {
            element.removeEventListener(failure_event, failure_handler);
        }

        reject(e);
    };

    element.addEventListener(success_event, success_handler);
    if (failure_event) {
        element.addEventListener(failure_event, failure_handler);
    }

    return promise;
}

export async function fetch(url) {
    let xhr = new XMLHttpRequest;
    let promise = promise_event(xhr, 'load', 'error');
    xhr.open('GET', url);
    xhr.responseType = 'arraybuffer';
    xhr.send();
    await promise;
    return xhr.response;
}