export const wait = (ms) => {
    return new Promise((res, rej) => {
        setTimeout(res, ms);
    });
}

export const fadeout = async (elems, ms = 200, force = false) => {
    if (!Array.isArray(elems)) elems = [elems];
    for (let i = 0; i < elems.length; i++) {
        elems[i].style.transition = `opacity ${ms}ms`;
        if(force){
            elems[i].style.opacity = "1";
            elems[i].style.display = "";
        }
    }
    await wait(10);
    for (let i = 0; i < elems.length; i++) {
        elems[i].style.opacity = "0";
    }
    await wait(ms);
    for (let i = 0; i < elems.length; i++) {
        elems[i].style.display = "none";
    }
}
export const fadein = async (elems, ms = 200, force = false) => {
    if (!Array.isArray(elems)) elems = [elems];
    for (let i = 0; i < elems.length; i++) {
        elems[i].style.transition = `opacity ${ms}ms`;
        elems[i].style.display = "";
        if (force) {
            elems[i].style.opacity = "0";
        }
    }
    await wait(10);
    for (let i = 0; i < elems.length; i++) {
        elems[i].style.opacity = "1";
    }
    await wait(ms);
}

var bStack = [];
export const subCancel = (callback) => {
    bStack.push(callback);
    return ()=>{
        var id;
        if ((id = bStack.indexOf(callback)) >= 0) {
            bStack.splice(id, 1);
        }
    }
}

function back() {
    if (bStack.length) {
        bStack.pop()();
    }
}

document.addEventListener("backbutton", back, false);
document.addEventListener('keyup', (e)=>{
    if (e.code == "Escape")back();
});