function ui_offline() {
    document.body.classList.add('offline');
    document.querySelector('.offline-toast').classList.remove('hidden');
}

function ui_online() {
    document.body.classList.remove('offline');
    document.querySelector('.offline-toast').classList.add('hidden');
}

function event_size(event) {
    let size = 1 + 3; // type + padding

    switch (event.type) {
        case EVENT.PREDRAW: {
            size += 4 * 2;
            break;
        }

        case EVENT.SET_COLOR: {
            size += 4;
            break;
        }

        case EVENT.SET_WIDTH: {
            size += 2;
            break;
        }

        case EVENT.STROKE: {
            size += 4 + 2 + 2 + 4 + event.points.length * 4 * 2; // u32 stroke id + u16 (count) + u16 (width) + u32 (color + count * (f32, f32) points
            break;
        }

        case EVENT.UNDO:
        case EVENT.REDO: {
            break;
        }

        case EVENT.IMAGE:
        case EVENT.IMAGE_MOVE: {
            size += 4 + 4 + 4; // file id + x + y
            break;
        }

        case EVENT.ERASER: {
            size += 4; // stroke id
            break;
        }

        default: {
            console.error('fuck');
        }
    }

    return size;
}

function find_touch(touchlist, id) {
    for (const touch of touchlist) {
        if (touch.identifier === id) {
            return touch;
        }
    }

    return null;
}