const St = imports.gi.St;
const Main = imports.ui.main;
const Shell = imports.gi.Shell;

const Clipboard = St.Clipboard.get_default();
const CLIPBOARD_TYPE = St.ClipboardType.CLIPBOARD;

const namespace = 'cuid';
const blockSize = 4;
const base = 36;
const discreteValues = Math.pow(base, blockSize);
let c = 0;
let button;

function init() {
    button = new St.Bin({
        style_class: 'panel-button',
        reactive: true,
        can_focus: true,
        x_fill: true,
        y_fill: false,
        track_hover: true
    });
    let icon = new St.Icon({ icon_name: 'preferences-system-privacy-symbolic',
                             style_class: 'system-status-icon' });

    button.set_child(icon);
    button.connect('button-press-event', function() {
        Clipboard.set_text(CLIPBOARD_TYPE, cuid());
    });
}

function enable() {
    Main.panel._rightBox.insert_child_at_index(button, 0);
}

function disable() {
    Main.panel._rightBox.remove_child(button);
}

function pad(num, size) {
    const s = "000000000" + num;
    return s.substr(s.length-size);
}

function randomBlock() {
    return pad((Math.random() * discreteValues << 0).toString(base), blockSize);
}

function safeCounter() {
    c = (c < discreteValues) ? c : 0;
    c++;
    return c - 1;
}

function cuid() {
    const letter = 'c';
    const timestamp = (new Date().getTime()).toString(base);
    const fingerprint = nodePrint();
    const random = randomBlock() + randomBlock();
    const counter = pad(safeCounter().toString(base), blockSize);

    return  (letter + timestamp + counter + fingerprint + random);
}

function nodePrint() {
    const padding = 2;
    const hostname = 'x1';
    const length = hostname.length;
    const pid = pad((21396).toString(36), 2);
    const hostId = pad(
        hostname
            .split('')
            .reduce(function (prev, char) {
                return +prev + char.charCodeAt(0);
            }, +length + 36)
            .toString(36),
        2
    );
    return pid + hostId;
}