import GLib from 'gi://GLib';
import Gio from 'gi://Gio';
import GObject from 'gi://GObject';
import St from 'gi://St';
import Clutter from 'gi://Clutter';

import {Extension} from 'resource:///org/gnome/shell/extensions/extension.js';
import * as Main from 'resource:///org/gnome/shell/ui/main.js';
import * as PanelMenu from 'resource:///org/gnome/shell/ui/panelMenu.js';
import * as PopupMenu from 'resource:///org/gnome/shell/ui/popupMenu.js';

// ── constants ────────────────────────────────────────────────────────────────

const SERVICE_NAME = 'nebula@jallen-nebula.service';
const IFACE_NAME   = 'jallen-nebula';

const POLL_INTERVAL_SECS = 5;

// ── helpers ──────────────────────────────────────────────────────────────────

/**
 * Run a command and return { success, stdout, stderr }.
 * The command is passed as an argv array (no shell expansion).
 */
function runCommand(argv) {
    try {
        const [ok, stdout, stderr, exitCode] = GLib.spawn_sync(
            null,           // working dir
            argv,
            null,           // inherit env
            GLib.SpawnFlags.SEARCH_PATH,
            null,
        );
        return {
            success: ok && exitCode === 0,
            stdout: ok ? new TextDecoder().decode(stdout).trim() : '',
            stderr: ok ? new TextDecoder().decode(stderr).trim() : '',
        };
    } catch (_e) {
        return {success: false, stdout: '', stderr: ''};
    }
}

/** Return true if the systemd service is currently active. */
function isServiceActive() {
    const r = runCommand([
        'systemctl', 'is-active', '--quiet', SERVICE_NAME,
    ]);
    return r.success;
}

/**
 * Get interface info for IFACE_NAME.
 * Returns { found, ipv4, ipv6 } where ipv4/ipv6 are strings or null.
 */
function getIfaceInfo() {
    // `ip -brief addr show <iface>` output:
    //   jallen-nebula    UP   10.1.1.3/24  fe80::…/64
    const r = runCommand(['ip', '-brief', 'addr', 'show', IFACE_NAME]);
    if (!r.success || r.stdout === '') {
        return {found: false, ipv4: null, ipv6: null};
    }

    const parts  = r.stdout.split(/\s+/);
    // parts[0] = iface, parts[1] = state, parts[2..] = addresses
    const addrs  = parts.slice(2);
    const ipv4   = addrs.find(a => /^\d+\.\d+\.\d+\.\d+\//.test(a)) ?? null;
    const ipv6   = addrs.find(a => a.includes(':') && !a.startsWith('fe80')) ?? null;
    return {found: true, ipv4, ipv6};
}

/** Start or stop the systemd service (requires polkit / passwordless sudo). */
function setServiceActive(enable) {
    const action = enable ? 'start' : 'stop';
    runCommand(['systemctl', action, SERVICE_NAME]);
}

// ── indicator ────────────────────────────────────────────────────────────────

const NebulaIndicator = GObject.registerClass(
class NebulaIndicator extends PanelMenu.Button {
    _init(extensionPath) {
        super._init(0.0, 'Nebula VPN Status');

        this._extensionPath = extensionPath;

        // ── panel icon + label ──
        const hbox = new St.BoxLayout({style_class: 'panel-status-menu-box'});

        this._icon = new St.Icon({
            style_class: 'system-status-icon',
            icon_size: 16,
        });

        this._label = new St.Label({
            text: '…',
            y_align: Clutter.ActorAlign.CENTER,
            style: 'margin-left: 4px; margin-right: 2px;',
        });

        hbox.add_child(this._icon);
        hbox.add_child(this._label);
        this.add_child(hbox);

        // ── dropdown menu ──
        this._statusItem = new PopupMenu.PopupMenuItem('', {reactive: false});
        this._statusItem.label.set_style('font-weight: bold;');
        this.menu.addMenuItem(this._statusItem);

        this._ipv4Item = new PopupMenu.PopupMenuItem('', {reactive: false});
        this.menu.addMenuItem(this._ipv4Item);

        this._ipv6Item = new PopupMenu.PopupMenuItem('', {reactive: false});
        this.menu.addMenuItem(this._ipv6Item);

        this.menu.addMenuItem(new PopupMenu.PopupSeparatorMenuItem());

        this._toggleItem = new PopupMenu.PopupMenuItem('');
        this._toggleItem.connect('activate', () => this._onToggle());
        this.menu.addMenuItem(this._toggleItem);

        this.menu.addMenuItem(new PopupMenu.PopupSeparatorMenuItem());

        const refreshItem = new PopupMenu.PopupMenuItem('Refresh');
        refreshItem.connect('activate', () => this._refresh());
        this.menu.addMenuItem(refreshItem);

        // ── initial state + polling ──
        this._active = false;
        this._refresh();
        this._timerId = GLib.timeout_add_seconds(
            GLib.PRIORITY_DEFAULT,
            POLL_INTERVAL_SECS,
            () => { this._refresh(); return GLib.SOURCE_CONTINUE; },
        );
    }

    // ── private ──────────────────────────────────────────────────────────────

    _refresh() {
        this._active = isServiceActive();
        const iface  = getIfaceInfo();
        this._updateUI(iface);
    }

    _updateUI(iface) {
        if (this._active) {
            this._icon.icon_name = 'network-vpn-symbolic';
            this._label.text     = 'VPN';
            this._label.style    = 'margin-left: 4px; margin-right: 2px; color: #57e389;'; // green
            this._statusItem.label.text = `Status: Connected`;
            this._ipv4Item.label.text   = iface.ipv4 ? `IPv4: ${iface.ipv4}` : 'IPv4: —';
            this._ipv6Item.label.text   = iface.ipv6 ? `IPv6: ${iface.ipv6}` : 'IPv6: —';
            this._ipv4Item.visible      = true;
            this._ipv6Item.visible      = true;
            this._toggleItem.label.text = 'Disconnect';
        } else {
            this._icon.icon_name = 'network-vpn-disabled-symbolic';
            this._label.text     = 'VPN';
            this._label.style    = 'margin-left: 4px; margin-right: 2px; color: #c01c28;'; // red
            this._statusItem.label.text = `Status: Disconnected`;
            this._ipv4Item.visible      = false;
            this._ipv6Item.visible      = false;
            this._toggleItem.label.text = 'Connect';
        }
    }

    _onToggle() {
        setServiceActive(!this._active);
        // Optimistic update while systemd races
        this._active = !this._active;
        this._updateUI(getIfaceInfo());
        // Re-poll shortly after to confirm real state
        GLib.timeout_add_seconds(GLib.PRIORITY_DEFAULT, 2, () => {
            this._refresh();
            return GLib.SOURCE_REMOVE;
        });
    }

    // ── cleanup ───────────────────────────────────────────────────────────────

    destroy() {
        if (this._timerId) {
            GLib.source_remove(this._timerId);
            this._timerId = null;
        }
        super.destroy();
    }
});

// ── extension lifecycle ───────────────────────────────────────────────────────

export default class NebulaVpnExtension extends Extension {
    enable() {
        this._indicator = new NebulaIndicator(this.path);
        Main.panel.addToStatusArea(this.uuid, this._indicator);
    }

    disable() {
        this._indicator?.destroy();
        this._indicator = null;
    }
}