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   = 'nebula.jallen-n';

const POLL_INTERVAL_SECS = 5;
const LOG_PREFIX = '[nebula-vpn]';

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

function log(msg) {
    console.log(`${LOG_PREFIX} ${msg}`);
}

function logErr(msg, err) {
    console.error(`${LOG_PREFIX} ${msg}`, err ?? '');
}

/**
 * Run a command and return { success, stdout, stderr }.
 * The command is passed as an argv array (no shell expansion).
 */
function runCommand(argv) {
    log(`runCommand: ${argv.join(' ')}`);
    try {
        const [ok, stdout, stderr, exitCode] = GLib.spawn_sync(
            null,
            argv,
            null,
            GLib.SpawnFlags.SEARCH_PATH,
            null,
        );
        const result = {
            success: ok && exitCode === 0,
            stdout: ok ? new TextDecoder().decode(stdout).trim() : '',
            stderr: ok ? new TextDecoder().decode(stderr).trim() : '',
        };
        log(`runCommand result: success=${result.success} exitCode=${exitCode} stdout="${result.stdout}" stderr="${result.stderr}"`);
        return result;
    } catch (e) {
        logErr(`runCommand exception for [${argv.join(' ')}]:`, 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]);
    log(`isServiceActive: ${r.success}`);
    return r.success;
}

/**
 * Get interface addresses 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 === '') {
        log(`getIfaceInfo: interface not found or no output`);
        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;
    log(`getIfaceInfo: found=true state=${parts[1]} ipv4=${ipv4} ipv6=${ipv6}`);
    return {found: true, ipv4, ipv6};
}

/**
 * Read a single integer from a sysfs file, returning null on failure.
 */
function readSysfs(path) {
    try {
        const f = Gio.File.new_for_path(path);
        const [ok, contents] = f.load_contents(null);
        if (!ok) return null;
        const val = parseInt(new TextDecoder().decode(contents).trim(), 10);
        return isNaN(val) ? null : val;
    } catch (_e) {
        return null;
    }
}

/**
 * Get TX/RX byte counters for IFACE_NAME from sysfs.
 * Returns { rx, tx } in bytes, or null values if unavailable.
 */
function getIfaceStats() {
    const base = `/sys/class/net/${IFACE_NAME}/statistics`;
    const rx   = readSysfs(`${base}/rx_bytes`);
    const tx   = readSysfs(`${base}/tx_bytes`);
    log(`getIfaceStats: rx=${rx} tx=${tx}`);
    return {rx, tx};
}

/** Format bytes into a human-readable string. */
function formatBytes(bytes) {
    if (bytes === null) return '—';
    if (bytes < 1024) return `${bytes} B`;
    if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
    if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
    return `${(bytes / (1024 * 1024 * 1024)).toFixed(2)} GB`;
}

/**
 * Get the service ActiveEnterTimestamp from systemctl show.
 * Returns a human-readable uptime string, or null.
 */
function getServiceUptime() {
    const r = runCommand([
        'systemctl', 'show', SERVICE_NAME,
        '--property=ActiveEnterTimestampMonotonic',
    ]);
    if (!r.success) return null;

    // Output: ActiveEnterTimestampMonotonic=1234567890
    const match = r.stdout.match(/=(\d+)/);
    if (!match) return null;

    const startMonoUs = parseInt(match[1], 10);
    const nowMonoUs   = GLib.get_monotonic_time();
    const elapsedSecs = Math.floor((nowMonoUs - startMonoUs) / 1_000_000);

    if (elapsedSecs < 0) return null;

    const h = Math.floor(elapsedSecs / 3600);
    const m = Math.floor((elapsedSecs % 3600) / 60);
    const s = elapsedSecs % 60;

    if (h > 0) return `${h}h ${m}m`;
    if (m > 0) return `${m}m ${s}s`;
    return `${s}s`;
}

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

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

const NebulaIndicator = GObject.registerClass(
class NebulaIndicator extends PanelMenu.Button {
    _init(extensionPath) {
        log('NebulaIndicator._init: start');
        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);

        // ── top-level status ──
        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());

        // ── "Network" expandable submenu ──
        this._networkSubmenu = new PopupMenu.PopupSubMenuMenuItem('Network');

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

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

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

        this.menu.addMenuItem(this._networkSubmenu);

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

        // ── actions ──
        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;
        log('NebulaIndicator._init: running initial refresh');
        this._refresh();
        this._timerId = GLib.timeout_add_seconds(
            GLib.PRIORITY_DEFAULT,
            POLL_INTERVAL_SECS,
            () => { this._refresh(); return GLib.SOURCE_CONTINUE; },
        );
        log(`NebulaIndicator._init: poll timer registered (id=${this._timerId})`);
    }

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

    _refresh() {
        log('_refresh: checking service and interface');
        this._active = isServiceActive();
        const iface  = getIfaceInfo();
        const stats  = getIfaceStats();
        const uptime = this._active ? getServiceUptime() : null;
        log(`_refresh: active=${this._active} iface=${JSON.stringify(iface)} stats=${JSON.stringify(stats)} uptime=${uptime}`);
        this._updateUI(iface, stats, uptime);
    }

    _updateUI(iface, stats, uptime) {
        log(`_updateUI: active=${this._active}`);
        if (this._active) {
            this._icon.icon_name = 'network-vpn-symbolic';
            this._label.style    = 'margin-left: 4px; margin-right: 2px; color: #57e389;';
            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';
            this._networkSubmenu.visible = true;
            this._uptimeItem.label.text = `Uptime: ${uptime ?? '—'}`;
            this._rxItem.label.text     = `RX: ${formatBytes(stats.rx)}`;
            this._txItem.label.text     = `TX: ${formatBytes(stats.tx)}`;
        } else {
            this._icon.icon_name = 'network-vpn-disabled-symbolic';
            this._label.style    = 'margin-left: 4px; margin-right: 2px; color: #c01c28;';
            this._statusItem.label.text = 'Status: Disconnected';
            this._ipv4Item.visible      = false;
            this._ipv6Item.visible      = false;
            this._toggleItem.label.text = 'Connect';
            this._networkSubmenu.visible = false;
        }
        // label is always "VPN"
        this._label.text = 'VPN';
    }

    _onToggle() {
        const target = !this._active;
        log(`_onToggle: toggling to ${target ? 'active' : 'inactive'}`);
        setServiceActive(target);
        // Optimistic update while systemd races
        this._active = target;
        this._updateUI(getIfaceInfo(), getIfaceStats(), null);
        // Re-poll shortly after to confirm real state
        GLib.timeout_add_seconds(GLib.PRIORITY_DEFAULT, 2, () => {
            log('_onToggle: confirmation poll');
            this._refresh();
            return GLib.SOURCE_REMOVE;
        });
    }

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

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

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

export default class NebulaVpnExtension extends Extension {
    enable() {
        log('enable: creating indicator');
        this._indicator = new NebulaIndicator(this.path);
        Main.panel.addToStatusArea(this.uuid, this._indicator);
        log('enable: indicator added to panel');
    }

    disable() {
        log('disable: destroying indicator');
        this._indicator?.destroy();
        this._indicator = null;
    }
}