"""PiCopy – WireGuard VPN: wg_state, wg_lock, alle wg_* Funktionen, wg_monitor."""

import os
import re
import shutil
import subprocess
import threading
import time
from pathlib import Path

from picopy.config import log

WG_CONF  = Path('/etc/wireguard/picopy.conf')
WG_IFACE = 'picopy'


def wg_is_installed():
    return shutil.which('wg-quick') is not None


wg_state = {
    'connected':   False,
    'ip':          '',
    'peer':        '',
    'error':       None,
    'has_config':  False,
    'installed':   False,
    'pkg_running': False,
    'pkg_action':  '',
    'pkg_error':   None,
}
wg_lock = threading.Lock()


def wg_update_state():
    inst     = wg_is_installed()
    has_conf = WG_CONF.exists()
    if not inst:
        with wg_lock:
            wg_state.update(installed=False, connected=False, ip='', peer='',
                            has_config=has_conf)
        return
    r = subprocess.run(['wg', 'show', WG_IFACE],
                       capture_output=True, text=True, timeout=5)
    if r.returncode != 0:
        with wg_lock:
            wg_state.update(installed=True, connected=False, ip='', peer='',
                            has_config=has_conf)
        return
    ip_r = subprocess.run(['ip', '-4', 'addr', 'show', WG_IFACE],
                          capture_output=True, text=True, timeout=5)
    ip = ''
    for line in ip_r.stdout.splitlines():
        if line.strip().startswith('inet '):
            ip = line.strip().split()[1].split('/')[0]
            break
    peer = ''
    for line in r.stdout.splitlines():
        if line.startswith('peer:'):
            peer = line.split(':', 1)[-1].strip()
            break
    with wg_lock:
        wg_state.update(installed=True, connected=True, ip=ip, peer=peer,
                        error=None, has_config=has_conf)


def wg_connect():
    if not WG_CONF.exists():
        with wg_lock:
            wg_state['error'] = 'Keine Konfiguration vorhanden'
        return False
    r = subprocess.run(['wg-quick', 'up', WG_IFACE],
                       capture_output=True, text=True, timeout=30)
    if r.returncode == 0:
        time.sleep(1)
        wg_update_state()
        log.info('WireGuard verbunden')
        return True
    lines = r.stderr.strip().splitlines() if r.stderr.strip() else []
    real_errors = [l for l in lines if not l.strip().startswith('[#]')]
    err = (real_errors[-1] if real_errors else lines[-1] if lines else 'Unbekannter Fehler')
    if 'resolvconf' in err and 'not found' in err:
        err = 'resolvconf fehlt - bitte WireGuard deinstallieren und neu installieren (openresolv wird dann mitinstalliert)'
    with wg_lock:
        wg_state.update(connected=False, error=err)
    log.error(f'WireGuard Fehler: {err}')
    return False


def wg_disconnect():
    r = subprocess.run(['wg-quick', 'down', WG_IFACE],
                       capture_output=True, text=True, timeout=15)
    with wg_lock:
        wg_state.update(connected=False, ip='', peer='', error=None)
    log.info('WireGuard getrennt')
    return r.returncode == 0


def _wg_apt(action: str, packages: list):
    """Führt apt-get install/remove aus und aktualisiert pkg_state."""
    with wg_lock:
        if wg_state['pkg_running']:
            return
        wg_state.update(pkg_running=True, pkg_action=action, pkg_error=None)
    try:
        cmd = ['apt-get', action, '-y'] + packages
        r = subprocess.run(cmd, capture_output=True, text=True, timeout=300,
                           env={**os.environ, 'DEBIAN_FRONTEND': 'noninteractive'})
        if r.returncode != 0:
            err = (r.stderr.strip().splitlines()[-1]
                   if r.stderr.strip() else f'apt-get {action} fehlgeschlagen')
            log.error(f'WireGuard apt {action}: {err}')
            with wg_lock:
                wg_state['pkg_error'] = err
        else:
            log.info(f'WireGuard apt {action} abgeschlossen')
    except Exception as e:
        with wg_lock:
            wg_state['pkg_error'] = str(e)
    finally:
        with wg_lock:
            wg_state['pkg_running'] = False
            wg_state['pkg_action']  = ''
        wg_update_state()


def wg_install():
    _wg_apt('install', ['wireguard', 'wireguard-tools', 'openresolv'])


def wg_uninstall():
    wg_disconnect()
    _wg_apt('remove', ['wireguard', 'wireguard-tools'])


def wg_save_config(content: str):
    try:
        WG_CONF.parent.mkdir(parents=True, exist_ok=True)
        WG_CONF.write_text(content, encoding='utf-8')
        WG_CONF.chmod(0o600)
        return True, ''
    except Exception as e:
        return False, str(e)


def wg_monitor():
    while True:
        try:
            wg_update_state()
        except Exception:
            pass
        time.sleep(10)