from datetime import datetime, timezone
from typing import List
import dbus

from app.models import ServiceState


class SystemdManager:
    def __init__(self) -> None:
        self.bus = dbus.SystemBus()
        systemd = self.bus.get_object('org.freedesktop.systemd1', '/org/freedesktop/systemd1')
        self.manager = dbus.Interface(systemd, 'org.freedesktop.systemd1.Manager')

    def list_services(self, names: list[str]) -> List[ServiceState]:
        items: list[ServiceState] = []
        for name in names:
            try:
                unit_path = self.manager.GetUnit(name)
                unit = self.bus.get_object('org.freedesktop.systemd1', unit_path)
                props = dbus.Interface(unit, 'org.freedesktop.DBus.Properties')
                active_state = str(props.Get('org.freedesktop.systemd1.Unit', 'ActiveState'))
                sub_state = str(props.Get('org.freedesktop.systemd1.Unit', 'SubState'))
                loaded = str(props.Get('org.freedesktop.systemd1.Unit', 'LoadState'))
                description = str(props.Get('org.freedesktop.systemd1.Unit', 'Description'))
                try:
                    pid = int(props.Get('org.freedesktop.systemd1.Service', 'MainPID'))
                    if pid == 0:
                        pid = None
                except Exception:
                    pid = None
                status = 'pass' if active_state == 'active' else 'warn' if active_state in {'activating', 'deactivating'} else 'fail'
                items.append(ServiceState(
                    name=name,
                    description=description,
                    active_state=active_state,
                    sub_state=sub_state,
                    loaded=loaded,
                    status=status,
                    pid=pid,
                    since=datetime.now(timezone.utc),
                ))
            except Exception as exc:
                items.append(ServiceState(
                    name=name,
                    active_state='failed',
                    sub_state='not-found',
                    loaded='not-found',
                    status='fail',
                    notes=str(exc),
                ))
        return items

    def _act(self, name: str, method: str) -> None:
        fn = getattr(self.manager, method)
        fn(name, 'replace')

    def start(self, name: str) -> None:
        self._act(name, 'StartUnit')

    def stop(self, name: str) -> None:
        self._act(name, 'StopUnit')

    def restart(self, name: str) -> None:
        self._act(name, 'RestartUnit')