# -*- coding: utf-8 -*-
# SPDX-FileCopyrightText: 2025 KUNBUS GmbH
# SPDX-License-Identifier: GPL-2.0-or-later
from enum import Enum
from logging import getLogger
from threading import Thread
from typing import Optional

from pydbus import SystemBus

log = getLogger(__name__)


class ServiceActions(Enum):
    """
    Enumeration class for defining configuration actions.

    This enumeration provides predefined constants for common configuration
    actions. It can be used to ensure consistency when working with or defining
    such actions in a system.
    """

    ENABLE = "enable"
    DISABLE = "disable"
    STATUS = "status"
    AVAILABLE = "available"


def simple_systemd(action: ServiceActions, unit: str, unmask: bool = False) -> Optional[bool]:
    """
    Perform systemd service actions such as enable, disable, check status, or availability.

    This function interacts with the systemd D-Bus API to manage and query the
    state of services on a system. The supported actions include enabling a systemd
    unit, disabling it, starting/stopping a unit, and checking its status or
    availability. The function supports asynchronous configuration changes through
    threads where applicable.

    Parameters:
        action (ServiceActions): The action to perform on the systemd service.
            Supported actions are ENABLE, DISABLE, STATUS, and AVAILABLE.
        unit (str): The name of the systemd unit to operate on (e.g., "example.service").
        unmask (bool): When enabling a unit, if True, any masked unit file will
            first be unmasked before proceeding with the operation. Defaults to False.

    Returns:
        Optional[bool]: The return value depends on the action. For STATUS or
            AVAILABLE actions, it returns True if the unit satisfies the condition
            (e.g., enabled and active, or available and loaded), False otherwise.
            For other actions, it returns None.
    """
    bus = SystemBus()
    systemd = bus.get(
        "org.freedesktop.systemd1",
        "/org/freedesktop/systemd1",
    )
    systemd_manager = systemd["org.freedesktop.systemd1.Manager"]

    if action is ServiceActions.ENABLE:

        def thread_unit_config():
            """Change configuration asynchronously."""
            lst_change_unmask = []
            if unmask:
                # Dbus call: UnmaskUnitFiles(in as files, in b runtime, out a(sss) changes
                lst_change_unmask = systemd_manager.UnmaskUnitFiles([unit], False)

            # Dbus call: EnableUnitFiles(in as files, in b runtime, in b force,
            #                            out b carries_install_info, out a(sss) changes
            lst_change_enable = systemd_manager.EnableUnitFiles([unit], False, False)
            if lst_change_unmask or lst_change_enable:
                # Reload systemd after modified unit property
                systemd_manager.Reload()

        Thread(target=thread_unit_config, daemon=True).start()

        # Dbus call: StartUnit(in s name, in s mode, out o job
        systemd_manager.StartUnit(unit, "replace")

    elif action is ServiceActions.DISABLE:

        def thread_unit_config():
            """Change configuration asynchronously."""
            # Dbus call: DisableUnitFiles (in as files, in b runtime, out a(sss) changes)
            change = systemd_manager.DisableUnitFiles([unit], False)
            if change:
                # Reload systemd after modified unit property
                systemd_manager.Reload()

        Thread(target=thread_unit_config, daemon=True).start()

        # Dbus call: StopUnit(in s name,in s mode, out o job
        systemd_manager.StopUnit(unit, "replace")

    elif action is ServiceActions.STATUS:
        try:
            unit_path = systemd_manager.LoadUnit(unit)
            properties = bus.get("org.freedesktop.systemd1", unit_path)
        except Exception:
            log.warning(f"could not get systemd unit {unit}")
            return False

        return properties.UnitFileState == "enabled" and properties.ActiveState in (
            "active",
            "activating",
        )

    elif action is ServiceActions.AVAILABLE:
        try:
            unit_path = systemd_manager.LoadUnit(unit)
            properties = bus.get("org.freedesktop.systemd1", unit_path)
        except Exception:
            log.warning(f"could not get systemd unit {unit}")
            return False

        return properties.LoadState != "not-found"

    else:
        raise ValueError(f"action {action} not supported")

    return None