import asyncio
import logging
import os
import subprocess as su
from typing import Iterable

from defence360agent.contracts.config import Core
from defence360agent.utils import check_run, CheckRunError, run, OsReleaseInfo

logger = logging.getLogger(__name__)

DOS_PROTECTOR_SERVICE_NAME = "imunify360-dos-protection"
UAL_SERVICE_NAME = "imunify360-unified-access-logger"
PAM_SERVICE_NAME = "imunify360-pam"
AUDITD_SERVICE_NAME = "imunify-auditd-log-reader"
SCANLOGD_SERVICE_NAME = "imunify360-scanlogd"
AGENT_SERVICE_NAME = "imunify360-agent"


def _apply_cmd(func):
    async def wrapper(*args, **kwargs):
        cmd = func(*args, **kwargs)
        logger.debug("check_call(%r)", cmd)
        await check_run(cmd)

    return wrapper


async def _reset_failed_state(
    services: Iterable["_SystemctlBased"],
):
    for s in services:
        try:
            await s.reset_failed()
            await s.restart()
        except CheckRunError as e:
            logger.warning(
                "Failed to reset failed state for service %s: %s", s, e
            )
            return
        for _ in range(10):
            if await s.is_active():
                break
            logger.warning(
                "Service %s is still not active, sleep for %s seconds", s, 1
            )
            await asyncio.sleep(1)


class _SystemctlBased:
    SVC_CTL_BIN = "systemctl"

    def __init__(self, service_name):
        self._service_name = service_name

    @_apply_cmd
    def start(self):
        return [self.SVC_CTL_BIN, "start", self._service_name]

    @_apply_cmd
    def stop(self):
        return [self.SVC_CTL_BIN, "stop", self._service_name]

    @_apply_cmd
    def restart(self):
        return [self.SVC_CTL_BIN, "restart", self._service_name]

    @_apply_cmd
    def _enable_now(self, *, now: bool):
        return [
            self.SVC_CTL_BIN,
            "enable",
            *(["--now"] if now else []),
            self._service_name,
        ]

    async def enable(self, *, now: bool):
        await self._enable_now(now=now)

        # WARN: Ubuntu 16.04 demonstrates very special behavior of the
        # `systemcl enable --now` command - if the unit is stopped it
        # wouldn't be started. We need to handle that case.
        # TODO: Remove this case on dropping support for Ubuntu 16.04.
        osinfo = {}
        try:
            OsReleaseInfo.dict_from_file(osinfo)
        except (FileNotFoundError, PermissionError):
            return
        if osinfo.get("ID", "").lower() != "ubuntu":
            return
        if osinfo.get("VERSION_ID", "") == "16.04":
            await self.restart()

    async def is_enabled(self):
        cmd = [self.SVC_CTL_BIN, "is-enabled", self._service_name]
        proc = await asyncio.create_subprocess_exec(
            *cmd, stdout=su.DEVNULL, stderr=su.DEVNULL
        )
        await proc.communicate()
        rc = await proc.wait()
        return rc == 0

    def is_enabled_sync(self):
        cmd = [self.SVC_CTL_BIN, "is-enabled", self._service_name]
        rc = su.call(cmd, stdout=su.DEVNULL, stderr=su.DEVNULL)
        return rc == 0

    @_apply_cmd
    def disable(self, *, now: bool):
        return [
            self.SVC_CTL_BIN,
            "disable",
            *(["--now"] if now else []),
            self._service_name,
        ]

    @_apply_cmd
    def reload(self):
        return [self.SVC_CTL_BIN, "reload", self._service_name]

    async def is_active(self):
        cmd = [self.SVC_CTL_BIN, "is-active", self._service_name]
        exit_code, _, _ = await run(cmd)
        return exit_code == 0

    @_apply_cmd
    def reset_failed(self):
        return [self.SVC_CTL_BIN, "reset-failed", self._service_name]

    def unit_exists(self):
        cp = su.run(
            [self.SVC_CTL_BIN, "cat", self._service_name],
            stdout=su.DEVNULL,
            stderr=su.DEVNULL,
        )
        return cp.returncode == 0


class _CentOs7(_SystemctlBased):
    SVC_CTL_BIN = "/usr/bin/systemctl"


class _DebianUbuntu(_SystemctlBased):
    SVC_CTL_BIN = "/bin/systemctl"


def adaptor(service_name):
    for a in (_DebianUbuntu, _CentOs7):
        if os.path.exists(a.SVC_CTL_BIN):
            return a(service_name)
    raise RuntimeError("Cannot instantiate appropriate adaptor.")


async def activate_socket_service(service_name):
    agent_service = adaptor(service_name)
    agent_service_socket = adaptor(f"{service_name}.socket")

    if (
        await agent_service_socket.is_enabled()
        and not await agent_service_socket.is_active()
    ):
        # reset the main service, which will trigger socket activation
        await agent_service_socket.reset_failed()
        await _reset_failed_state((agent_service,))

        # wait some times until socket activates
        for _ in range(5):
            await asyncio.sleep(1)
            if await agent_service_socket.is_active():
                return

        logger.error(
            f"Failed to await active {service_name}.socket after reseting"
            f" {service_name}"
        )


def imunify360_service():
    return adaptor(Core.SVC_NAME)


def imunify360_dos_protector_service():
    try:
        return adaptor(DOS_PROTECTOR_SERVICE_NAME)
    except RuntimeError:
        logger.info("DOS Protector service is not available on this system")
        return None


def imunify360_ual_service():
    return adaptor(UAL_SERVICE_NAME)


def imunify360_pam_service():
    return adaptor(PAM_SERVICE_NAME)


def imunify360_scanlogd_service():
    return adaptor(SCANLOGD_SERVICE_NAME)


def imunify360_agent_service():
    return adaptor(AGENT_SERVICE_NAME)


def imunify360_auditd_service():
    unit = adaptor(AUDITD_SERVICE_NAME)
    if unit.unit_exists():
        return adaptor(AUDITD_SERVICE_NAME)
    logger.info("Auditd-log-reader service is not available on this system")
    return None
