"""
This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License,
or (at your option) any later version.


This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
See the GNU General Public License for more details.


You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.

Copyright © 2019 Cloud Linux Software Inc.

This software is also available under ImunifyAV commercial license,
see <https://www.imunify360.com/legal/eula>
"""
from contextlib import suppress
from logging import getLogger
from pathlib import Path

from defence360agent import utils
from defence360agent.contracts.config import ANTIVIRUS_MODE
from defence360agent.contracts.config import MalwareScanSchedule as Config
from defence360agent.contracts.config import (
    MalwareScanScheduleInterval as Interval,
)
from defence360agent.contracts.config import SystemConfig
from defence360agent.contracts.license import LicenseCLN
from defence360agent.contracts.messages import MessageType
from defence360agent.contracts.plugins import (
    MessageSink,
    MessageSource,
    expect,
)
from imav.malwarelib.utils import reset_malware_schedule

logger = getLogger(__name__)

AVAILABLE_INTERVALS = [
    Interval.NONE,
    Interval.DAY,
    Interval.WEEK,
    Interval.MONTH,
]

AVP_INTERVALS = [
    Interval.NONE,
    Interval.MONTH,
]


def allowed_schedule_interval():
    valid_avp = LicenseCLN.is_valid_av_plus()
    condition = (not ANTIVIRUS_MODE) or valid_avp
    return AVAILABLE_INTERVALS if condition else AVP_INTERVALS


class ScheduleWatcher(MessageSink, MessageSource):
    def __init__(self):
        self._cron = self._read_cron()
        self._update_cron()
        self._sink = None

    async def create_sink(self, loop):
        pass

    async def create_source(self, loop, sink):
        self._sink = sink

    @staticmethod
    def _read_cron():
        with suppress(FileNotFoundError):
            return Path(Config.CRON_PATH).read_text()

    @staticmethod
    def _write_cron(job):
        path = Path(Config.CRON_PATH)

        with suppress(FileNotFoundError):
            path.unlink()

        if job:
            path.touch(mode=0o600)
            path.write_text(job)

    def _get_job(self):
        if Config.INTERVAL == Interval.NONE:
            return None
        elif Config.INTERVAL not in AVAILABLE_INTERVALS:
            logger.error("Unsupported interval value: %s", Config.INTERVAL)
            return self._cron
        elif Config.INTERVAL not in allowed_schedule_interval():
            logger.info("Malware schedule interval is being reset to defaults")
            reset_malware_schedule()

        schedule_schema = {
            Interval.DAY: (Config.HOUR, "*", "*"),
            Interval.WEEK: (Config.HOUR, "*", Config.DAY_OF_WEEK),
            Interval.MONTH: (Config.HOUR, Config.DAY_OF_MONTH, "*"),
        }

        schedule = schedule_schema[Config.INTERVAL]
        job = Config.CRON_STRING.format(*schedule, cmd=Config.CMD)
        return job

    def _update_cron(self):
        job = self._get_job()

        if self._cron != job:
            logger.info("Update background scan schedule")
            self._write_cron(job)
            self._cron = job

            return True

        return False

    async def _stop_background_scan(self):
        await self._sink.process_message(
            MessageType.MalwareScanQueueStopBackground()
        )

    @expect(MessageType.ConfigUpdate)
    @utils.log_error_and_ignore()
    async def schedule_config_updated(self, message):
        if isinstance(message["conf"], SystemConfig):
            if self._update_cron() and not self._cron:
                await self._stop_background_scan()