import logging
from typing import List, Optional

import pytimeparse2
from diskcache import Cache
from nio import AsyncClient, MatrixRoom

from matrix_alertbot.alertmanager import AlertmanagerClient
from matrix_alertbot.chat_functions import send_text_to_room
from matrix_alertbot.config import Config
from matrix_alertbot.errors import (
    AlertmanagerError,
    AlertNotFoundError,
    SilenceNotFoundError,
)
from matrix_alertbot.matcher import AlertMatcher, AlertRegexMatcher

logger = logging.getLogger(__name__)


class BaseCommand:
    def __init__(
        self,
        client: AsyncClient,
        cache: Cache,
        alertmanager: AlertmanagerClient,
        config: Config,
        cmd: str,
        room: MatrixRoom,
        sender: str,
        event_id: str,
    ) -> None:
        """A command made by a user.

        Args:
            client: The client to communicate with Matrix.

            cache: Bot cache.

            alertmanager: The client to communicate with Alertmanager.

            config: Bot configuration parameters.

            cmd: The command and arguments.

            room: The room the command was sent in.

            sender: The sender of the event

            event_id: The ID of the event describing the command.
        """
        self.client = client
        self.cache = cache
        self.alertmanager = alertmanager
        self.config = config
        self.cmd = cmd
        self.args = cmd.split()[1:]
        self.room = room
        self.sender = sender
        self.event_id = event_id

    async def process(self) -> None:
        raise NotImplementedError


class BaseAlertCommand(BaseCommand):
    def __init__(
        self,
        client: AsyncClient,
        cache: Cache,
        alertmanager: AlertmanagerClient,
        config: Config,
        cmd: str,
        room: MatrixRoom,
        sender: str,
        event_id: str,
        alert_event_id: str,
    ) -> None:
        super().__init__(
            client, cache, alertmanager, config, cmd, room, sender, event_id
        )

        self.alert_event_id = alert_event_id


class AckAlertCommand(BaseAlertCommand):
    async def process(self) -> None:
        """Acknowledge an alert and silence it for a certain duration in Alertmanager"""
        matchers: List[AlertMatcher] = []
        durations = []
        for arg in self.args:
            if "=~" in arg:
                label, regex = arg.split("=~")
                regex_matcher = AlertRegexMatcher(label, regex)
                matchers.append(regex_matcher)
            elif "=" in arg:
                label, value = arg.split("=")
                matcher = AlertMatcher(label, value)
                matchers.append(matcher)
            else:
                durations.append(arg)

        if len(durations) > 0:
            duration = " ".join(durations)
        else:
            duration = "1d"

        logger.debug(
            f"Receiving a command to create a silence for a duration of {duration}"
        )

        duration_seconds = pytimeparse2.parse(duration)
        if duration_seconds is None:
            logger.error(f"Unable to create silence: Invalid duration '{duration}'")
            await send_text_to_room(
                self.client,
                self.room.room_id,
                f"I tried really hard, but I can't convert the duration '{duration}' to a number of seconds.",
            )
            return

        logger.debug(
            f"Read alert fingerprints for alert event {self.alert_event_id} from cache"
        )

        if self.alert_event_id not in self.cache:
            logger.error(
                f"Cannot find fingerprints for alert event {self.alert_event_id} in cache"
            )
            return

        alert_fingerprints = self.cache[self.alert_event_id]
        logger.debug(f"Found {len(alert_fingerprints)} in cache")

        count_alert_not_found = 0
        created_silences = []
        for alert_fingerprint in alert_fingerprints:
            logger.debug(
                f"Create silence for alert with fingerprint {alert_fingerprint} for a duration of {duration}"
            )

            try:
                silence_id = await self.alertmanager.create_silence(
                    alert_fingerprint,
                    duration_seconds,
                    self.room.user_name(self.sender),
                    matchers,
                )
                created_silences.append(silence_id)
            except AlertNotFoundError as e:
                logger.warning(f"Unable to create silence: {e}")
                count_alert_not_found += 1
            except AlertmanagerError as e:
                logger.exception(f"Unable to create silence: {e}", exc_info=e)

        self.cache.set(self.event_id, tuple(created_silences), expire=duration_seconds)

        if count_alert_not_found > 0:
            await send_text_to_room(
                self.client,
                self.room.room_id,
                f"Sorry, I couldn't find {count_alert_not_found} alerts, therefore I couldn't create their silence.",
            )

        if len(created_silences) > 0:
            await send_text_to_room(
                self.client,
                self.room.room_id,
                f"Created {len(created_silences)} silences with a duration of {duration}.",
            )


class UnackAlertCommand(BaseAlertCommand):
    async def process(self) -> None:
        """Delete an alert's acknowledgement of an alert and remove corresponding silence in Alertmanager"""
        matchers: List[AlertMatcher] = []
        for arg in self.args:
            if "=~" in arg:
                label, regex = arg.split("=~")
                regex_matcher = AlertRegexMatcher(label, regex)
                matchers.append(regex_matcher)
            elif "=" in arg:
                label, value = arg.split("=")
                matcher = AlertMatcher(label, value)
                matchers.append(matcher)

        logger.debug("Receiving a command to delete a silence")
        logger.debug(
            f"Read alert fingerprints for alert event {self.alert_event_id} from cache"
        )

        if self.alert_event_id not in self.cache:
            logger.error(
                f"Cannot find fingerprints for event {self.alert_event_id} in cache"
            )
            return

        alert_fingerprints = self.cache[self.alert_event_id]
        logger.debug(f"Found {len(alert_fingerprints)} in cache")

        count_alert_not_found = 0
        count_removed_silences = 0
        for alert_fingerprint in alert_fingerprints:
            logger.debug(
                f"Delete silence for alert with fingerprint {alert_fingerprint}"
            )
            try:
                removed_silences = await self.alertmanager.delete_silences(
                    alert_fingerprint, matchers
                )
                count_removed_silences += len(removed_silences)
            except (AlertNotFoundError, SilenceNotFoundError) as e:
                logger.error(f"Unable to delete silence: {e}")
                count_alert_not_found += 1
            except AlertmanagerError as e:
                logger.exception(f"Unable to delete silence: {e}", exc_info=e)

        if count_alert_not_found > 0:
            await send_text_to_room(
                self.client,
                self.room.room_id,
                f"Sorry, I couldn't find {count_alert_not_found} alerts, therefore I couldn't remove their silences.",
            )

        if count_removed_silences > 0:
            await send_text_to_room(
                self.client,
                self.room.room_id,
                f"Removed {count_removed_silences} silences.",
            )


class HelpCommand(BaseCommand):
    async def process(self) -> None:
        """Show the help text"""
        logger.debug(f"Displaying help to room {self.room.display_name}")
        if not self.args:
            text = (
                "Hello, I am a bot made with matrix-nio! Use `help commands` to view "
                "available commands."
            )
            await send_text_to_room(self.client, self.room.room_id, text)
            return

        topic = self.args[0]
        if topic == "rules":
            text = "These are the rules!"
        elif topic == "commands":
            text = "Available commands: ..."
        else:
            text = "Unknown help topic!"
        await send_text_to_room(self.client, self.room.room_id, text)


class UnknownCommand(BaseCommand):
    async def process(self) -> None:
        logger.debug(
            f"Sending unknown command response to room {self.room.display_name}"
        )
        await send_text_to_room(
            self.client,
            self.room.room_id,
            f"Unknown command '{self.cmd}'. Try the 'help' command for more information.",
        )


class CommandFactory:
    @staticmethod
    def create(
        cmd: str,
        client: AsyncClient,
        cache: Cache,
        alertmanager: AlertmanagerClient,
        config: Config,
        room: MatrixRoom,
        sender: str,
        event_id: str,
        reacted_to_event_id: Optional[str] = None,
    ) -> BaseCommand:
        if cmd.startswith("ack"):
            assert reacted_to_event_id is not None
            return AckAlertCommand(
                client,
                cache,
                alertmanager,
                config,
                cmd,
                room,
                sender,
                event_id,
                reacted_to_event_id,
            )
        elif cmd.startswith("unack") or cmd.startswith("nack"):
            assert reacted_to_event_id is not None
            return UnackAlertCommand(
                client,
                cache,
                alertmanager,
                config,
                cmd,
                room,
                sender,
                event_id,
                reacted_to_event_id,
            )
        elif cmd.startswith("help"):
            return HelpCommand(
                client, cache, alertmanager, config, cmd, room, sender, event_id
            )
        else:
            return UnknownCommand(
                client, cache, alertmanager, config, cmd, room, sender, event_id
            )