import queue
import time
from abc import abstractmethod
from collections.abc import Generator
from enum import Enum
from typing import Any

from sqlalchemy.orm import DeclarativeMeta

from core.app.entities.app_invoke_entities import InvokeFrom
from core.app.entities.queue_entities import (
    AppQueueEvent,
    QueueErrorEvent,
    QueuePingEvent,
    QueueStopEvent,
)
from extensions.ext_redis import redis_client


class PublishFrom(Enum):
    APPLICATION_MANAGER = 1
    TASK_PIPELINE = 2


class AppQueueManager:
    def __init__(self, task_id: str,
                 user_id: str,
                 invoke_from: InvokeFrom) -> None:
        if not user_id:
            raise ValueError("user is required")

        self._task_id = task_id
        self._user_id = user_id
        self._invoke_from = invoke_from

        user_prefix = 'account' if self._invoke_from in [InvokeFrom.EXPLORE, InvokeFrom.DEBUGGER] else 'end-user'
        redis_client.setex(AppQueueManager._generate_task_belong_cache_key(self._task_id), 1800,
                           f"{user_prefix}-{self._user_id}")

        q = queue.Queue()

        self._q = q

    def listen(self) -> Generator:
        """
        Listen to queue
        :return:
        """
        # wait for 10 minutes to stop listen
        listen_timeout = 600
        start_time = time.time()
        last_ping_time = 0

        while True:
            try:
                message = self._q.get(timeout=1)
                if message is None:
                    break

                yield message
            except queue.Empty:
                continue
            finally:
                elapsed_time = time.time() - start_time
                if elapsed_time >= listen_timeout or self._is_stopped():
                    # publish two messages to make sure the client can receive the stop signal
                    # and stop listening after the stop signal processed
                    self.publish(
                        QueueStopEvent(stopped_by=QueueStopEvent.StopBy.USER_MANUAL),
                        PublishFrom.TASK_PIPELINE
                    )

                if elapsed_time // 10 > last_ping_time:
                    self.publish(QueuePingEvent(), PublishFrom.TASK_PIPELINE)
                    last_ping_time = elapsed_time // 10

    def stop_listen(self) -> None:
        """
        Stop listen to queue
        :return:
        """
        self._q.put(None)

    def publish_error(self, e, pub_from: PublishFrom) -> None:
        """
        Publish error
        :param e: error
        :param pub_from: publish from
        :return:
        """
        self.publish(QueueErrorEvent(
            error=e
        ), pub_from)

    def publish(self, event: AppQueueEvent, pub_from: PublishFrom) -> None:
        """
        Publish event to queue
        :param event:
        :param pub_from:
        :return:
        """
        self._check_for_sqlalchemy_models(event.dict())
        self._publish(event, pub_from)

    @abstractmethod
    def _publish(self, event: AppQueueEvent, pub_from: PublishFrom) -> None:
        """
        Publish event to queue
        :param event:
        :param pub_from:
        :return:
        """
        raise NotImplementedError

    @classmethod
    def set_stop_flag(cls, task_id: str, invoke_from: InvokeFrom, user_id: str) -> None:
        """
        Set task stop flag
        :return:
        """
        result = redis_client.get(cls._generate_task_belong_cache_key(task_id))
        if result is None:
            return

        user_prefix = 'account' if invoke_from in [InvokeFrom.EXPLORE, InvokeFrom.DEBUGGER] else 'end-user'
        if result.decode('utf-8') != f"{user_prefix}-{user_id}":
            return

        stopped_cache_key = cls._generate_stopped_cache_key(task_id)
        redis_client.setex(stopped_cache_key, 600, 1)

    def _is_stopped(self) -> bool:
        """
        Check if task is stopped
        :return:
        """
        stopped_cache_key = AppQueueManager._generate_stopped_cache_key(self._task_id)
        result = redis_client.get(stopped_cache_key)
        if result is not None:
            return True

        return False

    @classmethod
    def _generate_task_belong_cache_key(cls, task_id: str) -> str:
        """
        Generate task belong cache key
        :param task_id: task id
        :return:
        """
        return f"generate_task_belong:{task_id}"

    @classmethod
    def _generate_stopped_cache_key(cls, task_id: str) -> str:
        """
        Generate stopped cache key
        :param task_id: task id
        :return:
        """
        return f"generate_task_stopped:{task_id}"

    def _check_for_sqlalchemy_models(self, data: Any):
        # from entity to dict or list
        if isinstance(data, dict):
            for key, value in data.items():
                self._check_for_sqlalchemy_models(value)
        elif isinstance(data, list):
            for item in data:
                self._check_for_sqlalchemy_models(item)
        else:
            if isinstance(data, DeclarativeMeta) or hasattr(data, '_sa_instance_state'):
                raise TypeError("Critical Error: Passing SQLAlchemy Model instances "
                                "that cause thread safety issues is not allowed.")


class GenerateTaskStoppedException(Exception):
    pass
