# Copyright (c) 2022 Kyle Schouviller (https://github.com/kyle0654)

import asyncio
from queue import Empty, Queue
from typing import Any
from fastapi_events.dispatcher import dispatch
from ..services.events import EventServiceBase
import threading

class FastAPIEventService(EventServiceBase):
    event_handler_id: int
    __queue: Queue
    __stop_event: threading.Event

    def __init__(self, event_handler_id: int) -> None:
        self.event_handler_id = event_handler_id
        self.__queue = Queue()
        self.__stop_event = threading.Event()
        asyncio.create_task(self.__dispatch_from_queue(stop_event = self.__stop_event))

        super().__init__()


    def stop(self, *args, **kwargs):
        self.__stop_event.set()
        self.__queue.put(None)


    def dispatch(self, event_name: str, payload: Any) -> None:
        self.__queue.put(dict(
            event_name = event_name,
            payload = payload
        ))


    async def __dispatch_from_queue(self, stop_event: threading.Event):
        """Get events on from the queue and dispatch them, from the correct thread"""
        while not stop_event.is_set():
            try:
                event = self.__queue.get(block = False)
                if not event: # Probably stopping
                    continue

                dispatch(
                    event.get('event_name'),
                    payload       = event.get('payload'),
                    middleware_id = self.event_handler_id)

            except Empty:
                await asyncio.sleep(0.001)
                pass

            except asyncio.CancelledError as e:
                raise e # Raise a proper error