#encoding = utf8

import asyncio
import threading


class AsyncTaskQueue:
    def __init__(self):
        self._queue = asyncio.Queue()
        self._loop = asyncio.new_event_loop()
        self._thread = threading.Thread(target=self._run_loop)
        self._worker_task = None
        self._loop_running = threading.Event()
        self._thread.start()

    def _run_loop(self):
        asyncio.set_event_loop(self._loop)
        self._loop_running.set()
        self._loop.run_forever()

    async def _worker(self):
        while self._loop_running.is_set():
            task = await self._queue.get()
            if task is None:
                break
            await task
            self._queue.task_done()

    def add_task(self, coro):
        asyncio.run_coroutine_threadsafe(self._queue.put(coro), self._loop)

    def start_worker(self):
        if not self._worker_task:
            self._worker_task = asyncio.run_coroutine_threadsafe(self._worker(), self._loop)

    def stop(self):
        self._loop_running.clear()
        asyncio.run_coroutine_threadsafe(self._queue.put(None), self._loop).result()
        if self._worker_task:
            self._worker_task.result()
        self._loop.call_soon_threadsafe(self._loop.stop)
        self._thread.join()
        self._loop.close()