from contextlib import suppress
from os import O_NONBLOCK, O_RDONLY, close
from os import open as osopen
from queue import Queue
from threading import Thread

from .terminate_process_on_failure import terminate_process_on_failure


class PipeWriterThread(Thread):
    def __init__(self, pipe_path, stop_event):
        super().__init__()
        self._pipe_path = pipe_path
        self._stop_event = stop_event
        self._write_queue = Queue()

    def write(self, message):
        self._write_queue.put(message, block=True)

    @terminate_process_on_failure
    def run(self):
        try:
            with open(self._pipe_path, 'wb') as pipe:
                while True:
                    message = self._write_queue.get(block=True)
                    if message is None:
                        self._stop_event.set()
                        break
                    pipe.write(message + b'\n')
                    pipe.flush()
        except BrokenPipeError:
            self._stop_event.set()

    def stop(self):
        self.unblock()
        self.join()

    def unblock(self):
        self._write_queue.put(None)
        with suppress(OSError):
            fd = osopen(self._pipe_path, O_RDONLY | O_NONBLOCK)
            close(fd)