from threading import Thread, Event

from .pipe_reader_thread import PipeReaderThread
from .pipe_writer_thread import PipeWriterThread
from .pipe import Pipe
from .terminate_process_on_failure import terminate_process_on_failure


class PipeIOServer(Thread):
    def __init__(self, in_pipe, out_pipe, permissions=0o600):
        super().__init__(daemon=True)
        self._in_pipe, self._out_pipe = in_pipe, out_pipe
        self._create_pipes(permissions)
        self._stop_event = Event()
        self._reader_thread, self._writer_thread = None, None
        self._io_threads = None

    def _create_pipes(self, permissions):
        Pipe(self.in_pipe).recreate(permissions)
        Pipe(self.out_pipe).recreate(permissions)

    @property
    def in_pipe(self):
        return self._in_pipe

    @property
    def out_pipe(self):
        return self._out_pipe

    def handle_message(self, message):
        raise NotImplementedError()

    def send_message(self, message):
        self._writer_thread.write(message)

    @terminate_process_on_failure
    def run(self):
        self._init_io_threads()
        for thread in self._io_threads:
            thread.start()
        self._stop_event.wait()
        self._stop_threads()

    def _init_io_threads(self):
        self._reader_thread = PipeReaderThread(
            self.in_pipe,
            self._stop_event,
            self.handle_message
        )
        self._writer_thread = PipeWriterThread(
            self.out_pipe,
            self._stop_event
        )
        self._io_threads = (self._reader_thread, self._writer_thread)

    def stop(self):
        self._stop_event.set()
        if self.is_alive():
            self.join()

    def _stop_threads(self):
        for thread in self._io_threads:
            if thread.is_alive():
                thread.stop()
        Pipe(self.in_pipe).remove()
        Pipe(self.out_pipe).remove()
        self.on_stop()

    def on_stop(self):
        pass

    def wait(self):
        self._stop_event.wait()

    def __enter__(self):
        self.start()
        return self

    def __exit__(self, type_, value, tb):
        self.stop()