from abc import ABC, abstractmethod
from threading import Thread, Event
from typing import Callable

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(ABC, Thread):
    def __init__(self, in_pipe=None, out_pipe=None, 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 = self._create_io_threads()
        self._io_threads = (self._reader_thread, self._writer_thread)
        self._on_stop = lambda: 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 _create_io_threads(self):
        reader_thread = PipeReaderThread(self.in_pipe, self._stop_event, self.handle_message)
        writer_thread = PipeWriterThread(self.out_pipe, self._stop_event)
        return reader_thread, writer_thread

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

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

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

    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 _set_on_stop(self, value):
        if not isinstance(value, Callable):
            raise ValueError("Supplied object is not callable!")
        self._on_stop = value

    on_stop = property(fset=_set_on_stop)

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