# pylint: disable=redefined-outer-name
from os import stat, urandom
from os.path import exists, dirname, realpath, join
from stat import S_ISFIFO
from secrets import token_urlsafe
from random import randint
from threading import Thread
from contextlib import contextmanager

import pytest

from echo_server import EchoPipeIOServer


BLOCK_TIMEOUT = 1
SHUTDOWN_FAILURE_MSG = 'PipeIOServer failed to shut down!'


@pytest.fixture
def io_pipes():
    with pipe_io_server() as pipe_io:
        with IOPipes(pipe_io.in_pipe, pipe_io.out_pipe) as io_pipes:
            yield io_pipes


@contextmanager
def pipe_io_server(pipe_io_server_type=EchoPipeIOServer):
    pipe_io_server = build_pipe_io_server(pipe_io_server_type)
    thread = Thread(target=pipe_io_server.run)
    thread.start()
    yield pipe_io_server
    pipe_io_server.stop()
    thread.join(timeout=BLOCK_TIMEOUT)
    if thread.is_alive():
        raise RuntimeError(SHUTDOWN_FAILURE_MSG)


def raise_if_thread_blocks(thread_target_function, unblock_function, timeout=BLOCK_TIMEOUT):
    thread = Thread(target=thread_target_function)
    thread.start()
    unblock_function()
    thread.join(timeout=timeout)
    if thread.is_alive():
        raise RuntimeError(SHUTDOWN_FAILURE_MSG)


def build_pipe_io_server(pipe_io_server_type=EchoPipeIOServer):
    here = dirname(realpath(__file__))
    return pipe_io_server_type(
        join(here, 'in_pipe_tests'),
        join(here, 'out_pipe_tests')
    )


class IOPipes:
    def __init__(self, in_pipe_path, out_pipe_path):
        self.in_pipe_path = in_pipe_path
        self.out_pipe_path = out_pipe_path

    def __enter__(self):
        # pylint: disable=attribute-defined-outside-init
        self.in_pipe = open(self.in_pipe_path, 'wb')
        self.out_pipe = open(self.out_pipe_path, 'rb')
        return self

    def __exit__(self, type_, value, traceback):
        self.close()

    def close(self):
        self.in_pipe.close()
        self.out_pipe.close()

    def send(self, message):
        self.in_pipe.write(message + b'\n')
        self.in_pipe.flush()

    def recv(self):
        return self.out_pipe.readline().rstrip(b'\n')


def test_run_creates_pipes(io_pipes):
    for path in (io_pipes.in_pipe_path, io_pipes.out_pipe_path):
        assert exists(path)
        assert S_ISFIFO(stat(path).st_mode)


def test_stop():
    pipe_io = build_pipe_io_server()
    def open_close_in_pipe():
        pipe_io.stop()
    raise_if_thread_blocks(pipe_io.run, open_close_in_pipe)
    for path in (pipe_io.in_pipe, pipe_io.out_pipe):
        assert not exists(path)


def test_eof_stop():
    pipe_io = build_pipe_io_server()
    def open_close_in_pipe():
        open(pipe_io.in_pipe, 'wb').close()
    raise_if_thread_blocks(pipe_io.run, open_close_in_pipe)


def test_out_pipe_closed_stop():
    pipe_io = build_pipe_io_server()
    def close_out_pipe_and_write():
        in_pipe = open(pipe_io.in_pipe, 'wb')
        open(pipe_io.out_pipe, 'rb').close()
        in_pipe.write(b'lel\n')
        in_pipe.flush()
    raise_if_thread_blocks(pipe_io.run, close_out_pipe_and_write)


@pytest.mark.parametrize(
    'test_data', [
        'Cats and cheese',
        'You ever wonder why we are here?',
        'Lorem ipsum dolor sit amet',
        'You always have a plan, Dutch!',
        token_urlsafe(32),
        token_urlsafe(32),
        token_urlsafe(32),
        token_urlsafe(32)
    ]
)
def test_io(io_pipes, test_data):
    io_pipes.send(test_data.encode())
    assert io_pipes.recv().decode() == test_data


@pytest.mark.parametrize(
    'test_data_size', [
        1024,
        1024*1024,
        2*1024*1024,
        4*1024*1024,
        8*1024*1024,
        16*1024*1024,
        32*1024*1024
    ]
)
def test_io_large_data(io_pipes, test_data_size):
    test_data = urandom(test_data_size).replace(b'\n', b'')
    io_pipes.send(test_data)
    received_data = io_pipes.recv()
    assert received_data == test_data


def test_io_stress(io_pipes):
    for _ in range(2222):
        test_data = urandom(randint(1, 1024)).replace(b'\n', b'')
        io_pipes.send(test_data)
        assert io_pipes.recv() == test_data


def test_io_newlines(io_pipes):
    times = randint(1, 512)
    io_pipes.send(b'\n' * times)
    for _ in range(times + 1):  # IOPipes.send appends +1
        assert io_pipes.recv() == b''