from __future__ import absolute_import, unicode_literals

import atexit
import os
import pytest
import sys

from kombu.exceptions import VersionMismatch


@pytest.fixture(scope='session')
def multiprocessing_workaround(request):
    def fin():
        # Workaround for multiprocessing bug where logging
        # is attempted after global already collected at shutdown.
        canceled = set()
        try:
            import multiprocessing.util
            canceled.add(multiprocessing.util._exit_function)
        except (AttributeError, ImportError):
            pass

        try:
            atexit._exithandlers[:] = [
                e for e in atexit._exithandlers if e[0] not in canceled
            ]
        except AttributeError:  # pragma: no cover
            pass  # Py3 missing _exithandlers
    request.addfinalizer(fin)


@pytest.fixture(autouse=True)
def zzzz_test_cases_calls_setup_teardown(request):
    if request.instance:
        # we set the .patching attribute for every test class.
        setup = getattr(request.instance, 'setup', None)
        # we also call .setup() and .teardown() after every test method.
        teardown = getattr(request.instance, 'teardown', None)
        setup and setup()
        teardown and request.addfinalizer(teardown)


@pytest.fixture(autouse=True)
def test_cases_has_patching(request, patching):
    if request.instance:
        request.instance.patching = patching


@pytest.fixture
def hub(request):
    from kombu.async import Hub, get_event_loop, set_event_loop
    _prev_hub = get_event_loop()
    hub = Hub()
    set_event_loop(hub)

    def fin():
        if _prev_hub is not None:
            set_event_loop(_prev_hub)
    request.addfinalizer(fin)
    return hub


def find_distribution_modules(name=__name__, file=__file__):
    current_dist_depth = len(name.split('.')) - 1
    current_dist = os.path.join(os.path.dirname(file),
                                *([os.pardir] * current_dist_depth))
    abs = os.path.abspath(current_dist)
    dist_name = os.path.basename(abs)

    for dirpath, dirnames, filenames in os.walk(abs):
        package = (dist_name + dirpath[len(abs):]).replace('/', '.')
        if '__init__.py' in filenames:
            yield package
            for filename in filenames:
                if filename.endswith('.py') and filename != '__init__.py':
                    yield '.'.join([package, filename])[:-3]


def import_all_modules(name=__name__, file=__file__, skip=[]):
    for module in find_distribution_modules(name, file):
        if module not in skip:
            print('preimporting %r for coverage...' % (module,))
            try:
                __import__(module)
            except (ImportError, VersionMismatch, AttributeError):
                pass


def is_in_coverage():
    return (os.environ.get('COVER_ALL_MODULES') or
            any('--cov' in arg for arg in sys.argv))


@pytest.fixture(scope='session')
def cover_all_modules():
    # so coverage sees all our modules.
    if is_in_coverage():
        import_all_modules()