"""Fixtures and testing utilities for :pypi:`py.test <pytest>`."""
from __future__ import absolute_import, unicode_literals

import os
from contextlib import contextmanager

import pytest

from .testing import worker
from .testing.app import TestApp, setup_default_app

NO_WORKER = os.environ.get('NO_WORKER')

# pylint: disable=redefined-outer-name
# Well, they're called fixtures....


@contextmanager
def _create_app(enable_logging=False,
                use_trap=False,
                parameters={},
                **config):
    # type: (Any, **Any) -> Celery
    """Utility context used to setup Celery app for pytest fixtures."""
    test_app = TestApp(
        set_as_current=False,
        enable_logging=enable_logging,
        config=config,
        **parameters
    )
    with setup_default_app(test_app, use_trap=use_trap):
        yield test_app


@pytest.fixture(scope='session')
def use_celery_app_trap():
    # type: () -> bool
    """You can override this fixture to enable the app trap.

    The app trap raises an exception whenever something attempts
    to use the current or default apps.
    """
    return False


@pytest.fixture(scope='session')
def celery_session_app(request,
                       celery_config,
                       celery_parameters,
                       celery_enable_logging,
                       use_celery_app_trap):
    # type: (Any) -> Celery
    """Session Fixture: Return app for session fixtures."""
    mark = request.node.get_marker('celery')
    config = dict(celery_config, **mark.kwargs if mark else {})
    with _create_app(enable_logging=celery_enable_logging,
                     use_trap=use_celery_app_trap,
                     parameters=celery_parameters,
                     **config) as app:
        if not use_celery_app_trap:
            app.set_default()
            app.set_current()
        yield app


@pytest.fixture(scope='session')
def celery_session_worker(request,
                          celery_session_app,
                          celery_includes,
                          celery_worker_pool,
                          celery_worker_parameters):
    # type: (Any, Celery, Sequence[str], str) -> WorkController
    """Session Fixture: Start worker that lives throughout test suite."""
    if not NO_WORKER:
        for module in celery_includes:
            celery_session_app.loader.import_task_module(module)
        with worker.start_worker(celery_session_app,
                                 pool=celery_worker_pool,
                                 **celery_worker_parameters) as w:
            yield w


@pytest.fixture(scope='session')
def celery_enable_logging():
    # type: () -> bool
    """You can override this fixture to enable logging."""
    return False


@pytest.fixture(scope='session')
def celery_includes():
    # type: () -> Sequence[str]
    """You can override this include modules when a worker start.

    You can have this return a list of module names to import,
    these can be task modules, modules registering signals, and so on.
    """
    return ()


@pytest.fixture(scope='session')
def celery_worker_pool():
    # type: () -> Union[str, Any]
    """You can override this fixture to set the worker pool.

    The "solo" pool is used by default, but you can set this to
    return e.g. "prefork".
    """
    return 'solo'


@pytest.fixture(scope='session')
def celery_config():
    # type: () -> Mapping[str, Any]
    """Redefine this fixture to configure the test Celery app.

    The config returned by your fixture will then be used
    to configure the :func:`celery_app` fixture.
    """
    return {}


@pytest.fixture(scope='session')
def celery_parameters():
    # type: () -> Mapping[str, Any]
    """Redefine this fixture to change the init parameters of test Celery app.

    The dict returned by your fixture will then be used
    as parameters when instantiating :class:`~celery.Celery`.
    """
    return {}


@pytest.fixture(scope='session')
def celery_worker_parameters():
    # type: () -> Mapping[str, Any]
    """Redefine this fixture to change the init parameters of Celery workers.

    This can be used e. g. to define queues the worker will consume tasks from.

    The dict returned by your fixture will then be used
    as parameters when instantiating :class:`~celery.worker.WorkController`.
    """
    return {}


@pytest.fixture()
def celery_app(request,
               celery_config,
               celery_parameters,
               celery_enable_logging,
               use_celery_app_trap):
    """Fixture creating a Celery application instance."""
    mark = request.node.get_marker('celery')
    config = dict(celery_config, **mark.kwargs if mark else {})
    with _create_app(enable_logging=celery_enable_logging,
                     use_trap=use_celery_app_trap,
                     parameters=celery_parameters,
                     **config) as app:
        yield app


@pytest.fixture()
def celery_worker(request,
                  celery_app,
                  celery_includes,
                  celery_worker_pool,
                  celery_worker_parameters):
    # type: (Any, Celery, Sequence[str], str) -> WorkController
    """Fixture: Start worker in a thread, stop it when the test returns."""
    if not NO_WORKER:
        for module in celery_includes:
            celery_app.loader.import_task_module(module)
        with worker.start_worker(celery_app,
                                 pool=celery_worker_pool,
                                 **celery_worker_parameters) as w:
            yield w


@pytest.fixture()
def depends_on_current_app(celery_app):
    """Fixture that sets app as current."""
    celery_app.set_current()
