import pytest
import sys
import matplotlib
from matplotlib import _api


def pytest_configure(config):
    # config is initialized here rather than in pytest.ini so that `pytest
    # --pyargs matplotlib` (which would not find pytest.ini) works.  The only
    # entries in pytest.ini set minversion (which is checked earlier),
    # testpaths/python_files, as they are required to properly find the tests
    for key, value in [
        ("markers", "flaky: (Provided by pytest-rerunfailures.)"),
        ("markers", "timeout: (Provided by pytest-timeout.)"),
        ("markers", "backend: Set alternate Matplotlib backend temporarily."),
        ("markers", "baseline_images: Compare output against references."),
        ("markers", "pytz: Tests that require pytz to be installed."),
        ("filterwarnings", "error"),
        ("filterwarnings",
         "ignore:.*The py23 module has been deprecated:DeprecationWarning"),
        ("filterwarnings",
         r"ignore:DynamicImporter.find_spec\(\) not found; "
         r"falling back to find_module\(\):ImportWarning"),
    ]:
        config.addinivalue_line(key, value)

    matplotlib.use('agg', force=True)
    matplotlib._called_from_pytest = True
    matplotlib._init_tests()


def pytest_unconfigure(config):
    matplotlib._called_from_pytest = False


@pytest.fixture(autouse=True)
def mpl_test_settings(request):
    from matplotlib.testing.decorators import _cleanup_cm

    with _cleanup_cm():

        backend = None
        backend_marker = request.node.get_closest_marker('backend')
        prev_backend = matplotlib.get_backend()
        if backend_marker is not None:
            assert len(backend_marker.args) == 1, \
                "Marker 'backend' must specify 1 backend."
            backend, = backend_marker.args
            skip_on_importerror = backend_marker.kwargs.get(
                'skip_on_importerror', False)

            # special case Qt backend importing to avoid conflicts
            if backend.lower().startswith('qt5'):
                if any(sys.modules.get(k) for k in ('PyQt4', 'PySide')):
                    pytest.skip('Qt4 binding already imported')

        matplotlib.testing.setup()
        with _api.suppress_matplotlib_deprecation_warning():
            if backend is not None:
                # This import must come after setup() so it doesn't load the
                # default backend prematurely.
                import matplotlib.pyplot as plt
                try:
                    plt.switch_backend(backend)
                except ImportError as exc:
                    # Should only occur for the cairo backend tests, if neither
                    # pycairo nor cairocffi are installed.
                    if 'cairo' in backend.lower() or skip_on_importerror:
                        pytest.skip("Failed to switch to backend {} ({})."
                                    .format(backend, exc))
                    else:
                        raise
            # Default of cleanup and image_comparison too.
            matplotlib.style.use(["classic", "_classic_test_patch"])
        try:
            yield
        finally:
            matplotlib.use(prev_backend)


@pytest.fixture
def pd():
    """Fixture to import and configure pandas."""
    pd = pytest.importorskip('pandas')
    try:
        from pandas.plotting import (
            deregister_matplotlib_converters as deregister)
        deregister()
    except ImportError:
        pass
    return pd


@pytest.fixture
def xr():
    """Fixture to import xarray."""
    xr = pytest.importorskip('xarray')
    return xr
