import os
import sys


def _show_skimage_info():
    import skimage
    print(f"skimage version {skimage.__version__}")


class PytestTester:
    """
    Pytest test runner.

    This class is made available in ``skimage._shared.testing``, and a test
    function is typically added to a package's __init__.py like so::

      from skimage._shared.testing import PytestTester
      test = PytestTester(__name__)
      del PytestTester

    Calling this test function finds and runs all tests associated with the
    module and all its sub-modules.

    Attributes
    ----------
    module_name : str
        Full path to the package to test.

    Parameters
    ----------
    module_name : module name
        The name of the module to test.

    """
    def __init__(self, module_name):
        self.module_name = module_name

    def __call__(self, label='fast', verbose=1, extra_argv=None,
                 doctests=False, coverage=False, durations=-1, tests=None):
        """
        Run tests for module using pytest.

        Parameters
        ----------
        label : {'fast', 'full'}, optional
            Identifies the tests to run. When set to 'fast', tests decorated
            with `pytest.mark.slow` are skipped, when 'full', the slow marker
            is ignored.
        verbose : int, optional
            Verbosity value for test outputs, in the range 1-3. Default is 1.
        extra_argv : list, optional
            List with any extra arguments to pass to pytests.
        doctests : bool, optional
            .. note:: Not supported
        coverage : bool, optional
            If True, report coverage of scikit-image code. Default is False.
            Requires installation of (pip) pytest-cov.
        durations : int, optional
            If < 0, do nothing, If 0, report time of all tests, if > 0,
            report the time of the slowest `timer` tests. Default is -1.
        tests : test or list of tests
            Tests to be executed with pytest '--pyargs'

        Returns
        -------
        result : bool
            Return True on success, false otherwise.
        """
        import pytest

        module = sys.modules[self.module_name]
        module_path = os.path.abspath(module.__path__[0])

        # setup the pytest arguments
        pytest_args = ["-l"]

        # offset verbosity. The "-q" cancels a "-v".
        pytest_args += ["-q"]

        # Filter out annoying import messages. Want these in both develop and
        # release mode.
        pytest_args += [
            "-W ignore:Not importing directory",
            "-W ignore:numpy.dtype size changed",
            "-W ignore:numpy.ufunc size changed", ]

        if doctests:
            raise ValueError("Doctests not supported")

        if extra_argv:
            pytest_args += list(extra_argv)

        if verbose > 1:
            pytest_args += ["-" + "v" * (verbose - 1)]

        if coverage:
            pytest_args += ["--cov=" + module_path]

        if label == "fast":
            pytest_args += ["-m", "not slow"]
        elif label != "full":
            pytest_args += ["-m", label]

        if durations >= 0:
            pytest_args += [f"--durations={durations}"]

        if tests is None:
            tests = [self.module_name]

        pytest_args += ["--pyargs"] + list(tests)

        # run tests.
        _show_skimage_info()

        try:
            code = pytest.main(pytest_args)
        except SystemExit as exc:
            code = exc.code

        return code == 0
