# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
# For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt

"""Helpers for coverage.py tests."""

import os
import subprocess
import sys

from coverage import env
from coverage.backward import unicode_class
from coverage.misc import output_encoding


def run_command(cmd):
    """Run a command in a sub-process.

    Returns the exit status code and the combined stdout and stderr.

    """
    if env.PY2 and isinstance(cmd, unicode_class):
        cmd = cmd.encode(sys.getfilesystemencoding())

    # In some strange cases (PyPy3 in a virtualenv!?) the stdout encoding of
    # the subprocess is set incorrectly to ascii.  Use an environment variable
    # to force the encoding to be the same as ours.
    sub_env = dict(os.environ)
    encoding = output_encoding()
    if encoding:
        sub_env['PYTHONIOENCODING'] = encoding

    proc = subprocess.Popen(
        cmd,
        shell=True,
        env=sub_env,
        stdin=subprocess.PIPE, stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT
        )
    output, _ = proc.communicate()
    status = proc.returncode

    # Get the output, and canonicalize it to strings with newlines.
    if not isinstance(output, str):
        output = output.decode(output_encoding())
    output = output.replace('\r', '')

    return status, output


class CheckUniqueFilenames(object):
    """Asserts the uniqueness of file names passed to a function."""
    def __init__(self, wrapped):
        self.filenames = set()
        self.wrapped = wrapped

    @classmethod
    def hook(cls, obj, method_name):
        """Replace a method with our checking wrapper.

        The method must take a string as a first argument. That argument
        will be checked for uniqueness across all the calls to this method.

        The values don't have to be file names actually, just strings, but
        we only use it for filename arguments.

        """
        method = getattr(obj, method_name)
        hook = cls(method)
        setattr(obj, method_name, hook.wrapper)
        return hook

    def wrapper(self, filename, *args, **kwargs):
        """The replacement method.  Check that we don't have dupes."""
        assert filename not in self.filenames, (
            "File name %r passed to %r twice" % (filename, self.wrapped)
            )
        self.filenames.add(filename)
        ret = self.wrapped(filename, *args, **kwargs)
        return ret