"""
python version compatibility code
"""
from __future__ import absolute_import, division, print_function

import codecs
import functools
import inspect
import re
import sys

import py

import _pytest
from _pytest.outcomes import TEST_OUTCOME

try:
    import enum
except ImportError:  # pragma: no cover
    # Only available in Python 3.4+ or as a backport
    enum = None


_PY3 = sys.version_info > (3, 0)
_PY2 = not _PY3


if _PY3:
    from inspect import signature, Parameter as Parameter
else:
    from funcsigs import signature, Parameter as Parameter


NoneType = type(None)
NOTSET = object()

PY35 = sys.version_info[:2] >= (3, 5)
PY36 = sys.version_info[:2] >= (3, 6)
MODULE_NOT_FOUND_ERROR = 'ModuleNotFoundError' if PY36 else 'ImportError'


def _format_args(func):
    return str(signature(func))


isfunction = inspect.isfunction
isclass = inspect.isclass
# used to work around a python2 exception info leak
exc_clear = getattr(sys, 'exc_clear', lambda: None)
# The type of re.compile objects is not exposed in Python.
REGEX_TYPE = type(re.compile(''))


def is_generator(func):
    genfunc = inspect.isgeneratorfunction(func)
    return genfunc and not iscoroutinefunction(func)


def iscoroutinefunction(func):
    """Return True if func is a decorated coroutine function.

    Note: copied and modified from Python 3.5's builtin couroutines.py to avoid import asyncio directly,
    which in turns also initializes the "logging" module as side-effect (see issue #8).
    """
    return (getattr(func, '_is_coroutine', False) or
            (hasattr(inspect, 'iscoroutinefunction') and inspect.iscoroutinefunction(func)))


def getlocation(function, curdir):
    fn = py.path.local(inspect.getfile(function))
    lineno = py.builtin._getcode(function).co_firstlineno
    if fn.relto(curdir):
        fn = fn.relto(curdir)
    return "%s:%d" % (fn, lineno + 1)


def num_mock_patch_args(function):
    """ return number of arguments used up by mock arguments (if any) """
    patchings = getattr(function, "patchings", None)
    if not patchings:
        return 0
    mock = sys.modules.get("mock", sys.modules.get("unittest.mock", None))
    if mock is not None:
        return len([p for p in patchings
                    if not p.attribute_name and p.new is mock.DEFAULT])
    return len(patchings)


def getfuncargnames(function, is_method=False, cls=None):
    """Returns the names of a function's mandatory arguments.

    This should return the names of all function arguments that:
        * Aren't bound to an instance or type as in instance or class methods.
        * Don't have default values.
        * Aren't bound with functools.partial.
        * Aren't replaced with mocks.

    The is_method and cls arguments indicate that the function should
    be treated as a bound method even though it's not unless, only in
    the case of cls, the function is a static method.

    @RonnyPfannschmidt: This function should be refactored when we
    revisit fixtures. The fixture mechanism should ask the node for
    the fixture names, and not try to obtain directly from the
    function object well after collection has occurred.

    """
    # The parameters attribute of a Signature object contains an
    # ordered mapping of parameter names to Parameter instances.  This
    # creates a tuple of the names of the parameters that don't have
    # defaults.
    arg_names = tuple(p.name for p in signature(function).parameters.values()
                      if (p.kind is Parameter.POSITIONAL_OR_KEYWORD or
                          p.kind is Parameter.KEYWORD_ONLY) and
                      p.default is Parameter.empty)
    # If this function should be treated as a bound method even though
    # it's passed as an unbound method or function, remove the first
    # parameter name.
    if (is_method or
        (cls and not isinstance(cls.__dict__.get(function.__name__, None),
                                staticmethod))):
        arg_names = arg_names[1:]
    # Remove any names that will be replaced with mocks.
    if hasattr(function, "__wrapped__"):
        arg_names = arg_names[num_mock_patch_args(function):]
    return arg_names


if _PY3:
    STRING_TYPES = bytes, str
    UNICODE_TYPES = str,

    if PY35:
        def _bytes_to_ascii(val):
            return val.decode('ascii', 'backslashreplace')
    else:
        def _bytes_to_ascii(val):
            if val:
                # source: http://goo.gl/bGsnwC
                encoded_bytes, _ = codecs.escape_encode(val)
                return encoded_bytes.decode('ascii')
            else:
                # empty bytes crashes codecs.escape_encode (#1087)
                return ''

    def ascii_escaped(val):
        """If val is pure ascii, returns it as a str().  Otherwise, escapes
        bytes objects into a sequence of escaped bytes:

        b'\xc3\xb4\xc5\xd6' -> u'\\xc3\\xb4\\xc5\\xd6'

        and escapes unicode objects into a sequence of escaped unicode
        ids, e.g.:

        '4\\nV\\U00043efa\\x0eMXWB\\x1e\\u3028\\u15fd\\xcd\\U0007d944'

        note:
           the obvious "v.decode('unicode-escape')" will return
           valid utf-8 unicode if it finds them in bytes, but we
           want to return escaped bytes for any byte, even if they match
           a utf-8 string.

        """
        if isinstance(val, bytes):
            return _bytes_to_ascii(val)
        else:
            return val.encode('unicode_escape').decode('ascii')
else:
    STRING_TYPES = bytes, str, unicode
    UNICODE_TYPES = unicode,

    def ascii_escaped(val):
        """In py2 bytes and str are the same type, so return if it's a bytes
        object, return it unchanged if it is a full ascii string,
        otherwise escape it into its binary form.

        If it's a unicode string, change the unicode characters into
        unicode escapes.

        """
        if isinstance(val, bytes):
            try:
                return val.encode('ascii')
            except UnicodeDecodeError:
                return val.encode('string-escape')
        else:
            return val.encode('unicode-escape')


def get_real_func(obj):
    """ gets the real function object of the (possibly) wrapped object by
    functools.wraps or functools.partial.
    """
    start_obj = obj
    for i in range(100):
        new_obj = getattr(obj, '__wrapped__', None)
        if new_obj is None:
            break
        obj = new_obj
    else:
        raise ValueError(
            ("could not find real function of {start}"
             "\nstopped at {current}").format(
                start=py.io.saferepr(start_obj),
                current=py.io.saferepr(obj)))
    if isinstance(obj, functools.partial):
        obj = obj.func
    return obj


def getfslineno(obj):
    # xxx let decorators etc specify a sane ordering
    obj = get_real_func(obj)
    if hasattr(obj, 'place_as'):
        obj = obj.place_as
    fslineno = _pytest._code.getfslineno(obj)
    assert isinstance(fslineno[1], int), obj
    return fslineno


def getimfunc(func):
    try:
        return func.__func__
    except AttributeError:
        return func


def safe_getattr(object, name, default):
    """ Like getattr but return default upon any Exception or any OutcomeException.

    Attribute access can potentially fail for 'evil' Python objects.
    See issue #214.
    It catches OutcomeException because of #2490 (issue #580), new outcomes are derived from BaseException
    instead of Exception (for more details check #2707)
    """
    try:
        return getattr(object, name, default)
    except TEST_OUTCOME:
        return default


def _is_unittest_unexpected_success_a_failure():
    """Return if the test suite should fail if a @expectedFailure unittest test PASSES.

    From https://docs.python.org/3/library/unittest.html?highlight=unittest#unittest.TestResult.wasSuccessful:
        Changed in version 3.4: Returns False if there were any
        unexpectedSuccesses from tests marked with the expectedFailure() decorator.
    """
    return sys.version_info >= (3, 4)


if _PY3:
    def safe_str(v):
        """returns v as string"""
        return str(v)
else:
    def safe_str(v):
        """returns v as string, converting to ascii if necessary"""
        try:
            return str(v)
        except UnicodeError:
            if not isinstance(v, unicode):
                v = unicode(v)
            errors = 'replace'
            return v.encode('utf-8', errors)


COLLECT_FAKEMODULE_ATTRIBUTES = (
    'Collector',
    'Module',
    'Generator',
    'Function',
    'Instance',
    'Session',
    'Item',
    'Class',
    'File',
    '_fillfuncargs',
)


def _setup_collect_fakemodule():
    from types import ModuleType
    import pytest
    pytest.collect = ModuleType('pytest.collect')
    pytest.collect.__all__ = []  # used for setns
    for attr in COLLECT_FAKEMODULE_ATTRIBUTES:
        setattr(pytest.collect, attr, getattr(pytest, attr))


if _PY2:
    # Without this the test_dupfile_on_textio will fail, otherwise CaptureIO could directly inherit from StringIO.
    from py.io import TextIO

    class CaptureIO(TextIO):

        @property
        def encoding(self):
            return getattr(self, '_encoding', 'UTF-8')

else:
    import io

    class CaptureIO(io.TextIOWrapper):
        def __init__(self):
            super(CaptureIO, self).__init__(
                io.BytesIO(),
                encoding='UTF-8', newline='', write_through=True,
            )

        def getvalue(self):
            return self.buffer.getvalue().decode('UTF-8')


class FuncargnamesCompatAttr(object):
    """ helper class so that Metafunc, Function and FixtureRequest
    don't need to each define the "funcargnames" compatibility attribute.
    """
    @property
    def funcargnames(self):
        """ alias attribute for ``fixturenames`` for pre-2.3 compatibility"""
        return self.fixturenames
