# Copyright 2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.
import errno
import inspect
import os
import socket
import sys

if sys.platform.startswith('win'):
    def rename_file(current_filename, new_filename):
        try:
            os.remove(new_filename)
        except OSError as e:
            if not e.errno == errno.ENOENT:
                # We only want to a ignore trying to remove
                # a file that does not exist.  If it fails
                # for any other reason we should be propagating
                # that exception.
                raise
        os.rename(current_filename, new_filename)
else:
    rename_file = os.rename


def accepts_kwargs(func):
    return inspect.getfullargspec(func)[2]


# In python 3, socket.error is OSError, which is too general
# for what we want (i.e FileNotFoundError is a subclass of OSError).
# In python 3, all the socket related errors are in a newly created
# ConnectionError.
SOCKET_ERROR = ConnectionError
MAXINT = None


def seekable(fileobj):
    """Backwards compat function to determine if a fileobj is seekable

    :param fileobj: The file-like object to determine if seekable

    :returns: True, if seekable. False, otherwise.
    """
    # If the fileobj has a seekable attr, try calling the seekable()
    # method on it.
    if hasattr(fileobj, 'seekable'):
        return fileobj.seekable()
    # If there is no seekable attr, check if the object can be seeked
    # or telled. If it can, try to seek to the current position.
    elif hasattr(fileobj, 'seek') and hasattr(fileobj, 'tell'):
        try:
            fileobj.seek(0, 1)
            return True
        except OSError:
            # If an io related error was thrown then it is not seekable.
            return False
    # Else, the fileobj is not seekable
    return False


def readable(fileobj):
    """Determines whether or not a file-like object is readable.

    :param fileobj: The file-like object to determine if readable

    :returns: True, if readable. False otherwise.
    """
    if hasattr(fileobj, 'readable'):
        return fileobj.readable()

    return hasattr(fileobj, 'read')


def fallocate(fileobj, size):
    if hasattr(os, 'posix_fallocate'):
        os.posix_fallocate(fileobj.fileno(), 0, size)
    else:
        fileobj.truncate(size)


# Import at end of file to avoid circular dependencies
from multiprocessing.managers import BaseManager  # noqa: F401,E402
