"""
The temp module provides a NamedTemporaryFile that can be reopened in the same
process on any platform. Most platforms use the standard Python
tempfile.NamedTemporaryFile class, but Windows users are given a custom class.

This is needed because the Python implementation of NamedTemporaryFile uses the
O_TEMPORARY flag under Windows, which prevents the file from being reopened
if the same flag is not provided [1][2]. Note that this does not address the
more general issue of opening a file for writing and reading in multiple
processes in a manner that works across platforms.

Also note that the custom version of NamedTemporaryFile does not support the
full range of keyword arguments available in Python 2.6+ and 3.0+.

1: https://mail.python.org/pipermail/python-list/2005-December/336957.html
2: http://bugs.python.org/issue14243
"""

import os
import tempfile

from django.core.files.utils import FileProxyMixin

__all__ = ('NamedTemporaryFile', 'gettempdir',)


if os.name == 'nt':
    class TemporaryFile(FileProxyMixin):
        """
        Temporary file object constructor that supports reopening of the
        temporary file in Windows.

        Note that unlike tempfile.NamedTemporaryFile from the standard library,
        __init__() does not support the 'delete' keyword argument in
        Python 2.6+, or the 'delete', 'buffering', 'encoding', or 'newline'
        keyword arguments in Python 3.0+.
        """
        def __init__(self, mode='w+b', bufsize=-1, suffix='', prefix='', dir=None):
            fd, name = tempfile.mkstemp(suffix=suffix, prefix=prefix, dir=dir)
            self.name = name
            self.file = os.fdopen(fd, mode, bufsize)
            self.close_called = False

        # Because close can be called during shutdown
        # we need to cache os.unlink and access it
        # as self.unlink only
        unlink = os.unlink

        def close(self):
            if not self.close_called:
                self.close_called = True
                try:
                    self.file.close()
                except (OSError, IOError):
                    pass
                try:
                    self.unlink(self.name)
                except (OSError):
                    pass

        @property
        def closed(self):
            """
            This attribute needs to be accessible in certain situations,
            because this class is supposed to mock the API of the class
            tempfile.NamedTemporaryFile in the Python standard library.
            """
            return self.file.closed

        def __del__(self):
            self.close()

        def __enter__(self):
            self.file.__enter__()
            return self

        def __exit__(self, exc, value, tb):
            self.file.__exit__(exc, value, tb)

    NamedTemporaryFile = TemporaryFile
else:
    NamedTemporaryFile = tempfile.NamedTemporaryFile

gettempdir = tempfile.gettempdir
