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# Copyright (C) 2005-2010 Aaron Bentley and Panometrics, Inc.
#                         Gianluca Montecchi <gian@grys.it>
#                         W. Trevor King <wking@drexel.edu>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

"""
Assorted utility functions that don't fit in anywhere else.
"""

import calendar
import codecs
import os
import shutil
import tempfile
import time
import types

import libbe
if libbe.TESTING == True:
    import doctest

class InvalidXML(ValueError):
    """Invalid XML while parsing for a `*.from_xml()` method.

    Parameters
    ----------
    type : str
        String identifying `*`, e.g. "bug", "comment", ...
    element : :class:`ElementTree.Element`
        ElementTree.Element instance which caused the error.
    error : str
        Error description.
    """
    def __init__(self, type, element, error):
        msg = 'Invalid %s xml: %s\n  %s\n' \
            % (type, error, ElementTree.tostring(element))
        ValueError.__init__(self, msg)
        self.type = type
        self.element = element
        self.error = error

def search_parent_directories(path, filename):
    """
    Find the file (or directory) named filename in path or in any
    of path's parents.  For example::

         search_parent_directories("/a/b/c", ".be")

    will return the path to the first existing file from::

        /a/b/c/.be
        /a/b/.be
        /a/.be
        /.be

    or `None` if none of those files exist.
    """
    path = os.path.realpath(path)
    assert os.path.exists(path)
    old_path = None
    while True:
        check_path = os.path.join(path, filename)
        if os.path.exists(check_path):
            return check_path
        if path == old_path:
            return None
        old_path = path
        path = os.path.dirname(path)

class Dir (object):
    """A temporary directory for testing use.

    Make sure you run :meth:`cleanup` after you're done using the
    directory.
    """
    def __init__(self):
        self.path = tempfile.mkdtemp(prefix="BEtest")
        self.removed = False
    def cleanup(self):
        if self.removed == False:
            shutil.rmtree(self.path)
            self.removed = True
    def __call__(self):
        return self.path

RFC_2822_TIME_FMT = "%a, %d %b %Y %H:%M:%S +0000"
"""RFC 2822 [#]_ format string for :func:`time.strftime` and
:func:`time.strptime`.

.. [#] See `RFC 2822`_, sections 3.3 and A.1.1.
.. _RFC 2822: http://www.faqs.org/rfcs/rfc2822.html
"""

def time_to_str(time_val):
    """Convert a time number into an RFC 2822-formatted string.

    Parameters
    ----------
    time_val : float
      Float seconds since the Epoc, see :func:`time.time`.
      Note that while `time_val` may contain sub-second data,
      the output string will not.

    Examples
    --------

    >>> time_to_str(0)
    'Thu, 01 Jan 1970 00:00:00 +0000'

    See Also
    --------
    str_to_time : inverse
    handy_time : localtime string
    """
    return time.strftime(RFC_2822_TIME_FMT, time.gmtime(time_val))

def str_to_time(str_time):
    """Convert an RFC 2822-fomatted string into a time value.

    Parameters
    ----------
    str_time : str
      An RFC 2822-formatted string.

    Examples
    --------

    >>> str_to_time("Thu, 01 Jan 1970 00:00:00 +0000")
    0
    >>> q = time.time()
    >>> str_to_time(time_to_str(q)) == int(q)
    True
    >>> str_to_time("Thu, 01 Jan 1970 00:00:00 -1000")
    36000

    See Also
    --------
    time_to_str : inverse
    """
    timezone_str = str_time[-5:]
    if timezone_str != "+0000":
        str_time = str_time.replace(timezone_str, "+0000")
    time_val = calendar.timegm(time.strptime(str_time, RFC_2822_TIME_FMT))
    timesign = -int(timezone_str[0]+"1") # "+" -> time_val ahead of GMT
    timezone_tuple = time.strptime(timezone_str[1:], "%H%M")
    timezone = timezone_tuple.tm_hour*3600 + timezone_tuple.tm_min*60
    return time_val + timesign*timezone

def handy_time(time_val):
    """Convert a time number into a useful localtime.

    Where :func:`time_to_str` returns GMT +0000, `handy_time` returns
    a string in local time.  This may be more accessible for the user.

    Parameters
    ----------
    time_val : float
      Float seconds since the Epoc, see :func:`time.time`.
    """
    return time.strftime("%a, %d %b %Y %H:%M", time.localtime(time_val))

def time_to_gmtime(str_time):
    """Convert an RFC 2822-fomatted string to a GMT string.

    Parameters
    ----------
    str_time : str
      An RFC 2822-formatted string.

    Examples
    --------

    >>> time_to_gmtime("Thu, 01 Jan 1970 00:00:00 -1000")
    'Thu, 01 Jan 1970 10:00:00 +0000'
    """
    time_val = str_to_time(str_time)
    return time_to_str(time_val)

def iterable_full_of_strings(value, alternative=None):
    """Require an iterable full of strings.

    This is useful, for example, in validating `*.extra_strings`.
    See :attr:`libbe.bugdir.BugDir.extra_strings`

    Parameters
    ----------
    value : list or None
      The potential list of strings.
    alternative
      Allow a default (e.g. `None`), such that::

        iterable_full_of_strings(value=x, alternative=x) -> True

    Examples
    --------

    >>> iterable_full_of_strings([])
    True
    >>> iterable_full_of_strings(["abc", "def", u"hij"])
    True
    >>> iterable_full_of_strings(["abc", None, u"hij"])
    False
    >>> iterable_full_of_strings(None, alternative=None)
    True
    """
    if value == alternative:
        return True
    elif not hasattr(value, '__iter__'):
        return False
    for x in value:
        if type(x) not in types.StringTypes:
            return False
    return True

def underlined(string, char='='):
    """Produces a version of a string that is underlined.

    Parameters
    ----------
    string : str
      The string to underline
    char : str
      The character to use for the underlining.

    Examples
    --------

    >>> underlined("Underlined String")
    'Underlined String\\n================='
    """
    assert len(char) == 0, char
    return '%s\n%s' % (string, char*len(string))

if libbe.TESTING == True:
    suite = doctest.DocTestSuite()