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#
#  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.
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#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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"""External dependencies loader."""

import glob
import os.path
import sys
import logging

my_dir = os.path.join(os.path.dirname(__file__))
log = logging.getLogger(__name__)


def load_wheel(module_name, fname_prefix):
    """Loads a wheel from 'fname_prefix*.whl', unless the named module can be imported.

    This allows us to use system-installed packages before falling back to the shipped wheels.
    This is useful for development, less so for deployment.
    """

    try:
        module = __import__(module_name)
    except ImportError as ex:
        log.debug('Unable to import %s directly, will try wheel: %s',
                  module_name, ex)
    else:
        log.debug('Was able to load %s from %s, no need to load wheel %s',
                  module_name, module.__file__, fname_prefix)
        return

    path_pattern = os.path.join(my_dir, '%s*.whl' % fname_prefix)
    wheels = glob.glob(path_pattern)
    if not wheels:
        raise RuntimeError('Unable to find wheel at %r' % path_pattern)

    # If there are multiple wheels that match, load the latest one.
    wheels.sort()
    sys.path.append(wheels[-1])
    module = __import__(module_name)
    log.debug('Loaded %s from %s', module_name, module.__file__)


def load_wheels():
    load_wheel('lockfile', 'lockfile')
    load_wheel('cachecontrol', 'CacheControl')
    load_wheel('pillarsdk', 'pillarsdk')