#!/usr/bin/python

# Unix SMB/CIFS implementation.
# Copyright (C) Andrew Tridgell 2010
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#

import sys, os

def samba_find_external(directory):
    '''insert into out module search path the path to an
       external library'''
    for p in sys.path:
        dir = os.path.join(p, directory)
        if os.path.isdir(dir):
            sys.path.insert(0, dir)
            return

    # finally try in the local directory, to handle in-tree testing
    dir = os.path.join("scripting/python", directory)
    if os.path.isdir(dir):
        sys.path.insert(0, dir)
        return

    print "Failed to find external python library %s" % directory
    raise


def samba_external_dns_resolver():
    '''try and import the dns.resolver library, and if it fails
    then use a local copy from the external directory'''

    try:
        import dns.resolver as dns
    except:
        samba_find_external("samba_external/dnspython")
        import dns.resolver as dns
    return dns