# Authors:
#   Jason Gerard DeRose <jderose@redhat.com>
#
# Copyright (C) 2008  Red Hat
# see file 'COPYING' for use and warranty information
#
# 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; version 2 only
#
# 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

"""
Various utility functions.
"""

import os
import imp
import logging
import time
import socket
import re
from types import NoneType

from ipalib import errors
from ipapython import dnsclient


def json_serialize(obj):
    if isinstance(obj, (list, tuple)):
        return [json_serialize(o) for o in obj]
    if isinstance(obj, dict):
        return dict((k, json_serialize(v)) for (k, v) in obj.iteritems())
    if isinstance(obj, (bool, float, int, unicode, NoneType)):
        return obj
    if isinstance(obj, str):
        return obj.decode('utf-8')
    if not callable(getattr(obj, '__json__', None)):
        # raise TypeError('%r is not JSON serializable')
        return ''
    return json_serialize(obj.__json__())

def get_current_principal():
    try:
        # krbV isn't necessarily available on client machines, fail gracefully
        import krbV
        return unicode(krbV.default_context().default_ccache().principal().name)
    except ImportError:
        raise RuntimeError('python-krbV is not available.')
    except krbV.Krb5Error:
        #TODO: do a kinit?
        raise errors.CCacheError()

def get_fqdn():
    fqdn = ""
    try:
        fqdn = socket.getfqdn()
    except:
        try:
            fqdn = socket.gethostname()
        except:
            fqdn = ""
    return fqdn

# FIXME: This function has no unit test
def find_modules_in_dir(src_dir):
    """
    Iterate through module names found in ``src_dir``.
    """
    if not (os.path.abspath(src_dir) == src_dir and os.path.isdir(src_dir)):
        return
    if os.path.islink(src_dir):
        return
    suffix = '.py'
    for name in sorted(os.listdir(src_dir)):
        if not name.endswith(suffix):
            continue
        pyfile = os.path.join(src_dir, name)
        if os.path.islink(pyfile) or not os.path.isfile(pyfile):
            continue
        module = name[:-len(suffix)]
        if module == '__init__':
            continue
        yield (module, pyfile)


# FIXME: This function has no unit test
def load_plugins_in_dir(src_dir):
    """
    Import each Python module found in ``src_dir``.
    """
    for module in find_modules_in_dir(src_dir):
        imp.load_module(module, *imp.find_module(module, [src_dir]))


# FIXME: This function has no unit test
def import_plugins_subpackage(name):
    """
    Import everythig in ``plugins`` sub-package of package named ``name``.
    """
    try:
        plugins = __import__(name + '.plugins').plugins
    except ImportError:
        return
    src_dir = os.path.dirname(os.path.abspath(plugins.__file__))
    for name in find_modules_in_dir(src_dir):
        full_name = '%s.%s' % (plugins.__name__, name)
        __import__(full_name)


class LogFormatter(logging.Formatter):
    """
    Log formatter that uses UTC for all timestamps.
    """
    converter = time.gmtime


def make_repr(name, *args, **kw):
    """
    Construct a standard representation of a class instance.
    """
    args = [repr(a) for a in args]
    kw = ['%s=%r' % (k, kw[k]) for k in sorted(kw)]
    return '%s(%s)' % (name, ', '.join(args + kw))

def realm_to_suffix(realm_name):
    s = realm_name.split(".")
    terms = ["dc=" + x.lower() for x in s]
    return ",".join(terms)

def validate_host_dns(log, fqdn):
    """
    See if the hostname has a DNS A record.
    """
    rs = dnsclient.query(fqdn + '.', dnsclient.DNS_C_IN, dnsclient.DNS_T_A)
    if len(rs) == 0:
        log.debug(
            'IPA: DNS A record lookup failed for %s' % fqdn
        )
        raise errors.DNSNotARecordError()
    else:
        log.debug(
            'IPA: found %d records for %s' % (len(rs), fqdn)
        )

def isvalid_base64(data):
    """
    Validate the incoming data as valid base64 data or not.

    The character set must only include of a-z, A-Z, 0-9, + or / and
    be padded with = to be a length divisible by 4 (so only 0-2 =s are
    allowed). Its length must be divisible by 4. White space is
    not significant so it is removed.

    This doesn't guarantee we have a base64-encoded value, just that it
    fits the base64 requirements.
    """

    data = ''.join(data.split())

    if len(data) % 4 > 0 or \
        re.match('^[a-zA-Z0-9\+\/]+\={0,2}$', data) is None:
        return False
    else:
        return True