import ldap
import settings
from django.contrib.auth.models import User

class LdapBackend:
    def authenticate(self, username=None, password=None):
        base = settings.AUTH_LDAP_BASE_DN
        filter = '(&(objectclass=person) (uid=%s))' % username
        ret = ['dn', 'mail']

        try:
            l = ldap.initialize(settings.AUTH_LDAP_SERVER_URI)
            l.protocol_version = ldap.VERSION3
        except ldap.LDAPError:
            return None

        try:
            result_id = l.search(base, ldap.SCOPE_SUBTREE, filter, ret)
            result_type, result_data = l.result(result_id, 0)
            if (len(result_data) != 1):
                return None

            l.simple_bind_s(result_data[0][0], password)

            try:
                user = User.objects.get(username__exact=username)
            except:
                user = User.objects.create_user(username, result_data[0][1]['mail'][0])
                user.is_staff = False
                user.save()
            return user
        except ldap.INVALID_CREDENTIALS:
            return None

    def get_user(self, user_id):
        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None