#!/usr/bin/env python

import psycopg
import Settings

class InvalidDomain(Exception):
  """This Exception is thrown if an invalid domain is used."""
  def __init__(self, domain):
    self.domain = domain
  
  def __str__(self):
    return repr("Invalid domain %s" % (self.domain))

def validate_domain(domain):
  """This function validates whether the given domain is allowed.
  That means that the domain needs to be registered in the database.
  
  If the domain is invalid InvalidDomain is raised."""
  cnx = psycopg.connect("user=%(dbuser)s password=%(dbpassword)s dbname=%(dbname)s" % Settings.dbsettings)
  cr = cnx.cursor()

  cr.execute("SELECT * FROM domain WHERE domainname=%(name)s" %
             {'name': psycopg.QuotedString(domain)})
  cnx.commit()

  result = cr.fetchall()
  if (not result):
    raise InvalidDomain(domain)