class User(db.Model):
  email = db.EmailProperty()
  salt = db.StringProperty()
  password = db.StringProperty()
  first_name = db.StringProperty()
  last_name = db.StringProperty()
  organization = db.ReferenceProperty(Organization)
  stati = db.StringListProperty()
  ORDERING = ('last_name', 'first_name')
  USEFUL_FIELDS = (
      'email',
      'salt',
      'password',
      'first_name',
      'last_name',
      'stati')

  @staticmethod
  def generate_password(plaintext_pwd = None):
    if plaintext_pwd is None:
      pwd = []
      for i in range(16):
        pwd.append(random.choice(salt_chars))
      plaintext_pwd = ''.join(pwd)
      del pwd
    salt = []
    for i in xrange(64):
      salt.append(random.choice(salt_chars))
    salt = ''.join(salt)
    return (salt, hashlib.sha512(salt + plaintext_pwd).hexdigest(), plaintext_pwd)

  @staticmethod
  def get_user(email, password):
    user = User.all().filter('email =', email).filter('stati =', 'active').get()
    if user is None:
      return None
    salt = user.salt
    candidate_hash = hashlib.sha512(salt + password).hexdigest()
    if user.password == candidate_hash:
      return user
    else:
      return None