from abc import ABCMeta, abstractmethod
from collections import namedtuple

from six import add_metaclass

import data.model


class ServiceKey(namedtuple('ServiceKey', ['name', 'kid', 'service', 'jwk', 'metadata',
                                           'created_date', 'expiration_date', 'rotation_duration',
                                           'approval'])):
  """
  Service Key represents a public key (JWK) being used by an instance of a particular service to
  authenticate with other services.
  """
  pass


class ServiceKeyException(Exception):
  pass


class ServiceKeyDoesNotExist(ServiceKeyException):
  pass


# TODO(jzelinskie): maybe make this interface support superuser API
@add_metaclass(ABCMeta)
class KeyServerDataInterface(object):
  """
  Interface that represents all data store interactions required by a JWT key service.
  """

  @abstractmethod
  def list_service_keys(self, service):
    """
    Returns a list of service keys or an empty list if the service does not exist.
    """
    pass

  @abstractmethod
  def get_service_key(self, signer_kid, service=None, alive_only=None, approved_only=None):
    """
    Returns a service kid with the given kid or raises ServiceKeyNotFound.
    """
    pass

  @abstractmethod
  def create_service_key(self, name, kid, service, jwk, metadata, expiration_date,
                         rotation_duration=None):
    """
    Stores a service key.
    """
    pass

  @abstractmethod
  def replace_service_key(self, old_kid, kid, jwk, metadata, expiration_date):
    """
    Replaces a service with a new key or raises ServiceKeyNotFound.
    """
    pass

  @abstractmethod
  def delete_service_key(self, kid):
    """
    Deletes and returns a service key with the given kid or raises ServiceKeyNotFound.
    """
    pass


class PreOCIModel(KeyServerDataInterface):
  """
  PreOCIModel implements the data model for JWT key service using a database schema before it was
  changed to support the OCI specification.
  """
  def list_service_keys(self, service):
    return data.model.service_keys.list_service_keys(service)

  def get_service_key(self, signer_kid, service=None, alive_only=True, approved_only=True):
    try:
      key = data.model.service_keys.get_service_key(signer_kid, service, alive_only, approved_only)
      return _db_key_to_servicekey(key)
    except data.model.ServiceKeyDoesNotExist:
      raise ServiceKeyDoesNotExist()

  def create_service_key(self, name, kid, service, jwk, metadata, expiration_date,
                         rotation_duration=None):
    key = data.model.service_keys.create_service_key(name, kid, service, jwk, metadata,
                                                     expiration_date, rotation_duration)
    return _db_key_to_servicekey(key)

  def replace_service_key(self, old_kid, kid, jwk, metadata, expiration_date):
    try:
      data.model.service_keys.replace_service_key(old_kid, kid, jwk, metadata, expiration_date)
    except data.model.ServiceKeyDoesNotExist:
      raise ServiceKeyDoesNotExist()

  def delete_service_key(self, kid):
    try:
      key = data.model.service_keys.delete_service_key(kid)
      return _db_key_to_servicekey(key)
    except data.model.ServiceKeyDoesNotExist:
      raise ServiceKeyDoesNotExist()


pre_oci_model = PreOCIModel()


def _db_key_to_servicekey(key):
  """
  Converts the Pre-OCI database model of a service key into a ServiceKey.
  """
  return ServiceKey(
    name=key.name,
    kid=key.kid,
    service=key.service,
    jwk=key.jwk,
    metadata=key.metadata,
    created_date=key.created_date,
    expiration_date=key.expiration_date,
    rotation_duration=key.rotation_duration,
    approval=key.approval,
  )