from cachetools import lru_cache
from data import model
from util.expiresdict import ExpiresDict, ExpiresEntry
from util.security import jwtutil


class CachingKey(object):
  def __init__(self, service_key):
    self._service_key = service_key
    self._cached_public_key = None

  @property
  def public_key(self):
    cached_key = self._cached_public_key
    if cached_key is not None:
      return cached_key

    # Convert the JWK into a public key and cache it (since the conversion can take > 200ms).
    public_key = jwtutil.jwk_dict_to_public_key(self._service_key.jwk)
    self._cached_public_key = public_key
    return public_key


class InstanceKeys(object):
  """ InstanceKeys defines a helper class for interacting with the Quay instance service keys
      used for JWT signing of registry tokens as well as requests from Quay to other services
      such as Clair. Each container will have a single registered instance key.
  """
  def __init__(self, app):
    self.app = app
    self.instance_keys = ExpiresDict(self._load_instance_keys)

  def clear_cache(self):
    """ Clears the cache of instance keys. """
    self.instance_keys = ExpiresDict(self._load_instance_keys)

  def _load_instance_keys(self):
    # Load all the instance keys.
    keys = {}
    for key in model.service_keys.list_service_keys(self.service_name):
      keys[key.kid] = ExpiresEntry(CachingKey(key), key.expiration_date)

    return keys

  @property
  def service_name(self):
    """ Returns the name of the instance key's service (i.e. 'quay'). """
    return self.app.config['INSTANCE_SERVICE_KEY_SERVICE']

  @property
  def service_key_expiration(self):
    """ Returns the defined expiration for instance service keys, in minutes. """
    return self.app.config.get('INSTANCE_SERVICE_KEY_EXPIRATION', 120)

  @property
  @lru_cache(maxsize=1)
  def local_key_id(self):
    """ Returns the ID of the local instance service key. """
    return _load_file_contents(self.app.config['INSTANCE_SERVICE_KEY_KID_LOCATION'])

  @property
  @lru_cache(maxsize=1)
  def local_private_key(self):
    """ Returns the private key of the local instance service key. """
    return _load_file_contents(self.app.config['INSTANCE_SERVICE_KEY_LOCATION'])

  def get_service_key_public_key(self, kid):
    """ Returns the public key associated with the given instance service key or None if none. """
    caching_key = self.instance_keys.get(kid)
    if caching_key is None:
      return None

    return caching_key.public_key


def _load_file_contents(path):
  """ Returns the contents of the specified file path. """
  with open(path) as f:
    return f.read()