text: # Copyright 2012-2018 CERN for the benefit of the ATLAS collaboration.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  #
  # Authors:
  # - Vincent Garonne <vgaronne@gmail.com>, 2012-2018
  # - Cedric Serfon <cedric.serfon@cern.ch>, 2014
  # - Ralph Vigne <ralph.vigne@cern.ch>, 2015
  # - Brian Bockelman <bbockelm@cse.unl.edu>, 2018
  # - Martin Barisits <martin.barisits@cern.ch>, 2018
  #
  # PY3K COMPATIBLE
  
  try:
      from urllib import quote_plus
  except ImportError:
      from urllib.parse import quote_plus
  
  from json import dumps, loads
  
  from requests.status_codes import codes
  
  from rucio.client.baseclient import BaseClient
  from rucio.client.baseclient import choice
  from rucio.common.utils import build_url
  
  
  class MetaClient(BaseClient):
  
      """Meta client class for working with data identifier attributes"""
  
      META_BASEURL = 'meta'
  
      def __init__(self, rucio_host=None, auth_host=None, account=None, ca_cert=None, auth_type=None, creds=None, timeout=600, user_agent='rucio-clients'):
          super(MetaClient, self).__init__(rucio_host, auth_host, account, ca_cert, auth_type, creds, timeout, user_agent)
  
      def add_key(self, key, key_type, value_type=None, value_regexp=None):
          """
          Sends the request to add a new key.
  
          :param key: the name for the new key.
          :param key_type: the type of the key: all(container, dataset, file), collection(dataset or container), file, derived(compute from file for collection).
          :param value_type: the type of the value, if defined.
          :param value_regexp: the regular expression that values should match, if defined.
  
          :return: True if key was created successfully.
          :raises Duplicate: if key already exists.
          """
  
          path = '/'.join([self.META_BASEURL, quote_plus(key)])
          url = build_url(choice(self.list_hosts), path=path)
          data = dumps({'value_type': value_type and str(value_type),
                        'value_regexp': value_regexp,
                        'key_type': key_type})
  
          r = self._send_request(url, type='POST', data=data)
  
          if r.status_code == codes.created:
              return True
          else:
              exc_cls, exc_msg = self._get_exception(headers=r.headers, status_code=r.status_code, data=r.content)
              raise exc_cls(exc_msg)
  
      def list_keys(self):
          """
          Sends the request to list all keys.
  
          :return: a list containing the names of all keys.
          """
          path = self.META_BASEURL + '/'
          url = build_url(choice(self.list_hosts), path=path)
          r = self._send_request(url)
          if r.status_code == codes.ok:
              keys = loads(r.text)
              return keys
          else:
              exc_cls, exc_msg = self._get_exception(headers=r.headers, status_code=r.status_code, data=r.content)
              raise exc_cls(exc_msg)
  
      def list_values(self, key):
          """
          Sends the request to list all values for a key.
  
          :return: a list containing the names of all values for a key.
          """
          path = '/'.join([self.META_BASEURL, quote_plus(key)]) + '/'
          url = build_url(choice(self.list_hosts), path=path)
          r = self._send_request(url)
          if r.status_code == codes.ok:
              values = loads(r.text)
              return values
          else:
              exc_cls, exc_msg = self._get_exception(headers=r.headers, status_code=r.status_code, data=r.content)
              raise exc_cls(exc_msg)
  
      def add_value(self, key, value):
          """
          Sends the request to add a value to a key.
  
          :param key: the name for key.
          :param value: the value.
  
          :return: True if value was created successfully.
          :raises Duplicate: if valid already exists.
          """
  
          path = '/'.join([self.META_BASEURL, quote_plus(key)]) + '/'
          data = dumps({'value': value})
          url = build_url(choice(self.list_hosts), path=path)
          r = self._send_request(url, type='POST', data=data)
          if r.status_code == codes.created:
              return True
          else:
              exc_cls, exc_msg = self._get_exception(headers=r.headers, status_code=r.status_code, data=r.content)
              raise exc_cls(exc_msg)
  
      def del_value(self, key, value):
          """
          Delete a value for a key.
  
          :param key: the name for key.
          :param value: the value.
          """
          pass
  
      def del_key(self, key):
          """
          Delete an allowed key.
  
          :param key: the name for key.
          """
          pass
  
      def update_key(self, key, type=None, regepx=None):
          """
          Update a key.
  
          :param key: the name for key.
          :param type: the type of the value, if defined.
          :param regexp: the regular expression that values should match, if defined.
          """
          pass
  