text: # Copyright 2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License"). You
  # may not use this file except in compliance with the License. A copy of
  # the License is located at
  #
  # http://aws.amazon.com/apache2.0/
  #
  # or in the "license" file accompanying this file. This file 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.
  """Resolves regions and endpoints.
  
  This module implements endpoint resolution, including resolving endpoints for a
  given service and region and resolving the available endpoints for a service
  in a specific AWS partition.
  """
  import logging
  import re
  
  from botocore.exceptions import NoRegionError
  
  LOG = logging.getLogger(__name__)
  DEFAULT_URI_TEMPLATE = '{service}.{region}.{dnsSuffix}'
  DEFAULT_SERVICE_DATA = {'endpoints': {}}
  
  
  class BaseEndpointResolver(object):
      """Resolves regions and endpoints. Must be subclassed."""
      def construct_endpoint(self, service_name, region_name=None):
          """Resolves an endpoint for a service and region combination.
  
          :type service_name: string
          :param service_name: Name of the service to resolve an endpoint for
              (e.g., s3)
  
          :type region_name: string
          :param region_name: Region/endpoint name to resolve (e.g., us-east-1)
              if no region is provided, the first found partition-wide endpoint
              will be used if available.
  
          :rtype: dict
          :return: Returns a dict containing the following keys:
              - partition: (string, required) Resolved partition name
              - endpointName: (string, required) Resolved endpoint name
              - hostname: (string, required) Hostname to use for this endpoint
              - sslCommonName: (string) sslCommonName to use for this endpoint.
              - credentialScope: (dict) Signature version 4 credential scope
                - region: (string) region name override when signing.
                - service: (string) service name override when signing.
              - signatureVersions: (list<string>) A list of possible signature
                versions, including s3, v4, v2, and s3v4
              - protocols: (list<string>) A list of supported protocols
                (e.g., http, https)
              - ...: Other keys may be included as well based on the metadata
          """
          raise NotImplementedError
  
      def get_available_partitions(self):
          """Lists the partitions available to the endpoint resolver.
  
          :return: Returns a list of partition names (e.g., ["aws", "aws-cn"]).
          """
          raise NotImplementedError
  
      def get_available_endpoints(self, service_name, partition_name='aws',
                                  allow_non_regional=False):
          """Lists the endpoint names of a particular partition.
  
          :type service_name: string
          :param service_name: Name of a service to list endpoint for (e.g., s3)
  
          :type partition_name: string
          :param partition_name: Name of the partition to limit endpoints to.
              (e.g., aws for the public AWS endpoints, aws-cn for AWS China
              endpoints, aws-us-gov for AWS GovCloud (US) Endpoints, etc.
  
          :type allow_non_regional: bool
          :param allow_non_regional: Set to True to include endpoints that are
               not regional endpoints (e.g., s3-external-1,
               fips-us-gov-west-1, etc).
          :return: Returns a list of endpoint names (e.g., ["us-east-1"]).
          """
          raise NotImplementedError
  
  
  class EndpointResolver(BaseEndpointResolver):
      """Resolves endpoints based on partition endpoint metadata"""
      def __init__(self, endpoint_data):
          """
          :param endpoint_data: A dict of partition data.
          """
          if 'partitions' not in endpoint_data:
              raise ValueError('Missing "partitions" in endpoint data')
          self._endpoint_data = endpoint_data
  
      def get_available_partitions(self):
          result = []
          for partition in self._endpoint_data['partitions']:
              result.append(partition['partition'])
          return result
  
      def get_available_endpoints(self, service_name, partition_name='aws',
                                  allow_non_regional=False):
          result = []
          for partition in self._endpoint_data['partitions']:
              if partition['partition'] != partition_name:
                  continue
              services = partition['services']
              if service_name not in services:
                  continue
              for endpoint_name in services[service_name]['endpoints']:
                  if allow_non_regional or endpoint_name in partition['regions']:
                      result.append(endpoint_name)
          return result
  
      def get_partition_dns_suffix(self, partition_name):
          for partition in self._endpoint_data['partitions']:
              if partition['partition'] == partition_name:
                  return partition['dnsSuffix']
          return None
  
      def construct_endpoint(self, service_name, region_name=None, partition_name=None):
          if partition_name is not None:
              valid_partition = None
              for partition in self._endpoint_data['partitions']:
                  if partition['partition'] == partition_name:
                      valid_partition = partition
  
              if valid_partition is not None:
                  result = self._endpoint_for_partition(valid_partition, service_name,
                               region_name, True)
                  return result
              return None
  
          # Iterate over each partition until a match is found.
          for partition in self._endpoint_data['partitions']:
              result = self._endpoint_for_partition(
                  partition, service_name, region_name)
              if result:
                  return result
  
      def _endpoint_for_partition(self, partition, service_name, region_name,
              force_partition=False):
          # Get the service from the partition, or an empty template.
          service_data = partition['services'].get(
              service_name, DEFAULT_SERVICE_DATA)
          # Use the partition endpoint if no region is supplied.
          if region_name is None:
              if 'partitionEndpoint' in service_data:
                  region_name = service_data['partitionEndpoint']
              else:
                  raise NoRegionError()
          # Attempt to resolve the exact region for this partition.
          if region_name in service_data['endpoints']:
              return self._resolve(
                  partition, service_name, service_data, region_name)
          # Check to see if the endpoint provided is valid for the partition.
          if self._region_match(partition, region_name) or force_partition:
              # Use the partition endpoint if set and not regionalized.
              partition_endpoint = service_data.get('partitionEndpoint')
              is_regionalized = service_data.get('isRegionalized', True)
              if partition_endpoint and not is_regionalized:
                  LOG.debug('Using partition endpoint for %s, %s: %s',
                            service_name, region_name, partition_endpoint)
                  return self._resolve(
                      partition, service_name, service_data, partition_endpoint)
              LOG.debug('Creating a regex based endpoint for %s, %s',
                        service_name, region_name)
              return self._resolve(
                  partition, service_name, service_data, region_name)
  
      def _region_match(self, partition, region_name):
          if region_name in partition['regions']:
              return True
          if 'regionRegex' in partition:
              return re.compile(partition['regionRegex']).match(region_name)
          return False
  
      def _resolve(self, partition, service_name, service_data, endpoint_name):
          result = service_data['endpoints'].get(endpoint_name, {})
          result['partition'] = partition['partition']
          result['endpointName'] = endpoint_name
          # Merge in the service defaults then the partition defaults.
          self._merge_keys(service_data.get('defaults', {}), result)
          self._merge_keys(partition.get('defaults', {}), result)
          hostname = result.get('hostname', DEFAULT_URI_TEMPLATE)
          result['hostname'] = self._expand_template(
              partition, result['hostname'], service_name, endpoint_name)
          if 'sslCommonName' in result:
              result['sslCommonName'] = self._expand_template(
                  partition, result['sslCommonName'], service_name,
                  endpoint_name)
          result['dnsSuffix'] = partition['dnsSuffix']
          return result
  
      def _merge_keys(self, from_data, result):
          for key in from_data:
              if key not in result:
                  result[key] = from_data[key]
  
      def _expand_template(self, partition, template, service_name,
                           endpoint_name):
          return template.format(
              service=service_name, region=endpoint_name,
              dnsSuffix=partition['dnsSuffix'])
  