text: # -------------------------------------------------------------------------
  # Copyright (c) Microsoft Corporation. All rights reserved.
  # Licensed under the MIT License. See License.txt in the project root for
  # license information.
  # --------------------------------------------------------------------------
  from ._common_conversion import (
      _sign_string,
  )
  from ._constants import (
      DEV_ACCOUNT_NAME,
      DEV_ACCOUNT_SECONDARY_NAME
  )
  import sys
  if sys.version_info >= (3,):
      from urllib.parse import parse_qsl
  else:
      from urlparse import parse_qsl
  
  
  import logging
  logger = logging.getLogger(__name__)
  
  
  class _StorageSharedKeyAuthentication(object):
      def __init__(self, account_name, account_key, is_emulated=False):
          self.account_name = account_name
          self.account_key = account_key
          self.is_emulated = is_emulated
  
      def _get_headers(self, request, headers_to_sign):
          headers = dict((name.lower(), value) for name, value in request.headers.items() if value)
          if 'content-length' in headers and headers['content-length'] == '0':
              del headers['content-length']
          return '\n'.join(headers.get(x, '') for x in headers_to_sign) + '\n'
  
      def _get_verb(self, request):
          return request.method + '\n'
  
      def _get_canonicalized_resource(self, request):
          uri_path = request.path.split('?')[0]
  
          # for emulator, use the DEV_ACCOUNT_NAME instead of DEV_ACCOUNT_SECONDARY_NAME
          # as this is how the emulator works
          if self.is_emulated and uri_path.find(DEV_ACCOUNT_SECONDARY_NAME) == 1:
              # only replace the first instance
              uri_path = uri_path.replace(DEV_ACCOUNT_SECONDARY_NAME, DEV_ACCOUNT_NAME, 1)
  
          return '/' + self.account_name + uri_path
  
      def _get_canonicalized_headers(self, request):
          string_to_sign = ''
          x_ms_headers = []
          for name, value in request.headers.items():
              if name.startswith('x-ms-'):
                  x_ms_headers.append((name.lower(), value))
          x_ms_headers.sort()
          for name, value in x_ms_headers:
              if value is not None:
                  string_to_sign += ''.join([name, ':', value, '\n'])
          return string_to_sign
  
      def _add_authorization_header(self, request, string_to_sign):
          signature = _sign_string(self.account_key, string_to_sign)
          auth_string = 'SharedKey ' + self.account_name + ':' + signature
          request.headers['Authorization'] = auth_string
  
  
  class _StorageSharedKeyAuthentication(_StorageSharedKeyAuthentication):
      def sign_request(self, request):
          string_to_sign = \
              self._get_verb(request) + \
              self._get_headers(
                  request,
                  [
                      'content-encoding', 'content-language', 'content-length',
                      'content-md5', 'content-type', 'date', 'if-modified-since',
                      'if-match', 'if-none-match', 'if-unmodified-since', 'byte_range'
                  ]
              ) + \
              self._get_canonicalized_headers(request) + \
              self._get_canonicalized_resource(request) + \
              self._get_canonicalized_resource_query(request)
  
          self._add_authorization_header(request, string_to_sign)
          logger.debug("String_to_sign=%s", string_to_sign)
  
      def _get_canonicalized_resource_query(self, request):
          sorted_queries = [(name, value) for name, value in request.query.items()]
          sorted_queries.sort()
  
          string_to_sign = ''
          for name, value in sorted_queries:
              if value is not None:
                  string_to_sign += '\n' + name.lower() + ':' + value
  
          return string_to_sign
  
  
  class _StorageNoAuthentication(object):
      def sign_request(self, request):
          pass
  
  
  class _StorageSASAuthentication(object):
      def __init__(self, sas_token):
          # ignore ?-prefix (added by tools such as Azure Portal) on sas tokens
          # doing so avoids double question marks when signing
          if sas_token[0] == '?':
              sas_token = sas_token[1:]
          self.sas_qs = parse_qsl(sas_token)
  
      def sign_request(self, request):
          # if 'sig=' is present, then the request has already been signed
          # as is the case when performing retries
          if 'sig' in request.query:
              return
  
          request.query.update(self.sas_qs)
  