text: from datetime import timedelta
  from hashlib import (
      md5,
      sha256,
  )
  import logging
  try:
      from urllib import urlencode
      from urlparse import urlsplit, parse_qs, urlunsplit
  except ImportError:
      from urllib.parse import urlsplit, parse_qs, urlunsplit, urlencode
  from uuid import uuid4
  
  from django.utils import timezone
  
  from oidc_provider.lib.claims import StandardScopeClaims
  from oidc_provider.lib.errors import (
      AuthorizeError,
      ClientIdError,
      RedirectUriError,
  )
  from oidc_provider.lib.utils.token import (
      create_code,
      create_id_token,
      create_token,
      encode_id_token,
  )
  from oidc_provider.models import (
      Client,
      UserConsent,
  )
  from oidc_provider import settings
  from oidc_provider.lib.utils.common import get_browser_state_or_default
  
  logger = logging.getLogger(__name__)
  
  
  class AuthorizeEndpoint(object):
      _allowed_prompt_params = {'none', 'login', 'consent', 'select_account'}
  
      def __init__(self, request):
          self.request = request
          self.params = {}
  
          self._extract_params()
  
          # Determine which flow to use.
          if self.params['response_type'] in ['code']:
              self.grant_type = 'authorization_code'
          elif self.params['response_type'] in ['id_token', 'id_token token', 'token']:
              self.grant_type = 'implicit'
          elif self.params['response_type'] in [
               'code token', 'code id_token', 'code id_token token']:
              self.grant_type = 'hybrid'
          else:
              self.grant_type = None
  
          # Determine if it's an OpenID Authentication request (or OAuth2).
          self.is_authentication = 'openid' in self.params['scope']
  
      def _extract_params(self):
          """
          Get all the params used by the Authorization Code Flow
          (and also for the Implicit and Hybrid).
  
          See: http://openid.net/specs/openid-connect-core-1_0.html#AuthRequest
          """
          # Because in this endpoint we handle both GET
          # and POST request.
          query_dict = (self.request.POST if self.request.method == 'POST'
                        else self.request.GET)
  
          self.params['client_id'] = query_dict.get('client_id', '')
          self.params['redirect_uri'] = query_dict.get('redirect_uri', '')
          self.params['response_type'] = query_dict.get('response_type', '')
          self.params['scope'] = query_dict.get('scope', '').split()
          self.params['state'] = query_dict.get('state', '')
          self.params['nonce'] = query_dict.get('nonce', '')
  
          self.params['prompt'] = self._allowed_prompt_params.intersection(
              set(query_dict.get('prompt', '').split()))
  
          self.params['code_challenge'] = query_dict.get('code_challenge', '')
          self.params['code_challenge_method'] = query_dict.get('code_challenge_method', '')
  
      def validate_params(self):
          # Client validation.
          try:
              self.client = Client.objects.get(client_id=self.params['client_id'])
          except Client.DoesNotExist:
              logger.debug('[Authorize] Invalid client identifier: %s', self.params['client_id'])
              raise ClientIdError()
  
          # Redirect URI validation.
          if self.is_authentication and not self.params['redirect_uri']:
              logger.debug('[Authorize] Missing redirect uri.')
              raise RedirectUriError()
          if not (self.params['redirect_uri'] in self.client.redirect_uris):
              logger.debug('[Authorize] Invalid redirect uri: %s', self.params['redirect_uri'])
              raise RedirectUriError()
  
          # Grant type validation.
          if not self.grant_type:
              logger.debug('[Authorize] Invalid response type: %s', self.params['response_type'])
              raise AuthorizeError(
                  self.params['redirect_uri'], 'unsupported_response_type', self.grant_type)
  
          if (not self.is_authentication and (self.grant_type == 'hybrid' or
             self.params['response_type'] in ['id_token', 'id_token token'])):
              logger.debug('[Authorize] Missing openid scope.')
              raise AuthorizeError(self.params['redirect_uri'], 'invalid_scope', self.grant_type)
  
          # Nonce parameter validation.
          if self.is_authentication and self.grant_type == 'implicit' and not self.params['nonce']:
              raise AuthorizeError(self.params['redirect_uri'], 'invalid_request', self.grant_type)
  
          # Response type parameter validation.
          if self.is_authentication and self.params['response_type'] != self.client.response_type:
              raise AuthorizeError(self.params['redirect_uri'], 'invalid_request', self.grant_type)
  
          # PKCE validation of the transformation method.
          if self.params['code_challenge']:
              if not (self.params['code_challenge_method'] in ['plain', 'S256']):
                  raise AuthorizeError(
                      self.params['redirect_uri'], 'invalid_request', self.grant_type)
  
      def create_response_uri(self):
          uri = urlsplit(self.params['redirect_uri'])
          query_params = parse_qs(uri.query)
          query_fragment = {}
  
          try:
              if self.grant_type in ['authorization_code', 'hybrid']:
                  code = create_code(
                      user=self.request.user,
                      client=self.client,
                      scope=self.params['scope'],
                      nonce=self.params['nonce'],
                      is_authentication=self.is_authentication,
                      code_challenge=self.params['code_challenge'],
                      code_challenge_method=self.params['code_challenge_method'])
                  code.save()
  
              if self.grant_type == 'authorization_code':
                  query_params['code'] = code.code
                  query_params['state'] = self.params['state'] if self.params['state'] else ''
              elif self.grant_type in ['implicit', 'hybrid']:
                  token = create_token(
                      user=self.request.user,
                      client=self.client,
                      scope=self.params['scope'])
  
                  # Check if response_type must include access_token in the response.
                  if (self.params['response_type'] in
                     ['id_token token', 'token', 'code token', 'code id_token token']):
                      query_fragment['access_token'] = token.access_token
  
                  # We don't need id_token if it's an OAuth2 request.
                  if self.is_authentication:
                      kwargs = {
                          'token': token,
                          'user': self.request.user,
                          'aud': self.client.client_id,
                          'nonce': self.params['nonce'],
                          'request': self.request,
                          'scope': self.params['scope'],
                      }
                      # Include at_hash when access_token is being returned.
                      if 'access_token' in query_fragment:
                          kwargs['at_hash'] = token.at_hash
                      id_token_dic = create_id_token(**kwargs)
  
                      # Check if response_type must include id_token in the response.
                      if self.params['response_type'] in [
                              'id_token', 'id_token token', 'code id_token', 'code id_token token']:
                          query_fragment['id_token'] = encode_id_token(id_token_dic, self.client)
                  else:
                      id_token_dic = {}
  
                  # Store the token.
                  token.id_token = id_token_dic
                  token.save()
  
                  # Code parameter must be present if it's Hybrid Flow.
                  if self.grant_type == 'hybrid':
                      query_fragment['code'] = code.code
  
                  query_fragment['token_type'] = 'bearer'
  
                  query_fragment['expires_in'] = settings.get('OIDC_TOKEN_EXPIRE')
  
                  query_fragment['state'] = self.params['state'] if self.params['state'] else ''
  
              if settings.get('OIDC_SESSION_MANAGEMENT_ENABLE'):
                  # Generate client origin URI from the redirect_uri param.
                  redirect_uri_parsed = urlsplit(self.params['redirect_uri'])
                  client_origin = '{0}://{1}'.format(
                      redirect_uri_parsed.scheme, redirect_uri_parsed.netloc)
  
                  # Create random salt.
                  salt = md5(uuid4().hex.encode()).hexdigest()
  
                  # The generation of suitable Session State values is based
                  # on a salted cryptographic hash of Client ID, origin URL,
                  # and OP browser state.
                  session_state = '{client_id} {origin} {browser_state} {salt}'.format(
                      client_id=self.client.client_id,
                      origin=client_origin,
                      browser_state=get_browser_state_or_default(self.request),
                      salt=salt)
                  session_state = sha256(session_state.encode('utf-8')).hexdigest()
                  session_state += '.' + salt
                  if self.grant_type == 'authorization_code':
                      query_params['session_state'] = session_state
                  elif self.grant_type in ['implicit', 'hybrid']:
                      query_fragment['session_state'] = session_state
  
          except Exception as error:
              logger.exception('[Authorize] Error when trying to create response uri: %s', error)
              raise AuthorizeError(self.params['redirect_uri'], 'server_error', self.grant_type)
  
          uri = uri._replace(
              query=urlencode(query_params, doseq=True),
              fragment=uri.fragment + urlencode(query_fragment, doseq=True))
  
          return urlunsplit(uri)
  
      def set_client_user_consent(self):
          """
          Save the user consent given to a specific client.
  
          Return None.
          """
          date_given = timezone.now()
          expires_at = date_given + timedelta(
              days=settings.get('OIDC_SKIP_CONSENT_EXPIRE'))
  
          uc, created = UserConsent.objects.get_or_create(
              user=self.request.user,
              client=self.client,
              defaults={
                  'expires_at': expires_at,
                  'date_given': date_given,
              }
          )
          uc.scope = self.params['scope']
  
          # Rewrite expires_at and date_given if object already exists.
          if not created:
              uc.expires_at = expires_at
              uc.date_given = date_given
  
          uc.save()
  
      def client_has_user_consent(self):
          """
          Check if already exists user consent for some client.
  
          Return bool.
          """
          value = False
          try:
              uc = UserConsent.objects.get(user=self.request.user, client=self.client)
              if (set(self.params['scope']).issubset(uc.scope)) and not (uc.has_expired()):
                  value = True
          except UserConsent.DoesNotExist:
              pass
  
          return value
  
      def get_scopes_information(self):
          """
          Return a list with the description of all the scopes requested.
          """
          scopes = StandardScopeClaims.get_scopes_info(self.params['scope'])
          if settings.get('OIDC_EXTRA_SCOPE_CLAIMS'):
              scopes_extra = settings.get(
                  'OIDC_EXTRA_SCOPE_CLAIMS', import_str=True).get_scopes_info(self.params['scope'])
              for index_extra, scope_extra in enumerate(scopes_extra):
                  for index, scope in enumerate(scopes[:]):
                      if scope_extra['scope'] == scope['scope']:
                          del scopes[index]
          else:
              scopes_extra = []
  
          return scopes + scopes_extra
  