text: from typing import Optional
  from fastapi.exceptions import HTTPException
  import os
  from fastapi import Request
  from fastapi.security.utils import get_authorization_scheme_param
  from jose.exceptions import JWTError
  from starlette.types import Scope, Receive, Send, ASGIApp
  from jose import jwt
  from sqlalchemy.orm import sessionmaker
  from sqlalchemy import create_engine
  from src.opencdms_api import models
  from src.opencdms_api.config import settings
  from src.opencdms_api.db import db_session_scope
  from src.opencdms_api import climsoft_rbac_config
  from src.opencdms_api.schema import CurrentUserSchema
  from opencdms.models.climsoft import v4_1_1_core as climsoft_models
  
  
  class AuthMiddleWare:
      """Middleware for authenticating a request before passing it on
      to the mounted application.
      """
  
      def __init__(self, app: ASGIApp):
          self.app = app
  
      def get_user(self, username: str) -> Optional[CurrentUserSchema]:
          with db_session_scope() as session:
              user: models.AuthUser = (
                  session.query(models.AuthUser)
                  .filter(models.AuthUser.username == username)
                  .one_or_none()
              )
              return CurrentUserSchema.from_orm(user) if user is not None else None
  
      def authenticate_request(self, request: Request):
          authorization_header = request.headers.get("authorization")
          if authorization_header is None:
              raise HTTPException(401, "Unauthorized request")
          scheme, token = get_authorization_scheme_param(authorization_header)
          if scheme.lower() != "bearer":
              raise HTTPException(401, "Invalid authorization header scheme")
          try:
              claims = jwt.decode(token, settings.SURFACE_SECRET_KEY)
          except JWTError:
              raise HTTPException(401, "Unauthorized request")
          username = claims["sub"]
          user = self.get_user(username)
          if user is None:
              raise HTTPException(401, "Unauthorized request")
          return user
  
      async def __call__(self, scope: Scope, receive: Receive, send: Send):
          request = Request(scope, receive, send)
          self.authenticate_request(request)
          await self.app(scope, receive, send)
  
  
  class ClimsoftRBACMiddleware(AuthMiddleWare):
      def __init__(self, app: ASGIApp):
          super().__init__(app)
  
      def get_climsoft_role_for_username(self, username: str):
          climsoft_engine = create_engine(os.getenv("CLIMSOFT_DATABASE_URI"))
          ClimsoftSessionLocal = sessionmaker(climsoft_engine)
          session = ClimsoftSessionLocal()
  
          role = None
  
          try:
              user_role = session.query(climsoft_models.ClimsoftUser).filter_by(userName=username).one_or_none()
              role = user_role.userRole
          except Exception as e:
              pass
  
          session.close()
  
          return role
  
      async def __call__(self, scope: Scope, receive: Receive, send: Send):
          def extract_resource_from_path(string, sep, start, end):
              string = string.split(sep)
              return sep.join(string[start:end])
  
          request = Request(scope, receive, send)
          user = None
          if request.url.path not in {
              "/climsoft",
              "/climsoft/openapi.json",
              "/climsoft/"
          }:
              user = self.authenticate_request(request)
  
          resource_url = extract_resource_from_path(request.url.path, "/", 3, 4)
          required_role = climsoft_rbac_config.required_role_lookup.get(
              resource_url, {}
          ).get(
              request.method.lower()
          )
  
          if (not required_role) or (self.get_climsoft_role_for_username(user.username) in required_role):
              await self.app(scope, receive, send)
          else:
              raise HTTPException(status_code=403)
  
  
  
  
  