Implementing SAP Security Middleware in Effect Typescript Library

const { createSecurityContext, XsuaaService, SECURITY_CONTEXT, errors: { ValidationError }} = require("@sap/xssec");

const credentials = { clientid, ... } // access service credentials, e.g. via @sap/xsenv
const authService = new XsuaaService(credentials) // or: IdentityService, XsaService, UaaService ...

async function authMiddleware(req, res, next) {
  try {
    const secContext = await createSecurityContext(authService, { req });
    // or: const secContext = await createSecurityContext([xsuaaService, identityService]], { req }); for hybrid authentication
    // user is authenticated -> tie the SecurityContext to this req object via the dedicated Symbol
    req[SECURITY_CONTEXT] = secContext;
    return next();
  } catch (e) {
    // user could not be authenticated
    if(e instanceof ValidationError) {
      // request has invalid authentication (e.g. JWT expired, wrong audience, ...)
      LOG.debug("Unauthenticated request: ", e);
      return res.sendStatus(401);
    } else {
      // authentication could not be validated due to Error
      LOG.error("Error while authenticating user: ", e);
      return res.sendStatus(500);
    }
  }
}
app.use(authMiddleware);