logEvent:
  Purpose: Records HTTP GET requests accepting HTML by inserting analytics data into SQLite.
  "Lifecycle Role": Early middleware; logs request details asynchronously before route handlers.
  Dependencies:
    Upstream: []
    Downstream::
      - setupMiddleware
      - Downstream modules using analytics data
  "Data Flow":
    Inputs:
      - req.method
      - req.accepts()
      - req.ip
      - req.connection.remoteAddress
      - req.originalUrl
      - headers: Referer, User-Agent
    Outputs: Inserts new row in analytics SQLite table
    "Side Effects": Database writes with potential I/O latency
  "Performance and Scalability":
    Bottlenecks:
      - SQLite insert failures (DB locked, disk issues)
      - DB write contention under high traffic
      - Missing error handling around db.run
      - No rate limiting or batching of analytics writes
    Concurrency: None
  "Security and Stability":
    Validation: None
    Vulnerabilities:
      - Logging IP addresses raises privacy and GDPR concerns
      - Direct DB writes without async error handling risks silent failures
      - Lack of batching or async queue risks performance degradation
  "Architecture Assessment":
    Coupling: Direct DB interaction; no synchronous middleware communication
    Abstraction: Simple logging middleware, no abstraction layers
    Recommendations:
      - Add async/await or callback error handling for db.run
      - Implement event queue and batch inserts
      - Anonymize or hash IP addresses
      - Offload analytics to dedicated service/process
      - Add rate limiting to middleware

applyProductionSecurity:
  Purpose: Sets HTTP security headers and middleware to harden production environment.
  "Lifecycle Role": Early middleware; applies security headers and request filtering before routes.
  Dependencies:
    Upstream: []
    Downstream:
      - setupMiddleware
  "Data Flow":
    Inputs:
      - HTTP request metadata: method, path, hostname
    Outputs:
      - Modified HTTP response headers
      - Potential HTTP error responses blocking localhost access
    "Side Effects": Blocks requests to localhost hostnames in production
  "Performance and Scalability":
    Bottlenecks:
      - Incorrect hostname matching blocking valid traffic
      - Misconfigured CSP breaking front-end resources
      - No rate limiting reduces DoS protection
    Concurrency: None
  "Security and Stability":
    Validation: CSP directives require careful maintenance
    Vulnerabilities:
      - Missing rate limiting middleware
      - Potential issues blocking localhost in container or proxy setups
  "Architecture Assessment":
    Coupling: Integrates external modules helmet, hpp, custom xssSanitizer
    Abstraction: Middleware chain with composable security layers
    Recommendations:
      - Add rate limiting middleware
      - Validate CSP directives continuously
      - Log blocked requests for monitoring
      - Consider dynamic CSP based on environment or route

authCheck:
  Purpose: Verifies request authentication using cached tokens or external verification; IP whitelist bypass.
  "Lifecycle Role": Early middleware before route handlers; sets req.isAuthenticated flag.
  Dependencies:
    Upstream: []
    Downstream:
      - baseContext
      - controllers and route handlers using req.isAuthenticated
  "Data Flow":
    Inputs:
      - req.headers.cookie
      - req.headers.authorization
      - req.ip
    Outputs:
      - req.isAuthenticated boolean
    "Side Effects":
      - External network request for verification
      - In-memory cache eviction timer
  "Performance and Scalability":
    Bottlenecks:
      - External auth service downtime causes auth failures
      - Cache eviction may cause stale or excessive cache usage
      - IP-based bypass vulnerable to spoofing
    Concurrency: None
  "Security and Stability":
    Validation: Token and IP checks applied
    Vulnerabilities:
      - IP bypass risks unauthorized access
      - No retry or fallback on auth service calls
      - In-memory cache not scalable across instances
  "Architecture Assessment":
    Coupling: External auth endpoint, in-memory cache dependency
    Abstraction: Auth verification abstracted via external service and cache
    Recommendations:
      - Remove or harden IP bypass mechanism
      - Use distributed caching (Redis) for multi-instance
      - Add retries and fallback for auth requests
      - Log auth failures and suspicious IP bypass attempts

baseContext:
  Purpose: Builds base rendering context including authentication status and admin login URL.
  "Lifecycle Role": Runs after auth middleware, before route handlers; prepares data for views.
  Dependencies:
    Upstream:
      - authCheck
      - utilities: getBaseContext, generateToken, qualifyLink
    Downstream:
      - route handlers and views using renderWithBaseContext or renderGenericMessage
  "Data Flow":
    Inputs:
      - req.isAuthenticated
      - request URL for links
    Outputs:
      - Sets res.locals.baseContext
      - Extends res with custom render methods
    "Side Effects": Prepares common template context for downstream rendering
  "Performance and Scalability":
    Bottlenecks:
      - Potential token generation failure
      - Possible async failure in getBaseContext
    Concurrency: None
  "Security and Stability":
    Validation: Secure token generation required
    Vulnerabilities:
      - Risk of leaking sensitive info in base context
  "Architecture Assessment":
    Coupling: Depends on authCheck and utility functions
    Abstraction: Centralized context builder for views
    Recommendations:
      - Validate cryptographic strength of token generator
      - Cache static parts of base context to reduce async overhead

csrfToken:
  Purpose: Provides CSRF protection by setting token cookie and exposing token to templates.
  "Lifecycle Role": Early middleware before state-changing routes requiring CSRF protection.
  Dependencies:
    Upstream: cookie-parser, csurf package
    Downstream: POST or state-changing route handlers
  "Data Flow":
    Inputs:
      - Request cookies and headers
    Outputs:
      - CSRF token cookie
      - res.locals.csrfToken
    "Side Effects": Blocks requests missing valid CSRF tokens
  "Performance and Scalability":
    Bottlenecks:
      - Cookie parsing failure disables protection
      - Incorrect token handling breaks forms
    Concurrency: None
  "Security and Stability":
    Validation: Tokens verified on requests
    Vulnerabilities:
      - Requires secure cookie flags in production
      - Tokens must be unguessable
  "Architecture Assessment":
    Coupling: Middleware integrating third-party packages
    Abstraction: Standard CSRF protection abstraction
    Recommendations:
      - Ensure HttpOnly, Secure flags on cookies in production
      - Handle token expiration gracefully

errorHandler:
  Purpose: Catches errors, logs them, and renders error pages or messages.
  "Lifecycle Role": Final middleware in chain; handles errors from all prior middleware.
  Dependencies:
    Upstream: all routes and middleware
    Downstream: none
  "Data Flow":
    Inputs: Error objects from previous middleware
    Outputs: HTTP error responses with rendered error pages
    "Side Effects": Logs errors to console or persistent logs
  "Performance and Scalability":
    Bottlenecks:
      - Overly generic error messages
      - Missing stack trace logging in production
    Concurrency: None
  "Security and Stability":
    Validation: Sanitizes error output to avoid sensitive info leakage
    Vulnerabilities:
      - Potential info leakage if error messages expose internals
  "Architecture Assessment":
    Coupling: Last middleware, no downstream Dependencies
    Abstraction: Centralized error handling abstraction
    Recommendations:
      - Log errors persistently with context
      - Customize error messages to balance info and security

"Cross Cutting Summary":
  Themes:
    - Most middleware operate early in the lifecycle before route handlers.
    - "Common risk: lack of proper async error handling and logging."
    - Security concerns include IP logging, token management, and bypass risks.
    - Scalability limited by in-memory caches and direct DB writes without batching.
    - Recommendations focus on adding async error handling, queuing, rate limiting, and using distributed caches.
    - Coupling generally low to moderate; dynamic loading and external services introduce risks.
    - Architectural improvements include abstraction of logging, centralized security controls, and fallback strategies for external Dependencies.
