Dynamic Rate Limiting Middleware for Express API

Design a sophisticated rate limiting middleware for an Express.js API that dynamically adjusts rate limits based on user roles, request types, and real-time system load. Implement a token bucket algorithm that can automatically scale limits, with configurable thresholds for admin users, standard users, and guest users. Include adaptive backoff strategies and detailed logging for monitoring potential abuse patterns. The solution should be easily pluggable into existing Express route configurations and provide granular control over different endpoint categories.