Multiple issues addressed (#76)

- Issue #74
- Issue #14

universal_cache_singleton.go

@@ -7,13 +7,14 @@ import (
 
 // UniversalCacheManager manages all cache instances using the universal cache
 type UniversalCacheManager struct {
-	tokenCache     *UniversalCache
-	blacklistCache *UniversalCache
-	metadataCache  *UniversalCache
-	jwkCache       *UniversalCache
-	sessionCache   *UniversalCache
-	mu             sync.RWMutex
-	logger         *Logger
+	tokenCache         *UniversalCache
+	blacklistCache     *UniversalCache
+	metadataCache      *UniversalCache
+	jwkCache           *UniversalCache
+	sessionCache       *UniversalCache
+	introspectionCache *UniversalCache // OAuth 2.0 Token Introspection cache (RFC 7662)
+	mu                 sync.RWMutex
+	logger             *Logger
 }
 
 var (
@@ -85,6 +86,14 @@ func GetUniversalCacheManager(logger *Logger) *UniversalCacheManager {
 			DefaultTTL:     30 * time.Minute,
 			Logger:         logger,
 		})
+
+		// Initialize introspection cache for OAuth 2.0 Token Introspection (RFC 7662)
+		universalCacheManager.introspectionCache = NewUniversalCache(UniversalCacheConfig{
+			Type:       CacheTypeToken,  // Use token cache type for introspection results
+			MaxSize:    1000,            // Cache up to 1000 introspection results
+			DefaultTTL: 5 * time.Minute, // Short TTL for security (introspect frequently)
+			Logger:     logger,
+		})
 	})
 
 	return universalCacheManager
@@ -125,13 +134,20 @@ func (m *UniversalCacheManager) GetSessionCache() *UniversalCache {
 	return m.sessionCache
 }
 
+// GetIntrospectionCache returns the token introspection cache
+func (m *UniversalCacheManager) GetIntrospectionCache() *UniversalCache {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	return m.introspectionCache
+}
+
 // Close shuts down all caches
 func (m *UniversalCacheManager) Close() error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
 	for _, cache := range []*UniversalCache{
-		m.tokenCache, m.blacklistCache, m.metadataCache, m.jwkCache, m.sessionCache,
+		m.tokenCache, m.blacklistCache, m.metadataCache, m.jwkCache, m.sessionCache, m.introspectionCache,
 	} {
 		if cache != nil {
 			cache.Close()