Code sanity fixes, added middlewares

pkg/metrics/interfaces.go

@@ -0,0 +1,68 @@
+package metrics
+
+import (
+	"net/http"
+	"time"
+)
+
+// Provider defines the interface for metric collection
+type Provider interface {
+	// RecordHTTPRequest records metrics for an HTTP request
+	RecordHTTPRequest(method, path, status string, duration time.Duration)
+
+	// IncRequestsInFlight increments the in-flight requests counter
+	IncRequestsInFlight()
+
+	// DecRequestsInFlight decrements the in-flight requests counter
+	DecRequestsInFlight()
+
+	// RecordDBQuery records metrics for a database query
+	RecordDBQuery(operation, table string, duration time.Duration, err error)
+
+	// RecordCacheHit records a cache hit
+	RecordCacheHit(provider string)
+
+	// RecordCacheMiss records a cache miss
+	RecordCacheMiss(provider string)
+
+	// UpdateCacheSize updates the cache size metric
+	UpdateCacheSize(provider string, size int64)
+
+	// Handler returns an HTTP handler for exposing metrics (e.g., /metrics endpoint)
+	Handler() http.Handler
+}
+
+// globalProvider is the global metrics provider
+var globalProvider Provider
+
+// SetProvider sets the global metrics provider
+func SetProvider(p Provider) {
+	globalProvider = p
+}
+
+// GetProvider returns the current metrics provider
+func GetProvider() Provider {
+	if globalProvider == nil {
+		// Return no-op provider if none is set
+		return &NoOpProvider{}
+	}
+	return globalProvider
+}
+
+// NoOpProvider is a no-op implementation of Provider
+type NoOpProvider struct{}
+
+func (n *NoOpProvider) RecordHTTPRequest(method, path, status string, duration time.Duration) {}
+func (n *NoOpProvider) IncRequestsInFlight()                                                  {}
+func (n *NoOpProvider) DecRequestsInFlight()                                                  {}
+func (n *NoOpProvider) RecordDBQuery(operation, table string, duration time.Duration, err error) {
+}
+func (n *NoOpProvider) RecordCacheHit(provider string)            {}
+func (n *NoOpProvider) RecordCacheMiss(provider string)           {}
+func (n *NoOpProvider) UpdateCacheSize(provider string, size int64) {}
+func (n *NoOpProvider) Handler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		w.Write([]byte("Metrics provider not configured"))
+	})
+}