feat/auth-hook: add post auth hook

internal/misc/credentials.go

@@ -1,6 +1,7 @@
 package misc
 
 import (
+	"encoding/json"
 	"fmt"
 	"path/filepath"
 	"strings"
@@ -24,3 +25,37 @@ func LogSavingCredentials(path string) {
 func LogCredentialSeparator() {
 	log.Debug(credentialSeparator)
 }
+
+// MergeMetadata serializes the source struct into a map and merges the provided metadata into it.
+func MergeMetadata(source any, metadata map[string]any) (map[string]any, error) {
+	var data map[string]any
+
+	// Fast path: if source is already a map, just copy it to avoid mutation of original
+	if srcMap, ok := source.(map[string]any); ok {
+		data = make(map[string]any, len(srcMap)+len(metadata))
+		for k, v := range srcMap {
+			data[k] = v
+		}
+	} else {
+		// Slow path: marshal to JSON and back to map to respect JSON tags
+		temp, err := json.Marshal(source)
+		if err != nil {
+			return nil, fmt.Errorf("failed to marshal source: %w", err)
+		}
+		if err := json.Unmarshal(temp, &data); err != nil {
+			return nil, fmt.Errorf("failed to unmarshal to map: %w", err)
+		}
+	}
+
+	// Merge extra metadata
+	if metadata != nil {
+		if data == nil {
+			data = make(map[string]any)
+		}
+		for k, v := range metadata {
+			data[k] = v
+		}
+	}
+
+	return data, nil
+}