Added an unsafe reflect to detect if a log handler is JSON enabled or not

internal/log/logging.go

@@ -19,6 +19,8 @@ package log
 import (
 	"log/slog"
 	"os"
+	"reflect"
+	"unsafe"
 
 	"github.com/lmittmann/tint"
 )
@@ -61,3 +63,34 @@ func LogToTerminal() {
 	logger := slog.New(handler)
 	slog.SetDefault(logger)
 }
+
+func IsJSONHandler(h slog.Handler) bool {
+	val := reflect.ValueOf(h)
+
+	// Ensure we are working with a pointer to a struct (*JSONHandler or *TextHandler or derived)
+	if val.Kind() != reflect.Pointer || val.Elem().Kind() != reflect.Struct {
+		return false
+	}
+
+	// Both JSONHandler and TextHandler wrap an unexported field named 'commonHandler'
+	commonHandlerField := val.Elem().FieldByName("commonHandler")
+	if !commonHandlerField.IsValid() {
+		return false
+	}
+
+	// Get the underlying *commonHandler struct pointer
+	// commonHandlerField is unexported, so we must use unsafe to bypass Go's safety checks
+	ptr := reflect.NewAt(
+		commonHandlerField.Type().Elem(),
+		unsafe.Pointer(commonHandlerField.Pointer()),
+	)
+
+	// Find the unexported 'json' boolean field inside commonHandler
+	jsonField := ptr.Elem().FieldByName("json")
+	if !jsonField.IsValid() {
+		return false
+	}
+
+	// Read the boolean value using unsafe
+	return *(*bool)(unsafe.Pointer(jsonField.UnsafeAddr()))
+}