feat: complete contract-driven business development and MySQL integration

config/clone.go

@@ -0,0 +1,81 @@
+package config
+
+import (
+	"errors"
+	"reflect"
+	"strings"
+)
+
+// Clone only configuration data. json:"-" capabilities remain borrowed and
+// are never traversed (log writers, clients and mutex-bearing runtime objects).
+// Unexported immutable implementation details such as time.Time are copied.
+func cloneConfiguration(v reflect.Value, depth int) (reflect.Value, error) {
+	if depth > 64 {
+		return reflect.Value{}, errors.New("config: defaults contain cycles or excessive nesting")
+	}
+	result := reflect.New(v.Type()).Elem()
+	result.Set(v)
+	switch v.Kind() {
+	case reflect.Struct:
+		for i := 0; i < v.NumField(); i++ {
+			field := v.Type().Field(i)
+			if field.PkgPath != "" || strings.Split(field.Tag.Get("json"), ",")[0] == "-" {
+				continue
+			}
+			child, err := cloneConfiguration(v.Field(i), depth+1)
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			result.Field(i).Set(child)
+		}
+	case reflect.Pointer:
+		if !v.IsNil() {
+			child, err := cloneConfiguration(v.Elem(), depth+1)
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			result.Set(reflect.New(v.Type().Elem()))
+			result.Elem().Set(child)
+		}
+	case reflect.Interface:
+		if !v.IsNil() {
+			child, err := cloneConfiguration(v.Elem(), depth+1)
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			result.Set(child)
+		}
+	case reflect.Slice:
+		if !v.IsNil() {
+			result = reflect.MakeSlice(v.Type(), v.Len(), v.Len())
+			for i := 0; i < v.Len(); i++ {
+				child, err := cloneConfiguration(v.Index(i), depth+1)
+				if err != nil {
+					return reflect.Value{}, err
+				}
+				result.Index(i).Set(child)
+			}
+		}
+	case reflect.Array:
+		for i := 0; i < v.Len(); i++ {
+			child, err := cloneConfiguration(v.Index(i), depth+1)
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			result.Index(i).Set(child)
+		}
+	case reflect.Map:
+		if !v.IsNil() {
+			result = reflect.MakeMapWithSize(v.Type(), v.Len())
+			iter := v.MapRange()
+			for iter.Next() {
+				child, err := cloneConfiguration(iter.Value(), depth+1)
+				if err != nil {
+					return reflect.Value{}, err
+				}
+				result.SetMapIndex(iter.Key(), child)
+			}
+		}
+	}
+	return result, nil
+}