package copy

import (
	"reflect"
	"time"
)

func CopyInterface(src interface{}) interface{} {
	if src == nil {
		return nil
	}
	original := reflect.ValueOf(src)
	cpy := reflect.New(original.Type()).Elem()
	copyRecursive(original, cpy)

	return cpy.Interface()
}

func copyRecursive(src, dst reflect.Value) {
	switch src.Kind() {
	case reflect.Ptr:
		originalValue := src.Elem()

		if !originalValue.IsValid() {
			return
		}
		dst.Set(reflect.New(originalValue.Type()))
		copyRecursive(originalValue, dst.Elem())

	case reflect.Interface:
		if src.IsNil() {
			return
		}
		originalValue := src.Elem()
		copyValue := reflect.New(originalValue.Type()).Elem()
		copyRecursive(originalValue, copyValue)
		dst.Set(copyValue)

	case reflect.Struct:
		t, ok := src.Interface().(time.Time)
		if ok {
			dst.Set(reflect.ValueOf(t))
			return
		}
		for i := 0; i < src.NumField(); i++ {
			if src.Type().Field(i).PkgPath != "" {
				continue
			}
			copyRecursive(src.Field(i), dst.Field(i))
		}

	case reflect.Slice:
		if src.IsNil() {
			return
		}
		dst.Set(reflect.MakeSlice(src.Type(), src.Len(), src.Cap()))
		for i := 0; i < src.Len(); i++ {
			copyRecursive(src.Index(i), dst.Index(i))
		}

	case reflect.Map:
		if src.IsNil() {
			return
		}
		dst.Set(reflect.MakeMap(src.Type()))
		for _, key := range src.MapKeys() {
			originalValue := src.MapIndex(key)
			copyValue := reflect.New(originalValue.Type()).Elem()
			copyRecursive(originalValue, copyValue)
			copyKey := CopyInterface(key.Interface())
			dst.SetMapIndex(reflect.ValueOf(copyKey), copyValue)
		}

	default:
		dst.Set(src)
	}
}