// 首先定義一個int類型別名，新類型名稱就是枚舉類型名稱
type KeyboardLayout int
// 然后定義若干常量，作為枚舉值
// 第一個常量是默認值
const (
	UNKNOWN KeyboardLayout = iota
	QWERTZ
	AZERTY
	QWERTY
)
// 再定義setter方法將傳入字符串類型枚舉值轉成上面定義的常量
func (k *KeyboardLayout) StringSetter(value string) {
	switch value {
	case "UNKNOWN":
		*k = UNKNOWN
	case "QWERTY":
		*k = QWERTY
	case "QWERTZ":
		*k = QWERTZ
	case "AZERTY":
		*k = AZERTY
	default:
		*k = UNKNOWN
	}
}
// 有setter自然就有getter
func (k *KeyboardLayout) StringGetter() string {
	switch *k {
	case UNKNOWN:
		return "UNKNOWN"
	case QWERTY:
		return "QWERTY"
	case QWERTZ:
		return "QWERTZ"
	case AZERTY:
		return "AZERTY"
	default:
		return "UNKNOWN"
	}
}
// 最后再定義一組UnmarshalJSON和MarshalJSON方法
// UnmarshalJSON用于json反序列化
func (k *KeyboardLayout) UnmarshalJSON(bytes []byte) error {
	var _k string
	err := json.Unmarshal(bytes, &_k)
	if err != nil {
		return err
	}
	k.StringSetter(_k)
	return nil
}
// MarshalJSON用于json序列化
func (k KeyboardLayout) MarshalJSON() ([]byte, error) {
	return json.Marshal(k.StringGetter())
}

type Keyboard struct {
	Layout  KeyboardLayout `json:"layout,omitempty"`
	Backlit bool            `json:"backlit,omitempty"`
}

type EnumDemo interface {
	GetKeyboard(ctx context.Context, layout vo.KeyboardLayout) (data string, err error)
	GetKeyboard2(ctx context.Context, layout *vo.KeyboardLayout) (data string, err error)
	GetKeyboards(ctx context.Context, layout []vo.KeyboardLayout) (data []string, err error)
	GetKeyboards2(ctx context.Context, layout *[]vo.KeyboardLayout) (data []string, err error)
	GetKeyboards5(ctx context.Context, layout ...vo.KeyboardLayout) (data []string, err error)
	Keyboard(ctx context.Context, keyboard vo.Keyboard) (data string, err error)
}