Chore: improve code architecture

tunnel/mode.go

@@ -0,0 +1,53 @@
+package tunnel
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+type Mode int
+
+var (
+	// ModeMapping is a mapping for Mode enum
+	ModeMapping = map[string]Mode{
+		"Global": Global,
+		"Rule":   Rule,
+		"Direct": Direct,
+	}
+)
+
+const (
+	Global Mode = iota
+	Rule
+	Direct
+)
+
+// UnmarshalJSON unserialize Mode
+func (m *Mode) UnmarshalJSON(data []byte) error {
+	var tp string
+	json.Unmarshal(data, tp)
+	mode, exist := ModeMapping[tp]
+	if !exist {
+		return errors.New("invalid mode")
+	}
+	*m = mode
+	return nil
+}
+
+// MarshalJSON serialize Mode
+func (m Mode) MarshalJSON() ([]byte, error) {
+	return json.Marshal(m.String())
+}
+
+func (m Mode) String() string {
+	switch m {
+	case Global:
+		return "Global"
+	case Rule:
+		return "Rule"
+	case Direct:
+		return "Direct"
+	default:
+		return "Unknow"
+	}
+}