feat: add system setting to allow user signup (#407)

api/system_setting.go

@@ -0,0 +1,70 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type SystemSettingName string
+
+const (
+	// SystemSettingAllowSignUpName is the key type of allow signup setting.
+	SystemSettingAllowSignUpName SystemSettingName = "allowSignUp"
+	SystemSettingPlaceholderName SystemSettingName = "placeholder"
+)
+
+func (key SystemSettingName) String() string {
+	switch key {
+	case SystemSettingAllowSignUpName:
+		return "allowSignUp"
+	case SystemSettingPlaceholderName:
+		return "placeholder"
+	}
+	return ""
+}
+
+var (
+	SystemSettingAllowSignUpValue = []bool{true, false}
+)
+
+type SystemSetting struct {
+	Name SystemSettingName
+	// Value is a JSON string with basic value
+	Value       string
+	Description string
+}
+
+type SystemSettingUpsert struct {
+	Name        SystemSettingName `json:"name"`
+	Value       string            `json:"value"`
+	Description string            `json:"description"`
+}
+
+func (upsert SystemSettingUpsert) Validate() error {
+	if upsert.Name == SystemSettingAllowSignUpName {
+		value := false
+		err := json.Unmarshal([]byte(upsert.Value), &value)
+		if err != nil {
+			return fmt.Errorf("failed to unmarshal system setting allow signup value")
+		}
+
+		invalid := true
+		for _, v := range SystemSettingAllowSignUpValue {
+			if value == v {
+				invalid = false
+				break
+			}
+		}
+		if invalid {
+			return fmt.Errorf("invalid system setting allow signup value")
+		}
+	} else {
+		return fmt.Errorf("invalid system setting name")
+	}
+
+	return nil
+}
+
+type SystemSettingFind struct {
+	Name *SystemSettingName `json:"name"`
+}