Add dashboard support for API service

option/api.go

@@ -1,11 +1,50 @@
 package option
 
-import "github.com/sagernet/sing/common/json/badoption"
+import (
+	"github.com/sagernet/sing/common/json"
+	"github.com/sagernet/sing/common/json/badoption"
+)
 
 type APIServiceOptions struct {
 	ListenOptions
 	Secret                           string                     `json:"secret,omitempty"`
 	AccessControlAllowOrigin         badoption.Listable[string] `json:"access_control_allow_origin,omitempty"`
 	AccessControlAllowPrivateNetwork bool                       `json:"access_control_allow_private_network,omitempty"`
+	Dashboard                        *APIDashboardOptions       `json:"dashboard,omitempty"`
 	InboundTLSOptionsContainer
 }
+
+type _APIDashboardOptions struct {
+	Enabled        bool               `json:"enabled,omitempty"`
+	Path           string             `json:"path,omitempty"`
+	DownloadURL    string             `json:"download_url,omitempty"`
+	HTTPClient     *HTTPClientOptions `json:"http_client,omitempty"`
+	UpdateInterval badoption.Duration `json:"update_interval,omitempty"`
+}
+
+type APIDashboardOptions _APIDashboardOptions
+
+func (o APIDashboardOptions) MarshalJSON() ([]byte, error) {
+	if o.DownloadURL == "" && o.HTTPClient == nil && o.UpdateInterval == 0 {
+		if o.Path == "" {
+			return json.Marshal(o.Enabled)
+		}
+		if o.Enabled {
+			return json.Marshal(o.Path)
+		}
+	}
+	return json.Marshal(_APIDashboardOptions(o))
+}
+
+func (o *APIDashboardOptions) UnmarshalJSON(bytes []byte) error {
+	err := json.Unmarshal(bytes, &o.Enabled)
+	if err == nil {
+		return nil
+	}
+	err = json.Unmarshal(bytes, &o.Path)
+	if err == nil {
+		o.Enabled = true
+		return nil
+	}
+	return json.UnmarshalDisallowUnknownFields(bytes, (*_APIDashboardOptions)(o))
+}