Migrate json wrapper and badjson to library

common/json/badjson/merge.go

@@ -0,0 +1,79 @@
+package badjson
+
+import (
+	"reflect"
+
+	"github.com/sagernet/sing/common"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/json"
+)
+
+func MergeOptions[T any](source T, destination T) (T, error) {
+	rawSource, err := json.Marshal(source)
+	if err != nil {
+		return common.DefaultValue[T](), E.Cause(err, "marshal source")
+	}
+	rawDestination, err := json.Marshal(destination)
+	if err != nil {
+		return common.DefaultValue[T](), E.Cause(err, "marshal destination")
+	}
+	rawMerged, err := MergeJSON(rawSource, rawDestination)
+	if err != nil {
+		return common.DefaultValue[T](), E.Cause(err, "merge options")
+	}
+	var merged T
+	err = json.Unmarshal(rawMerged, &merged)
+	if err != nil {
+		return common.DefaultValue[T](), E.Cause(err, "unmarshal merged options")
+	}
+	return merged, nil
+}
+
+func MergeJSON(rawSource json.RawMessage, rawDestination json.RawMessage) (json.RawMessage, error) {
+	source, err := Decode(rawSource)
+	if err != nil {
+		return nil, E.Cause(err, "decode source")
+	}
+	destination, err := Decode(rawDestination)
+	if err != nil {
+		return nil, E.Cause(err, "decode destination")
+	}
+	merged, err := mergeJSON(source, destination)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(merged)
+}
+
+func mergeJSON(anySource any, anyDestination any) (any, error) {
+	switch destination := anyDestination.(type) {
+	case JSONArray:
+		switch source := anySource.(type) {
+		case JSONArray:
+			destination = append(destination, source...)
+		default:
+			destination = append(destination, source)
+		}
+		return destination, nil
+	case *JSONObject:
+		switch source := anySource.(type) {
+		case *JSONObject:
+			for _, entry := range source.Entries() {
+				oldValue, loaded := destination.Get(entry.Key)
+				if loaded {
+					var err error
+					entry.Value, err = mergeJSON(entry.Value, oldValue)
+					if err != nil {
+						return nil, E.Cause(err, "merge object item ", entry.Key)
+					}
+				}
+				destination.Put(entry.Key, entry.Value)
+			}
+		default:
+			return nil, E.New("cannot merge json object into ", reflect.TypeOf(destination))
+		}
+		return destination, nil
+	default:
+		return destination, nil
+	}
+}