refactor: update ExtraMetadata MarshalJSON and add UnmarshalJSON

metadata/extra.go

@@ -1,24 +1,14 @@
 package metadata
 
 import (
+	"encoding/json"
+	"errors"
 	"git.lumeweb.com/LumeWeb/libs5-go/encoding"
 	"git.lumeweb.com/LumeWeb/libs5-go/types"
 	"github.com/vmihailenco/msgpack/v5"
 )
 
-type ExtraMetadata struct {
-	Data map[int]interface{}
-}
-
-func NewExtraMetadata(data map[int]interface{}) *ExtraMetadata {
-	return &ExtraMetadata{
-		Data: data,
-	}
-}
-
-func (em *ExtraMetadata) ToJSON() map[string]interface{} {
-	jsonObject := make(map[string]interface{})
-	names := map[types.MetadataExtension]string{
+var names = map[types.MetadataExtension]string{
 	types.MetadataExtensionLicenses:           "licenses",
 	types.MetadataExtensionDonationKeys:       "donationKeys",
 	types.MetadataExtensionWikidataClaims:     "wikidataClaims",
@@ -35,6 +25,37 @@ func (em *ExtraMetadata) ToJSON() map[string]interface{} {
 	types.MetadataExtensionRoutingHints:       "routingHints",
 }
 
+var namesReverse = map[string]types.MetadataExtension{
+	"licenses":           types.MetadataExtensionLicenses,
+	"donationKeys":       types.MetadataExtensionDonationKeys,
+	"wikidataClaims":     types.MetadataExtensionWikidataClaims,
+	"languages":          types.MetadataExtensionLanguages,
+	"sourceUris":         types.MetadataExtensionSourceUris,
+	"previousVersions":   types.MetadataExtensionPreviousVersions,
+	"timestamp":          types.MetadataExtensionTimestamp,
+	"originalTimestamp":  types.MetadataExtensionOriginalTimestamp,
+	"tags":               types.MetadataExtensionTags,
+	"categories":         types.MetadataExtensionCategories,
+	"basicMediaMetadata": types.MetadataExtensionBasicMediaMetadata,
+	"viewTypes":          types.MetadataExtensionViewTypes,
+	"bridge":             types.MetadataExtensionBridge,
+	"routingHints":       types.MetadataExtensionRoutingHints,
+}
+
+type ExtraMetadata struct {
+	Data map[int]interface{}
+}
+
+var _ SerializableMetadata = (*ExtraMetadata)(nil)
+
+func NewExtraMetadata(data map[int]interface{}) *ExtraMetadata {
+	return &ExtraMetadata{
+		Data: data,
+	}
+}
+
+func (em ExtraMetadata) MarshalJSON() ([]byte, error) {
+	jsonObject := make(map[string]interface{})
 	for key, value := range em.Data {
 		name, ok := names[types.MetadataExtension(key)]
 		if ok {
@@ -50,15 +71,43 @@ func (em *ExtraMetadata) ToJSON() map[string]interface{} {
 				} else {
 					jsonObject["updateCID"] = ""
 				}
-
 			} else {
 				jsonObject[name] = value
 			}
 		}
 	}
 
-	return jsonObject
+	return json.Marshal(jsonObject)
 }
+
+func (em *ExtraMetadata) UnmarshalJSON(data []byte) error {
+	// Intermediate representation of the expected JSON structure
+	jsonObject := make(map[string]interface{})
+	if err := json.Unmarshal(data, &jsonObject); err != nil {
+		return err
+	}
+
+	em.Data = make(map[int]interface{})
+	for name, value := range jsonObject {
+		if key, ok := namesReverse[name]; ok {
+			if key == types.MetadataExtensionUpdateCID {
+				// Convert string back to CID bytes
+				cid, err := encoding.Decode(value.(string))
+				if err != nil {
+					return err
+				}
+				em.Data[int(key)] = cid
+			} else {
+				em.Data[int(key)] = value
+			}
+		} else {
+			return errors.New("unknown key in JSON: " + name)
+		}
+	}
+
+	return nil
+}
+
 func (em *ExtraMetadata) DecodeMsgpack(dec *msgpack.Decoder) error {
 	mapLen, err := dec.DecodeMapLen()