internal/rosa: key metadata by string

For upcoming azalea integration. The API is quite ugly right now to ease migration.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/internal/pkgserver/api.go

@@ -30,7 +30,7 @@ var (
 // handleInfo writes constant system information.
 func handleInfo(w http.ResponseWriter, _ *http.Request) {
 	infoPayloadOnce.Do(func() {
-		infoPayload.Count = int(rosa.PresetUnexportedStart)
+		infoPayload.Count = int(rosa.Native().Count())
 		infoPayload.HakureiVersion = info.Version()
 	})
 	// TODO(mae): cache entire response if no additional fields are planned
@@ -91,7 +91,7 @@ func (index *packageIndex) handleGet(w http.ResponseWriter, r *http.Request) {
 	if err != nil || i >= len(index.sorts[0]) || i < 0 {
 		http.Error(
 			w, "index must be an integer between 0 and "+
-				strconv.Itoa(int(rosa.PresetUnexportedStart-1)),
+				strconv.Itoa(len(index.sorts[0])-1),
 			http.StatusBadRequest,
 		)
 		return
@@ -125,7 +125,7 @@ func (index *packageIndex) handleSearch(w http.ResponseWriter, r *http.Request)
 	if err != nil || i >= len(index.sorts[0]) || i < 0 {
 		http.Error(
 			w, "index must be an integer between 0 and "+
-				strconv.Itoa(int(rosa.PresetUnexportedStart-1)),
+				strconv.Itoa(len(index.sorts[0])-1),
 			http.StatusBadRequest,
 		)
 		return