1 files changed, 31 insertions, 0 deletions
diff --git a/mobile/mobile.go b/mobile/mobile.go
index e79e748..d863463 100644
--- a/mobile/mobile.go
+++ b/mobile/mobile.go
@@ -184,6 +184,37 @@ func Days(start string, count int, form, lang string) string {
 	return string(b)
 }
 
+// partLabel is one section's machine ID and its human label.
+type partLabel struct {
+	Part  string `json:"part"`
+	Label string `json:"label"`
+}
+
+// PartLabels returns the form's section IDs and their labels in lang, in display
+// order, as a JSON array. The app builds its reading filters from this instead
+// of hardcoding part IDs -- which is how it came to ship seven 1962 checkboxes
+// the engine never emits.
+//
+// An array, not an object: JSON object key order is not guaranteed and the app
+// renders these in order.
+func PartLabels(form, lang string) string {
+	ids := readings.PartIDs(lectByForm(form))
+	ui := i18n.Get(lang)
+	out := make([]partLabel, 0, len(ids))
+	for _, id := range ids {
+		label := ui.PartLabel[id]
+		if label == "" {
+			label = id
+		}
+		out = append(out, partLabel{Part: id, Label: label})
+	}
+	b, err := json.Marshal(out)
+	if err != nil {
+		return "[]"
+	}
+	return string(b)
+}
+
 // Ping is a trivial JNI smoke test: it returns "pong" so the app can confirm the
 // native engine loaded before issuing a real query.
 func Ping() string { return "pong" }