nip29: add .MergeInRolesEvent()

nip29/group.go

@@ -333,3 +333,38 @@ func (group *Group) MergeInMembersEvent(evt *nostr.Event) error {
 
 	return nil
 }
+
+func (group *Group) MergeInRolesEvent(evt *nostr.Event) error {
+	if evt.Kind != nostr.KindSimpleGroupRoles {
+		return fmt.Errorf("expected kind %d, got %d", nostr.KindSimpleGroupRoles, evt.Kind)
+	}
+	if evt.CreatedAt < group.LastRolesUpdate {
+		return fmt.Errorf("event is older than our last update (%d vs %d)", evt.CreatedAt, group.LastRolesUpdate)
+	}
+
+	group.LastRolesUpdate = evt.CreatedAt
+	for _, tag := range evt.Tags {
+		if len(tag) < 2 {
+			continue
+		}
+		if tag[0] != "role" {
+			continue
+		}
+
+		roleName := tag[1]
+		roleDescription := ""
+		if len(tag) >= 3 {
+			roleDescription = tag[2]
+		}
+
+		if idx := slices.IndexFunc(group.Roles, func(role *Role) bool { return role.Name == roleName }); idx >= 0 {
+			// update existing role description
+			group.Roles[idx].Description = roleDescription
+		} else {
+			// add new role
+			group.Roles = append(group.Roles, &Role{Name: roleName, Description: roleDescription})
+		}
+	}
+
+	return nil
+}