feat: allow to fetch collections

pkg/platform.go

@@ -23,3 +23,32 @@ type Platform struct {
 	Node                      // Underlaying node info
 	collections []*Collection // Child nodes
 }
+
+type Fetcher = func(conn *DB, pagination Pagination) ([]*Collection, Pagination, error)
+
+type Pagination struct {
+	Total   int
+	HasMore bool
+	Limit   int
+	Offset  int
+}
+
+var StartPagination = Pagination{
+	Total:   0,
+	HasMore: false,
+	Limit:   10,
+	Offset:  0,
+}
+
+func (platform *Platform) FetchCollections(fetcher Fetcher, start_pagination Pagination) error {
+	collections, pagination, err := fetcher(platform._conn, start_pagination)
+	if err != nil {
+		return err
+	}
+	platform.collections = collections
+
+	if pagination.HasMore {
+		return platform.FetchCollections(fetcher, pagination)
+	}
+	return nil
+}