1 files changed, 51 insertions, 0 deletions
diff --git a/internal/id/page.go b/internal/id/page.go
new file mode 100644
index 000000000..b43ccd4e2
--- /dev/null
+++ b/internal/id/page.go
@@ -0,0 +1,51 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package id
+
+import (
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
+)
+
+// ValidatePage ensures that passed page has valid paging
+// values for the current defined ordering. That is, it
+// ensures a valid page *cursor* value, using id.Highest
+// or id.Lowest where appropriate when none given.
+func ValidatePage(page *paging.Page) {
+	if page == nil {
+		// unpaged
+		return
+	}
+
+	switch page.Order() {
+	// If the page order is ascending,
+	// ensure that a minimum value is set.
+	// This will be used as the cursor.
+	case paging.OrderAscending:
+		if page.Min.Value == "" {
+			page.Min.Value = Lowest
+		}
+
+	// If the page order is descending,
+	// ensure that a maximum value is set.
+	// This will be used as the cursor.
+	case paging.OrderDescending:
+		if page.Max.Value == "" {
+			page.Max.Value = Highest
+		}
+	}
+}