1 files changed, 41 insertions, 0 deletions
diff --git a/modules/indexer/internal/paginator.go b/modules/indexer/internal/paginator.go
new file mode 100644
index 0000000000..de0a33c06f
--- /dev/null
+++ b/modules/indexer/internal/paginator.go
@@ -0,0 +1,41 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package internal
+
+import (
+	"math"
+
+	"code.gitea.io/gitea/models/db"
+)
+
+// ParsePaginator parses a db.Paginator into a skip and limit
+func ParsePaginator(paginator db.Paginator, max ...int) (int, int) {
+	// Use a very large number to indicate no limit
+	unlimited := math.MaxInt32
+	if len(max) > 0 {
+		// Some indexer engines have a limit on the page size, respect that
+		unlimited = max[0]
+	}
+
+	if paginator == nil || paginator.IsListAll() {
+		return 0, unlimited
+	}
+
+	// Warning: Do not use GetSkipTake() for *db.ListOptions
+	// Its implementation could reset the page size with setting.API.MaxResponseItems
+	if listOptions, ok := paginator.(*db.ListOptions); ok {
+		if listOptions.Page >= 0 && listOptions.PageSize > 0 {
+			var start int
+			if listOptions.Page == 0 {
+				start = 0
+			} else {
+				start = (listOptions.Page - 1) * listOptions.PageSize
+			}
+			return start, listOptions.PageSize
+		}
+		return 0, unlimited
+	}
+
+	return paginator.GetSkipTake()
+}