chore: refactor

internal/service/pagination.go

@@ -0,0 +1,18 @@
+package service
+
+// Paginate calculates pagination values from a page number, total count, and page size.
+// Returns the adjusted page, total pages, and offset for the query.
+func Paginate(page, total, perPage int) (adjustedPage, totalPages, offset int) {
+	totalPages = (total + perPage - 1) / perPage
+	if totalPages < 1 {
+		totalPages = 1
+	}
+	if page < 1 {
+		page = 1
+	}
+	if page > totalPages {
+		page = totalPages
+	}
+	offset = (page - 1) * perPage
+	return page, totalPages, offset
+}