From 9a95541797901a4bf029c4fea79f9f46f979b947 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 16 Jul 2019 12:30:01 +0300
Subject: [PATCH] sort records for pagination

---
 apps/explorer/lib/explorer/etherscan/logs.ex | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/apps/explorer/lib/explorer/etherscan/logs.ex b/apps/explorer/lib/explorer/etherscan/logs.ex
index 921ae1bcdb..fa3ea646c3 100644
--- a/apps/explorer/lib/explorer/etherscan/logs.ex
+++ b/apps/explorer/lib/explorer/etherscan/logs.ex
@@ -5,7 +5,7 @@ defmodule Explorer.Etherscan.Logs do
 
   """
 
-  import Ecto.Query, only: [from: 2, where: 3, subquery: 1]
+  import Ecto.Query, only: [from: 2, where: 3, subquery: 1, order_by: 3]
 
   alias Explorer.Chain.{Block, InternalTransaction, Log, Transaction}
   alias Explorer.Repo
@@ -38,7 +38,7 @@ defmodule Explorer.Etherscan.Logs do
     :type
   ]
 
-  @default_paging_options %{block_number: nil, transaction_index: nil}
+  @default_paging_options %{block_number: nil, transaction_index: nil, log_index: nil}
 
   @doc """
   Gets a list of logs that meet the criteria in a given filter map.
@@ -240,5 +240,18 @@ defmodule Explorer.Etherscan.Logs do
 
   defp where_multiple_topics_match(query, _, _, _), do: query
 
-  defp page_logs(query, _paging_options), do: query
+  defp page_logs(query, %{block_number: nil, transaction_index: nil, log_index: nil}) do
+    query
+    |> order_by([log], asc: log.index)
+  end
+
+  defp page_logs(query, %{block_number: block_number, transaction_index: transaction_index, log_index: log_index}) do
+    sorted_query = order_by(query, [log], asc: log.index)
+
+    from(data in sorted_query,
+      where:
+        data.index > ^log_index and data.block_number >= ^block_number and
+          data.transaction_index >= ^transaction_index
+    )
+  end
 end