From d3e415d3bd0ffe7ecd51b76db30ca5fad8158844 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Tue, 8 Sep 2020 12:57:45 +0300
Subject: [PATCH] core/state: reverse the order of ForEachTransfer

When using limits we're usually concerned about the most recent
transfers. Returning 3 transfers from the middle of the chain isn't very
helpful.
---
 pkg/core/blockchain.go        |  8 ++++----
 pkg/core/state/nep5.go        |  4 ++--
 pkg/core/state/nep5_test.go   |  4 ++--
 pkg/rpc/server/server_test.go | 19 ++++++++++---------
 4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 2119f22a3..bfe617767 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -1031,8 +1031,8 @@ func (bc *Blockchain) ForEachTransfer(acc util.Uint160, tr *state.Transfer, f fu
 	if err != nil {
 		return nil
 	}
-	for i := uint32(0); i <= nb; i++ {
-		lg, err := bc.dao.GetTransferLog(acc, i)
+	for i := int(nb); i >= 0; i-- {
+		lg, err := bc.dao.GetTransferLog(acc, uint32(i))
 		if err != nil {
 			return nil
 		}
@@ -1050,8 +1050,8 @@ func (bc *Blockchain) ForEachNEP5Transfer(acc util.Uint160, tr *state.NEP5Transf
 	if err != nil {
 		return nil
 	}
-	for i := uint32(0); i <= balances.NextTransferBatch; i++ {
-		lg, err := bc.dao.GetNEP5TransferLog(acc, i)
+	for i := int(balances.NextTransferBatch); i >= 0; i-- {
+		lg, err := bc.dao.GetNEP5TransferLog(acc, uint32(i))
 		if err != nil {
 			return nil
 		}
diff --git a/pkg/core/state/nep5.go b/pkg/core/state/nep5.go
index 0ef8543f5..877b87049 100644
--- a/pkg/core/state/nep5.go
+++ b/pkg/core/state/nep5.go
@@ -114,8 +114,8 @@ func (lg *TransferLog) ForEach(size int, tr io.Serializable, f func() error) err
 	if lg == nil {
 		return nil
 	}
-	for i := 0; i < len(lg.Raw); i += size {
-		r := io.NewBinReaderFromBuf(lg.Raw[i : i+size])
+	for i := len(lg.Raw); i > 0; i -= size {
+		r := io.NewBinReaderFromBuf(lg.Raw[i-size : i])
 		tr.DecodeBinary(r)
 		if r.Err != nil {
 			return r.Err
diff --git a/pkg/core/state/nep5_test.go b/pkg/core/state/nep5_test.go
index 90fb01e16..3776821a2 100644
--- a/pkg/core/state/nep5_test.go
+++ b/pkg/core/state/nep5_test.go
@@ -28,11 +28,11 @@ func TestNEP5TransferLog_Append(t *testing.T) {
 
 	require.Equal(t, len(expected), lg.Size()/NEP5TransferSize)
 
-	i := 0
+	i := len(expected) - 1
 	tr := new(NEP5Transfer)
 	err := lg.ForEach(NEP5TransferSize, tr, func() error {
 		require.Equal(t, expected[i], tr)
-		i++
+		i--
 		return nil
 	})
 	require.NoError(t, err)
diff --git a/pkg/rpc/server/server_test.go b/pkg/rpc/server/server_test.go
index e21e27a71..ce08abaeb 100644
--- a/pkg/rpc/server/server_test.go
+++ b/pkg/rpc/server/server_test.go
@@ -1284,24 +1284,25 @@ func checkNep5TransfersAux(t *testing.T, e *executor, acc interface{}, onlyFirst
 
 	if onlyFirst {
 		require.Equal(t, 1, len(res.Received))
+		require.Equal(t, "1000", res.Received[0].Amount)
+		require.Equal(t, assetHashOld, res.Received[0].Asset)
+		require.Equal(t, address.Uint160ToString(assetHashOld), res.Received[0].Address)
 	} else {
 		require.Equal(t, 3, len(res.Received))
-	}
 
-	require.Equal(t, "1000", res.Received[0].Amount)
-	require.Equal(t, assetHashOld, res.Received[0].Asset)
-	require.Equal(t, address.Uint160ToString(assetHashOld), res.Received[0].Address)
+		require.Equal(t, "1000", res.Received[2].Amount)
+		require.Equal(t, assetHashOld, res.Received[2].Asset)
+		require.Equal(t, address.Uint160ToString(assetHashOld), res.Received[2].Address)
 
-	if !onlyFirst {
 		require.Equal(t, "2", res.Received[1].Amount)
 		require.Equal(t, assetHash, res.Received[1].Asset)
 		require.Equal(t, "AWLYWXB8C9Lt1nHdDZJnC5cpYJjgRDLk17", res.Received[1].Address)
 		require.Equal(t, uint32(0), res.Received[1].NotifyIndex)
 
-		require.Equal(t, "1", res.Received[2].Amount)
-		require.Equal(t, assetHash, res.Received[2].Asset)
-		require.Equal(t, "AWLYWXB8C9Lt1nHdDZJnC5cpYJjgRDLk17", res.Received[2].Address)
-		require.Equal(t, uint32(1), res.Received[2].NotifyIndex)
+		require.Equal(t, "1", res.Received[0].Amount)
+		require.Equal(t, assetHash, res.Received[0].Asset)
+		require.Equal(t, "AWLYWXB8C9Lt1nHdDZJnC5cpYJjgRDLk17", res.Received[0].Address)
+		require.Equal(t, uint32(1), res.Received[0].NotifyIndex)
 	}
 
 	require.Equal(t, 1, len(res.Sent))