From a67398ca44fb34b66db9fd3e90c1644c3e7b36dc Mon Sep 17 00:00:00 2001
From: Vitalis Salis <vitsalis@gmail.com>
Date: Mon, 11 Jul 2022 14:50:27 +0300
Subject: [PATCH] Minor fixes

---
 proto/babylon/btclightclient/event.proto | 8 +++++++-
 x/btclightclient/keeper/state.go         | 8 ++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/proto/babylon/btclightclient/event.proto b/proto/babylon/btclightclient/event.proto
index 60d005996..4a4fb9e74 100644
--- a/proto/babylon/btclightclient/event.proto
+++ b/proto/babylon/btclightclient/event.proto
@@ -6,12 +6,18 @@ import "babylon/btclightclient/btclightclient.proto";
 
 option go_package = "github.com/babylonchain/babylon/x/btclightclient/types";
 
-// EventBTCRollBack is emitted on Msg/InsertHeader
+// The header included in the event is the block in the history
+// of the current mainchain to which we are rolling back to.
+// In other words, there is one rollback event emitted per re-org, to the
+// greatest common ancestor of the old and the new fork.
 message EventBTCRollBack {
   BTCHeaderInfo header = 1;
 }
 
 // EventBTCRollForward is emitted on Msg/InsertHeader
+// The header included in the event is the one the main chain is extended with.
+// In the event of a reorg, each block on the new fork that comes after
+// the greatest common ancestor will have a corresponding roll forward event.
 message EventBTCRollForward {
   BTCHeaderInfo header = 1;
 }
diff --git a/x/btclightclient/keeper/state.go b/x/btclightclient/keeper/state.go
index e42b37058..8910058f8 100644
--- a/x/btclightclient/keeper/state.go
+++ b/x/btclightclient/keeper/state.go
@@ -269,16 +269,16 @@ func (s HeadersState) GetHighestCommonAncestor(header1 *wire.BlockHeader, header
 }
 
 // GetInOrderAncestorsUntil returns the list of nodes starting from the child and ending with the block *before* the `ancestor`.
-func (s HeadersState) GetInOrderAncestorsUntil(child *wire.BlockHeader, parent *wire.BlockHeader) []*wire.BlockHeader {
+func (s HeadersState) GetInOrderAncestorsUntil(child *wire.BlockHeader, ancestor *wire.BlockHeader) []*wire.BlockHeader {
 	currentHeader := child
 
 	var ancestors []*wire.BlockHeader
 	ancestors = append(ancestors, child)
-	if isParent(child, parent) {
+	if isParent(child, ancestor) {
 		return ancestors
 	}
 	s.iterateReverseHeaders(func(header *wire.BlockHeader) bool {
-		if header.BlockHash() == parent.BlockHash() {
+		if header.BlockHash() == ancestor.BlockHash() {
 			return true
 		}
 		if header.BlockHash().String() == currentHeader.PrevBlock.String() {
@@ -313,7 +313,7 @@ func (s HeadersState) TipExists() bool {
 
 // updateLongestChain checks whether the tip should be updated and returns true if it does
 func (s HeadersState) updateLongestChain(header *wire.BlockHeader, cumulativeWork *big.Int) {
-	// If there is no existing tip, then the header is set as the tiBTCp
+	// If there is no existing tip, then the header is set as the tip
 	if !s.TipExists() {
 		s.CreateTip(header)
 		return