From 8321c1633a9751e87a8b4757b52272311c60235f Mon Sep 17 00:00:00 2001
From: Henrik Hautakoski <henrik.hautakoski@gmail.com>
Date: Sun, 7 Jan 2024 19:25:57 +0100
Subject: [PATCH 1/3] api/channel.go: Adding rollback channel.

---
 api/channel.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/api/channel.go b/api/channel.go
index a843f54..ffe2fba 100644
--- a/api/channel.go
+++ b/api/channel.go
@@ -45,6 +45,7 @@ func (c Channel) Is(other Channel) bool {
 var (
 	TransactionChannel = Channel{"transactions"}
 	HeartbeatChannel   = Channel{"heartbeat"}
+	RollbackChannel    = Channel{"rollback"}
 )
 
 // Action Channel

From 5b5b28669a4474a29761b226ed1df1d6d7f276fc Mon Sep 17 00:00:00 2001
From: Henrik Hautakoski <henrik.hautakoski@gmail.com>
Date: Sun, 7 Jan 2024 19:26:30 +0100
Subject: [PATCH 2/3] api/message/types.go: Adding RollbackMessage struct

---
 api/message/types.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/api/message/types.go b/api/message/types.go
index 5a2111e..081a517 100644
--- a/api/message/types.go
+++ b/api/message/types.go
@@ -80,3 +80,8 @@ func (act ActionTrace) GetData() (map[string]any, error) {
 	}
 	return nil, errors.New("failed to convert data to map")
 }
+
+type RollbackMessage struct {
+	OldBlockNum uint32 `json:"old_block" msgpack:"old_block"`
+	NewBlockNum uint32 `json:"new_block" msgpack:"new_block"`
+}

From a8490f85c4fd11d54d2fa2c402151ba8caba0900 Mon Sep 17 00:00:00 2001
From: Henrik Hautakoski <henrik.hautakoski@gmail.com>
Date: Sun, 7 Jan 2024 19:28:59 +0100
Subject: [PATCH 3/3] app/ship_processor.go: Implement support to send rollback
 messages on forks.

---
 app/ship_processor.go | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/app/ship_processor.go b/app/ship_processor.go
index 3fe0901..2aae7b4 100644
--- a/app/ship_processor.go
+++ b/app/ship_processor.go
@@ -135,6 +135,19 @@ func (processor *ShipProcessor) GetCurrentBlock() uint32 {
 
 // Callback function called by shipclient.Stream when a new block arrives.
 func (processor *ShipProcessor) processBlock(block *ship.GetBlocksResultV0) {
+	// Check to see if we have a microfork and post a message to
+	// the rollback channel in that case.
+	if processor.state.CurrentBlock > 0 && block.ThisBlock.BlockNum < processor.state.CurrentBlock {
+		log.WithField("old_block", processor.state.CurrentBlock).
+			WithField("new_block", block.ThisBlock.BlockNum).
+			Warn("Fork detected, old_block is greater than new_block")
+
+		processor.encodeQueue(api.RollbackChannel, message.RollbackMessage{
+			OldBlockNum: processor.state.CurrentBlock,
+			NewBlockNum: block.ThisBlock.BlockNum,
+		})
+	}
+
 	processor.state.CurrentBlock = block.ThisBlock.BlockNum
 
 	if block.ThisBlock.BlockNum%100 == 0 {