From e86b52028425740edc76d4bf83daf891dccbc3b6 Mon Sep 17 00:00:00 2001
From: haammar-ledger <hakim.aammar-ext@ledger.fr>
Date: Mon, 15 Nov 2021 18:23:28 +0100
Subject: [PATCH] LL-8115 Additional fix for correct handling of change output

---
 src/families/bitcoin/js-synchronisation.ts | 48 +++++++++++++++++-----
 1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/src/families/bitcoin/js-synchronisation.ts b/src/families/bitcoin/js-synchronisation.ts
index d8ca22f837..36700e980a 100644
--- a/src/families/bitcoin/js-synchronisation.ts
+++ b/src/families/bitcoin/js-synchronisation.ts
@@ -129,24 +129,50 @@ const mapTxToOperations = (
   const transactionSequenceNumber =
     (accountInputs.length > 0 && accountInputs[0].sequence) || undefined;
 
-  // Change output is the last one
+  const hasSpentNothing = value.eq(0);
+  // Change output is always the last one
   const changeOutputIndex = tx.outputs
     .map((o) => o.output_index)
     .reduce((p, c) => (p > c ? p : c));
 
   for (const output of tx.outputs) {
     if (output.address) {
-      if (accountAddresses.includes(output.address)) {
+      if (!accountAddresses.includes(output.address)) {
+        // The output doesn't belong to this account
+        if (output.output_index < changeOutputIndex) {
+          // The output isn't the change output
+          recipients.push(
+            syncReplaceAddress
+              ? syncReplaceAddress(output.address)
+              : output.address
+          );
+        }
+      } else {
+        // The output belongs to this account
         accountOutputs.push(output);
-      } else if (
-        !changeAddresses.includes(output.address) ||
-        output.output_index !== changeOutputIndex
-      ) {
-        recipients.push(
-          syncReplaceAddress
-            ? syncReplaceAddress(output.address)
-            : output.address
-        );
+
+        if (!changeAddresses.includes(output.address)) {
+          // The output isn't a change output of this account
+          recipients.push(
+            syncReplaceAddress
+              ? syncReplaceAddress(output.address)
+              : output.address
+          );
+        } else {
+          // The output is a change output of this account,
+          // we count it as a recipient only in some special cases
+          if (
+            (recipients.length === 0 &&
+              output.output_index >= changeOutputIndex) ||
+            hasSpentNothing
+          ) {
+            recipients.push(
+              syncReplaceAddress
+                ? syncReplaceAddress(output.address)
+                : output.address
+            );
+          }
+        }
       }
     }
   }