From fa07a2d2486ad10f456ec195b1105fa002fb87b1 Mon Sep 17 00:00:00 2001
From: Olaoluwa Osuntokun <laolu32@gmail.com>
Date: Wed, 1 Mar 2023 21:50:55 -0800
Subject: [PATCH] input: HtlcSucceedInput to support sweeping for taproot chans

---
 input/input.go | 44 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/input/input.go b/input/input.go
index f1595e553..ad5bce163 100644
--- a/input/input.go
+++ b/input/input.go
@@ -153,8 +153,8 @@ func (i *inputKit) UnconfParent() *TxInfo {
 	return i.unconfParent
 }
 
-// BaseInput contains all the information needed to sweep a basic output
-// (CSV/CLTV/no time lock)
+// BaseInput contains all the information needed to sweep a basic
+// output (CSV/CLTV/no time lock).
 type BaseInput struct {
 	inputKit
 }
@@ -267,6 +267,24 @@ func MakeHtlcSucceedInput(outpoint *wire.OutPoint,
 	}
 }
 
+// MakeTaprootHtlcSucceedInput creates a new HtlcSucceedInput that can be used
+// to spend an HTLC output for a taproot channel on the remote party's
+// commitment transaction.
+func MakeTaprootHtlcSucceedInput(op *wire.OutPoint, signDesc *SignDescriptor,
+	preimage []byte, heightHint, blocksToMaturity uint32) HtlcSucceedInput {
+
+	return HtlcSucceedInput{
+		inputKit: inputKit{
+			outpoint:        *op,
+			witnessType:     TaprootHtlcAcceptedRemoteSuccess,
+			signDesc:        *signDesc,
+			heightHint:      heightHint,
+			blockToMaturity: blocksToMaturity,
+		},
+		preimage: preimage,
+	}
+}
+
 // CraftInputScript returns a valid set of input scripts allowing this output
 // to be spent. The returns input scripts should target the input at location
 // txIndex within the passed transaction. The input scripts generated by this
@@ -281,9 +299,27 @@ func (h *HtlcSucceedInput) CraftInputScript(signer Signer, txn *wire.MsgTx,
 	desc.InputIndex = txinIdx
 	desc.PrevOutputFetcher = prevOutputFetcher
 
-	witness, err := SenderHtlcSpendRedeem(
-		signer, &desc, txn, h.preimage,
+	isTaproot := txscript.IsPayToTaproot(desc.Output.PkScript)
+
+	var (
+		witness wire.TxWitness
+		err     error
 	)
+	if isTaproot {
+		if desc.ControlBlock == nil {
+			return nil, fmt.Errorf("ctrl block must be set")
+		}
+
+		desc.SignMethod = TaprootScriptSpendSignMethod
+
+		witness, err = SenderHTLCScriptTaprootRedeem(
+			signer, &desc, txn, h.preimage, nil, nil,
+		)
+	} else {
+		witness, err = SenderHtlcSpendRedeem(
+			signer, &desc, txn, h.preimage,
+		)
+	}
 	if err != nil {
 		return nil, err
 	}