From 9f903932dc59e1cc955112492b699330b8806d93 Mon Sep 17 00:00:00 2001
From: Steve Myers <steve@notmandatory.org>
Date: Mon, 2 May 2022 19:23:47 -0700
Subject: [PATCH] Add BumpFeeTxBuilder

---
 CHANGELOG.md |  1 +
 src/bdk.udl  |  9 +++++++
 src/lib.rs   | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 73fd99e..713c56e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 - Update BDK to version 0.18.0
+- Add BumpFeeTxBuilder to bump the fee on an unconfirmed tx created by the Wallet
 
 ## [v0.5.0]
 
diff --git a/src/bdk.udl b/src/bdk.udl
index 5429127..b722f09 100644
--- a/src/bdk.udl
+++ b/src/bdk.udl
@@ -158,6 +158,15 @@ interface TxBuilder {
   PartiallySignedBitcoinTransaction build([ByRef] Wallet wallet);
 };
 
+interface BumpFeeTxBuilder {
+  constructor(string txid, float new_fee_rate);
+  BumpFeeTxBuilder allow_shrinking(string address);
+  BumpFeeTxBuilder enable_rbf();
+  BumpFeeTxBuilder enable_rbf_with_sequence(u32 nsequence);
+  [Throws=BdkError]
+  PartiallySignedBitcoinTransaction build([ByRef] Wallet wallet);
+};
+
 dictionary ExtendedKeyInfo {
   string mnemonic;
   string xprv;
diff --git a/src/lib.rs b/src/lib.rs
index caa1396..22d99bd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
 use bdk::bitcoin::hashes::hex::ToHex;
 use bdk::bitcoin::secp256k1::Secp256k1;
 use bdk::bitcoin::util::psbt::PartiallySignedTransaction;
-use bdk::bitcoin::{Address, Network, Script};
+use bdk::bitcoin::{Address, Network, Script, Txid};
 use bdk::blockchain::any::{AnyBlockchain, AnyBlockchainConfig};
 use bdk::blockchain::{
     electrum::ElectrumBlockchainConfig, esplora::EsploraBlockchainConfig, ConfigurableBlockchain,
@@ -440,4 +440,78 @@ impl TxBuilder {
     }
 }
 
+struct BumpFeeTxBuilder {
+    txid: String,
+    fee_rate: f32,
+    rbf: Option<RbfValue>,
+    allow_shrinking: Option<String>,
+}
+
+impl BumpFeeTxBuilder {
+    fn new(txid: String, fee_rate: f32) -> Self {
+        Self {
+            txid,
+            fee_rate,
+            allow_shrinking: None,
+            rbf: None,
+        }
+    }
+
+    fn allow_shrinking(&self, address: String) -> Arc<Self> {
+        Arc::new(Self {
+            txid: self.txid.clone(),
+            fee_rate: self.fee_rate,
+            allow_shrinking: Some(address),
+            rbf: self.rbf.clone(),
+        })
+    }
+
+    fn enable_rbf(&self) -> Arc<Self> {
+        Arc::new(Self {
+            txid: self.txid.clone(),
+            fee_rate: self.fee_rate,
+            rbf: Some(RbfValue::Default),
+            allow_shrinking: self.allow_shrinking.clone(),
+        })
+    }
+
+    fn enable_rbf_with_sequence(&self, nsequence: u32) -> Arc<Self> {
+        Arc::new(Self {
+            txid: self.txid.clone(),
+            fee_rate: self.fee_rate,
+            rbf: Some(RbfValue::Value(nsequence)),
+            allow_shrinking: self.allow_shrinking.clone(),
+        })
+    }
+
+    fn build(&self, wallet: &Wallet) -> Result<Arc<PartiallySignedBitcoinTransaction>, Error> {
+        let wallet = wallet.get_wallet();
+        let txid = Txid::from_str(self.txid.as_str())?;
+        let mut tx_builder = wallet.build_fee_bump(txid)?;
+        tx_builder.fee_rate(FeeRate::from_sat_per_vb(self.fee_rate));
+        if let Some(rbf) = &self.rbf {
+            match *rbf {
+                RbfValue::Default => {
+                    tx_builder.enable_rbf();
+                }
+                RbfValue::Value(nsequence) => {
+                    tx_builder.enable_rbf_with_sequence(nsequence);
+                }
+            }
+        }
+        if let Some(allow_shrinking) = &self.allow_shrinking {
+            let address =
+                Address::from_str(allow_shrinking).map_err(|e| Error::Generic(e.to_string()))?;
+            let script = address.script_pubkey();
+            tx_builder.allow_shrinking(script)?;
+        }
+        tx_builder
+            .finish()
+            .map(|(psbt, _)| PartiallySignedBitcoinTransaction {
+                internal: Mutex::new(psbt),
+            })
+            .map(Arc::new)
+    }
+}
+
 uniffi::deps::static_assertions::assert_impl_all!(Wallet: Sync, Send);