feat: add calculate_fee and calculate_fee_rate on wallet

Author: reez

bdk-ffi/src/bdk.udl

@@ -82,6 +82,17 @@ enum BdkError {
   "Psbt",
 };
 
+[Error]
+interface CalculateFeeError {
+  MissingTxOut(sequence<OutPoint> out_points);
+  NegativeFee(i64 fee);
+};
+
+interface FeeRate {
+  [Name=from_sat_per_vb]
+  constructor(float sat_per_vb);
+};
+
 enum ChangeSpendPolicy {
   "ChangeAllowed",
   "OnlyChange",
@@ -111,6 +122,12 @@ interface Wallet {
   SentAndReceivedValues sent_and_received([ByRef] Transaction tx);
 
   sequence<Transaction> transactions();
+
+  [Throws=CalculateFeeError]
+  u64 calculate_fee([ByRef] Transaction tx);
+
+  [Throws=CalculateFeeError]
+  FeeRate calculate_fee_rate([ByRef] Transaction tx);
 };
 
 interface Update {};
@@ -348,4 +365,4 @@ interface PartiallySignedTransaction {
 dictionary OutPoint {
   string txid;
   u32 vout;
-};
+};

bdk-ffi/src/bitcoin.rs

@@ -300,6 +300,15 @@ impl From<&OutPoint> for BdkOutPoint {
     }
 }
 
+impl From<&BdkOutPoint> for OutPoint {
+    fn from(outpoint: &BdkOutPoint) -> Self {
+        OutPoint {
+            txid: outpoint.txid.to_string(),
+            vout: outpoint.vout,
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct TxOut {
     pub value: u64,

bdk-ffi/src/error.rs

@@ -0,0 +1,35 @@
+use crate::bitcoin::OutPoint;
+
+use bdk::chain::tx_graph::CalculateFeeError as BdkCalculateFeeError;
+
+use std::fmt;
+
+#[derive(Debug)]
+pub enum CalculateFeeError {
+    MissingTxOut { out_points: Vec<OutPoint> },
+    NegativeFee { fee: i64 },
+}
+
+impl fmt::Display for CalculateFeeError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            CalculateFeeError::MissingTxOut { out_points } => {
+                write!(f, "Missing transaction output: {:?}", out_points)
+            }
+            CalculateFeeError::NegativeFee { fee } => write!(f, "Negative fee value: {}", fee),
+        }
+    }
+}
+
+impl From<BdkCalculateFeeError> for CalculateFeeError {
+    fn from(error: BdkCalculateFeeError) -> Self {
+        match error {
+            BdkCalculateFeeError::MissingTxOut(out_points) => CalculateFeeError::MissingTxOut {
+                out_points: out_points.iter().map(|op| op.into()).collect(),
+            },
+            BdkCalculateFeeError::NegativeFee(fee) => CalculateFeeError::NegativeFee { fee },
+        }
+    }
+}
+
+impl std::error::Error for CalculateFeeError {}

bdk-ffi/src/lib.rs

@@ -1,5 +1,6 @@
 mod bitcoin;
 mod descriptor;
+mod error;
 mod esplora;
 mod keys;
 mod types;
@@ -13,6 +14,7 @@ use crate::bitcoin::Script;
 use crate::bitcoin::Transaction;
 use crate::bitcoin::TxOut;
 use crate::descriptor::Descriptor;
+use crate::error::CalculateFeeError;
 use crate::esplora::EsploraClient;
 use crate::keys::DerivationPath;
 use crate::keys::DescriptorPublicKey;
@@ -29,6 +31,8 @@ use crate::wallet::TxBuilder;
 use crate::wallet::Update;
 use crate::wallet::Wallet;
 
+use crate::types::FeeRate;
+
 use bdk::keys::bip39::WordCount;
 use bdk::wallet::tx_builder::ChangeSpendPolicy;
 use bdk::Error as BdkError;

bdk-ffi/src/types.rs

@@ -7,8 +7,18 @@ use bdk::KeychainKind;
 
 use bdk::LocalUtxo as BdkLocalUtxo;
 
+use bdk::FeeRate as BdkFeeRate;
+
 use std::sync::Arc;
 
+pub struct FeeRate(BdkFeeRate);
+
+impl FeeRate {
+    pub fn from_sat_per_vb(sat_per_vb: f32) -> Self {
+        FeeRate(BdkFeeRate::from_sat_per_vb(sat_per_vb))
+    }
+}
+
 pub struct ScriptAmount {
     pub script: Arc<Script>,
     pub amount: u64,

bdk-ffi/src/wallet.rs

@@ -1,7 +1,8 @@
 use crate::bitcoin::{OutPoint, PartiallySignedTransaction, Transaction};
 use crate::descriptor::Descriptor;
-use crate::types::Balance;
+use crate::error::CalculateFeeError;
 use crate::types::ScriptAmount;
+use crate::types::{Balance, FeeRate};
 use crate::Script;
 use crate::{AddressIndex, AddressInfo, Network};
 
@@ -10,7 +11,7 @@ use bdk::bitcoin::psbt::PartiallySignedTransaction as BdkPartiallySignedTransact
 use bdk::bitcoin::{OutPoint as BdkOutPoint, Sequence, Txid};
 use bdk::wallet::tx_builder::ChangeSpendPolicy;
 use bdk::wallet::Update as BdkUpdate;
-use bdk::{Error as BdkError, FeeRate};
+use bdk::{Error as BdkError, FeeRate as BdkFeeRate};
 use bdk::{SignOptions, Wallet as BdkWallet};
 
 use std::collections::HashSet;
@@ -98,6 +99,18 @@ impl Wallet {
             .map(|tx| Arc::new(tx.tx_node.tx.clone().into()))
             .collect()
     }
+
+    pub fn calculate_fee(&self, tx: &Transaction) -> Result<u64, CalculateFeeError> {
+        let fee_result = self.get_wallet().calculate_fee(&tx.clone().into());
+        fee_result.map_err(|err| err.into())
+    }
+
+    pub fn calculate_fee_rate(&self, tx: &Transaction) -> Result<Arc<FeeRate>, CalculateFeeError> {
+        let fee_rate_result = self.get_wallet().calculate_fee_rate(&tx.clone().into());
+        fee_rate_result
+            .map(|fee_rate| Arc::new(FeeRate::from_sat_per_vb(fee_rate.as_sat_per_vb())))
+            .map_err(|err| err.into())
+    }
 }
 
 pub struct SentAndReceivedValues {
@@ -473,7 +486,7 @@ impl TxBuilder {
             tx_builder.manually_selected_only();
         }
         if let Some(sat_per_vb) = self.fee_rate {
-            tx_builder.fee_rate(FeeRate::from_sat_per_vb(sat_per_vb));
+            tx_builder.fee_rate(BdkFeeRate::from_sat_per_vb(sat_per_vb));
         }
         if let Some(fee_amount) = self.fee_absolute {
             tx_builder.fee_absolute(fee_amount);
@@ -551,7 +564,7 @@ impl BumpFeeTxBuilder {
             Txid::from_str(self.txid.as_str()).map_err(|e| BdkError::Generic(e.to_string()))?;
         let mut wallet = wallet.get_wallet();
         let mut tx_builder = wallet.build_fee_bump(txid)?;
-        tx_builder.fee_rate(FeeRate::from_sat_per_vb(self.fee_rate));
+        tx_builder.fee_rate(BdkFeeRate::from_sat_per_vb(self.fee_rate));
         if let Some(allow_shrinking) = &self.allow_shrinking {
             tx_builder.allow_shrinking(allow_shrinking.0.clone())?;
         }