feat: add finalize to Psbt

bdk-ffi/src/bdk.udl

@@ -258,6 +258,13 @@ interface PsbtParseError {
   Base64Encoding(string error_message);
 };
 
+[Error]
+interface PsbtFinalizeError {
+  InputError(string reason, u32 index);
+  WrongInputCount(u32 in_tx, u32 in_map);
+  InputIdxOutofBounds(u32 psbt_inp, u32 requested);
+};
+
 [Error]
 interface RequestBuilderError {
   RequestAlreadyConsumed();
@@ -958,9 +965,17 @@ interface Psbt {
   [Throws=PsbtError]
   Psbt combine(Psbt other);
 
+  FinalizedPsbtResult finalize();
+
   string json_serialize();
 };
 
+dictionary FinalizedPsbtResult {
+  Psbt psbt;
+  boolean could_finalize;
+  sequence<PsbtFinalizeError>? errors;
+};
+
 dictionary TxIn {
   OutPoint previous_output;
   Script script_sig;

bdk-ffi/src/bitcoin.rs

@@ -1,3 +1,4 @@
+use crate::error::PsbtFinalizeError;
 use crate::error::{
     AddressParseError, FromScriptError, PsbtError, PsbtParseError, TransactionError,
 };
@@ -10,12 +11,14 @@ use bdk_wallet::bitcoin::consensus::encode::serialize;
 use bdk_wallet::bitcoin::consensus::Decodable;
 use bdk_wallet::bitcoin::io::Cursor;
 use bdk_wallet::bitcoin::psbt::ExtractTxError;
+use bdk_wallet::bitcoin::secp256k1::Secp256k1;
 use bdk_wallet::bitcoin::Address as BdkAddress;
 use bdk_wallet::bitcoin::Network;
 use bdk_wallet::bitcoin::Psbt as BdkPsbt;
 use bdk_wallet::bitcoin::Transaction as BdkTransaction;
 use bdk_wallet::bitcoin::TxIn as BdkTxIn;
 use bdk_wallet::bitcoin::TxOut as BdkTxOut;
+use bdk_wallet::miniscript::psbt::PsbtExt;
 use bdk_wallet::serde_json;
 
 use std::fmt::Display;
@@ -188,6 +191,26 @@ impl Psbt {
         Ok(Arc::new(Psbt(Mutex::new(original_psbt))))
     }
 
+    pub(crate) fn finalize(&self) -> FinalizedPsbtResult {
+        let curve = Secp256k1::verification_only();
+        let finalized = self.0.lock().unwrap().clone().finalize(&curve);
+        match finalized {
+            Ok(psbt) => FinalizedPsbtResult {
+                psbt: Arc::new(psbt.into()),
+                could_finalize: true,
+                errors: None,
+            },
+            Err((psbt, errors)) => {
+                let errors = errors.into_iter().map(|e| e.into()).collect();
+                FinalizedPsbtResult {
+                    psbt: Arc::new(psbt.into()),
+                    could_finalize: false,
+                    errors: Some(errors),
+                }
+            }
+        }
+    }
+
     pub(crate) fn json_serialize(&self) -> String {
         let psbt = self.0.lock().unwrap();
         serde_json::to_string(psbt.deref()).unwrap()
@@ -200,6 +223,12 @@ impl From<BdkPsbt> for Psbt {
     }
 }
 
+pub struct FinalizedPsbtResult {
+    pub psbt: Arc<Psbt>,
+    pub could_finalize: bool,
+    pub errors: Option<Vec<PsbtFinalizeError>>,
+}
+
 #[derive(Debug, Clone)]
 pub struct TxIn {
     pub previous_output: OutPoint,

bdk-ffi/src/error.rs

@@ -19,6 +19,7 @@ use bdk_wallet::error::BuildFeeBumpError;
 use bdk_wallet::error::CreateTxError as BdkCreateTxError;
 use bdk_wallet::keys::bip39::Error as BdkBip39Error;
 use bdk_wallet::miniscript::descriptor::DescriptorKeyParseError as BdkDescriptorKeyParseError;
+use bdk_wallet::miniscript::psbt::Error as BdkPsbtFinalizeError;
 use bdk_wallet::signer::SignerError as BdkSignerError;
 use bdk_wallet::tx_builder::AddUtxoError;
 use bdk_wallet::LoadWithPersistError as BdkLoadWithPersistError;
@@ -642,6 +643,16 @@ pub enum PsbtParseError {
     Base64Encoding { error_message: String },
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum PsbtFinalizeError {
+    #[error("an input at index {index} is invalid: {reason}")]
+    InputError { reason: String, index: u32 },
+    #[error("wrong input count; expected: {in_tx}, got: {in_map}")]
+    WrongInputCount { in_tx: u32, in_map: u32 },
+    #[error("input index out of bounds; inputs: {psbt_inp}, requested: {requested}")]
+    InputIdxOutofBounds { psbt_inp: u32, requested: u32 },
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum SignerError {
     #[error("missing key for signing")]
@@ -1344,6 +1355,29 @@ impl From<BdkPsbtParseError> for PsbtParseError {
     }
 }
 
+impl From<BdkPsbtFinalizeError> for PsbtFinalizeError {
+    fn from(value: BdkPsbtFinalizeError) -> Self {
+        match value {
+            BdkPsbtFinalizeError::InputError(input_error, index) => PsbtFinalizeError::InputError {
+                reason: input_error.to_string(),
+                index: index as u32,
+            },
+            BdkPsbtFinalizeError::WrongInputCount { in_tx, in_map } => {
+                PsbtFinalizeError::WrongInputCount {
+                    in_tx: in_tx as u32,
+                    in_map: in_map as u32,
+                }
+            }
+            BdkPsbtFinalizeError::InputIdxOutofBounds { psbt_inp, index } => {
+                PsbtFinalizeError::InputIdxOutofBounds {
+                    psbt_inp: psbt_inp as u32,
+                    requested: index as u32,
+                }
+            }
+        }
+    }
+}
+
 impl From<BdkSignerError> for SignerError {
     fn from(error: BdkSignerError) -> Self {
         match error {

bdk-ffi/src/lib.rs

@@ -10,6 +10,7 @@ mod types;
 mod wallet;
 
 use crate::bitcoin::Address;
+use crate::bitcoin::FinalizedPsbtResult;
 use crate::bitcoin::Psbt;
 use crate::bitcoin::Transaction;
 use crate::bitcoin::TxIn;
@@ -33,6 +34,7 @@ use crate::error::LoadWithPersistError;
 use crate::error::MiniscriptError;
 use crate::error::PersistenceError;
 use crate::error::PsbtError;
+use crate::error::PsbtFinalizeError;
 use crate::error::PsbtParseError;
 use crate::error::RequestBuilderError;
 use crate::error::SignerError;