feat: add MVP transaction builder type

bdk-ffi/src/bdk.udl

@@ -1,7 +1,7 @@
 namespace bdk {};
 
 // ------------------------------------------------------------------------
-// bdk crate
+// bdk crate - root module
 // ------------------------------------------------------------------------
 
 enum KeychainKind {
@@ -86,6 +86,17 @@ interface Wallet {
 
 interface Update {};
 
+interface TxBuilder {
+  constructor();
+
+  TxBuilder add_recipient(Script script, u64 amount);
+
+  TxBuilder fee_rate(float sat_per_vbyte);
+
+  [Throws=BdkError]
+  string finish([ByRef] Wallet wallet);
+};
+
 // ------------------------------------------------------------------------
 // bdk crate - descriptor module
 // ------------------------------------------------------------------------

bdk-ffi/src/lib.rs

@@ -6,6 +6,7 @@ mod psbt;
 mod wallet;
 
 use bdk::bitcoin::address::{NetworkChecked, NetworkUnchecked};
+use bdk::bitcoin::blockdata::script::ScriptBuf as BdkScriptBuf;
 use bdk::bitcoin::Address as BdkAddress;
 use bdk::bitcoin::Network as BdkNetwork;
 use bdk::wallet::AddressIndex as BdkAddressIndex;
@@ -23,6 +24,7 @@ use crate::keys::DerivationPath;
 use crate::keys::DescriptorPublicKey;
 use crate::keys::DescriptorSecretKey;
 use crate::keys::Mnemonic;
+use crate::wallet::TxBuilder;
 use crate::wallet::Update;
 use crate::wallet::Wallet;
 use bdk::keys::bip39::WordCount;
@@ -453,11 +455,11 @@ impl Address {
         self.inner.network.into()
     }
 
-    // fn script_pubkey(&self) -> Arc<Script> {
+    fn script_pubkey(&self) -> Arc<Script> {
-    //     Arc::new(Script {
+        Arc::new(Script {
-    //         inner: self.inner.script_pubkey(),
+            inner: self.inner.script_pubkey(),
-    //     })
+        })
-    // }
+    }
 
     fn to_qr_uri(&self) -> String {
         self.inner.to_qr_uri()
@@ -495,24 +497,24 @@ impl From<Address> for BdkAddress {
 //         program: Vec<u8>,
 //     },
 // }
-//
+
-// /// A Bitcoin script.
+/// A Bitcoin script.
-// #[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
-// pub struct Script {
+pub struct Script {
-//     inner: BdkScript,
+    inner: BdkScriptBuf,
-// }
+}
-//
+
-// impl Script {
+impl Script {
-//     fn new(raw_output_script: Vec<u8>) -> Self {
+    fn new(raw_output_script: Vec<u8>) -> Self {
-//         let script: BdkScript = BdkScript::from(raw_output_script);
+        let script: BdkScriptBuf = BdkScriptBuf::from(raw_output_script);
-//         Script { inner: script }
+        Script { inner: script }
-//     }
+    }
-//
+
-//     fn to_bytes(&self) -> Vec<u8> {
+    fn to_bytes(&self) -> Vec<u8> {
-//         self.inner.to_bytes()
+        self.inner.to_bytes()
-//     }
+    }
-// }
+}
-//
+
 // impl From<BdkScript> for Script {
 //     fn from(bdk_script: BdkScript) -> Self {
 //         Script { inner: bdk_script }

bdk-ffi/src/wallet.rs

@@ -1,10 +1,11 @@
 use crate::descriptor::Descriptor;
-use crate::Balance;
 use crate::{AddressIndex, AddressInfo, Network};
+use crate::{Balance, Script};
 use bdk::wallet::Update as BdkUpdate;
-use bdk::Error as BdkError;
 use bdk::Wallet as BdkWallet;
+use bdk::{Error as BdkError, FeeRate};
 use std::sync::{Arc, Mutex, MutexGuard};
+use bdk::bitcoin::blockdata::script::ScriptBuf as BdkScriptBuf;
 
 #[derive(Debug)]
 pub struct Wallet {
@@ -314,51 +315,52 @@ pub struct Update(pub(crate) BdkUpdate);
 //     }
 // }
 //
-// /// A transaction builder.
+/// A transaction builder.
-// /// After creating the TxBuilder, you set options on it until finally calling finish to consume the builder and generate the transaction.
+/// After creating the TxBuilder, you set options on it until finally calling finish to consume the builder and generate the transaction.
-// /// Each method on the TxBuilder returns an instance of a new TxBuilder with the option set/added.
+/// Each method on the TxBuilder returns an instance of a new TxBuilder with the option set/added.
-// #[derive(Clone, Debug)]
+#[derive(Clone, Debug)]
-// pub(crate) struct TxBuilder {
+pub(crate) struct TxBuilder {
-//     pub(crate) recipients: Vec<(BdkScript, u64)>,
+    pub(crate) recipients: Vec<(BdkScriptBuf, u64)>,
     // pub(crate) utxos: Vec<OutPoint>,
     // pub(crate) unspendable: HashSet<OutPoint>,
     // pub(crate) change_policy: ChangeSpendPolicy,
     // pub(crate) manually_selected_only: bool,
-//     pub(crate) fee_rate: Option<f32>,
+    pub(crate) fee_rate: Option<f32>,
     // pub(crate) fee_absolute: Option<u64>,
     // pub(crate) drain_wallet: bool,
     // pub(crate) drain_to: Option<BdkScript>,
     // pub(crate) rbf: Option<RbfValue>,
     // pub(crate) data: Vec<u8>,
-// }
+}
-//
+
-// impl TxBuilder {
+impl TxBuilder {
-//     pub(crate) fn new() -> Self {
+    pub(crate) fn new() -> Self {
-//         TxBuilder {
+        TxBuilder {
-//             recipients: Vec::new(),
+            recipients: Vec::new(),
             // utxos: Vec::new(),
             // unspendable: HashSet::new(),
             // change_policy: ChangeSpendPolicy::ChangeAllowed,
             // manually_selected_only: false,
-//             fee_rate: None,
+            fee_rate: None,
             // fee_absolute: None,
             // drain_wallet: false,
             // drain_to: None,
             // rbf: None,
             // data: Vec::new(),
-//         }
+        }
-//     }
+    }
-//
+
-//     /// Add a recipient to the internal list.
+    /// Add a recipient to the internal list.
-//     pub(crate) fn add_recipient(&self, script: Arc<Script>, amount: u64) -> Arc<Self> {
+    pub(crate) fn add_recipient(&self, script: Arc<Script>, amount: u64) -> Arc<Self> {
-//         let mut recipients: Vec<(BdkScript, u64)> = self.recipients.clone();
+        let mut recipients: Vec<(BdkScriptBuf, u64)> = self.recipients.clone();
-//         recipients.append(&mut vec![(script.inner.clone(), amount)]);
+        recipients.append(&mut vec![(script.inner.clone(), amount)]);
-//         Arc::new(TxBuilder {
+
-//             recipients,
+        Arc::new(TxBuilder {
-//             ..self.clone()
+            recipients,
-//         })
+            ..self.clone()
-//     }
+        })
-//
+    }
+
     // pub(crate) fn set_recipients(&self, recipients: Vec<ScriptAmount>) -> Arc<Self> {
     //     let recipients = recipients
     //         .iter()
@@ -369,7 +371,7 @@ pub struct Update(pub(crate) BdkUpdate);
     //         ..self.clone()
     //     })
     // }
-//
+
     //     /// Add a utxo to the internal list of unspendable utxos. It’s important to note that the "must-be-spent"
     //     /// utxos added with [TxBuilder.addUtxo] have priority over this. See the Rust docs of the two linked methods for more details.
     //     pub(crate) fn add_unspendable(&self, unspendable: OutPoint) -> Arc<Self> {
@@ -433,13 +435,13 @@ pub struct Update(pub(crate) BdkUpdate);
     //         })
     //     }
     //
-//     /// Set a custom fee rate.
+    /// Set a custom fee rate.
-//     pub(crate) fn fee_rate(&self, sat_per_vb: f32) -> Arc<Self> {
+    pub(crate) fn fee_rate(&self, sat_per_vb: f32) -> Arc<Self> {
-//         Arc::new(TxBuilder {
+        Arc::new(TxBuilder {
-//             fee_rate: Some(sat_per_vb),
+            fee_rate: Some(sat_per_vb),
-//             ..self.clone()
+            ..self.clone()
-//         })
+        })
-//     }
+    }
     //
     //     /// Set an absolute fee.
     //     pub(crate) fn fee_absolute(&self, fee_amount: u64) -> Arc<Self> {
@@ -498,13 +500,17 @@ pub struct Update(pub(crate) BdkUpdate);
     //         })
     //     }
     //
-//     /// Finish building the transaction. Returns the BIP174 PSBT.
+    /// Finish building the transaction. Returns the BIP174 PSBT.
-//     pub(crate) fn finish(&self, wallet: &Wallet) -> Result<TxBuilderResult, BdkError> {
+    /// TODO: The TxBuilder in bdk returns a Psbt type
-//         let wallet = wallet.get_wallet();
+    pub(crate) fn finish(&self, wallet: &Wallet) -> Result<String, BdkError> {
-//         let mut tx_builder = wallet.build_tx();
+        // TODO: I had to change the wallet here to be mutable. Why is that now required with the 1.0 API?
-//         for (script, amount) in &self.recipients {
+        let mut wallet = wallet.get_wallet();
-//             tx_builder.add_recipient(script.clone(), *amount);
+        let mut tx_builder = wallet.build_tx();
-//         }
+        // TODO: I'm not yet clear on the Script/ScriptBuf differences and whether this is the best
+        //       way to do this.
+        for (script, amount) in &self.recipients {
+            tx_builder.add_recipient(script.clone(), *amount);
+        }
         // tx_builder.change_policy(self.change_policy);
         // if !self.utxos.is_empty() {
         //     let bdk_utxos: Vec<BdkOutPoint> = self.utxos.iter().map(BdkOutPoint::from).collect();
@@ -519,9 +525,9 @@ pub struct Update(pub(crate) BdkUpdate);
         // if self.manually_selected_only {
         //     tx_builder.manually_selected_only();
         // }
-//         if let Some(sat_per_vb) = self.fee_rate {
+        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(FeeRate::from_sat_per_vb(sat_per_vb));
-//         }
+        }
         // if let Some(fee_amount) = self.fee_absolute {
         //     tx_builder.fee_absolute(fee_amount);
         // }
@@ -544,17 +550,10 @@ pub struct Update(pub(crate) BdkUpdate);
         // if !&self.data.is_empty() {
         //     tx_builder.add_data(self.data.as_slice());
         // }
-//
+
-//         tx_builder
+        tx_builder.finish().map(|psbt| psbt.serialize_hex())
-//             .finish()
+    }
-//             .map(|(psbt, tx_details)| TxBuilderResult {
+}
-//                 psbt: Arc::new(PartiallySignedTransaction {
-//                     inner: Mutex::new(psbt),
-//                 }),
-//                 transaction_details: TransactionDetails::from(tx_details),
-//             })
-//     }
-// }
 //
 // /// The BumpFeeTxBuilder is used to bump the fee on a transaction that has been broadcast and has its RBF flag set to true.
 // #[derive(Clone)]