feat: expose two path descriptor wallet loading

bdk-ffi/src/tests/wallet.rs

@@ -150,3 +150,41 @@ fn test_create_two_path_wallet() {
     assert_eq!(wallet.derivation_index(KeychainKind::External), Some(0));
     assert_eq!(wallet.derivation_index(KeychainKind::Internal), Some(0));
 }
+
+#[test]
+fn test_load_from_two_path_descriptor() {
+    let persister = Arc::new(Persister::new_in_memory().unwrap());
+    let wallet = Wallet::create_from_two_path_descriptor(
+        two_path_descriptor(),
+        Network::Signet,
+        Arc::clone(&persister),
+        25,
+    )
+    .unwrap();
+
+    wallet.reveal_next_address(KeychainKind::External);
+    wallet.reveal_next_address(KeychainKind::Internal);
+    assert!(wallet.persist(Arc::clone(&persister)).unwrap());
+
+    let loaded_wallet =
+        Wallet::load_from_two_path_descriptor(two_path_descriptor(), Arc::clone(&persister), 25)
+            .unwrap();
+
+    assert_eq!(loaded_wallet.network(), Network::Signet);
+    assert_eq!(
+        loaded_wallet.derivation_index(KeychainKind::External),
+        Some(0)
+    );
+    assert_eq!(
+        loaded_wallet.derivation_index(KeychainKind::Internal),
+        Some(0)
+    );
+    assert_eq!(
+        loaded_wallet.next_derivation_index(KeychainKind::External),
+        1
+    );
+    assert_eq!(
+        loaded_wallet.next_derivation_index(KeychainKind::Internal),
+        1
+    );
+}

bdk-ffi/src/wallet.rs

@@ -109,13 +109,18 @@ impl Wallet {
 
     /// Build a new `Wallet` from a two-path descriptor.
     ///
-    /// This function parses a multipath descriptor with exactly 2 paths and creates a wallet using the existing receive and change wallet creation logic.
+    /// This function parses a multipath descriptor with exactly 2 paths and creates a wallet
+    /// using the existing receive and change wallet creation logic.
     ///
-    /// Multipath descriptors follow [BIP-389](https://github.com/bitcoin/bips/blob/master/bip-0389.mediawiki) and allow defining both receive and change derivation paths in a single descriptor using the <0;1> syntax.
+    /// The provided descriptor may only contain extended public keys (`xpub`) with exactly 2 paths.
+    ///
+    /// Multipath descriptors follow [BIP-389](https://github.com/bitcoin/bips/blob/master/bip-0389.mediawiki)
+    /// and allow defining both receive and change derivation paths in a single descriptor using
+    /// the `<0;1>` syntax.
     ///
     /// If you have previously created a wallet, use load instead.
     ///
-    /// Returns an error if the descriptor is invalid or not a 2-path multipath descriptor.
+    /// Returns an error if the descriptor is not a 2-path multipath descriptor.
     #[uniffi::constructor(default(lookahead = 25))]
     pub fn create_from_two_path_descriptor(
         two_path_descriptor: Arc<Descriptor>,
@@ -168,6 +173,34 @@ impl Wallet {
         })
     }
 
+    /// Build a two-path descriptor `Wallet` by loading from persistence.
+    ///
+    /// Checks that the provided two-path descriptor matches exactly what is loaded
+    /// for both the external and internal keychains.
+    ///
+    /// The provided descriptor may only contain extended public keys (`xpub`) with exactly 2 paths.
+    #[uniffi::constructor(default(lookahead = 25))]
+    pub fn load_from_two_path_descriptor(
+        two_path_descriptor: Arc<Descriptor>,
+        persister: Arc<Persister>,
+        lookahead: u32,
+    ) -> Result<Wallet, LoadWithPersistError> {
+        let descriptor = two_path_descriptor.to_string();
+        let mut persist_lock = persister.inner.lock().unwrap();
+        let deref = persist_lock.deref_mut();
+
+        let wallet: PersistedWallet<PersistenceType> = BdkWallet::load()
+            .two_path_descriptor(descriptor)
+            .lookahead(lookahead)
+            .load_wallet(deref)
+            .map_err(LoadWithPersistError::from)?
+            .ok_or(LoadWithPersistError::CouldNotLoad)?;
+
+        Ok(Wallet {
+            inner_mutex: Mutex::new(wallet),
+        })
+    }
+
     /// Build a single-descriptor Wallet by loading from persistence.
     ///
     /// Note that the descriptor secret keys are not persisted to the db.