Add LightWalletClient.Rescan method

src/Nerdbank.Zcash/LightWalletClient.cs

@@ -184,6 +184,25 @@ public IEnumerable<ZcashAccount> GetAccounts()
 		return this.accountIds.Keys;
 	}
 
+	/// <summary>
+	/// Gets the minimum block height corresponding to an unspent note in the wallet.
+	/// </summary>
+	/// <returns>The minimum block height, or <see langword="null" /> if there are no unspent notes.</returns>
+	public uint? GetMinUnspentHeight() => LightWalletMethods.GetMinUnspentHeight(this.dbinit);
+
+	/// <summary>
+	/// Invalidates any scanned blocks beyond a given block.
+	/// </summary>
+	/// <param name="blockHeight">
+	/// The height of the last block to consider valid.
+	/// This must either be within 100 blocks of the current tip (<see cref="GetLatestBlockHeightAsync(CancellationToken)"/>,
+	/// or less than the height of the oldest unspent note in the wallet (<see cref="GetMinUnspentHeight"/>).
+	/// </param>
+	/// <remarks>
+	/// This method can be very slow, and should not be run concurrently with <see cref="DownloadTransactionsAsync"/>.
+	/// </remarks>
+	public void Rescan(uint blockHeight) => LightWalletMethods.Rescan(this.dbinit, blockHeight);
+
 	/// <summary>
 	/// Records a diversifier index as having been used by the given account.
 	/// </summary>

src/Nerdbank.Zcash/PublicAPI.Unshipped.txt

@@ -85,10 +85,12 @@ Nerdbank.Zcash.LightWalletClient.GetBalances(Nerdbank.Zcash.ZcashAccount! accoun
 Nerdbank.Zcash.LightWalletClient.GetBirthdayHeights(Nerdbank.Zcash.ZcashAccount! account) -> Nerdbank.Zcash.LightWalletClient.BirthdayHeights
 Nerdbank.Zcash.LightWalletClient.GetDownloadedTransactions(Nerdbank.Zcash.ZcashAccount! account, uint startingBlock = 0) -> System.Collections.Generic.List<Nerdbank.Zcash.Transaction!>!
 Nerdbank.Zcash.LightWalletClient.GetLatestBlockHeightAsync(System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.ValueTask<uint>
+Nerdbank.Zcash.LightWalletClient.GetMinUnspentHeight() -> uint?
 Nerdbank.Zcash.LightWalletClient.GetUnshieldedBalances(Nerdbank.Zcash.ZcashAccount! account) -> System.Collections.Generic.IReadOnlyList<(Nerdbank.Zcash.TransparentAddress! Address, decimal Balance)>!
 Nerdbank.Zcash.LightWalletClient.LastDownloadHeight.get -> uint?
 Nerdbank.Zcash.LightWalletClient.LightWalletClient(System.Uri! serverUrl, Nerdbank.Zcash.ZcashNetwork network, string! dataFile) -> void
 Nerdbank.Zcash.LightWalletClient.Network.get -> Nerdbank.Zcash.ZcashNetwork
+Nerdbank.Zcash.LightWalletClient.Rescan(uint blockHeight) -> void
 Nerdbank.Zcash.LightWalletClient.SendAsync(Nerdbank.Zcash.ZcashAccount! account, System.Collections.Generic.IReadOnlyCollection<Nerdbank.Zcash.Transaction.LineItem>! payments, System.IProgress<Nerdbank.Zcash.LightWalletClient.SendProgress!>? progress, System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.Task<System.ReadOnlyMemory<Nerdbank.Zcash.TxId>>!
 Nerdbank.Zcash.LightWalletClient.SendProgress
 Nerdbank.Zcash.LightWalletClient.SendProgress.Deconstruct(out uint Id, out bool IsSendInProgress, out uint Progress, out uint Total, out string? LastError, out string? LastTransactionId) -> void

src/Nerdbank.Zcash/RustBindings/LightWallet.cs

@@ -623,6 +623,12 @@ public static extern uint uniffi_nerdbank_zcash_rust_fn_func_get_block_height(
 		ref RustCallStatus _uniffi_out_err
 	);
 
+	[DllImport("nerdbank_zcash_rust")]
+	public static extern RustBuffer uniffi_nerdbank_zcash_rust_fn_func_get_min_unspent_height(
+		RustBuffer @config,
+		ref RustCallStatus _uniffi_out_err
+	);
+
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern RustBuffer uniffi_nerdbank_zcash_rust_fn_func_get_sync_height(
 		RustBuffer @config,
@@ -668,6 +674,13 @@ public static extern void uniffi_nerdbank_zcash_rust_fn_func_init(
 		ref RustCallStatus _uniffi_out_err
 	);
 
+	[DllImport("nerdbank_zcash_rust")]
+	public static extern void uniffi_nerdbank_zcash_rust_fn_func_rescan(
+		RustBuffer @config,
+		uint @blockHeight,
+		ref RustCallStatus _uniffi_out_err
+	);
+
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern RustBuffer uniffi_nerdbank_zcash_rust_fn_func_send(
 		RustBuffer @config,
@@ -994,6 +1007,9 @@ ref RustCallStatus _uniffi_out_err
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_get_block_height();
 
+	[DllImport("nerdbank_zcash_rust")]
+	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_get_min_unspent_height();
+
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_get_sync_height();
 
@@ -1012,6 +1028,9 @@ ref RustCallStatus _uniffi_out_err
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_init();
 
+	[DllImport("nerdbank_zcash_rust")]
+	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_rescan();
+
 	[DllImport("nerdbank_zcash_rust")]
 	public static extern ushort uniffi_nerdbank_zcash_rust_checksum_func_send();
 
@@ -1124,6 +1143,16 @@ static void uniffiCheckApiChecksums()
 				);
 			}
 		}
+		{
+			var checksum =
+				_UniFFILib.uniffi_nerdbank_zcash_rust_checksum_func_get_min_unspent_height();
+			if (checksum != 51541)
+			{
+				throw new UniffiContractChecksumException(
+					$"uniffi.LightWallet: uniffi bindings expected function `uniffi_nerdbank_zcash_rust_checksum_func_get_min_unspent_height` checksum `51541`, library returned `{checksum}`"
+				);
+			}
+		}
 		{
 			var checksum = _UniFFILib.uniffi_nerdbank_zcash_rust_checksum_func_get_sync_height();
 			if (checksum != 61447)
@@ -1180,6 +1209,15 @@ static void uniffiCheckApiChecksums()
 				);
 			}
 		}
+		{
+			var checksum = _UniFFILib.uniffi_nerdbank_zcash_rust_checksum_func_rescan();
+			if (checksum != 9888)
+			{
+				throw new UniffiContractChecksumException(
+					$"uniffi.LightWallet: uniffi bindings expected function `uniffi_nerdbank_zcash_rust_checksum_func_rescan` checksum `9888`, library returned `{checksum}`"
+				);
+			}
+		}
 		{
 			var checksum = _UniFFILib.uniffi_nerdbank_zcash_rust_checksum_func_send();
 			if (checksum != 5940)
@@ -3180,6 +3218,21 @@ ref _status
 		);
 	}
 
+	/// <exception cref="LightWalletException"></exception>
+	public static uint? GetMinUnspentHeight(DbInit @config)
+	{
+		return FfiConverterOptionalUInt32.INSTANCE.Lift(
+			_UniffiHelpers.RustCallWithError(
+				FfiConverterTypeLightWalletException.INSTANCE,
+				(ref RustCallStatus _status) =>
+					_UniFFILib.uniffi_nerdbank_zcash_rust_fn_func_get_min_unspent_height(
+						FfiConverterTypeDbInit.INSTANCE.Lower(@config),
+						ref _status
+					)
+			)
+		);
+	}
+
 	/// <exception cref="LightWalletException"></exception>
 	public static uint? GetSyncHeight(DbInit @config)
 	{
@@ -3288,6 +3341,26 @@ ref _status
 		);
 	}
 
+	/// <summary>
+	/// Resets the database to consider the specified block height to be the tip, such that the next
+	/// scan begins from there.
+	/// The block height must be either within 100 of the current tip (get_block_height)
+	/// so no greater than the oldest unspent input (get_min_unspent_height).
+	/// </summary>
+	/// <exception cref="LightWalletException"></exception>
+	public static void Rescan(DbInit @config, uint @blockHeight)
+	{
+		_UniffiHelpers.RustCallWithError(
+			FfiConverterTypeLightWalletException.INSTANCE,
+			(ref RustCallStatus _status) =>
+				_UniFFILib.uniffi_nerdbank_zcash_rust_fn_func_rescan(
+					FfiConverterTypeDbInit.INSTANCE.Lower(@config),
+					FfiConverterUInt32.INSTANCE.Lower(@blockHeight),
+					ref _status
+				)
+		);
+	}
+
 	/// <exception cref="LightWalletException"></exception>
 	public static List<SendTransactionResult> Send(
 		DbInit @config,

src/nerdbank-zcash-rust/src/ffi.udl

@@ -124,6 +124,9 @@ namespace LightWallet {
 	[Throws=LightWalletError]
 	u32? get_birthday_height(DbInit config);
 
+	[Throws=LightWalletError]
+	u32? get_min_unspent_height(DbInit config);
+
 	[Throws=LightWalletError]
 	u32 get_block_height(string uri, CancellationSource? cancellation);
 
@@ -162,4 +165,11 @@ namespace LightWallet {
 
 	[Throws=LightWalletError]
 	string add_diversifier(DbInit config, u32 account_id, bytes diversifier_index);
+
+	/// Resets the database to consider the specified block height to be the tip, such that the next
+	/// scan begins from there.
+	/// The block height must be either within 100 of the current tip (get_block_height)
+	/// so no greater than the oldest unspent input (get_min_unspent_height).
+	[Throws=LightWalletError]
+	void rescan(DbInit config, u32 block_height);
 };

src/nerdbank-zcash-rust/src/interop.rs

@@ -14,13 +14,17 @@ use secrecy::SecretVec;
 use tokio::runtime::Runtime;
 use tokio_util::sync::CancellationToken;
 use zcash_client_backend::{
-    data_api::{Account, AccountPurpose, WalletRead},
+    data_api::{Account, AccountPurpose, WalletRead, WalletWrite},
     encoding::AddressCodec,
     keys::{Era, UnifiedSpendingKey},
 };
 use zcash_client_sqlite::error::SqliteClientError;
 use zcash_keys::keys::UnifiedFullViewingKey;
-use zcash_primitives::{consensus::Network, legacy::TransparentAddress, zip32::DiversifierIndex};
+use zcash_primitives::{
+    consensus::{BlockHeight, Network},
+    legacy::TransparentAddress,
+    zip32::DiversifierIndex,
+};
 
 use crate::{
     analysis::{BirthdayHeights, UserBalances},
@@ -577,6 +581,19 @@ pub fn shield(
     })
 }
 
+pub fn rescan(config: DbInit, block_height: u32) -> Result<(), LightWalletError> {
+    let network = config.network.into();
+    let mut db = Db::init(config.data_file, network)?;
+    db.data
+        .truncate_to_height(BlockHeight::from_u32(block_height))?;
+    Ok(())
+}
+
+pub fn get_min_unspent_height(config: DbInit) -> Result<Option<u32>, LightWalletError> {
+    let db = Db::load(config.data_file, config.network.into())?;
+    Ok(db.data.get_min_unspent_height()?.map(|h| h.into()))
+}
+
 #[cfg(test)]
 mod tests {
     use crate::test_constants::setup_test;

src/nerdbank-zcash-rust/src/lib.rs

@@ -26,9 +26,9 @@ mod test_constants;
 use analysis::{BirthdayHeights, UserBalances};
 use interop::{
     add_account, add_diversifier, cancel, disconnect_server, get_accounts, get_birthday_height,
-    get_birthday_heights, get_block_height, get_sync_height, get_transactions,
-    get_unshielded_utxos, get_user_balances, import_account_ufvk, init, send, shield,
-    simulate_send, sync, AccountInfo, CancellationSource, ChainType, DbInit, LightWalletError,
-    Pool, SendDetails, SendTransactionResult, SyncUpdate, SyncUpdateData, Transaction,
-    TransactionNote, TransactionSendDetail, TransparentNote,
+    get_birthday_heights, get_block_height, get_min_unspent_height, get_sync_height,
+    get_transactions, get_unshielded_utxos, get_user_balances, import_account_ufvk, init, rescan,
+    send, shield, simulate_send, sync, AccountInfo, CancellationSource, ChainType, DbInit,
+    LightWalletError, Pool, SendDetails, SendTransactionResult, SyncUpdate, SyncUpdateData,
+    Transaction, TransactionNote, TransactionSendDetail, TransparentNote,
 };