zcash_client_backend: Add `WalletRead::get_seed_account`

zcash_client_backend/CHANGELOG.md

@@ -51,9 +51,10 @@ and this library adheres to Rust's notion of
   - Arguments to `ScannedBlock::from_parts` have changed.
   - Changes to the `WalletRead` trait:
     - Added `Account` associated type.
-    - Added `get_orchard_nullifiers`
+    - Added `get_orchard_nullifiers` method.
     - `get_account_for_ufvk` now returns an `Self::Account` instead of a bare
       `AccountId`
+    - Added `get_seed_account` method.
   - Changes to the `InputSource` trait:
     - `select_spendable_notes` now takes its `target_value` argument as a
       `NonNegativeAmount`. Also, the values of the returned map are also

zcash_client_backend/src/data_api.rs

@@ -66,6 +66,7 @@ use std::{
 use incrementalmerkletree::{frontier::Frontier, Retention};
 use secrecy::SecretVec;
 use shardtree::{error::ShardTreeError, store::ShardStore, ShardTree};
+use zcash_keys::keys::HdSeedFingerprint;
 
 use self::{chain::CommitmentTreeRoot, scanning::ScanRange};
 use crate::{
@@ -655,6 +656,14 @@ pub trait WalletRead {
         ufvk: &UnifiedFullViewingKey,
     ) -> Result<Option<Self::Account>, Self::Error>;
 
+    /// Returns the account corresponding to a given [`HdSeedFingerprint`] and
+    /// [`zip32::AccountId`], if any.
+    fn get_seed_account(
+        &self,
+        seed: &HdSeedFingerprint,
+        account_id: zip32::AccountId,
+    ) -> Result<Option<Self::Account>, Self::Error>;
+
     /// Returns the wallet balances and sync status for an account given the specified minimum
     /// number of confirmations, or `Ok(None)` if the wallet has no balance data available.
     fn get_wallet_summary(
@@ -1416,6 +1425,7 @@ pub mod testing {
     use secrecy::{ExposeSecret, SecretVec};
     use shardtree::{error::ShardTreeError, store::memory::MemoryShardStore, ShardTree};
     use std::{collections::HashMap, convert::Infallible, num::NonZeroU32};
+    use zcash_keys::keys::HdSeedFingerprint;
 
     use zcash_primitives::{
         block::BlockHash,
@@ -1588,6 +1598,14 @@ pub mod testing {
             Ok(None)
         }
 
+        fn get_seed_account(
+            &self,
+            _seed: &HdSeedFingerprint,
+            _account_id: zip32::AccountId,
+        ) -> Result<Option<Self::Account>, Self::Error> {
+            Ok(None)
+        }
+
         fn get_wallet_summary(
             &self,
             _min_confirmations: u32,

zcash_client_sqlite/src/lib.rs

@@ -405,6 +405,14 @@ impl<C: Borrow<rusqlite::Connection>, P: consensus::Parameters> WalletRead for W
         wallet::get_account_for_ufvk(self.conn.borrow(), &self.params, ufvk)
     }
 
+    fn get_seed_account(
+        &self,
+        seed: &HdSeedFingerprint,
+        account_id: zip32::AccountId,
+    ) -> Result<Option<Self::Account>, Self::Error> {
+        wallet::get_seed_account(self.conn.borrow(), &self.params, seed, account_id)
+    }
+
     fn get_wallet_summary(
         &self,
         min_confirmations: u32,

zcash_client_sqlite/src/wallet.rs

@@ -779,6 +779,46 @@ pub(crate) fn get_account_for_ufvk<P: consensus::Parameters>(
     }
 }
 
+/// Returns the account id corresponding to a given [`HdSeedFingerprint`]
+/// and [`zip32::AccountId`], if any.
+pub(crate) fn get_seed_account<P: consensus::Parameters>(
+    conn: &rusqlite::Connection,
+    params: &P,
+    seed: &HdSeedFingerprint,
+    account_id: zip32::AccountId,
+) -> Result<Option<(AccountId, Option<UnifiedFullViewingKey>)>, SqliteClientError> {
+    let mut stmt = conn.prepare(
+        "SELECT id, ufvk
+        FROM accounts
+        WHERE hd_seed_fingerprint = :hd_seed_fingerprint
+          AND hd_account_index = :account_id",
+    )?;
+
+    let mut accounts = stmt.query_and_then::<_, SqliteClientError, _, _>(
+        named_params![
+            ":hd_seed_fingerprint": seed.as_bytes(),
+            ":hd_account_index": u32::from(account_id),
+        ],
+        |row| {
+            let account_id = row.get::<_, u32>(0).map(AccountId)?;
+            Ok((
+                account_id,
+                row.get::<_, Option<String>>(1)?
+                    .map(|ufvk_str| UnifiedFullViewingKey::decode(params, &ufvk_str))
+                    .transpose()
+                    .map_err(|e| {
+                        SqliteClientError::CorruptedData(format!(
+                            "Could not decode unified full viewing key for account {:?}: {}",
+                            account_id, e
+                        ))
+                    })?,
+            ))
+        },
+    )?;
+
+    accounts.next().transpose()
+}
+
 pub(crate) trait ScanProgress {
     fn sapling_scan_progress(
         &self,