feat[rusqlite]: add get_pre_1_wallet_keychains migration helper

Author: notmandatory

crates/chain/src/rusqlite_impl.rs

@@ -12,7 +12,7 @@ use alloc::{
 };
 use bitcoin::consensus::{Decodable, Encodable};
 use rusqlite;
-use rusqlite::named_params;
+use rusqlite::{named_params, Connection};
 use rusqlite::types::{FromSql, FromSqlError, FromSqlResult, ToSql, ToSqlOutput, ValueRef};
 use rusqlite::OptionalExtension;
 use rusqlite::Transaction;
@@ -659,6 +659,52 @@ impl keychain_txout::ChangeSet {
     }
 }
 
+// pre-1.0 sqlite database migration helper functions
+
+/// `Pre1WalletKeychain` represents a structure that holds the keychain details
+/// and metadata required for managing a wallet's keys.
+#[derive(Debug)]
+pub struct Pre1WalletKeychain {
+    /// The name of the wallet keychains, "External" or "Internal".
+    pub keychain: String,
+    /// The index of the last derived key in the wallet keychain.
+    pub last_derivation_index: u32,
+    /// Checksum of the keychain descriptor, it must match the corresponding post-1.0 bdk wallet
+    /// descriptor checksum.
+    pub checksum: Vec<u8>,
+}
+
+/// Retrieves a list of [`Pre1WalletKeychain`] objects from a pre-1.0 bdk SQLite database.
+///
+/// This function uses a connection to a pre-1.0 bdk wallet SQLite database to execute a query that
+/// retrieves data from two tables (`last_derivation_indices` and `checksums`) and maps the
+/// resulting rows to a list of `Pre1WalletKeychain` objects.
+pub fn get_pre_1_wallet_keychains(
+    conn: &mut Connection,
+) -> Result<Vec<Pre1WalletKeychain>, rusqlite::Error> {
+    let db_tx = conn.transaction()?;
+    let mut statement = db_tx.prepare(
+        "SELECT idx.keychain AS keychain, value, checksum FROM last_derivation_indices AS idx \
+         JOIN checksums AS chk ON idx.keychain = chk.keychain")?;
+    let row_iter = statement.query_map([], |row| {
+        Ok((
+            row.get::<_, String>("keychain")?,
+            row.get::<_, u32>("value")?,
+            row.get::<_, Vec<u8>>("checksum")?,
+        ))
+    })?;
+    let mut keychains = vec![];
+    for row in row_iter {
+        let (keychain, value, checksum) = row?;
+        keychains.push(Pre1WalletKeychain {
+            keychain,
+            last_derivation_index: value,
+            checksum,
+        })
+    }
+    Ok(keychains)
+}
+
 #[cfg(test)]
 #[cfg_attr(coverage_nightly, coverage(off))]
 mod test {
@@ -903,4 +949,52 @@ mod test {
 
         Ok(())
     }
+
+    #[test]
+    fn test_get_pre_1_wallet_keychains() -> anyhow::Result<()> {
+        let mut conn = rusqlite::Connection::open_in_memory()?;
+        let external_checksum = vec![0x01u8, 0x02u8, 0x03u8, 0x04u8];
+        let internal_checksum = vec![0x05u8, 0x06u8, 0x07u8, 0x08u8];
+        // Init tables
+        {   // Create pre-1.0 bdk sqlite schema
+            conn.execute_batch(
+                "CREATE TABLE last_derivation_indices (keychain TEXT, value INTEGER);
+                 CREATE UNIQUE INDEX idx_indices_keychain ON last_derivation_indices(keychain);
+                 CREATE TABLE checksums (keychain TEXT, checksum BLOB);
+                 CREATE INDEX idx_checksums_keychain ON checksums(keychain);"
+            )?;
+            // Insert test data
+            conn.execute("INSERT INTO last_derivation_indices (keychain, value) VALUES (?, ?)",
+                         rusqlite::params!["External", 42])?;
+            conn.execute("INSERT INTO checksums (keychain, checksum) VALUES (?, ?)",
+                         rusqlite::params!["External", external_checksum])?;
+            conn.execute("INSERT INTO last_derivation_indices (keychain, value) VALUES (?, ?)",
+                         rusqlite::params!["Internal", 21])?;
+            conn.execute("INSERT INTO checksums (keychain, checksum) VALUES (?, ?)",
+                         rusqlite::params!["Internal", internal_checksum])?;
+        }
+        // test with a 2 keychain wallet
+        let result = get_pre_1_wallet_keychains(&mut conn)?;
+        assert_eq!(result.len(), 2);
+        assert_eq!(result[0].keychain, "External");
+        assert_eq!(result[0].last_derivation_index, 42);
+        assert_eq!(result[0].checksum, external_checksum);
+        assert_eq!(result[1].keychain, "Internal");
+        assert_eq!(result[1].last_derivation_index, 21);
+        assert_eq!(result[1].checksum, internal_checksum);
+
+        // delete "Internal" descriptor
+        {
+            conn.execute("DELETE FROM last_derivation_indices WHERE keychain = ?", rusqlite::params!["Internal"])?;
+            conn.execute("DELETE FROM checksums WHERE keychain = ?", rusqlite::params!["Internal"])?;
+        }
+        // test with a 1 keychain wallet
+        let result = get_pre_1_wallet_keychains(&mut conn)?;
+        assert_eq!(result.len(), 1);
+        assert_eq!(result[0].keychain, "External");
+        assert_eq!(result[0].last_derivation_index, 42);
+        assert_eq!(result[0].checksum, external_checksum);
+
+        Ok(())
+    }
 }