Support all chain sources for wallet birthday block hash lookup

Extend get_block_hash_by_height to work with Esplora and Electrum
in addition to bitcoind. Esplora uses its native get_block_hash API.
Electrum uses block_header_raw and extracts the hash from the header.

For Electrum, if the runtime client hasn't started yet (called during
build), a temporary connection is created for the lookup.

Author: FreeOnlineUser

src/chain/electrum.rs

@@ -89,6 +89,28 @@ impl ElectrumChainSource {
 		self.electrum_runtime_status.write().unwrap().stop();
 	}
 
+	pub(super) async fn get_block_hash_by_height(
+		&self, height: u32,
+	) -> Result<bitcoin::BlockHash, ()> {
+		// Try the runtime client if started, otherwise create a temporary connection.
+		let status = self.electrum_runtime_status.read().unwrap();
+		if let Some(client) = status.client() {
+			drop(status);
+			return client.get_block_hash_by_height(height);
+		}
+		drop(status);
+
+		// Runtime not started yet (called during build). Use a temporary client.
+		let config = ElectrumConfigBuilder::new()
+			.timeout(Some(self.sync_config.timeouts_config.per_request_timeout_secs))
+			.build();
+		let client = ElectrumClient::from_config(&self.server_url, config).map_err(|_| ())?;
+		let header_bytes = client.block_header_raw(height as usize).map_err(|_| ())?;
+		let header: bitcoin::block::Header =
+			bitcoin::consensus::deserialize(&header_bytes).map_err(|_| ())?;
+		Ok(header.block_hash())
+	}
+
 	pub(crate) async fn sync_onchain_wallet(
 		&self, onchain_wallet: Arc<Wallet>,
 	) -> Result<(), Error> {
@@ -420,6 +442,14 @@ impl ElectrumRuntimeClient {
 		})
 	}
 
+	fn get_block_hash_by_height(&self, height: u32) -> Result<bitcoin::BlockHash, ()> {
+		let header_bytes =
+			self.electrum_client.block_header_raw(height as usize).map_err(|_| ())?;
+		let header: bitcoin::block::Header =
+			bitcoin::consensus::deserialize(&header_bytes).map_err(|_| ())?;
+		Ok(header.block_hash())
+	}
+
 	async fn sync_confirmables(
 		&self, confirmables: Vec<Arc<dyn Confirm + Sync + Send>>,
 	) -> Result<(), Error> {

src/chain/esplora.rs

@@ -74,6 +74,12 @@ impl EsploraChainSource {
 		}
 	}
 
+	pub(super) async fn get_block_hash_by_height(
+		&self, height: u32,
+	) -> Result<bitcoin::BlockHash, ()> {
+		self.esplora_client.get_block_hash(height).await.map_err(|_| ())
+	}
+
 	pub(super) async fn sync_onchain_wallet(
 		&self, onchain_wallet: Arc<Wallet>,
 	) -> Result<(), Error> {

src/chain/mod.rs

@@ -224,7 +224,12 @@ impl ChainSource {
 				let utxo_source = bitcoind_chain_source.as_utxo_source();
 				utxo_source.get_block_hash_by_height(height).await.map_err(|_| ())
 			},
-			_ => Err(()),
+			ChainSourceKind::Esplora(esplora_chain_source) => {
+				esplora_chain_source.get_block_hash_by_height(height).await
+			},
+			ChainSourceKind::Electrum(electrum_chain_source) => {
+				electrum_chain_source.get_block_hash_by_height(height).await
+			},
 		}
 	}