From 9b5a134d01adaf033a03d259f3f89215d5cbe0f8 Mon Sep 17 00:00:00 2001
From: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date: Thu, 3 Nov 2016 14:37:58 +0300
Subject: [PATCH] initial BlocksWriter version

---
 sync/src/blocks_writer.rs | 77 +++++++++++++++++++++++++++++++++++++++
 sync/src/lib.rs           | 17 +++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 sync/src/blocks_writer.rs

diff --git a/sync/src/blocks_writer.rs b/sync/src/blocks_writer.rs
new file mode 100644
index 00000000..841490d0
--- /dev/null
+++ b/sync/src/blocks_writer.rs
@@ -0,0 +1,77 @@
+use std::sync::Arc;
+use chain;
+use db;
+use super::Error;
+use verification::{Verify, ChainVerifier};
+
+pub struct BlocksWriter {
+	storage: Arc<db::Store>,
+	verifier: ChainVerifier,
+}
+
+impl BlocksWriter {
+	pub fn new(storage: Arc<db::Store>) -> BlocksWriter {
+		BlocksWriter {
+			storage: storage.clone(),
+			verifier: ChainVerifier::new(storage),
+		}
+	}
+
+	pub fn append_block(&mut self, block: chain::Block) -> Result<(), Error> {
+		// TODO: share same verification code with synchronization_client
+		if self.storage.best_block().map_or(false, |bb| bb.hash != block.block_header.previous_header_hash) {
+			return Err(Error::OutOfOrderBlock);
+		}
+
+		match self.verifier.verify(&block) {
+			Err(err) => Err(Error::Verification(err)),
+			Ok(_chain) => self.storage.insert_block(&block).map_err(|err| Error::Database(err)),
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use db;
+	use db::Store;
+	use std::sync::Arc;
+	use super::super::Error;
+	use super::BlocksWriter;
+	use chain::RepresentH256;
+	use test_data;
+	use verification;
+
+	#[test]
+	fn blocks_writer_appends_blocks() {
+		let db = Arc::new(db::TestStorage::with_genesis_block());
+		let mut blocks_target = BlocksWriter::new(db.clone());
+		blocks_target.append_block(test_data::block_h1()).expect("Expecting no error");
+		assert_eq!(db.best_block().expect("Block is inserted").number, 1);
+	}
+
+	#[test]
+	fn blocks_writer_verification_error() {
+		let db = Arc::new(db::TestStorage::with_genesis_block());
+		let mut blocks_target = BlocksWriter::new(db.clone());
+		match blocks_target.append_block(test_data::block_h2()).unwrap_err() {
+			Error::OutOfOrderBlock => (),
+			_ => panic!("Unexpected error"),
+		};
+		assert_eq!(db.best_block().expect("Block is inserted").number, 0);
+	}
+
+	#[test]
+	fn blocks_writer_out_of_order_block() {
+		let db = Arc::new(db::TestStorage::with_genesis_block());
+		let mut blocks_target = BlocksWriter::new(db.clone());
+
+		let wrong_block = test_data::block_builder()
+			.header().parent(test_data::genesis().hash()).build()
+		.build();
+		match blocks_target.append_block(wrong_block).unwrap_err() {
+			Error::Verification(verification::Error::Empty) => (),
+			_ => panic!("Unexpected error"),
+		};
+		assert_eq!(db.best_block().expect("Block is inserted").number, 0);
+	}
+}
diff --git a/sync/src/lib.rs b/sync/src/lib.rs
index 79533c6b..1a3ee849 100644
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@@ -11,6 +11,7 @@ extern crate time;
 extern crate verification;
 extern crate miner;
 
+mod blocks_writer;
 mod hash_queue;
 mod inbound_connection;
 mod inbound_connection_factory;
@@ -24,6 +25,22 @@ mod synchronization_server;
 use std::sync::Arc;
 use parking_lot::{Mutex, RwLock};
 
+/// Sync errors.
+#[derive(Debug)]
+pub enum Error {
+	/// Out of order block.
+	OutOfOrderBlock,
+	/// Database error.
+	Database(db::Error),
+	/// Block verification error.
+	Verification(verification::Error),
+}
+
+/// Create blocks writer.
+pub fn create_sync_blocks_writer(db: Arc<db::Store>) -> blocks_writer::BlocksWriter {
+	blocks_writer::BlocksWriter::new(db)
+}
+
 /// Create inbound synchronization connections factory for given `db`.
 pub fn create_sync_connection_factory(db: Arc<db::Store>) -> p2p::LocalSyncNodeRef {
 	use synchronization_chain::Chain as SyncChain;