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    use std::sync::Arc;
    use parking_lot::{Mutex, Condvar};
    use time;
    use futures::{lazy, finished};
    use chain::{Transaction, IndexedTransaction, IndexedBlock};
    use message::types;
    use miner::BlockAssembler;
    use network::ConsensusParams;
    use synchronization_client::{Client};
    use synchronization_executor::{Task as SynchronizationTask, TaskExecutor};
    use synchronization_server::{Server, ServerTask};
    use synchronization_verifier::{TransactionVerificationSink};
    use primitives::hash::H256;
    use miner::BlockTemplate;
    use verification::median_timestamp_inclusive;
    use synchronization_peers::{TransactionAnnouncementType, BlockAnnouncementType};
    use types::{PeerIndex, RequestId, StorageRef, MemoryPoolRef, PeersRef, ExecutorRef,
    	ClientRef, ServerRef, SynchronizationStateRef, SyncListenerRef};

    /// Local synchronization node
    pub struct LocalNode<T: TaskExecutor, U: Server, V: Client> {
    	/// Network we are working on
    	consensus: ConsensusParams,
    	/// Storage reference
    	storage: StorageRef,
    	/// Memory pool reference
    	memory_pool: MemoryPoolRef,
    	/// Synchronization peers
    	peers: PeersRef,
    	/// Shared synchronization state
    	state: SynchronizationStateRef,
    	/// Synchronization executor
    	executor: ExecutorRef<T>,
    	/// Synchronization process
    	client: ClientRef<V>,
    	/// Synchronization server
    	server: ServerRef<U>,
    }

    /// Transaction accept verification sink
    struct TransactionAcceptSink {
    	data: Arc<TransactionAcceptSinkData>,
    }

    #[derive(Default)]
    struct TransactionAcceptSinkData {
    	result: Mutex<Option<Result<H256, String>>>,
    	waiter: Condvar,
    }

    impl<T, U, V> LocalNode<T, U, V> where T: TaskExecutor, U: Server, V: Client {
    	/// Create new synchronization node
    	#[cfg_attr(feature="cargo-clippy", allow(too_many_arguments))]
    	pub fn new(consensus: ConsensusParams, storage: StorageRef, memory_pool: MemoryPoolRef, peers: PeersRef,
    		state: SynchronizationStateRef, executor: ExecutorRef<T>, client: ClientRef<V>, server: ServerRef<U>) -> Self {
    		LocalNode {
    			consensus: consensus,
    			storage: storage,
    			memory_pool: memory_pool,
    			peers: peers,
    			state: state,
    			executor: executor,
    			client: client,
    			server: server,
    		}
    	}

    	/// When new peer connects to the node
    	pub fn on_connect(&self, peer_index: PeerIndex, peer_name: String, version: types::Version) {
    		trace!(target: "sync", "Starting new sync session with peer#{}: {}", peer_index, peer_name);

    		// light clients may not want transactions broadcasting until filter for connection is set
    		if !version.relay_transactions() {
    			self.peers.set_transaction_announcement_type(peer_index, TransactionAnnouncementType::DoNotAnnounce);
    		}

    		// start synchronization session with peer
    		self.client.on_connect(peer_index);
    	}

    	/// When peer disconnects
    	pub fn on_disconnect(&self, peer_index: PeerIndex) {
    		trace!(target: "sync", "Stopping sync session with peer#{}", peer_index);

    		// stop synchronization session with peer
    		self.client.on_disconnect(peer_index);
    	}

    	/// When inventory message is received
    	pub fn on_inventory(&self, peer_index: PeerIndex, message: types::Inv) {
    		trace!(target: "sync", "Got `inventory` message from peer#{}. Inventory len: {}", peer_index, message.inventory.len());
    		self.client.on_inventory(peer_index, message);
    	}

    	/// When headers message is received
    	pub fn on_headers(&self, peer_index: PeerIndex, message: types::Headers) {
    		trace!(target: "sync", "Got `headers` message from peer#{}. Headers len: {}", peer_index, message.headers.len());
    		self.client.on_headers(peer_index, message);
    	}

    	/// When transaction is received
    	pub fn on_transaction(&self, peer_index: PeerIndex, tx: IndexedTransaction) {
    		// we ignore all transactions while synchronizing, as memory pool contains
    		// only verified transactions && we can not verify on-top transactions while
    		// we are not on the top
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `transaction` message from peer#{}. Tx hash: {}", peer_index, tx.hash.to_reversed_str());
    			return;
    		}

    		trace!(target: "sync", "Got `transaction` message from peer#{}. Tx hash: {}", peer_index, tx.hash.to_reversed_str());
    		self.client.on_transaction(peer_index, tx);
    	}

    	/// When block is received
    	pub fn on_block(&self, peer_index: PeerIndex, block: IndexedBlock) {
    		trace!(target: "sync", "Got `block` message from peer#{}. Block hash: {}", peer_index, block.header.hash.to_reversed_str());
    		self.client.on_block(peer_index, block);
    	}

    	/// When notfound is received
    	pub fn on_notfound(&self, peer_index: PeerIndex, message: types::NotFound) {
    		trace!(target: "sync", "Got `notfound` message from peer#{}", peer_index);
    		self.client.on_notfound(peer_index, message);
    	}

    	/// When peer is requesting for items
    	pub fn on_getdata(&self, peer_index: PeerIndex, message: types::GetData) {
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `getdata` message from peer#{}. Inventory len: {}", peer_index, message.inventory.len());
    			return;
    		}

    		trace!(target: "sync", "Got `getdata` message from peer#{}. Inventory len: {}", peer_index, message.inventory.len());
    		self.server.execute(ServerTask::GetData(peer_index, message));
    	}

    	/// When peer is requesting for known blocks hashes
    	pub fn on_getblocks(&self, peer_index: PeerIndex, message: types::GetBlocks) {
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `getblocks` message from peer#{}", peer_index);
    			return;
    		}

    		trace!(target: "sync", "Got `getblocks` message from peer#{}", peer_index);
    		self.server.execute(ServerTask::GetBlocks(peer_index, message));
    	}

    	/// When peer is requesting for known blocks headers
    	pub fn on_getheaders(&self, peer_index: PeerIndex, message: types::GetHeaders, id: RequestId) {
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `getheaders` message from peer#{}", peer_index);
    			self.executor.execute(SynchronizationTask::Ignore(peer_index, id));
    			return;
    		}

    		trace!(target: "sync", "Got `getheaders` message from peer#{}", peer_index);

    		// simulating bitcoind for passing tests: if we are in nearly-saturated state
    		// and peer, which has just provided a new blocks to us, is asking for headers
    		// => do not serve getheaders until we have fully process his blocks + wait until headers are served before returning
    		let server = Arc::downgrade(&self.server);
    		let server_task = ServerTask::GetHeaders(peer_index, message, id);
    		let lazy_server_task = lazy(move || {
    			server.upgrade().map(|s| s.execute(server_task));
    			finished::<(), ()>(())
    		});
    		self.client.after_peer_nearly_blocks_verified(peer_index, Box::new(lazy_server_task));
    	}

    	/// When peer is requesting for memory pool contents
    	pub fn on_mempool(&self, peer_index: PeerIndex, _message: types::MemPool) {
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `mempool` message from peer#{}", peer_index);
    			return;
    		}

    		trace!(target: "sync", "Got `mempool` message from peer#{}", peer_index);
    		self.server.execute(ServerTask::Mempool(peer_index));
    	}

    	/// When peer asks us from specific transactions from specific block
    	pub fn on_get_block_txn(&self, peer_index: PeerIndex, message: types::GetBlockTxn) {
    		if self.state.synchronizing() {
    			trace!(target: "sync", "Ignored `getblocktxn` message from peer#{}", peer_index);
    			return;
    		}

    		trace!(target: "sync", "Got `getblocktxn` message from peer#{}", peer_index);
    		self.server.execute(ServerTask::GetBlockTxn(peer_index, message));
    	}

    	/// When peer sets bloom filter for connection
    	pub fn on_filterload(&self, peer_index: PeerIndex, message: types::FilterLoad) {
    		trace!(target: "sync", "Got `filterload` message from peer#{}", peer_index);
    		self.peers.set_bloom_filter(peer_index, message);
    	}

    	/// When peer updates bloom filter for connection
    	pub fn on_filteradd(&self, peer_index: PeerIndex, message: types::FilterAdd) {
    		trace!(target: "sync", "Got `filteradd` message from peer#{}", peer_index);
    		self.peers.update_bloom_filter(peer_index, message);
    	}

    	/// When peer removes bloom filter from connection
    	pub fn on_filterclear(&self, peer_index: PeerIndex, _message: types::FilterClear) {
    		trace!(target: "sync", "Got `filterclear` message from peer#{}", peer_index);
    		self.peers.clear_bloom_filter(peer_index);
    	}

    	/// When peer sets up a minimum fee rate filter for connection
    	pub fn on_feefilter(&self, peer_index: PeerIndex, message: types::FeeFilter) {
    		trace!(target: "sync", "Got `feefilter` message from peer#{}", peer_index);
    		self.peers.set_fee_filter(peer_index, message);
    	}

    	/// When peer asks us to announce new blocks using headers message
    	pub fn on_sendheaders(&self, peer_index: PeerIndex, _message: types::SendHeaders) {
    		trace!(target: "sync", "Got `sendheaders` message from peer#{}", peer_index);
    		self.peers.set_block_announcement_type(peer_index, BlockAnnouncementType::SendHeaders);
    	}

    	/// When peer asks us to announce new blocks using cpmctblock message
    	pub fn on_send_compact(&self, peer_index: PeerIndex, message: types::SendCompact) {
    		trace!(target: "sync", "Got `sendcmpct` message from peer#{}", peer_index);

    		// The second integer SHALL be interpreted as a little-endian version number. Nodes sending a sendcmpct message MUST currently set this value to 1.
    		// TODO: version 2 supports segregated witness transactions
    		if message.second != 1 {
    			return;
    		}

    		// Upon receipt of a "sendcmpct" message with the first and second integers set to 1, the node SHOULD announce new blocks by sending a cmpctblock message.
    		if message.first {
    			self.peers.set_block_announcement_type(peer_index, BlockAnnouncementType::SendCompactBlock);
    		}

    		// else:
    		// Upon receipt of a "sendcmpct" message with the first integer set to 0, the node SHOULD NOT announce new blocks by sending a cmpctblock message,
    		// but SHOULD announce new blocks by sending invs or headers, as defined by BIP130.
    		// => work as before
    	}

    	/// When peer sents us a merkle block
    	pub fn on_merkleblock(&self, peer_index: PeerIndex, _message: types::MerkleBlock) {
    		trace!(target: "sync", "Got `merkleblock` message from peer#{}", peer_index);
    		// we never setup filter on connections => misbehaving
    		self.peers.misbehaving(peer_index, "Got unrequested 'merkleblock' message");
    	}

    	/// When peer sents us a compact block
    	pub fn on_compact_block(&self, peer_index: PeerIndex, _message: types::CompactBlock) {
    		trace!(target: "sync", "Got `cmpctblock` message from peer#{}", peer_index);
    		// we never ask compact block from peers => misbehaving
    		self.peers.misbehaving(peer_index, "Got unrequested 'cmpctblock' message");
    	}

    	/// When peer sents us specific transactions for specific block
    	pub fn on_block_txn(&self, peer_index: PeerIndex, _message: types::BlockTxn) {
    		trace!(target: "sync", "Got `blocktxn` message from peer#{}", peer_index);
    		// we never ask for this => misbehaving
    		self.peers.misbehaving(peer_index, "Got unrequested 'blocktxn' message");
    	}

    	/// Verify and then schedule new transaction
    	pub fn accept_transaction(&self, transaction: Transaction) -> Result<H256, String> {
    		let sink_data = Arc::new(TransactionAcceptSinkData::default());
    		let sink = TransactionAcceptSink::new(sink_data.clone()).boxed();
    		{
    			if let Err(err) = self.client.accept_transaction(transaction, sink) {
    				return Err(err.into());
    			}
    		}
    		sink_data.wait()
    	}

    	/// Get block template for mining
    	pub fn get_block_template(&self) -> BlockTemplate {
    		let previous_block_height = self.storage.best_block().number;
    		let previous_block_header = self.storage.block_header(previous_block_height.into()).expect("best block is in db; qed");
    		let median_timestamp = median_timestamp_inclusive(previous_block_header.hash(), self.storage.as_block_header_provider());
    		let new_block_height = previous_block_height + 1;
    		let max_block_size = self.consensus.fork.max_block_size(new_block_height, median_timestamp);
    		let block_assembler = BlockAssembler {
    			max_block_size: max_block_size as u32,
    			max_block_sigops: self.consensus.fork.max_block_sigops(new_block_height, max_block_size) as u32,
    		};
    		let memory_pool = &*self.memory_pool.read();
    		block_assembler.create_new_block(&self.storage, memory_pool, time::get_time().sec as u32, median_timestamp, &self.consensus)
    	}

    	/// Install synchronization events listener
    	pub fn install_sync_listener(&self, listener: SyncListenerRef) {
    		self.client.install_sync_listener(listener);
    	}
    }

    impl TransactionAcceptSink {
    	pub fn new(data: Arc<TransactionAcceptSinkData>) -> Self {
    		TransactionAcceptSink {
    			data: data,
    		}
    	}

    	pub fn boxed(self) -> Box<Self> {
    		Box::new(self)
    	}
    }

    impl TransactionAcceptSinkData {
    	pub fn wait(&self) -> Result<H256, String> {
    		let mut lock = self.result.lock();
    		if lock.is_some() {
    			return lock.take().expect("checked line above");
    		}

    		self.waiter.wait(&mut lock);
    		lock.take().expect("waiter.wait returns only when result is set; lock.take() takes result from waiter.result; qed")
    	}
    }

    impl TransactionVerificationSink for TransactionAcceptSink {
    	fn on_transaction_verification_success(&self, tx: IndexedTransaction) {
    		*self.data.result.lock() = Some(Ok(tx.hash));
    		self.data.waiter.notify_all();
    	}

    	fn on_transaction_verification_error(&self, err: &str, _hash: &H256) {
    		*self.data.result.lock() = Some(Err(err.to_owned()));
    		self.data.waiter.notify_all();
    	}
    }

    #[cfg(test)]
    pub mod tests {
    	extern crate test_data;

    	use std::sync::Arc;
    	use parking_lot::RwLock;
    	use synchronization_executor::Task;
    	use synchronization_executor::tests::DummyTaskExecutor;
    	use synchronization_client::SynchronizationClient;
    	use synchronization_client_core::{Config, SynchronizationClientCore, CoreVerificationSink};
    	use synchronization_chain::Chain;
    	use message::types;
    	use message::common::{InventoryVector, InventoryType};
    	use network::{ConsensusParams, ConsensusFork, Network};
    	use chain::Transaction;
    	use db::{BlockChainDatabase};
    	use miner::MemoryPool;
    	use super::LocalNode;
    	use synchronization_server::ServerTask;
    	use synchronization_server::tests::DummyServer;
    	use synchronization_verifier::tests::DummyVerifier;
    	use primitives::bytes::Bytes;
    	use verification::BackwardsCompatibleChainVerifier as ChainVerifier;
    	use std::iter::repeat;
    	use synchronization_peers::PeersImpl;
    	use utils::SynchronizationState;
    	use types::SynchronizationStateRef;

    	pub fn default_filterload() -> types::FilterLoad {
    		types::FilterLoad {
    			filter: Bytes::from(repeat(0u8).take(1024).collect::<Vec<_>>()),
    			hash_functions: 10,
    			tweak: 5,
    			flags: types::FilterFlags::None,
    		}
    	}

    	pub fn make_filteradd(data: &[u8]) -> types::FilterAdd {
    		types::FilterAdd {
    			data: data.into(),
    		}
    	}

    	fn create_local_node(verifier: Option<DummyVerifier>) -> (Arc<DummyTaskExecutor>, Arc<DummyServer>, LocalNode<DummyTaskExecutor, DummyServer, SynchronizationClient<DummyTaskExecutor, DummyVerifier>>) {
    		let memory_pool = Arc::new(RwLock::new(MemoryPool::new()));
    		let storage = Arc::new(BlockChainDatabase::init_test_chain(vec![test_data::genesis().into()]));
    		let sync_state = SynchronizationStateRef::new(SynchronizationState::with_storage(storage.clone()));
    		let chain = Chain::new(storage.clone(), ConsensusParams::new(Network::Unitest, ConsensusFork::BitcoinCore), memory_pool.clone());
    		let sync_peers = Arc::new(PeersImpl::default());
    		let executor = DummyTaskExecutor::new();
    		let server = Arc::new(DummyServer::new());
    		let config = Config { close_connection_on_bad_block: true };
    		let chain_verifier = Arc::new(ChainVerifier::new(storage.clone(), ConsensusParams::new(Network::Mainnet, ConsensusFork::BitcoinCore)));
    		let client_core = SynchronizationClientCore::new(config, sync_state.clone(), sync_peers.clone(), executor.clone(), chain, chain_verifier);
    		let mut verifier = match verifier {
    			Some(verifier) => verifier,
    			None => DummyVerifier::default(),
    		};
    		verifier.set_sink(Arc::new(CoreVerificationSink::new(client_core.clone())));
    		let client = SynchronizationClient::new(sync_state.clone(), client_core, verifier);
    		let local_node = LocalNode::new(ConsensusParams::new(Network::Mainnet, ConsensusFork::BitcoinCore), storage, memory_pool, sync_peers, sync_state, executor.clone(), client, server.clone());
    		(executor, server, local_node)
    	}

    	#[test]
    	fn local_node_serves_block() {
    		let (_, server, local_node) = create_local_node(None);
    		let peer_index = 0; local_node.on_connect(peer_index, "test".into(), types::Version::default());
    		// peer requests genesis block
    		let genesis_block_hash = test_data::genesis().hash();
    		let inventory = vec![
    			InventoryVector {
    				inv_type: InventoryType::MessageBlock,
    				hash: genesis_block_hash.clone(),
    			}
    		];
    		local_node.on_getdata(peer_index, types::GetData {
    			inventory: inventory.clone()
    		});
    		// => `getdata` is served
    		let tasks = server.take_tasks();
    		assert_eq!(tasks, vec![ServerTask::GetData(peer_index, types::GetData::with_inventory(inventory))]);
    	}

    	#[test]
    	fn local_node_accepts_local_transaction() {
    		let (executor, _, local_node) = create_local_node(None);

    		// transaction will be relayed to this peer
    		let peer_index1 = 0; local_node.on_connect(peer_index1, "test".into(), types::Version::default());
    		executor.take_tasks();

    		let genesis = test_data::genesis();
    		let transaction: Transaction = test_data::TransactionBuilder::with_output(1).add_input(&genesis.transactions[0], 0).into();
    		let transaction_hash = transaction.hash();

    		let result = local_node.accept_transaction(transaction.clone());
    		assert_eq!(result, Ok(transaction_hash.clone()));

    		assert_eq!(executor.take_tasks(), vec![Task::RelayNewTransaction(transaction.into(), 83333333)]);
    	}

    	#[test]
    	fn local_node_discards_local_transaction() {
    		let genesis = test_data::genesis();
    		let transaction: Transaction = test_data::TransactionBuilder::with_output(1).add_input(&genesis.transactions[0], 0).into();
    		let transaction_hash = transaction.hash();

    		// simulate transaction verification fail
    		let mut verifier = DummyVerifier::default();
    		verifier.error_when_verifying(transaction_hash.clone(), "simulated");

    		let (executor, _, local_node) = create_local_node(Some(verifier));

    		let peer_index1 = 0; local_node.on_connect(peer_index1, "test".into(), types::Version::default());
    		executor.take_tasks();

    		let result = local_node.accept_transaction(transaction);
    		assert_eq!(result, Err("simulated".to_owned()));

    		assert_eq!(executor.take_tasks(), vec![]);
    	}
    }

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