// This file is part of Substrate.

// Copyright (C) 2017-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
#![allow(missing_docs)]

#[cfg(test)]
mod block_import;
#[cfg(test)]
mod sync;

use std::{
	borrow::Cow,
	collections::HashMap,
	pin::Pin,
	sync::Arc,
	task::{Context as FutureContext, Poll},
};

use futures::{future::BoxFuture, prelude::*};
use libp2p::{build_multiaddr, PeerId};
use log::trace;
use parking_lot::Mutex;
use sc_block_builder::{BlockBuilder, BlockBuilderProvider};
use sc_client_api::{
	backend::{AuxStore, Backend, Finalizer, TransactionFor},
	BlockBackend, BlockImportNotification, BlockchainEvents, FinalityNotification,
	FinalityNotifications, ImportNotifications,
};
use sc_consensus::{
	BasicQueue, BlockCheckParams, BlockImport, BlockImportParams, BoxJustificationImport,
	ForkChoiceStrategy, ImportResult, JustificationImport, LongestChain, Verifier,
};
pub use sc_network::config::EmptyTransactionPool;
use sc_network::{
	block_request_handler::{self, BlockRequestHandler},
	config::{
		MultiaddrWithPeerId, NetworkConfiguration, NonDefaultSetConfig, NonReservedPeerMode,
		ProtocolConfig, ProtocolId, Role, SyncMode, TransportConfig,
	},
	light_client_requests::{self, handler::LightClientRequestHandler},
	state_request_handler::{self, StateRequestHandler},
	Multiaddr, NetworkService, NetworkWorker,
};
use sc_service::client::Client;
use sp_blockchain::{
	well_known_cache_keys::{self, Id as CacheKeyId},
	HeaderBackend, Info as BlockchainInfo, Result as ClientResult,
};
use sp_consensus::{
	block_validation::{BlockAnnounceValidator, DefaultBlockAnnounceValidator},
	BlockOrigin, Error as ConsensusError,
};
use sp_core::H256;
use sp_runtime::{
	generic::{BlockId, OpaqueDigestItemId},
	traits::{Block as BlockT, Header as HeaderT, NumberFor},
	Justification, Justifications,
};
use substrate_test_runtime_client::AccountKeyring;
pub use substrate_test_runtime_client::{
	runtime::{Block, Extrinsic, Hash, Transfer},
	TestClient, TestClientBuilder, TestClientBuilderExt,
};

type AuthorityId = sp_consensus_babe::AuthorityId;

/// A Verifier that accepts all blocks and passes them on with the configured
/// finality to be imported.
#[derive(Clone)]
pub struct PassThroughVerifier {
	finalized: bool,
	fork_choice: ForkChoiceStrategy,
}

impl PassThroughVerifier {
	/// Create a new instance.
	///
	/// Every verified block will use `finalized` for the `BlockImportParams`.
	pub fn new(finalized: bool) -> Self {
		Self { finalized, fork_choice: ForkChoiceStrategy::LongestChain }
	}

	/// Create a new instance.
	///
	/// Every verified block will use `finalized` for the `BlockImportParams` and
	/// the given [`ForkChoiceStrategy`].
	pub fn new_with_fork_choice(finalized: bool, fork_choice: ForkChoiceStrategy) -> Self {
		Self { finalized, fork_choice }
	}
}

/// This `Verifier` accepts all data as valid.
#[async_trait::async_trait]
impl<B: BlockT> Verifier<B> for PassThroughVerifier {
	async fn verify(
		&mut self,
		mut block: BlockImportParams<B, ()>,
	) -> Result<(BlockImportParams<B, ()>, Option<Vec<(CacheKeyId, Vec<u8>)>>), String> {
		let maybe_keys = block
			.header
			.digest()
			.log(|l| {
				l.try_as_raw(OpaqueDigestItemId::Consensus(b"aura"))
					.or_else(|| l.try_as_raw(OpaqueDigestItemId::Consensus(b"babe")))
			})
			.map(|blob| vec![(well_known_cache_keys::AUTHORITIES, blob.to_vec())]);
		block.finalized = self.finalized;
		block.fork_choice = Some(self.fork_choice.clone());
		Ok((block, maybe_keys))
	}
}

pub type PeersFullClient = Client<
	substrate_test_runtime_client::Backend,
	substrate_test_runtime_client::ExecutorDispatch,
	Block,
	substrate_test_runtime_client::runtime::RuntimeApi,
>;
pub type PeersLightClient = Client<
	substrate_test_runtime_client::LightBackend,
	substrate_test_runtime_client::LightExecutor,
	Block,
	substrate_test_runtime_client::runtime::RuntimeApi,
>;

#[derive(Clone)]
pub enum PeersClient {
	Full(Arc<PeersFullClient>, Arc<substrate_test_runtime_client::Backend>),
	Light(Arc<PeersLightClient>, Arc<substrate_test_runtime_client::LightBackend>),
}

impl PeersClient {
	pub fn as_full(&self) -> Option<Arc<PeersFullClient>> {
		match *self {
			PeersClient::Full(ref client, _) => Some(client.clone()),
			_ => None,
		}
	}

	pub fn as_block_import(&self) -> BlockImportAdapter<Self> {
		BlockImportAdapter::new(self.clone())
	}

	pub fn get_aux(&self, key: &[u8]) -> ClientResult<Option<Vec<u8>>> {
		match *self {
			PeersClient::Full(ref client, _) => client.get_aux(key),
			PeersClient::Light(ref client, _) => client.get_aux(key),
		}
	}

	pub fn info(&self) -> BlockchainInfo<Block> {
		match *self {
			PeersClient::Full(ref client, _) => client.chain_info(),
			PeersClient::Light(ref client, _) => client.chain_info(),
		}
	}

	pub fn header(
		&self,
		block: &BlockId<Block>,
	) -> ClientResult<Option<<Block as BlockT>::Header>> {
		match *self {
			PeersClient::Full(ref client, _) => client.header(block),
			PeersClient::Light(ref client, _) => client.header(block),
		}
	}

	pub fn has_state_at(&self, block: &BlockId<Block>) -> bool {
		let header = match self.header(block).unwrap() {
			Some(header) => header,
			None => return false,
		};
		match self {
			PeersClient::Full(_client, backend) =>
				backend.have_state_at(&header.hash(), *header.number()),
			PeersClient::Light(_client, backend) =>
				backend.have_state_at(&header.hash(), *header.number()),
		}
	}

	pub fn justifications(&self, block: &BlockId<Block>) -> ClientResult<Option<Justifications>> {
		match *self {
			PeersClient::Full(ref client, _) => client.justifications(block),
			PeersClient::Light(ref client, _) => client.justifications(block),
		}
	}

	pub fn finality_notification_stream(&self) -> FinalityNotifications<Block> {
		match *self {
			PeersClient::Full(ref client, _) => client.finality_notification_stream(),
			PeersClient::Light(ref client, _) => client.finality_notification_stream(),
		}
	}

	pub fn import_notification_stream(&self) -> ImportNotifications<Block> {
		match *self {
			PeersClient::Full(ref client, _) => client.import_notification_stream(),
			PeersClient::Light(ref client, _) => client.import_notification_stream(),
		}
	}

	pub fn finalize_block(
		&self,
		id: BlockId<Block>,
		justification: Option<Justification>,
		notify: bool,
	) -> ClientResult<()> {
		match *self {
			PeersClient::Full(ref client, ref _backend) =>
				client.finalize_block(id, justification, notify),
			PeersClient::Light(ref client, ref _backend) =>
				client.finalize_block(id, justification, notify),
		}
	}
}

#[async_trait::async_trait]
impl BlockImport<Block> for PeersClient {
	type Error = ConsensusError;
	type Transaction = ();

	async fn check_block(
		&mut self,
		block: BlockCheckParams<Block>,
	) -> Result<ImportResult, Self::Error> {
		match self {
			PeersClient::Full(client, _) => client.check_block(block).await,
			PeersClient::Light(client, _) => client.check_block(block).await,
		}
	}

	async fn import_block(
		&mut self,
		block: BlockImportParams<Block, ()>,
		cache: HashMap<well_known_cache_keys::Id, Vec<u8>>,
	) -> Result<ImportResult, Self::Error> {
		match self {
			PeersClient::Full(client, _) =>
				client.import_block(block.clear_storage_changes_and_mutate(), cache).await,
			PeersClient::Light(client, _) =>
				client.import_block(block.clear_storage_changes_and_mutate(), cache).await,
		}
	}
}

pub struct Peer<D, BlockImport> {
	pub data: D,
	client: PeersClient,
	/// We keep a copy of the verifier so that we can invoke it for locally-generated blocks,
	/// instead of going through the import queue.
	verifier: VerifierAdapter<Block>,
	/// We keep a copy of the block_import so that we can invoke it for locally-generated blocks,
	/// instead of going through the import queue.
	block_import: BlockImportAdapter<BlockImport>,
	select_chain: Option<LongestChain<substrate_test_runtime_client::Backend, Block>>,
	backend: Option<Arc<substrate_test_runtime_client::Backend>>,
	network: NetworkWorker<Block, <Block as BlockT>::Hash>,
	imported_blocks_stream: Pin<Box<dyn Stream<Item = BlockImportNotification<Block>> + Send>>,
	finality_notification_stream: Pin<Box<dyn Stream<Item = FinalityNotification<Block>> + Send>>,
	listen_addr: Multiaddr,
}

impl<D, B> Peer<D, B>
where
	B: BlockImport<Block, Error = ConsensusError> + Send + Sync,
	B::Transaction: Send,
{
	/// Get this peer ID.
	pub fn id(&self) -> PeerId {
		self.network.service().local_peer_id().clone()
	}

	/// Returns true if we're major syncing.
	pub fn is_major_syncing(&self) -> bool {
		self.network.service().is_major_syncing()
	}

	// Returns a clone of the local SelectChain, only available on full nodes
	pub fn select_chain(
		&self,
	) -> Option<LongestChain<substrate_test_runtime_client::Backend, Block>> {
		self.select_chain.clone()
	}

	/// Returns the number of peers we're connected to.
	pub fn num_peers(&self) -> usize {
		self.network.num_connected_peers()
	}

	/// Returns the number of downloaded blocks.
	pub fn num_downloaded_blocks(&self) -> usize {
		self.network.num_downloaded_blocks()
	}

	/// Returns true if we have no peer.
	pub fn is_offline(&self) -> bool {
		self.num_peers() == 0
	}

	/// Request a justification for the given block.
	pub fn request_justification(&self, hash: &<Block as BlockT>::Hash, number: NumberFor<Block>) {
		self.network.service().request_justification(hash, number);
	}

	/// Announces an important block on the network.
	pub fn announce_block(&self, hash: <Block as BlockT>::Hash, data: Option<Vec<u8>>) {
		self.network.service().announce_block(hash, data);
	}

	/// Request explicit fork sync.
	pub fn set_sync_fork_request(
		&self,
		peers: Vec<PeerId>,
		hash: <Block as BlockT>::Hash,
		number: NumberFor<Block>,
	) {
		self.network.service().set_sync_fork_request(peers, hash, number);
	}

	/// Add blocks to the peer -- edit the block before adding
	pub fn generate_blocks<F>(&mut self, count: usize, origin: BlockOrigin, edit_block: F) -> H256
	where
		F: FnMut(
			BlockBuilder<Block, PeersFullClient, substrate_test_runtime_client::Backend>,
		) -> Block,
	{
		let best_hash = self.client.info().best_hash;
		self.generate_blocks_at(
			BlockId::Hash(best_hash),
			count,
			origin,
			edit_block,
			false,
			true,
			true,
		)
	}

	/// Add blocks to the peer -- edit the block before adding. The chain will
	/// start at the given block iD.
	fn generate_blocks_at<F>(
		&mut self,
		at: BlockId<Block>,
		count: usize,
		origin: BlockOrigin,
		mut edit_block: F,
		headers_only: bool,
		inform_sync_about_new_best_block: bool,
		announce_block: bool,
	) -> H256
	where
		F: FnMut(
			BlockBuilder<Block, PeersFullClient, substrate_test_runtime_client::Backend>,
		) -> Block,
	{
		let full_client =
			self.client.as_full().expect("blocks could only be generated by full clients");
		let mut at = full_client.header(&at).unwrap().unwrap().hash();
		for _ in 0..count {
			let builder =
				full_client.new_block_at(&BlockId::Hash(at), Default::default(), false).unwrap();
			let block = edit_block(builder);
			let hash = block.header.hash();
			trace!(
				target: "test_network",
				"Generating {}, (#{}, parent={})",
				hash,
				block.header.number,
				block.header.parent_hash,
			);
			let header = block.header.clone();
			let mut import_block = BlockImportParams::new(origin, header.clone());
			import_block.body = if headers_only { None } else { Some(block.extrinsics) };
			let (import_block, cache) =
				futures::executor::block_on(self.verifier.verify(import_block)).unwrap();
			let cache = if let Some(cache) = cache {
				cache.into_iter().collect()
			} else {
				Default::default()
			};

			futures::executor::block_on(self.block_import.import_block(import_block, cache))
				.expect("block_import failed");
			if announce_block {
				self.network.service().announce_block(hash, None);
			}
			at = hash;
		}

		if inform_sync_about_new_best_block {
			self.network.new_best_block_imported(
				at,
				full_client.header(&BlockId::Hash(at)).ok().flatten().unwrap().number().clone(),
			);
		}
		at
	}

	/// Push blocks to the peer (simplified: with or without a TX)
	pub fn push_blocks(&mut self, count: usize, with_tx: bool) -> H256 {
		let best_hash = self.client.info().best_hash;
		self.push_blocks_at(BlockId::Hash(best_hash), count, with_tx)
	}

	/// Push blocks to the peer (simplified: with or without a TX)
	pub fn push_headers(&mut self, count: usize) -> H256 {
		let best_hash = self.client.info().best_hash;
		self.generate_tx_blocks_at(BlockId::Hash(best_hash), count, false, true, true, true)
	}

	/// Push blocks to the peer (simplified: with or without a TX) starting from
	/// given hash.
	pub fn push_blocks_at(&mut self, at: BlockId<Block>, count: usize, with_tx: bool) -> H256 {
		self.generate_tx_blocks_at(at, count, with_tx, false, true, true)
	}

	/// Push blocks to the peer (simplified: with or without a TX) starting from
	/// given hash without informing the sync protocol about the new best block.
	pub fn push_blocks_at_without_informing_sync(
		&mut self,
		at: BlockId<Block>,
		count: usize,
		with_tx: bool,
	) -> H256 {
		self.generate_tx_blocks_at(at, count, with_tx, false, false, true)
	}

	/// Push blocks to the peer (simplified: with or without a TX) starting from
	/// given hash without announcing the block.
	pub fn push_blocks_at_without_announcing(
		&mut self,
		at: BlockId<Block>,
		count: usize,
		with_tx: bool,
	) -> H256 {
		self.generate_tx_blocks_at(at, count, with_tx, false, true, false)
	}

	/// Push blocks/headers to the peer (simplified: with or without a TX) starting from
	/// given hash.
	fn generate_tx_blocks_at(
		&mut self,
		at: BlockId<Block>,
		count: usize,
		with_tx: bool,
		headers_only: bool,
		inform_sync_about_new_best_block: bool,
		announce_block: bool,
	) -> H256 {
		let mut nonce = 0;
		if with_tx {
			self.generate_blocks_at(
				at,
				count,
				BlockOrigin::File,
				|mut builder| {
					let transfer = Transfer {
						from: AccountKeyring::Alice.into(),
						to: AccountKeyring::Alice.into(),
						amount: 1,
						nonce,
					};
					builder.push(transfer.into_signed_tx()).unwrap();
					nonce = nonce + 1;
					builder.build().unwrap().block
				},
				headers_only,
				inform_sync_about_new_best_block,
				announce_block,
			)
		} else {
			self.generate_blocks_at(
				at,
				count,
				BlockOrigin::File,
				|builder| builder.build().unwrap().block,
				headers_only,
				inform_sync_about_new_best_block,
				announce_block,
			)
		}
	}

	pub fn push_authorities_change_block(&mut self, new_authorities: Vec<AuthorityId>) -> H256 {
		self.generate_blocks(1, BlockOrigin::File, |mut builder| {
			builder.push(Extrinsic::AuthoritiesChange(new_authorities.clone())).unwrap();
			builder.build().unwrap().block
		})
	}

	/// Get a reference to the client.
	pub fn client(&self) -> &PeersClient {
		&self.client
	}

	/// Get a reference to the network service.
	pub fn network_service(&self) -> &Arc<NetworkService<Block, <Block as BlockT>::Hash>> {
		&self.network.service()
	}

	/// Get a reference to the network worker.
	pub fn network(&self) -> &NetworkWorker<Block, <Block as BlockT>::Hash> {
		&self.network
	}

	/// Test helper to compare the blockchain state of multiple (networked)
	/// clients.
	pub fn blockchain_canon_equals(&self, other: &Self) -> bool {
		if let (Some(mine), Some(others)) = (self.backend.clone(), other.backend.clone()) {
			mine.blockchain().info().best_hash == others.blockchain().info().best_hash
		} else {
			false
		}
	}

	/// Count the total number of imported blocks.
	pub fn blocks_count(&self) -> u64 {
		self.backend
			.as_ref()
			.map(|backend| backend.blockchain().info().best_number)
			.unwrap_or(0)
	}

	/// Return a collection of block hashes that failed verification
	pub fn failed_verifications(&self) -> HashMap<<Block as BlockT>::Hash, String> {
		self.verifier.failed_verifications.lock().clone()
	}

	pub fn has_block(&self, hash: &H256) -> bool {
		self.backend
			.as_ref()
			.map(|backend| backend.blockchain().header(BlockId::hash(*hash)).unwrap().is_some())
			.unwrap_or(false)
	}
}

pub trait BlockImportAdapterFull:
	BlockImport<
		Block,
		Transaction = TransactionFor<substrate_test_runtime_client::Backend, Block>,
		Error = ConsensusError,
	> + Send
	+ Sync
	+ Clone
{
}

impl<T> BlockImportAdapterFull for T where
	T: BlockImport<
			Block,
			Transaction = TransactionFor<substrate_test_runtime_client::Backend, Block>,
			Error = ConsensusError,
		> + Send
		+ Sync
		+ Clone
{
}

/// Implements `BlockImport` for any `Transaction`. Internally the transaction is
/// "converted", aka the field is set to `None`.
///
/// This is required as the `TestNetFactory` trait does not distinguish between
/// full and light nodes.
#[derive(Clone)]
pub struct BlockImportAdapter<I> {
	inner: I,
}

impl<I> BlockImportAdapter<I> {
	/// Create a new instance of `Self::Full`.
	pub fn new(inner: I) -> Self {
		Self { inner }
	}
}

#[async_trait::async_trait]
impl<I> BlockImport<Block> for BlockImportAdapter<I>
where
	I: BlockImport<Block, Error = ConsensusError> + Send + Sync,
	I::Transaction: Send,
{
	type Error = ConsensusError;
	type Transaction = ();

	async fn check_block(
		&mut self,
		block: BlockCheckParams<Block>,
	) -> Result<ImportResult, Self::Error> {
		self.inner.check_block(block).await
	}

	async fn import_block(
		&mut self,
		block: BlockImportParams<Block, ()>,
		cache: HashMap<well_known_cache_keys::Id, Vec<u8>>,
	) -> Result<ImportResult, Self::Error> {
		self.inner.import_block(block.clear_storage_changes_and_mutate(), cache).await
	}
}

/// Implements `Verifier` and keeps track of failed verifications.
struct VerifierAdapter<B: BlockT> {
	verifier: Arc<futures::lock::Mutex<Box<dyn Verifier<B>>>>,
	failed_verifications: Arc<Mutex<HashMap<B::Hash, String>>>,
}

#[async_trait::async_trait]
impl<B: BlockT> Verifier<B> for VerifierAdapter<B> {
	async fn verify(
		&mut self,
		block: BlockImportParams<B, ()>,
	) -> Result<(BlockImportParams<B, ()>, Option<Vec<(CacheKeyId, Vec<u8>)>>), String> {
		let hash = block.header.hash();
		self.verifier.lock().await.verify(block).await.map_err(|e| {
			self.failed_verifications.lock().insert(hash, e.clone());
			e
		})
	}
}

impl<B: BlockT> Clone for VerifierAdapter<B> {
	fn clone(&self) -> Self {
		Self {
			verifier: self.verifier.clone(),
			failed_verifications: self.failed_verifications.clone(),
		}
	}
}

impl<B: BlockT> VerifierAdapter<B> {
	fn new(verifier: impl Verifier<B> + 'static) -> Self {
		VerifierAdapter {
			verifier: Arc::new(futures::lock::Mutex::new(Box::new(verifier))),
			failed_verifications: Default::default(),
		}
	}
}

/// Configuration for a full peer.
#[derive(Default)]
pub struct FullPeerConfig {
	/// Pruning window size.
	pub keep_blocks: Option<u32>,
	/// Block announce validator.
	pub block_announce_validator: Option<Box<dyn BlockAnnounceValidator<Block> + Send + Sync>>,
	/// List of notification protocols that the network must support.
	pub notifications_protocols: Vec<Cow<'static, str>>,
	/// The indices of the peers the peer should be connected to.
	///
	/// If `None`, it will be connected to all other peers.
	pub connect_to_peers: Option<Vec<usize>>,
	/// Whether the full peer should have the authority role.
	pub is_authority: bool,
	/// Syncing mode
	pub sync_mode: SyncMode,
	/// Enable transaction indexing.
	pub storage_chain: bool,
}

pub trait TestNetFactory: Sized
where
	<Self::BlockImport as BlockImport<Block>>::Transaction: Send,
{
	type Verifier: 'static + Verifier<Block>;
	type BlockImport: BlockImport<Block, Error = ConsensusError> + Clone + Send + Sync + 'static;
	type PeerData: Default;

	/// These two need to be implemented!
	fn from_config(config: &ProtocolConfig) -> Self;
	fn make_verifier(
		&self,
		client: PeersClient,
		config: &ProtocolConfig,
		peer_data: &Self::PeerData,
	) -> Self::Verifier;

	/// Get reference to peer.
	fn peer(&mut self, i: usize) -> &mut Peer<Self::PeerData, Self::BlockImport>;
	fn peers(&self) -> &Vec<Peer<Self::PeerData, Self::BlockImport>>;
	fn mut_peers<F: FnOnce(&mut Vec<Peer<Self::PeerData, Self::BlockImport>>)>(
		&mut self,
		closure: F,
	);

	/// Get custom block import handle for fresh client, along with peer data.
	fn make_block_import(
		&self,
		client: PeersClient,
	) -> (
		BlockImportAdapter<Self::BlockImport>,
		Option<BoxJustificationImport<Block>>,
		Self::PeerData,
	);

	fn default_config() -> ProtocolConfig {
		ProtocolConfig::default()
	}

	/// Create new test network with this many peers.
	fn new(n: usize) -> Self {
		trace!(target: "test_network", "Creating test network");
		let config = Self::default_config();
		let mut net = Self::from_config(&config);

		for i in 0..n {
			trace!(target: "test_network", "Adding peer {}", i);
			net.add_full_peer();
		}
		net
	}

	fn add_full_peer(&mut self) {
		self.add_full_peer_with_config(Default::default())
	}

	/// Add a full peer.
	fn add_full_peer_with_config(&mut self, config: FullPeerConfig) {
		let mut test_client_builder = match (config.keep_blocks, config.storage_chain) {
			(Some(keep_blocks), true) => TestClientBuilder::with_tx_storage(keep_blocks),
			(None, true) => TestClientBuilder::with_tx_storage(u32::MAX),
			(Some(keep_blocks), false) => TestClientBuilder::with_pruning_window(keep_blocks),
			(None, false) => TestClientBuilder::with_default_backend(),
		};
		if matches!(config.sync_mode, SyncMode::Fast { .. }) {
			test_client_builder = test_client_builder.set_no_genesis();
		}
		let backend = test_client_builder.backend();
		let (c, longest_chain) = test_client_builder.build_with_longest_chain();
		let client = Arc::new(c);

		let (block_import, justification_import, data) =
			self.make_block_import(PeersClient::Full(client.clone(), backend.clone()));

		let verifier = self.make_verifier(
			PeersClient::Full(client.clone(), backend.clone()),
			&Default::default(),
			&data,
		);
		let verifier = VerifierAdapter::new(verifier);

		let import_queue = Box::new(BasicQueue::new(
			verifier.clone(),
			Box::new(block_import.clone()),
			justification_import,
			&sp_core::testing::TaskExecutor::new(),
			None,
		));

		let listen_addr = build_multiaddr![Memory(rand::random::<u64>())];

		let mut network_config =
			NetworkConfiguration::new("test-node", "test-client", Default::default(), None);
		network_config.sync_mode = config.sync_mode;
		network_config.transport = TransportConfig::MemoryOnly;
		network_config.listen_addresses = vec![listen_addr.clone()];
		network_config.allow_non_globals_in_dht = true;
		network_config.extra_sets = config
			.notifications_protocols
			.into_iter()
			.map(|p| NonDefaultSetConfig {
				notifications_protocol: p,
				fallback_names: Vec::new(),
				max_notification_size: 1024 * 1024,
				set_config: Default::default(),
			})
			.collect();
		if let Some(connect_to) = config.connect_to_peers {
			let addrs = connect_to
				.iter()
				.map(|v| {
					let peer_id = self.peer(*v).network_service().local_peer_id().clone();
					let multiaddr = self.peer(*v).listen_addr.clone();
					MultiaddrWithPeerId { peer_id, multiaddr }
				})
				.collect();
			network_config.default_peers_set.reserved_nodes = addrs;
			network_config.default_peers_set.non_reserved_mode = NonReservedPeerMode::Deny;
		}

		let protocol_id = ProtocolId::from("test-protocol-name");

		let block_request_protocol_config = {
			let (handler, protocol_config) =
				BlockRequestHandler::new(&protocol_id, client.clone(), 50);
			self.spawn_task(handler.run().boxed());
			protocol_config
		};

		let state_request_protocol_config = {
			let (handler, protocol_config) =
				StateRequestHandler::new(&protocol_id, client.clone(), 50);
			self.spawn_task(handler.run().boxed());
			protocol_config
		};

		let light_client_request_protocol_config = {
			let (handler, protocol_config) =
				LightClientRequestHandler::new(&protocol_id, client.clone());
			self.spawn_task(handler.run().boxed());
			protocol_config
		};

		let network = NetworkWorker::new(sc_network::config::Params {
			role: if config.is_authority { Role::Authority } else { Role::Full },
			executor: None,
			transactions_handler_executor: Box::new(|task| {
				async_std::task::spawn(task);
			}),
			network_config,
			chain: client.clone(),
			on_demand: None,
			transaction_pool: Arc::new(EmptyTransactionPool),
			protocol_id,
			import_queue,
			block_announce_validator: config
				.block_announce_validator
				.unwrap_or_else(|| Box::new(DefaultBlockAnnounceValidator)),
			metrics_registry: None,
			block_request_protocol_config,
			state_request_protocol_config,
			light_client_request_protocol_config,
			warp_sync: None,
		})
		.unwrap();

		trace!(target: "test_network", "Peer identifier: {}", network.service().local_peer_id());

		self.mut_peers(move |peers| {
			for peer in peers.iter_mut() {
				peer.network.add_known_address(
					network.service().local_peer_id().clone(),
					listen_addr.clone(),
				);
			}

			let imported_blocks_stream = Box::pin(client.import_notification_stream().fuse());
			let finality_notification_stream =
				Box::pin(client.finality_notification_stream().fuse());

			peers.push(Peer {
				data,
				client: PeersClient::Full(client.clone(), backend.clone()),
				select_chain: Some(longest_chain),
				backend: Some(backend),
				imported_blocks_stream,
				finality_notification_stream,
				block_import,
				verifier,
				network,
				listen_addr,
			});
		});
	}

	/// Add a light peer.
	fn add_light_peer(&mut self) {
		let (c, backend) = substrate_test_runtime_client::new_light();
		let client = Arc::new(c);
		let (block_import, justification_import, data) =
			self.make_block_import(PeersClient::Light(client.clone(), backend.clone()));

		let verifier = self.make_verifier(
			PeersClient::Light(client.clone(), backend.clone()),
			&Default::default(),
			&data,
		);
		let verifier = VerifierAdapter::new(verifier);

		let import_queue = Box::new(BasicQueue::new(
			verifier.clone(),
			Box::new(block_import.clone()),
			justification_import,
			&sp_core::testing::TaskExecutor::new(),
			None,
		));

		let listen_addr = build_multiaddr![Memory(rand::random::<u64>())];

		let mut network_config =
			NetworkConfiguration::new("test-node", "test-client", Default::default(), None);
		network_config.transport = TransportConfig::MemoryOnly;
		network_config.listen_addresses = vec![listen_addr.clone()];
		network_config.allow_non_globals_in_dht = true;

		let protocol_id = ProtocolId::from("test-protocol-name");

		let block_request_protocol_config =
			block_request_handler::generate_protocol_config(&protocol_id);
		let state_request_protocol_config =
			state_request_handler::generate_protocol_config(&protocol_id);

		let light_client_request_protocol_config =
			light_client_requests::generate_protocol_config(&protocol_id);

		let network = NetworkWorker::new(sc_network::config::Params {
			role: Role::Light,
			executor: None,
			transactions_handler_executor: Box::new(|task| {
				async_std::task::spawn(task);
			}),
			network_config,
			chain: client.clone(),
			on_demand: None,
			transaction_pool: Arc::new(EmptyTransactionPool),
			protocol_id,
			import_queue,
			block_announce_validator: Box::new(DefaultBlockAnnounceValidator),
			metrics_registry: None,
			block_request_protocol_config,
			state_request_protocol_config,
			light_client_request_protocol_config,
			warp_sync: None,
		})
		.unwrap();

		self.mut_peers(|peers| {
			for peer in peers.iter_mut() {
				peer.network.add_known_address(
					network.service().local_peer_id().clone(),
					listen_addr.clone(),
				);
			}

			let imported_blocks_stream = Box::pin(client.import_notification_stream().fuse());
			let finality_notification_stream =
				Box::pin(client.finality_notification_stream().fuse());

			peers.push(Peer {
				data,
				verifier,
				select_chain: None,
				backend: None,
				block_import,
				client: PeersClient::Light(client, backend),
				imported_blocks_stream,
				finality_notification_stream,
				network,
				listen_addr,
			});
		});
	}

	/// Used to spawn background tasks, e.g. the block request protocol handler.
	fn spawn_task(&self, f: BoxFuture<'static, ()>) {
		async_std::task::spawn(f);
	}

	/// Polls the testnet until all nodes are in sync.
	///
	/// Must be executed in a task context.
	fn poll_until_sync(&mut self, cx: &mut FutureContext) -> Poll<()> {
		self.poll(cx);

		// Return `NotReady` if there's a mismatch in the highest block number.
		let mut highest = None;
		for peer in self.peers().iter() {
			if peer.is_major_syncing() || peer.network.num_queued_blocks() != 0 {
				return Poll::Pending
			}
			if peer.network.num_sync_requests() != 0 {
				return Poll::Pending
			}
			match (highest, peer.client.info().best_hash) {
				(None, b) => highest = Some(b),
				(Some(ref a), ref b) if a == b => {},
				(Some(_), _) => return Poll::Pending,
			}
		}
		Poll::Ready(())
	}

	/// Polls the testnet until theres' no activiy of any kind.
	///
	/// Must be executed in a task context.
	fn poll_until_idle(&mut self, cx: &mut FutureContext) -> Poll<()> {
		self.poll(cx);

		for peer in self.peers().iter() {
			if peer.is_major_syncing() || peer.network.num_queued_blocks() != 0 {
				return Poll::Pending
			}
			if peer.network.num_sync_requests() != 0 {
				return Poll::Pending
			}
		}
		Poll::Ready(())
	}

	/// Polls the testnet until all peers are connected to each other.
	///
	/// Must be executed in a task context.
	fn poll_until_connected(&mut self, cx: &mut FutureContext) -> Poll<()> {
		self.poll(cx);

		let num_peers = self.peers().len();
		if self.peers().iter().all(|p| p.num_peers() == num_peers - 1) {
			return Poll::Ready(())
		}

		Poll::Pending
	}

	/// Blocks the current thread until we are sync'ed.
	///
	/// Calls `poll_until_sync` repeatedly.
	fn block_until_sync(&mut self) {
		futures::executor::block_on(futures::future::poll_fn::<(), _>(|cx| {
			self.poll_until_sync(cx)
		}));
	}

	/// Blocks the current thread until there are no pending packets.
	///
	/// Calls `poll_until_idle` repeatedly with the runtime passed as parameter.
	fn block_until_idle(&mut self) {
		futures::executor::block_on(futures::future::poll_fn::<(), _>(|cx| {
			self.poll_until_idle(cx)
		}));
	}

	/// Blocks the current thread until all peers are connected to each other.
	///
	/// Calls `poll_until_connected` repeatedly with the runtime passed as parameter.
	fn block_until_connected(&mut self) {
		futures::executor::block_on(futures::future::poll_fn::<(), _>(|cx| {
			self.poll_until_connected(cx)
		}));
	}

	/// Polls the testnet. Processes all the pending actions.
	fn poll(&mut self, cx: &mut FutureContext) {
		self.mut_peers(|peers| {
			for (i, peer) in peers.into_iter().enumerate() {
				trace!(target: "sync", "-- Polling {}: {}", i, peer.id());
				if let Poll::Ready(()) = peer.network.poll_unpin(cx) {
					panic!("NetworkWorker has terminated unexpectedly.")
				}
				trace!(target: "sync", "-- Polling complete {}: {}", i, peer.id());

				// We poll `imported_blocks_stream`.
				while let Poll::Ready(Some(notification)) =
					peer.imported_blocks_stream.as_mut().poll_next(cx)
				{
					peer.network.service().announce_block(notification.hash, None);
				}

				// We poll `finality_notification_stream`, but we only take the last event.
				let mut last = None;
				while let Poll::Ready(Some(item)) =
					peer.finality_notification_stream.as_mut().poll_next(cx)
				{
					last = Some(item);
				}
				if let Some(notification) = last {
					peer.network.on_block_finalized(notification.hash, notification.header);
				}
			}
		});
	}
}

pub struct TestNet {
	peers: Vec<Peer<(), PeersClient>>,
	fork_choice: ForkChoiceStrategy,
}

impl TestNet {
	/// Create a `TestNet` that used the given fork choice rule.
	pub fn with_fork_choice(fork_choice: ForkChoiceStrategy) -> Self {
		Self { peers: Vec::new(), fork_choice }
	}
}

impl TestNetFactory for TestNet {
	type Verifier = PassThroughVerifier;
	type PeerData = ();
	type BlockImport = PeersClient;

	/// Create new test network with peers and given config.
	fn from_config(_config: &ProtocolConfig) -> Self {
		TestNet { peers: Vec::new(), fork_choice: ForkChoiceStrategy::LongestChain }
	}

	fn make_verifier(
		&self,
		_client: PeersClient,
		_config: &ProtocolConfig,
		_peer_data: &(),
	) -> Self::Verifier {
		PassThroughVerifier::new_with_fork_choice(false, self.fork_choice.clone())
	}

	fn make_block_import(
		&self,
		client: PeersClient,
	) -> (
		BlockImportAdapter<Self::BlockImport>,
		Option<BoxJustificationImport<Block>>,
		Self::PeerData,
	) {
		(client.as_block_import(), None, ())
	}

	fn peer(&mut self, i: usize) -> &mut Peer<(), Self::BlockImport> {
		&mut self.peers[i]
	}

	fn peers(&self) -> &Vec<Peer<(), Self::BlockImport>> {
		&self.peers
	}

	fn mut_peers<F: FnOnce(&mut Vec<Peer<(), Self::BlockImport>>)>(&mut self, closure: F) {
		closure(&mut self.peers);
	}
}

pub struct ForceFinalized(PeersClient);

#[async_trait::async_trait]
impl JustificationImport<Block> for ForceFinalized {
	type Error = ConsensusError;

	async fn on_start(&mut self) -> Vec<(H256, NumberFor<Block>)> {
		Vec::new()
	}

	async fn import_justification(
		&mut self,
		hash: H256,
		_number: NumberFor<Block>,
		justification: Justification,
	) -> Result<(), Self::Error> {
		self.0
			.finalize_block(BlockId::Hash(hash), Some(justification), true)
			.map_err(|_| ConsensusError::InvalidJustification.into())
	}
}

pub struct JustificationTestNet(TestNet);

impl TestNetFactory for JustificationTestNet {
	type Verifier = PassThroughVerifier;
	type PeerData = ();
	type BlockImport = PeersClient;

	fn from_config(config: &ProtocolConfig) -> Self {
		JustificationTestNet(TestNet::from_config(config))
	}

	fn make_verifier(
		&self,
		client: PeersClient,
		config: &ProtocolConfig,
		peer_data: &(),
	) -> Self::Verifier {
		self.0.make_verifier(client, config, peer_data)
	}

	fn peer(&mut self, i: usize) -> &mut Peer<Self::PeerData, Self::BlockImport> {
		self.0.peer(i)
	}

	fn peers(&self) -> &Vec<Peer<Self::PeerData, Self::BlockImport>> {
		self.0.peers()
	}

	fn mut_peers<F: FnOnce(&mut Vec<Peer<Self::PeerData, Self::BlockImport>>)>(
		&mut self,
		closure: F,
	) {
		self.0.mut_peers(closure)
	}

	fn make_block_import(
		&self,
		client: PeersClient,
	) -> (
		BlockImportAdapter<Self::BlockImport>,
		Option<BoxJustificationImport<Block>>,
		Self::PeerData,
	) {
		(client.as_block_import(), Some(Box::new(ForceFinalized(client))), Default::default())
	}
}