// This file is part of Substrate.

// Copyright (C) 2017-2022 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/>.

use crate::{
	build_network_future,
	client::{Client, ClientConfig},
	config::{Configuration, KeystoreConfig, PrometheusConfig},
	error::Error,
	metrics::MetricsService,
	start_rpc_servers, BuildGenesisBlock, GenesisBlockBuilder, RpcHandlers, SpawnTaskHandle,
	TaskManager, TransactionPoolAdapter,
};
use futures::{channel::oneshot, future::ready, FutureExt, StreamExt};
use jsonrpsee::RpcModule;
use log::info;
use prometheus_endpoint::Registry;
use sc_chain_spec::get_extension;
use sc_client_api::{
	execution_extensions::ExecutionExtensions, proof_provider::ProofProvider, BadBlocks,
	BlockBackend, BlockchainEvents, ExecutorProvider, ForkBlocks, StorageProvider, UsageProvider,
};
use sc_client_db::{Backend, DatabaseSettings};
use sc_consensus::import_queue::ImportQueue;
use sc_executor::RuntimeVersionOf;
use sc_keystore::LocalKeystore;
use sc_network::{config::SyncMode, NetworkService};
use sc_network_bitswap::BitswapRequestHandler;
use sc_network_common::{
	protocol::role::Roles,
	service::{NetworkStateInfo, NetworkStatusProvider},
	sync::warp::WarpSyncProvider,
};
use sc_network_light::light_client_requests::handler::LightClientRequestHandler;
use sc_network_sync::{
	block_request_handler::BlockRequestHandler, service::network::NetworkServiceProvider,
	state_request_handler::StateRequestHandler,
	warp_request_handler::RequestHandler as WarpSyncRequestHandler, ChainSync,
};
use sc_rpc::{
	author::AuthorApiServer,
	chain::ChainApiServer,
	offchain::OffchainApiServer,
	state::{ChildStateApiServer, StateApiServer},
	system::SystemApiServer,
	DenyUnsafe, SubscriptionTaskExecutor,
};
use sc_rpc_spec_v2::{chain_head::ChainHeadApiServer, transaction::TransactionApiServer};
use sc_telemetry::{telemetry, ConnectionMessage, Telemetry, TelemetryHandle, SUBSTRATE_INFO};
use sc_transaction_pool_api::MaintainedTransactionPool;
use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedSender};
use sp_api::{CallApiAt, ProvideRuntimeApi};
use sp_blockchain::{HeaderBackend, HeaderMetadata};
use sp_consensus::block_validation::{
	BlockAnnounceValidator, Chain, DefaultBlockAnnounceValidator,
};
use sp_core::traits::{CodeExecutor, SpawnNamed};
use sp_keystore::{CryptoStore, SyncCryptoStore, SyncCryptoStorePtr};
use sp_runtime::traits::{Block as BlockT, BlockIdTo, NumberFor, Zero};
use std::{str::FromStr, sync::Arc, time::SystemTime};

/// Full client type.
pub type TFullClient<TBl, TRtApi, TExec> =
	Client<TFullBackend<TBl>, TFullCallExecutor<TBl, TExec>, TBl, TRtApi>;

/// Full client backend type.
pub type TFullBackend<TBl> = sc_client_db::Backend<TBl>;

/// Full client call executor type.
pub type TFullCallExecutor<TBl, TExec> =
	crate::client::LocalCallExecutor<TBl, sc_client_db::Backend<TBl>, TExec>;

type TFullParts<TBl, TRtApi, TExec> =
	(TFullClient<TBl, TRtApi, TExec>, Arc<TFullBackend<TBl>>, KeystoreContainer, TaskManager);

trait AsCryptoStoreRef {
	fn keystore_ref(&self) -> Arc<dyn CryptoStore>;
	fn sync_keystore_ref(&self) -> Arc<dyn SyncCryptoStore>;
}

impl<T> AsCryptoStoreRef for Arc<T>
where
	T: CryptoStore + SyncCryptoStore + 'static,
{
	fn keystore_ref(&self) -> Arc<dyn CryptoStore> {
		self.clone()
	}
	fn sync_keystore_ref(&self) -> Arc<dyn SyncCryptoStore> {
		self.clone()
	}
}

/// Construct and hold different layers of Keystore wrappers
pub struct KeystoreContainer {
	remote: Option<Box<dyn AsCryptoStoreRef>>,
	local: Arc<LocalKeystore>,
}

impl KeystoreContainer {
	/// Construct KeystoreContainer
	pub fn new(config: &KeystoreConfig) -> Result<Self, Error> {
		let keystore = Arc::new(match config {
			KeystoreConfig::Path { path, password } =>
				LocalKeystore::open(path.clone(), password.clone())?,
			KeystoreConfig::InMemory => LocalKeystore::in_memory(),
		});

		Ok(Self { remote: Default::default(), local: keystore })
	}

	/// Set the remote keystore.
	/// Should be called right away at startup and not at runtime:
	/// even though this overrides any previously set remote store, it
	/// does not reset any references previously handed out - they will
	/// stick around.
	pub fn set_remote_keystore<T>(&mut self, remote: Arc<T>)
	where
		T: CryptoStore + SyncCryptoStore + 'static,
	{
		self.remote = Some(Box::new(remote))
	}

	/// Returns an adapter to the asynchronous keystore that implements `CryptoStore`
	pub fn keystore(&self) -> Arc<dyn CryptoStore> {
		if let Some(c) = self.remote.as_ref() {
			c.keystore_ref()
		} else {
			self.local.clone()
		}
	}

	/// Returns the synchronous keystore wrapper
	pub fn sync_keystore(&self) -> SyncCryptoStorePtr {
		if let Some(c) = self.remote.as_ref() {
			c.sync_keystore_ref()
		} else {
			self.local.clone() as SyncCryptoStorePtr
		}
	}

	/// Returns the local keystore if available
	///
	/// The function will return None if the available keystore is not a local keystore.
	///
	/// # Note
	///
	/// Using the [`LocalKeystore`] will result in loosing the ability to use any other keystore
	/// implementation, like a remote keystore for example. Only use this if you a certain that you
	/// require it!
	pub fn local_keystore(&self) -> Option<Arc<LocalKeystore>> {
		Some(self.local.clone())
	}
}

/// Creates a new full client for the given config.
pub fn new_full_client<TBl, TRtApi, TExec>(
	config: &Configuration,
	telemetry: Option<TelemetryHandle>,
	executor: TExec,
) -> Result<TFullClient<TBl, TRtApi, TExec>, Error>
where
	TBl: BlockT,
	TExec: CodeExecutor + RuntimeVersionOf + Clone,
{
	new_full_parts(config, telemetry, executor).map(|parts| parts.0)
}

/// Create the initial parts of a full node with the default genesis block builder.
pub fn new_full_parts<TBl, TRtApi, TExec>(
	config: &Configuration,
	telemetry: Option<TelemetryHandle>,
	executor: TExec,
) -> Result<TFullParts<TBl, TRtApi, TExec>, Error>
where
	TBl: BlockT,
	TExec: CodeExecutor + RuntimeVersionOf + Clone,
{
	let backend = new_db_backend(config.db_config())?;

	let genesis_block_builder = GenesisBlockBuilder::new(
		config.chain_spec.as_storage_builder(),
		!config.no_genesis(),
		backend.clone(),
		executor.clone(),
	)?;

	new_full_parts_with_genesis_builder(config, telemetry, executor, backend, genesis_block_builder)
}

/// Create the initial parts of a full node.
pub fn new_full_parts_with_genesis_builder<TBl, TRtApi, TExec, TBuildGenesisBlock>(
	config: &Configuration,
	telemetry: Option<TelemetryHandle>,
	executor: TExec,
	backend: Arc<TFullBackend<TBl>>,
	genesis_block_builder: TBuildGenesisBlock,
) -> Result<TFullParts<TBl, TRtApi, TExec>, Error>
where
	TBl: BlockT,
	TExec: CodeExecutor + RuntimeVersionOf + Clone,
	TBuildGenesisBlock: BuildGenesisBlock<
		TBl,
		BlockImportOperation = <Backend<TBl> as sc_client_api::backend::Backend<TBl>>::BlockImportOperation
	>,
{
	let keystore_container = KeystoreContainer::new(&config.keystore)?;

	let task_manager = {
		let registry = config.prometheus_config.as_ref().map(|cfg| &cfg.registry);
		TaskManager::new(config.tokio_handle.clone(), registry)?
	};

	let chain_spec = &config.chain_spec;
	let fork_blocks = get_extension::<ForkBlocks<TBl>>(chain_spec.extensions())
		.cloned()
		.unwrap_or_default();

	let bad_blocks = get_extension::<BadBlocks<TBl>>(chain_spec.extensions())
		.cloned()
		.unwrap_or_default();

	let client = {
		let extensions = sc_client_api::execution_extensions::ExecutionExtensions::new(
			config.execution_strategies.clone(),
			Some(keystore_container.sync_keystore()),
			sc_offchain::OffchainDb::factory_from_backend(&*backend),
		);

		let wasm_runtime_substitutes = config
			.chain_spec
			.code_substitutes()
			.into_iter()
			.map(|(n, c)| {
				let number = NumberFor::<TBl>::from_str(&n).map_err(|_| {
					Error::Application(Box::from(format!(
						"Failed to parse `{}` as block number for code substitutes. \
						 In an old version the key for code substitute was a block hash. \
						 Please update the chain spec to a version that is compatible with your node.",
						n
					)))
				})?;
				Ok((number, c))
			})
			.collect::<Result<std::collections::HashMap<_, _>, Error>>()?;

		let client = new_client(
			backend.clone(),
			executor,
			genesis_block_builder,
			fork_blocks,
			bad_blocks,
			extensions,
			Box::new(task_manager.spawn_handle()),
			config.prometheus_config.as_ref().map(|config| config.registry.clone()),
			telemetry,
			ClientConfig {
				offchain_worker_enabled: config.offchain_worker.enabled,
				offchain_indexing_api: config.offchain_worker.indexing_enabled,
				wasm_runtime_overrides: config.wasm_runtime_overrides.clone(),
				no_genesis: matches!(
					config.network.sync_mode,
					SyncMode::Fast { .. } | SyncMode::Warp { .. }
				),
				wasm_runtime_substitutes,
			},
		)?;

		client
	};

	Ok((client, backend, keystore_container, task_manager))
}

/// Create an instance of default DB-backend backend.
pub fn new_db_backend<Block>(
	settings: DatabaseSettings,
) -> Result<Arc<Backend<Block>>, sp_blockchain::Error>
where
	Block: BlockT,
{
	const CANONICALIZATION_DELAY: u64 = 4096;

	Ok(Arc::new(Backend::new(settings, CANONICALIZATION_DELAY)?))
}

/// Create an instance of client backed by given backend.
pub fn new_client<E, Block, RA, G>(
	backend: Arc<Backend<Block>>,
	executor: E,
	genesis_block_builder: G,
	fork_blocks: ForkBlocks<Block>,
	bad_blocks: BadBlocks<Block>,
	execution_extensions: ExecutionExtensions<Block>,
	spawn_handle: Box<dyn SpawnNamed>,
	prometheus_registry: Option<Registry>,
	telemetry: Option<TelemetryHandle>,
	config: ClientConfig<Block>,
) -> Result<
	crate::client::Client<
		Backend<Block>,
		crate::client::LocalCallExecutor<Block, Backend<Block>, E>,
		Block,
		RA,
	>,
	sp_blockchain::Error,
>
where
	Block: BlockT,
	E: CodeExecutor + RuntimeVersionOf,
	G: BuildGenesisBlock<
		Block,
		BlockImportOperation = <Backend<Block> as sc_client_api::backend::Backend<Block>>::BlockImportOperation
	>,
{
	let executor = crate::client::LocalCallExecutor::new(
		backend.clone(),
		executor,
		spawn_handle,
		config.clone(),
		execution_extensions,
	)?;
	crate::client::Client::new(
		backend,
		executor,
		genesis_block_builder,
		fork_blocks,
		bad_blocks,
		prometheus_registry,
		telemetry,
		config,
	)
}

/// Shared network instance implementing a set of mandatory traits.
pub trait SpawnTaskNetwork<Block: BlockT>:
	sc_offchain::NetworkProvider
	+ NetworkStateInfo
	+ NetworkStatusProvider<Block>
	+ Send
	+ Sync
	+ 'static
{
}

impl<T, Block> SpawnTaskNetwork<Block> for T
where
	Block: BlockT,
	T: sc_offchain::NetworkProvider
		+ NetworkStateInfo
		+ NetworkStatusProvider<Block>
		+ Send
		+ Sync
		+ 'static,
{
}

/// Parameters to pass into `build`.
pub struct SpawnTasksParams<'a, TBl: BlockT, TCl, TExPool, TRpc, Backend> {
	/// The service configuration.
	pub config: Configuration,
	/// A shared client returned by `new_full_parts`.
	pub client: Arc<TCl>,
	/// A shared backend returned by `new_full_parts`.
	pub backend: Arc<Backend>,
	/// A task manager returned by `new_full_parts`.
	pub task_manager: &'a mut TaskManager,
	/// A shared keystore returned by `new_full_parts`.
	pub keystore: SyncCryptoStorePtr,
	/// A shared transaction pool.
	pub transaction_pool: Arc<TExPool>,
	/// Builds additional [`RpcModule`]s that should be added to the server
	pub rpc_builder:
		Box<dyn Fn(DenyUnsafe, SubscriptionTaskExecutor) -> Result<RpcModule<TRpc>, Error>>,
	/// A shared network instance.
	pub network: Arc<dyn SpawnTaskNetwork<TBl>>,
	/// A Sender for RPC requests.
	pub system_rpc_tx: TracingUnboundedSender<sc_rpc::system::Request<TBl>>,
	/// Controller for transactions handlers
	pub tx_handler_controller:
		sc_network_transactions::TransactionsHandlerController<<TBl as BlockT>::Hash>,
	/// Telemetry instance for this node.
	pub telemetry: Option<&'a mut Telemetry>,
}

/// Build a shared offchain workers instance.
pub fn build_offchain_workers<TBl, TCl>(
	config: &Configuration,
	spawn_handle: SpawnTaskHandle,
	client: Arc<TCl>,
	network: Arc<dyn sc_offchain::NetworkProvider + Send + Sync>,
) -> Option<Arc<sc_offchain::OffchainWorkers<TCl, TBl>>>
where
	TBl: BlockT,
	TCl: Send + Sync + ProvideRuntimeApi<TBl> + BlockchainEvents<TBl> + 'static,
	<TCl as ProvideRuntimeApi<TBl>>::Api: sc_offchain::OffchainWorkerApi<TBl>,
{
	let offchain_workers = Some(Arc::new(sc_offchain::OffchainWorkers::new(client.clone())));

	// Inform the offchain worker about new imported blocks
	if let Some(offchain) = offchain_workers.clone() {
		spawn_handle.spawn(
			"offchain-notifications",
			Some("offchain-worker"),
			sc_offchain::notification_future(
				config.role.is_authority(),
				client,
				offchain,
				Clone::clone(&spawn_handle),
				network,
			),
		);
	}

	offchain_workers
}

/// Spawn the tasks that are required to run a node.
pub fn spawn_tasks<TBl, TBackend, TExPool, TRpc, TCl>(
	params: SpawnTasksParams<TBl, TCl, TExPool, TRpc, TBackend>,
) -> Result<RpcHandlers, Error>
where
	TCl: ProvideRuntimeApi<TBl>
		+ HeaderMetadata<TBl, Error = sp_blockchain::Error>
		+ Chain<TBl>
		+ BlockBackend<TBl>
		+ BlockIdTo<TBl, Error = sp_blockchain::Error>
		+ ProofProvider<TBl>
		+ HeaderBackend<TBl>
		+ BlockchainEvents<TBl>
		+ ExecutorProvider<TBl>
		+ UsageProvider<TBl>
		+ StorageProvider<TBl, TBackend>
		+ CallApiAt<TBl>
		+ Send
		+ 'static,
	<TCl as ProvideRuntimeApi<TBl>>::Api: sp_api::Metadata<TBl>
		+ sc_offchain::OffchainWorkerApi<TBl>
		+ sp_transaction_pool::runtime_api::TaggedTransactionQueue<TBl>
		+ sp_session::SessionKeys<TBl>
		+ sp_api::ApiExt<TBl, StateBackend = TBackend::State>,
	TBl: BlockT,
	TBl::Hash: Unpin,
	TBl::Header: Unpin,
	TBackend: 'static + sc_client_api::backend::Backend<TBl> + Send,
	TExPool: MaintainedTransactionPool<Block = TBl, Hash = <TBl as BlockT>::Hash> + 'static,
{
	let SpawnTasksParams {
		mut config,
		task_manager,
		client,
		backend,
		keystore,
		transaction_pool,
		rpc_builder,
		network,
		system_rpc_tx,
		tx_handler_controller,
		telemetry,
	} = params;

	let chain_info = client.usage_info().chain;

	sp_session::generate_initial_session_keys(
		client.clone(),
		chain_info.best_hash,
		config.dev_key_seed.clone().map(|s| vec![s]).unwrap_or_default(),
	)
	.map_err(|e| Error::Application(Box::new(e)))?;

	let sysinfo = sc_sysinfo::gather_sysinfo();
	sc_sysinfo::print_sysinfo(&sysinfo);

	let telemetry = telemetry
		.map(|telemetry| {
			init_telemetry(&mut config, network.clone(), client.clone(), telemetry, Some(sysinfo))
		})
		.transpose()?;

	info!("📦 Highest known block at #{}", chain_info.best_number);

	let spawn_handle = task_manager.spawn_handle();

	// Inform the tx pool about imported and finalized blocks.
	spawn_handle.spawn(
		"txpool-notifications",
		Some("transaction-pool"),
		sc_transaction_pool::notification_future(client.clone(), transaction_pool.clone()),
	);

	spawn_handle.spawn(
		"on-transaction-imported",
		Some("transaction-pool"),
		transaction_notifications(
			transaction_pool.clone(),
			tx_handler_controller,
			telemetry.clone(),
		),
	);

	// Prometheus metrics.
	let metrics_service =
		if let Some(PrometheusConfig { port, registry }) = config.prometheus_config.clone() {
			// Set static metrics.
			let metrics = MetricsService::with_prometheus(telemetry, &registry, &config)?;
			spawn_handle.spawn(
				"prometheus-endpoint",
				None,
				prometheus_endpoint::init_prometheus(port, registry).map(drop),
			);

			metrics
		} else {
			MetricsService::new(telemetry)
		};

	// Periodically updated metrics and telemetry updates.
	spawn_handle.spawn(
		"telemetry-periodic-send",
		None,
		metrics_service.run(client.clone(), transaction_pool.clone(), network.clone()),
	);

	let rpc_id_provider = config.rpc_id_provider.take();

	// jsonrpsee RPC
	let gen_rpc_module = |deny_unsafe: DenyUnsafe| {
		gen_rpc_module(
			deny_unsafe,
			task_manager.spawn_handle(),
			client.clone(),
			transaction_pool.clone(),
			keystore.clone(),
			system_rpc_tx.clone(),
			&config,
			backend.clone(),
			&*rpc_builder,
		)
	};

	let rpc = start_rpc_servers(&config, gen_rpc_module, rpc_id_provider)?;
	let rpc_handlers = RpcHandlers(Arc::new(gen_rpc_module(sc_rpc::DenyUnsafe::No)?.into()));

	// Spawn informant task
	spawn_handle.spawn(
		"informant",
		None,
		sc_informant::build(client.clone(), network, config.informant_output_format),
	);

	task_manager.keep_alive((config.base_path, rpc));

	Ok(rpc_handlers)
}

async fn transaction_notifications<Block, ExPool>(
	transaction_pool: Arc<ExPool>,
	tx_handler_controller: sc_network_transactions::TransactionsHandlerController<
		<Block as BlockT>::Hash,
	>,
	telemetry: Option<TelemetryHandle>,
) where
	Block: BlockT,
	ExPool: MaintainedTransactionPool<Block = Block, Hash = <Block as BlockT>::Hash>,
{
	// transaction notifications
	transaction_pool
		.import_notification_stream()
		.for_each(move |hash| {
			tx_handler_controller.propagate_transaction(hash);
			let status = transaction_pool.status();
			telemetry!(
				telemetry;
				SUBSTRATE_INFO;
				"txpool.import";
				"ready" => status.ready,
				"future" => status.future,
			);
			ready(())
		})
		.await;
}

fn init_telemetry<Block, Client, Network>(
	config: &mut Configuration,
	network: Network,
	client: Arc<Client>,
	telemetry: &mut Telemetry,
	sysinfo: Option<sc_telemetry::SysInfo>,
) -> sc_telemetry::Result<TelemetryHandle>
where
	Block: BlockT,
	Client: BlockBackend<Block>,
	Network: NetworkStateInfo,
{
	let genesis_hash = client.block_hash(Zero::zero()).ok().flatten().unwrap_or_default();
	let connection_message = ConnectionMessage {
		name: config.network.node_name.to_owned(),
		implementation: config.impl_name.to_owned(),
		version: config.impl_version.to_owned(),
		target_os: sc_sysinfo::TARGET_OS.into(),
		target_arch: sc_sysinfo::TARGET_ARCH.into(),
		target_env: sc_sysinfo::TARGET_ENV.into(),
		config: String::new(),
		chain: config.chain_spec.name().to_owned(),
		genesis_hash: format!("{:?}", genesis_hash),
		authority: config.role.is_authority(),
		startup_time: SystemTime::UNIX_EPOCH
			.elapsed()
			.map(|dur| dur.as_millis())
			.unwrap_or(0)
			.to_string(),
		network_id: network.local_peer_id().to_base58(),
		sysinfo,
	};

	telemetry.start_telemetry(connection_message)?;

	Ok(telemetry.handle())
}

fn gen_rpc_module<TBl, TBackend, TCl, TRpc, TExPool>(
	deny_unsafe: DenyUnsafe,
	spawn_handle: SpawnTaskHandle,
	client: Arc<TCl>,
	transaction_pool: Arc<TExPool>,
	keystore: SyncCryptoStorePtr,
	system_rpc_tx: TracingUnboundedSender<sc_rpc::system::Request<TBl>>,
	config: &Configuration,
	backend: Arc<TBackend>,
	rpc_builder: &(dyn Fn(DenyUnsafe, SubscriptionTaskExecutor) -> Result<RpcModule<TRpc>, Error>),
) -> Result<RpcModule<()>, Error>
where
	TBl: BlockT,
	TCl: ProvideRuntimeApi<TBl>
		+ BlockchainEvents<TBl>
		+ HeaderBackend<TBl>
		+ HeaderMetadata<TBl, Error = sp_blockchain::Error>
		+ ExecutorProvider<TBl>
		+ CallApiAt<TBl>
		+ ProofProvider<TBl>
		+ StorageProvider<TBl, TBackend>
		+ BlockBackend<TBl>
		+ Send
		+ Sync
		+ 'static,
	TBackend: sc_client_api::backend::Backend<TBl> + 'static,
	<TCl as ProvideRuntimeApi<TBl>>::Api: sp_session::SessionKeys<TBl> + sp_api::Metadata<TBl>,
	TExPool: MaintainedTransactionPool<Block = TBl, Hash = <TBl as BlockT>::Hash> + 'static,
	TBl::Hash: Unpin,
	TBl::Header: Unpin,
{
	let system_info = sc_rpc::system::SystemInfo {
		chain_name: config.chain_spec.name().into(),
		impl_name: config.impl_name.clone(),
		impl_version: config.impl_version.clone(),
		properties: config.chain_spec.properties(),
		chain_type: config.chain_spec.chain_type(),
	};

	let mut rpc_api = RpcModule::new(());
	let task_executor = Arc::new(spawn_handle);

	let (chain, state, child_state) = {
		let chain = sc_rpc::chain::new_full(client.clone(), task_executor.clone()).into_rpc();
		let (state, child_state) = sc_rpc::state::new_full(
			client.clone(),
			task_executor.clone(),
			deny_unsafe,
			config.rpc_max_payload,
		);
		let state = state.into_rpc();
		let child_state = child_state.into_rpc();

		(chain, state, child_state)
	};

	let transaction_v2 = sc_rpc_spec_v2::transaction::Transaction::new(
		client.clone(),
		transaction_pool.clone(),
		task_executor.clone(),
	)
	.into_rpc();

	// Maximum pinned blocks per connection.
	// This number is large enough to consider immediate blocks,
	// but it will change to facilitate adequate limits for the pinning API.
	const MAX_PINNED_BLOCKS: usize = 4096;
	let chain_head_v2 = sc_rpc_spec_v2::chain_head::ChainHead::new(
		client.clone(),
		backend.clone(),
		task_executor.clone(),
		client.info().genesis_hash,
		MAX_PINNED_BLOCKS,
	)
	.into_rpc();

	let author = sc_rpc::author::Author::new(
		client.clone(),
		transaction_pool,
		keystore,
		deny_unsafe,
		task_executor.clone(),
	)
	.into_rpc();

	let system = sc_rpc::system::System::new(system_info, system_rpc_tx, deny_unsafe).into_rpc();

	if let Some(storage) = backend.offchain_storage() {
		let offchain = sc_rpc::offchain::Offchain::new(storage, deny_unsafe).into_rpc();

		rpc_api.merge(offchain).map_err(|e| Error::Application(e.into()))?;
	}

	// Part of the RPC v2 spec.
	rpc_api.merge(transaction_v2).map_err(|e| Error::Application(e.into()))?;
	rpc_api.merge(chain_head_v2).map_err(|e| Error::Application(e.into()))?;

	// Part of the old RPC spec.
	rpc_api.merge(chain).map_err(|e| Error::Application(e.into()))?;
	rpc_api.merge(author).map_err(|e| Error::Application(e.into()))?;
	rpc_api.merge(system).map_err(|e| Error::Application(e.into()))?;
	rpc_api.merge(state).map_err(|e| Error::Application(e.into()))?;
	rpc_api.merge(child_state).map_err(|e| Error::Application(e.into()))?;
	// Additional [`RpcModule`]s defined in the node to fit the specific blockchain
	let extra_rpcs = rpc_builder(deny_unsafe, task_executor.clone())?;
	rpc_api.merge(extra_rpcs).map_err(|e| Error::Application(e.into()))?;

	Ok(rpc_api)
}

/// Parameters to pass into `build_network`.
pub struct BuildNetworkParams<'a, TBl: BlockT, TExPool, TImpQu, TCl> {
	/// The service configuration.
	pub config: &'a Configuration,
	/// A shared client returned by `new_full_parts`.
	pub client: Arc<TCl>,
	/// A shared transaction pool.
	pub transaction_pool: Arc<TExPool>,
	/// A handle for spawning tasks.
	pub spawn_handle: SpawnTaskHandle,
	/// An import queue.
	pub import_queue: TImpQu,
	/// A block announce validator builder.
	pub block_announce_validator_builder:
		Option<Box<dyn FnOnce(Arc<TCl>) -> Box<dyn BlockAnnounceValidator<TBl> + Send> + Send>>,
	/// An optional warp sync provider.
	pub warp_sync: Option<Arc<dyn WarpSyncProvider<TBl>>>,
}
/// Build the network service, the network status sinks and an RPC sender.
pub fn build_network<TBl, TExPool, TImpQu, TCl>(
	params: BuildNetworkParams<TBl, TExPool, TImpQu, TCl>,
) -> Result<
	(
		Arc<NetworkService<TBl, <TBl as BlockT>::Hash>>,
		TracingUnboundedSender<sc_rpc::system::Request<TBl>>,
		sc_network_transactions::TransactionsHandlerController<<TBl as BlockT>::Hash>,
		NetworkStarter,
	),
	Error,
>
where
	TBl: BlockT,
	TCl: ProvideRuntimeApi<TBl>
		+ HeaderMetadata<TBl, Error = sp_blockchain::Error>
		+ Chain<TBl>
		+ BlockBackend<TBl>
		+ BlockIdTo<TBl, Error = sp_blockchain::Error>
		+ ProofProvider<TBl>
		+ HeaderBackend<TBl>
		+ BlockchainEvents<TBl>
		+ 'static,
	TExPool: MaintainedTransactionPool<Block = TBl, Hash = <TBl as BlockT>::Hash> + 'static,
	TImpQu: ImportQueue<TBl> + 'static,
{
	let BuildNetworkParams {
		config,
		client,
		transaction_pool,
		spawn_handle,
		import_queue,
		block_announce_validator_builder,
		warp_sync,
	} = params;

	let mut request_response_protocol_configs = Vec::new();

	if warp_sync.is_none() && config.network.sync_mode.is_warp() {
		return Err("Warp sync enabled, but no warp sync provider configured.".into())
	}

	if client.requires_full_sync() {
		match config.network.sync_mode {
			SyncMode::Fast { .. } => return Err("Fast sync doesn't work for archive nodes".into()),
			SyncMode::Warp => return Err("Warp sync doesn't work for archive nodes".into()),
			SyncMode::Full => {},
		}
	}

	let protocol_id = config.protocol_id();

	let block_announce_validator = if let Some(f) = block_announce_validator_builder {
		f(client.clone())
	} else {
		Box::new(DefaultBlockAnnounceValidator)
	};

	let block_request_protocol_config = {
		// Allow both outgoing and incoming requests.
		let (handler, protocol_config) = BlockRequestHandler::new(
			&protocol_id,
			config.chain_spec.fork_id(),
			client.clone(),
			config.network.default_peers_set.in_peers as usize +
				config.network.default_peers_set.out_peers as usize,
		);
		spawn_handle.spawn("block-request-handler", Some("networking"), handler.run());
		protocol_config
	};

	let state_request_protocol_config = {
		// Allow both outgoing and incoming requests.
		let (handler, protocol_config) = StateRequestHandler::new(
			&protocol_id,
			config.chain_spec.fork_id(),
			client.clone(),
			config.network.default_peers_set_num_full as usize,
		);
		spawn_handle.spawn("state-request-handler", Some("networking"), handler.run());
		protocol_config
	};

	let (warp_sync_provider, warp_sync_protocol_config) = warp_sync
		.map(|provider| {
			// Allow both outgoing and incoming requests.
			let (handler, protocol_config) = WarpSyncRequestHandler::new(
				protocol_id.clone(),
				client
					.block_hash(0u32.into())
					.ok()
					.flatten()
					.expect("Genesis block exists; qed"),
				config.chain_spec.fork_id(),
				provider.clone(),
			);
			spawn_handle.spawn("warp-sync-request-handler", Some("networking"), handler.run());
			(Some(provider), Some(protocol_config))
		})
		.unwrap_or_default();

	let light_client_request_protocol_config = {
		// Allow both outgoing and incoming requests.
		let (handler, protocol_config) = LightClientRequestHandler::new(
			&protocol_id,
			config.chain_spec.fork_id(),
			client.clone(),
		);
		spawn_handle.spawn("light-client-request-handler", Some("networking"), handler.run());
		protocol_config
	};

	let (chain_sync_network_provider, chain_sync_network_handle) = NetworkServiceProvider::new();
	let (chain_sync, chain_sync_service, block_announce_config) = ChainSync::new(
		match config.network.sync_mode {
			SyncMode::Full => sc_network_common::sync::SyncMode::Full,
			SyncMode::Fast { skip_proofs, storage_chain_mode } =>
				sc_network_common::sync::SyncMode::LightState { skip_proofs, storage_chain_mode },
			SyncMode::Warp => sc_network_common::sync::SyncMode::Warp,
		},
		client.clone(),
		protocol_id.clone(),
		&config.chain_spec.fork_id().map(ToOwned::to_owned),
		Roles::from(&config.role),
		block_announce_validator,
		config.network.max_parallel_downloads,
		warp_sync_provider,
		config.prometheus_config.as_ref().map(|config| config.registry.clone()).as_ref(),
		chain_sync_network_handle,
		import_queue.service(),
		block_request_protocol_config.name.clone(),
		state_request_protocol_config.name.clone(),
		warp_sync_protocol_config.as_ref().map(|config| config.name.clone()),
	)?;

	request_response_protocol_configs.push(config.network.ipfs_server.then(|| {
		let (handler, protocol_config) = BitswapRequestHandler::new(client.clone());
		spawn_handle.spawn("bitswap-request-handler", Some("networking"), handler.run());
		protocol_config
	}));

	let mut network_params = sc_network::config::Params {
		role: config.role.clone(),
		executor: {
			let spawn_handle = Clone::clone(&spawn_handle);
			Box::new(move |fut| {
				spawn_handle.spawn("libp2p-node", Some("networking"), fut);
			})
		},
		network_config: config.network.clone(),
		chain: client.clone(),
		protocol_id: protocol_id.clone(),
		fork_id: config.chain_spec.fork_id().map(ToOwned::to_owned),
		chain_sync: Box::new(chain_sync),
		chain_sync_service: Box::new(chain_sync_service.clone()),
		metrics_registry: config.prometheus_config.as_ref().map(|config| config.registry.clone()),
		block_announce_config,
		request_response_protocol_configs: request_response_protocol_configs
			.into_iter()
			.chain([
				Some(block_request_protocol_config),
				Some(state_request_protocol_config),
				Some(light_client_request_protocol_config),
				warp_sync_protocol_config,
			])
			.flatten()
			.collect::<Vec<_>>(),
	};

	// crate transactions protocol and add it to the list of supported protocols of `network_params`
	let transactions_handler_proto = sc_network_transactions::TransactionsHandlerPrototype::new(
		protocol_id.clone(),
		client
			.block_hash(0u32.into())
			.ok()
			.flatten()
			.expect("Genesis block exists; qed"),
		config.chain_spec.fork_id(),
	);
	network_params
		.network_config
		.extra_sets
		.insert(0, transactions_handler_proto.set_config());

	let has_bootnodes = !network_params.network_config.boot_nodes.is_empty();
	let network_mut = sc_network::NetworkWorker::new(network_params)?;
	let network = network_mut.service().clone();

	let (tx_handler, tx_handler_controller) = transactions_handler_proto.build(
		network.clone(),
		Arc::new(TransactionPoolAdapter { pool: transaction_pool, client: client.clone() }),
		config.prometheus_config.as_ref().map(|config| &config.registry),
	)?;

	spawn_handle.spawn("network-transactions-handler", Some("networking"), tx_handler.run());
	spawn_handle.spawn(
		"chain-sync-network-service-provider",
		Some("networking"),
		chain_sync_network_provider.run(network.clone()),
	);
	spawn_handle.spawn("import-queue", None, import_queue.run(Box::new(chain_sync_service)));

	let (system_rpc_tx, system_rpc_rx) = tracing_unbounded("mpsc_system_rpc", 10_000);

	let future = build_network_future(
		config.role.clone(),
		network_mut,
		client,
		system_rpc_rx,
		has_bootnodes,
		config.announce_block,
	);

	// TODO: Normally, one is supposed to pass a list of notifications protocols supported by the
	// node through the `NetworkConfiguration` struct. But because this function doesn't know in
	// advance which components, such as GrandPa or Polkadot, will be plugged on top of the
	// service, it is unfortunately not possible to do so without some deep refactoring. To bypass
	// this problem, the `NetworkService` provides a `register_notifications_protocol` method that
	// can be called even after the network has been initialized. However, we want to avoid the
	// situation where `register_notifications_protocol` is called *after* the network actually
	// connects to other peers. For this reason, we delay the process of the network future until
	// the user calls `NetworkStarter::start_network`.
	//
	// This entire hack should eventually be removed in favour of passing the list of protocols
	// through the configuration.
	//
	// See also https://github.com/paritytech/substrate/issues/6827
	let (network_start_tx, network_start_rx) = oneshot::channel();

	// The network worker is responsible for gathering all network messages and processing
	// them. This is quite a heavy task, and at the time of the writing of this comment it
	// frequently happens that this future takes several seconds or in some situations
	// even more than a minute until it has processed its entire queue. This is clearly an
	// issue, and ideally we would like to fix the network future to take as little time as
	// possible, but we also take the extra harm-prevention measure to execute the networking
	// future using `spawn_blocking`.
	spawn_handle.spawn_blocking("network-worker", Some("networking"), async move {
		if network_start_rx.await.is_err() {
			log::warn!(
				"The NetworkStart returned as part of `build_network` has been silently dropped"
			);
			// This `return` might seem unnecessary, but we don't want to make it look like
			// everything is working as normal even though the user is clearly misusing the API.
			return
		}

		future.await
	});

	Ok((network, system_rpc_tx, tx_handler_controller, NetworkStarter(network_start_tx)))
}

/// Object used to start the network.
#[must_use]
pub struct NetworkStarter(oneshot::Sender<()>);

impl NetworkStarter {
	/// Create a new NetworkStarter
	pub fn new(sender: oneshot::Sender<()>) -> Self {
		NetworkStarter(sender)
	}

	/// Start the network. Call this after all sub-components have been initialized.
	///
	/// > **Note**: If you don't call this function, the networking will not work.
	pub fn start_network(self) {
		let _ = self.0.send(());
	}
}