// Copyright 2017 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot 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.

// Polkadot 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.

//! Polkadot service. Starts a thread that spins the network, the client and the transaction pool.
//! Manages communication between them.

extern crate futures;
extern crate ed25519;
extern crate clap;
extern crate exit_future;
extern crate tokio_timer;
extern crate polkadot_primitives;
extern crate polkadot_runtime;
extern crate polkadot_executor;
extern crate polkadot_api;
extern crate polkadot_consensus as consensus;
extern crate polkadot_transaction_pool as transaction_pool;
extern crate substrate_keystore as keystore;
extern crate substrate_runtime_io as runtime_io;
extern crate substrate_primitives as primitives;
extern crate substrate_runtime_primitives as runtime_primitives;
extern crate substrate_network as network;
extern crate substrate_codec as codec;
extern crate substrate_executor;
extern crate substrate_state_machine as state_machine;

extern crate tokio_core;
extern crate substrate_client as client;
extern crate substrate_client_db as client_db;

#[macro_use]
extern crate substrate_telemetry;
#[macro_use]
extern crate error_chain;
#[macro_use]
extern crate slog;	// needed until we can reexport `slog_info` from `substrate_telemetry`
#[macro_use]
extern crate log;

mod components;
mod error;
mod config;

use std::sync::Arc;
use std::thread;
use futures::prelude::*;
use tokio_core::reactor::Core;
use transaction_pool::TransactionPool;
use keystore::Store as Keystore;
use polkadot_api::PolkadotApi;
use polkadot_primitives::{Block, BlockId, Hash};
use client::{Client, BlockchainEvents};
use network::ManageNetwork;
use exit_future::Signal;

pub use self::error::{ErrorKind, Error};
pub use self::components::{Components, FullComponents, LightComponents};
pub use config::{Configuration, Role};

/// Polkadot service.
pub struct Service<Components: components::Components> {
	thread: Option<thread::JoinHandle<()>>,
	client: Arc<Client<Components::Backend, Components::Executor, Block>>,
	network: Arc<network::Service<Block>>,
	transaction_pool: Arc<TransactionPool<Components::Api>>,
	signal: Option<Signal>,
	_consensus: Option<consensus::Service>,
}

/// Creates light client and register protocol with the network service
pub fn new_light(config: Configuration) -> Result<Service<components::LightComponents>, error::Error> {
	Service::new(components::LightComponents, config)
}

/// Creates full client and register protocol with the network service
pub fn new_full(config: Configuration) -> Result<Service<components::FullComponents>, error::Error> {
	let is_validator = (config.roles & Role::VALIDATOR) == Role::VALIDATOR;
	Service::new(components::FullComponents { is_validator }, config)
}

impl<Components> Service<Components>
	where
		Components: components::Components,
		client::error::Error: From<<<<Components as components::Components>::Backend as client::backend::Backend<Block>>::State as state_machine::Backend>::Error>,
{
	/// Creates and register protocol with the network service
	fn new(components: Components, config: Configuration) -> Result<Self, error::Error> {
		use std::sync::Barrier;

		let (signal, exit) = ::exit_future::signal();

		// Create client
		let executor = polkadot_executor::Executor::new();

		let mut keystore = Keystore::open(config.keystore_path.into())?;
		for seed in &config.keys {
			keystore.generate_from_seed(seed)?;
		}

		if keystore.contents()?.is_empty() {
			let key = keystore.generate("")?;
			info!("Generated a new keypair: {:?}", key.public());
		}

		let db_settings = client_db::DatabaseSettings {
			cache_size: None,
			path: config.database_path.into(),
		};

		let (client, on_demand) = components.build_client(db_settings, executor, config.genesis_storage)?;
		let api = components.build_api(client.clone());
		let best_header = client.best_block_header()?;

		info!("Best block is #{}", best_header.number);
		telemetry!("node.start"; "height" => best_header.number, "best" => ?best_header.hash());

		let transaction_pool = Arc::new(TransactionPool::new(config.transaction_pool, api.clone()));
		let transaction_pool_adapter = components.build_network_tx_pool(client.clone(), transaction_pool.clone());
		let network_params = network::Params {
			config: network::ProtocolConfig {
				roles: config.roles,
			},
			network_config: config.network,
			chain: client.clone(),
			on_demand: on_demand.clone().map(|d| d as Arc<network::OnDemandService>),
			transaction_pool: transaction_pool_adapter,
		};
		let network = network::Service::new(network_params)?;
		let barrier = ::std::sync::Arc::new(Barrier::new(2));
		on_demand.map(|on_demand| on_demand.set_service_link(Arc::downgrade(&network)));

		let thread = {
			let client = client.clone();
			let network = network.clone();
			let txpool = transaction_pool.clone();

			let thread_barrier = barrier.clone();
			thread::spawn(move || {
				network.start_network();

				thread_barrier.wait();
				let mut core = Core::new().expect("tokio::Core could not be created");

				// block notifications
				let network1 = network.clone();
				let txpool1 = txpool.clone();

				let events = client.import_notification_stream()
					.for_each(move |notification| {
						network1.on_block_imported(notification.hash, &notification.header);
						prune_imported(&*txpool1, notification.hash);

						Ok(())
					});
				core.handle().spawn(events);

				// transaction notifications
				let events = txpool.import_notification_stream()
					// TODO [ToDr] Consider throttling?
					.for_each(move |_| {
						network.trigger_repropagate();
						Ok(())
					});
				core.handle().spawn(events);

				if let Err(e) = core.run(exit) {
					debug!("Polkadot service event loop shutdown with {:?}", e);
				}
				debug!("Polkadot service shutdown");
			})
		};

		// wait for the network to start up before starting the consensus
		// service.
		barrier.wait();

		// Spin consensus service if configured
		let consensus_service = components.build_consensus(client.clone(), network.clone(), transaction_pool.clone(), &keystore)?;

		Ok(Service {
			thread: Some(thread),
			client: client,
			network: network,
			transaction_pool: transaction_pool,
			signal: Some(signal),
			_consensus: consensus_service,
		})
	}

	/// Get shared client instance.
	pub fn client(&self) -> Arc<Client<Components::Backend, Components::Executor, Block>> {
		self.client.clone()
	}

	/// Get shared network instance.
	pub fn network(&self) -> Arc<network::Service<Block>> {
		self.network.clone()
	}

	/// Get shared transaction pool instance.
	pub fn transaction_pool(&self) -> Arc<TransactionPool<Components::Api>> {
		self.transaction_pool.clone()
	}
}

/// Produce a task which prunes any finalized transactions from the pool.
pub fn prune_imported<A>(pool: &TransactionPool<A>, hash: Hash)
	where A: PolkadotApi,
{
	let block = BlockId::hash(hash);
	if let Err(e) = pool.cull(block) {
		warn!("Culling error: {:?}", e);
	}

	if let Err(e) = pool.retry_verification(block) {
		warn!("Re-verifying error: {:?}", e);
	}
}

impl<Components> Drop for Service<Components> where Components: components::Components {
	fn drop(&mut self) {
		self.network.stop_network();

		if let Some(signal) = self.signal.take() {
			signal.fire();
		}

		if let Some(thread) = self.thread.take() {
			thread.join().expect("The service thread has panicked");
		}
	}
}