// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum 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.

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

//! Stratum protocol implementation for parity ethereum/bitcoin clients

extern crate jsonrpc_tcp_server;
extern crate jsonrpc_core;
extern crate ethereum_types;
extern crate keccak_hash as hash;
extern crate parking_lot;

#[macro_use] extern crate log;

#[cfg(test)] extern crate tokio;
#[cfg(test)] extern crate tokio_io;
#[cfg(test)] extern crate env_logger;

mod traits;

pub use traits::{
	JobDispatcher, PushWorkHandler, Error, ServiceConfiguration,
};

use jsonrpc_tcp_server::{
	Server as JsonRpcServer, ServerBuilder as JsonRpcServerBuilder,
	RequestContext, MetaExtractor, Dispatcher, PushMessageError,
};
use jsonrpc_core::{MetaIoHandler, Params, to_value, Value, Metadata, Compatibility, IoDelegate};
use std::sync::Arc;

use std::net::SocketAddr;
use std::collections::{HashSet, HashMap};
use hash::keccak;
use ethereum_types::H256;
use parking_lot::RwLock;

type RpcResult = Result<jsonrpc_core::Value, jsonrpc_core::Error>;

const NOTIFY_COUNTER_INITIAL: u32 = 16;

/// Container which owns rpc server and stratum implementation
pub struct Stratum {
	/// RPC server
	///
	/// It is an `Option` so it can be easily closed and released during `drop` phase
	rpc_server: Option<JsonRpcServer>,
	/// stratum protocol implementation
	///
	/// It is owned by a container and rpc server
	implementation: Arc<StratumImpl>,
	/// Message dispatcher (tcp/ip service)
	///
	/// Used to push messages to peers
	tcp_dispatcher: Dispatcher,
}

impl Stratum {
	pub fn start(
		addr: &SocketAddr,
		dispatcher: Arc<JobDispatcher>,
		secret: Option<H256>,
	) -> Result<Arc<Stratum>, Error> {

		let implementation = Arc::new(StratumImpl {
			subscribers: RwLock::default(),
			job_que: RwLock::default(),
			dispatcher,
			workers: Arc::new(RwLock::default()),
			secret,
			notify_counter: RwLock::new(NOTIFY_COUNTER_INITIAL),
		});

		let mut delegate = IoDelegate::<StratumImpl, SocketMetadata>::new(implementation.clone());
		delegate.add_method_with_meta("mining.subscribe", StratumImpl::subscribe);
		delegate.add_method_with_meta("mining.authorize", StratumImpl::authorize);
		delegate.add_method_with_meta("mining.submit", StratumImpl::submit);
		let mut handler = MetaIoHandler::<SocketMetadata>::with_compatibility(Compatibility::Both);
		handler.extend_with(delegate);

		let server_builder = JsonRpcServerBuilder::new(handler);
		let tcp_dispatcher = server_builder.dispatcher();
		let server_builder = server_builder.session_meta_extractor(PeerMetaExtractor::new(tcp_dispatcher.clone()));
		let server = server_builder.start(addr)?;

		let stratum = Arc::new(Stratum {
			rpc_server: Some(server),
			implementation,
			tcp_dispatcher,
		});

		Ok(stratum)
	}
}

impl PushWorkHandler for Stratum {
	fn push_work_all(&self, payload: String) -> Result<(), Error> {
		self.implementation.push_work_all(payload, &self.tcp_dispatcher)
	}

	fn push_work(&self, payloads: Vec<String>) -> Result<(), Error> {
		self.implementation.push_work(payloads, &self.tcp_dispatcher)
	}
}

impl Drop for Stratum {
	fn drop(&mut self) {
		// shut down rpc server
		self.rpc_server.take().map(|server| server.close());
	}
}

struct StratumImpl {
	/// Subscribed clients
	subscribers: RwLock<Vec<SocketAddr>>,
	/// List of workers supposed to receive job update
	job_que: RwLock<HashSet<SocketAddr>>,
	/// Payload manager
	dispatcher: Arc<JobDispatcher>,
	/// Authorized workers (socket - worker_id)
	workers: Arc<RwLock<HashMap<SocketAddr, String>>>,
	/// Secret if any
	secret: Option<H256>,
	/// Dispatch notify couinter
	notify_counter: RwLock<u32>,
}

impl StratumImpl {
	/// rpc method `mining.subscribe`
	fn subscribe(&self, _params: Params, meta: SocketMetadata) -> RpcResult {
		use std::str::FromStr;

		self.subscribers.write().push(meta.addr().clone());
		self.job_que.write().insert(meta.addr().clone());
		trace!(target: "stratum", "Subscription request from {:?}", meta.addr());

		Ok(match self.dispatcher.initial() {
			Some(initial) => match jsonrpc_core::Value::from_str(&initial) {
				Ok(val) => Ok(val),
				Err(e) => {
					warn!(target: "stratum", "Invalid payload: '{}' ({:?})", &initial, e);
					to_value(&[0u8; 0])
				},
			},
			None => to_value(&[0u8; 0]),
		}.expect("Empty slices are serializable; qed"))
	}

	/// rpc method `mining.authorize`
	fn authorize(&self, params: Params, meta: SocketMetadata) -> RpcResult {
		params.parse::<(String, String)>().map(|(worker_id, secret)|{
			if let Some(valid_secret) = self.secret {
				let hash = keccak(secret);
				if hash != valid_secret {
					return to_value(&false);
				}
			}
			trace!(target: "stratum", "New worker #{} registered", worker_id);
			self.workers.write().insert(meta.addr().clone(), worker_id);
			to_value(true)
		}).map(|v| v.expect("Only true/false is returned and it's always serializable; qed"))
	}

	/// rpc method `mining.submit`
	fn submit(&self, params: Params, meta: SocketMetadata) -> RpcResult {
		Ok(match params {
			Params::Array(vals) => {
				// first two elements are service messages (worker_id & job_id)
				match self.dispatcher.submit(vals.iter().skip(2)
					.filter_map(|val| match *val {
						Value::String(ref s) => Some(s.to_owned()),
						_ => None
					})
					.collect::<Vec<String>>()) {
						Ok(()) => {
							self.update_peers(&meta.tcp_dispatcher.expect("tcp_dispatcher is always initialized; qed"));
							to_value(true)
						},
						Err(submit_err) => {
							warn!("Error while submitting share: {:?}", submit_err);
							to_value(false)
						}
					}
			},
			_ => {
				trace!(target: "stratum", "Invalid submit work format {:?}", params);
				to_value(false)
			}
		}.expect("Only true/false is returned and it's always serializable; qed"))
	}

	/// Helper method
	fn update_peers(&self, tcp_dispatcher: &Dispatcher) {
		if let Some(job) = self.dispatcher.job() {
			if let Err(e) = self.push_work_all(job, tcp_dispatcher) {
				warn!("Failed to update some of the peers: {:?}", e);
			}
		}
	}

	fn push_work_all(&self, payload: String, tcp_dispatcher: &Dispatcher) -> Result<(), Error> {
		let hup_peers = {
			let workers = self.workers.read();
			let next_request_id = {
				let mut counter = self.notify_counter.write();
				if *counter == ::std::u32::MAX { *counter = NOTIFY_COUNTER_INITIAL; }
				else { *counter = *counter + 1 }
				*counter
			};

			let mut hup_peers = HashSet::with_capacity(0); // most of the cases won't be needed, hence avoid allocation
			let workers_msg = format!("{{ \"id\": {}, \"method\": \"mining.notify\", \"params\": {} }}", next_request_id, payload);
			trace!(target: "stratum", "pushing work for {} workers (payload: '{}')", workers.len(), &workers_msg);
			for (ref addr, _) in workers.iter() {
				trace!(target: "stratum", "pusing work to {}", addr);
				match tcp_dispatcher.push_message(addr, workers_msg.clone()) {
					Err(PushMessageError::NoSuchPeer) => {
						trace!(target: "stratum", "Worker no longer connected: {}", &addr);
						hup_peers.insert(*addr.clone());
					},
					Err(e) => {
						warn!(target: "stratum", "Unexpected transport error: {:?}", e);
					},
					Ok(_) => { },
				}
			}
			hup_peers
		};

		if !hup_peers.is_empty() {
			let mut workers = self.workers.write();
			for hup_peer in hup_peers { workers.remove(&hup_peer); }
		}

		Ok(())
	}

	fn push_work(&self, payloads: Vec<String>, tcp_dispatcher: &Dispatcher) -> Result<(), Error> {
		if !payloads.len() > 0 {
			return Err(Error::NoWork);
		}
		let workers = self.workers.read();
		let addrs = workers.keys().collect::<Vec<&SocketAddr>>();
		if !workers.len() > 0 {
			return Err(Error::NoWorkers);
		}
		let mut que = payloads;
		let mut addr_index = 0;
		while que.len() > 0 {
			let next_worker = addrs[addr_index];
			let mut next_payload = que.drain(0..1);
			tcp_dispatcher.push_message(
				next_worker,
				next_payload.nth(0).expect("drained successfully of 0..1, so 0-th element should exist")
			)?;
			addr_index = addr_index + 1;
		}
		Ok(())
	}
}

#[derive(Clone)]
pub struct SocketMetadata {
	addr: SocketAddr,
	// with the new version of jsonrpc-core, SocketMetadata
	// won't have to implement default, so this field will not
	// have to be an Option
	tcp_dispatcher: Option<Dispatcher>,
}

impl Default for SocketMetadata {
	fn default() -> Self {
		SocketMetadata {
			addr: "0.0.0.0:0".parse().unwrap(),
			tcp_dispatcher: None,
		}
	}
}

impl SocketMetadata {
	pub fn addr(&self) -> &SocketAddr {
		&self.addr
	}
}

impl Metadata for SocketMetadata { }

pub struct PeerMetaExtractor {
	tcp_dispatcher: Dispatcher,
}

impl PeerMetaExtractor {
	fn new(tcp_dispatcher: Dispatcher) -> Self {
		PeerMetaExtractor {
			tcp_dispatcher,
		}
	}
}

impl MetaExtractor<SocketMetadata> for PeerMetaExtractor {
	fn extract(&self, context: &RequestContext) -> SocketMetadata {
		SocketMetadata {
			addr: context.peer_addr,
			tcp_dispatcher: Some(self.tcp_dispatcher.clone()),
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use std::net::{SocketAddr, Shutdown};
	use std::sync::Arc;

	use tokio::{io, runtime::Runtime, timer::timeout::{self, Timeout}, net::TcpStream};
	use jsonrpc_core::futures::{Future, future};

	pub struct VoidManager;

	impl JobDispatcher for VoidManager {
		fn submit(&self, _payload: Vec<String>) -> Result<(), Error> {
			Ok(())
		}
	}

	fn dummy_request(addr: &SocketAddr, data: &str) -> Vec<u8> {
		let mut runtime = Runtime::new().expect("Tokio Runtime should be created with no errors");

		let mut data_vec = data.as_bytes().to_vec();
		data_vec.extend(b"\n");

		let stream = TcpStream::connect(addr)
			.and_then(move |stream| {
				io::write_all(stream, data_vec)
			})
			.and_then(|(stream, _)| {
				stream.shutdown(Shutdown::Write).unwrap();
				io::read_to_end(stream, Vec::with_capacity(2048))
			})
			.and_then(|(_stream, read_buf)| {
				future::ok(read_buf)
			});
			let result = runtime.block_on(stream).expect("Runtime should run with no errors");

			result
	}

	#[test]
	fn can_be_started() {
		let stratum = Stratum::start(&"127.0.0.1:19980".parse().unwrap(), Arc::new(VoidManager), None);
		assert!(stratum.is_ok());
	}

	#[test]
	fn records_subscriber() {
		let _ = ::env_logger::try_init();

		let addr = "127.0.0.1:19985".parse().unwrap();
		let stratum = Stratum::start(&addr, Arc::new(VoidManager), None).unwrap();
		let request = r#"{"jsonrpc": "2.0", "method": "mining.subscribe", "params": [], "id": 1}"#;
		dummy_request(&addr, request);
		assert_eq!(1, stratum.implementation.subscribers.read().len());
	}

	struct DummyManager {
		initial_payload: String
	}

	impl DummyManager {
		fn new() -> Arc<DummyManager> {
			Arc::new(Self::build())
		}

		fn build() -> DummyManager {
			DummyManager { initial_payload: r#"[ "dummy payload" ]"#.to_owned() }
		}

		fn of_initial(mut self, new_initial: &str) -> DummyManager {
			self.initial_payload = new_initial.to_owned();
			self
		}
	}

	impl JobDispatcher for DummyManager {
		fn initial(&self) -> Option<String> {
			Some(self.initial_payload.clone())
		}

		fn submit(&self, _payload: Vec<String>) -> Result<(), Error> {
			Ok(())
		}
	}

	fn terminated_str(origin: &'static str) -> String {
		let mut s = String::new();
		s.push_str(origin);
		s.push_str("\n");
		s
	}

	#[test]
	fn receives_initial_payload() {
		let addr = "127.0.0.1:19975".parse().unwrap();
		let _stratum = Stratum::start(&addr, DummyManager::new(), None).expect("There should be no error starting stratum");
		let request = r#"{"jsonrpc": "2.0", "method": "mining.subscribe", "params": [], "id": 2}"#;

		let response = String::from_utf8(dummy_request(&addr, request)).unwrap();

		assert_eq!(terminated_str(r#"{"jsonrpc":"2.0","result":["dummy payload"],"id":2}"#), response);
	}

	#[test]
	fn can_authorize() {
		let addr = "127.0.0.1:19970".parse().unwrap();
		let stratum = Stratum::start(
			&addr,
			Arc::new(DummyManager::build().of_initial(r#"["dummy autorize payload"]"#)),
			None
		).expect("There should be no error starting stratum");

		let request = r#"{"jsonrpc": "2.0", "method": "mining.authorize", "params": ["miner1", ""], "id": 1}"#;
		let response = String::from_utf8(dummy_request(&addr, request)).unwrap();

		assert_eq!(terminated_str(r#"{"jsonrpc":"2.0","result":true,"id":1}"#), response);
		assert_eq!(1, stratum.implementation.workers.read().len());
	}

	#[test]
	fn can_push_work() {
		let _ = ::env_logger::try_init();

		let addr = "127.0.0.1:19995".parse().unwrap();
		let stratum = Stratum::start(
			&addr,
			Arc::new(DummyManager::build().of_initial(r#"["dummy autorize payload"]"#)),
			None
		).expect("There should be no error starting stratum");

		let mut auth_request =
			r#"{"jsonrpc": "2.0", "method": "mining.authorize", "params": ["miner1", ""], "id": 1}"#
			.as_bytes()
			.to_vec();
		auth_request.extend(b"\n");

		let auth_response = "{\"jsonrpc\":\"2.0\",\"result\":true,\"id\":1}\n";

		let mut runtime = Runtime::new().expect("Tokio Runtime should be created with no errors");
		let read_buf0 = vec![0u8; auth_response.len()];
		let read_buf1 = Vec::with_capacity(2048);
		let stream = TcpStream::connect(&addr)
			.and_then(move |stream| {
				io::write_all(stream, auth_request)
			})
			.and_then(|(stream, _)| {
				io::read_exact(stream, read_buf0)
			})
			.map_err(|err| panic!("{:?}", err))
			.and_then(move |(stream, read_buf0)| {
				assert_eq!(String::from_utf8(read_buf0).unwrap(), auth_response);
				trace!(target: "stratum", "Received authorization confirmation");
				Timeout::new(future::ok(stream), ::std::time::Duration::from_millis(100))
			})
			.map_err(|err: timeout::Error<()>| panic!("Timeout: {:?}", err))
			.and_then(move |stream| {
				trace!(target: "stratum", "Pusing work to peers");
				stratum.push_work_all(r#"{ "00040008", "100500" }"#.to_owned())
					.expect("Pushing work should produce no errors");
				Timeout::new(future::ok(stream), ::std::time::Duration::from_millis(100))
			})
			.map_err(|err: timeout::Error<()>| panic!("Timeout: {:?}", err))
			.and_then(|stream| {
				trace!(target: "stratum", "Ready to read work from server");
				stream.shutdown(Shutdown::Write).unwrap();
				io::read_to_end(stream, read_buf1)
			})
			.and_then(|(_, read_buf1)| {
				trace!(target: "stratum", "Received work from server");
				future::ok(read_buf1)
			});
		let response = String::from_utf8(
			runtime.block_on(stream).expect("Runtime should run with no errors")
		).expect("Response should be utf-8");

		assert_eq!(
			"{ \"id\": 17, \"method\": \"mining.notify\", \"params\": { \"00040008\", \"100500\" } }\n",
			response);
	}
}