// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.

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

//! Eth rpc implementation.

extern crate ethash;

use std::io::{Write};
use std::process::{Command, Stdio};
use std::thread;
use std::time::{Instant, Duration};
use std::sync::{Arc, Weak};
use time::get_time;
use ethsync::{SyncProvider, SyncState};
use ethcore::miner::{MinerService, ExternalMinerService};
use jsonrpc_core::*;
use util::{H256, Address, FixedHash, U256, H64, Uint};
use util::sha3::*;
use util::rlp::{encode, decode, UntrustedRlp, View};
use util::{FromHex, Mutex};
use ethcore::account_provider::AccountProvider;
use ethcore::client::{MiningBlockChainClient, BlockID, TransactionID, UncleID};
use ethcore::header::Header as BlockHeader;
use ethcore::block::IsBlock;
use ethcore::views::*;
use ethcore::ethereum::Ethash;
use ethcore::transaction::{Transaction as EthTransaction, SignedTransaction, Action};
use ethcore::log_entry::LogEntry;
use ethcore::filter::Filter as EthcoreFilter;
use self::ethash::SeedHashCompute;
use v1::traits::Eth;
use v1::types::{Block, BlockTransactions, BlockNumber, Bytes, SyncStatus, SyncInfo, Transaction, CallRequest, Index, Filter, Log, Receipt, H64 as RpcH64, H256 as RpcH256, H160 as RpcH160, U256 as RpcU256};
use v1::helpers::{CallRequest as CRequest, errors};
use v1::helpers::dispatch::{default_gas_price, dispatch_transaction};
use v1::helpers::params::{expect_no_params, from_params_default_second, from_params_default_third};

/// Eth RPC options
pub struct EthClientOptions {
	/// Returns receipt from pending blocks
	pub allow_pending_receipt_query: bool,
	/// Send additional block number when asking for work
	pub send_block_number_in_get_work: bool,
}

impl Default for EthClientOptions {
	fn default() -> Self {
		EthClientOptions {
			allow_pending_receipt_query: true,
			send_block_number_in_get_work: true,
		}
	}
}

/// Eth rpc implementation.
pub struct EthClient<C, S: ?Sized, M, EM> where
	C: MiningBlockChainClient,
	S: SyncProvider,
	M: MinerService,
	EM: ExternalMinerService {

	client: Weak<C>,
	sync: Weak<S>,
	accounts: Weak<AccountProvider>,
	miner: Weak<M>,
	external_miner: Arc<EM>,
	seed_compute: Mutex<SeedHashCompute>,
	options: EthClientOptions,
}

impl<C, S: ?Sized, M, EM> EthClient<C, S, M, EM> where
	C: MiningBlockChainClient,
	S: SyncProvider,
	M: MinerService,
	EM: ExternalMinerService {

	/// Creates new EthClient.
	pub fn new(client: &Arc<C>, sync: &Arc<S>, accounts: &Arc<AccountProvider>, miner: &Arc<M>, em: &Arc<EM>, options: EthClientOptions)
		-> EthClient<C, S, M, EM> {
		EthClient {
			client: Arc::downgrade(client),
			sync: Arc::downgrade(sync),
			miner: Arc::downgrade(miner),
			accounts: Arc::downgrade(accounts),
			external_miner: em.clone(),
			seed_compute: Mutex::new(SeedHashCompute::new()),
			options: options,
		}
	}

	fn block(&self, id: BlockID, include_txs: bool) -> Result<Value, Error> {
		let client = take_weak!(self.client);
		match (client.block(id.clone()), client.block_total_difficulty(id)) {
			(Some(bytes), Some(total_difficulty)) => {
				let block_view = BlockView::new(&bytes);
				let view = block_view.header_view();
				let block = Block {
					hash: Some(view.sha3().into()),
					size: Some(bytes.len().into()),
					parent_hash: view.parent_hash().into(),
					uncles_hash: view.uncles_hash().into(),
					author: view.author().into(),
					miner: view.author().into(),
					state_root: view.state_root().into(),
					transactions_root: view.transactions_root().into(),
					receipts_root: view.receipts_root().into(),
					number: Some(view.number().into()),
					gas_used: view.gas_used().into(),
					gas_limit: view.gas_limit().into(),
					logs_bloom: view.log_bloom().into(),
					timestamp: view.timestamp().into(),
					difficulty: view.difficulty().into(),
					total_difficulty: total_difficulty.into(),
					seal_fields: view.seal().into_iter().map(|f| decode(&f)).map(Bytes::new).collect(),
					uncles: block_view.uncle_hashes().into_iter().map(Into::into).collect(),
					transactions: match include_txs {
						true => BlockTransactions::Full(block_view.localized_transactions().into_iter().map(Into::into).collect()),
						false => BlockTransactions::Hashes(block_view.transaction_hashes().into_iter().map(Into::into).collect()),
					},
					extra_data: Bytes::new(view.extra_data())
				};
				to_value(&block)
			},
			_ => Ok(Value::Null)
		}
	}

	fn transaction(&self, id: TransactionID) -> Result<Value, Error> {
		match take_weak!(self.client).transaction(id) {
			Some(t) => to_value(&Transaction::from(t)),
			None => Ok(Value::Null)
		}
	}

	fn uncle(&self, id: UncleID) -> Result<Value, Error> {
		let client = take_weak!(self.client);
		let uncle: BlockHeader = match client.uncle(id) {
			Some(rlp) => decode(&rlp),
			None => { return Ok(Value::Null); }
		};
		let parent_difficulty = match client.block_total_difficulty(BlockID::Hash(uncle.parent_hash().clone())) {
			Some(difficulty) => difficulty,
			None => { return Ok(Value::Null); }
		};

		let block = Block {
			hash: Some(uncle.hash().into()),
			size: None,
			parent_hash: uncle.parent_hash().clone().into(),
			uncles_hash: uncle.uncles_hash().clone().into(),
			author: uncle.author().clone().into(),
			miner: uncle.author().clone().into(),
			state_root: uncle.state_root().clone().into(),
			transactions_root: uncle.transactions_root().clone().into(),
			number: Some(uncle.number().into()),
			gas_used: uncle.gas_used().clone().into(),
			gas_limit: uncle.gas_limit().clone().into(),
			logs_bloom: uncle.log_bloom().clone().into(),
			timestamp: uncle.timestamp().into(),
			difficulty: uncle.difficulty().clone().into(),
			total_difficulty: (uncle.difficulty().clone() + parent_difficulty).into(),
			receipts_root: uncle.receipts_root().clone().into(),
			extra_data: uncle.extra_data().clone().into(),
			seal_fields: uncle.seal().clone().into_iter().map(|f| decode(&f)).map(Bytes::new).collect(),
			uncles: vec![],
			transactions: BlockTransactions::Hashes(vec![]),
		};
		to_value(&block)
	}

	fn sign_call(&self, request: CRequest) -> Result<SignedTransaction, Error> {
		let (client, miner) = (take_weak!(self.client), take_weak!(self.miner));
		let from = request.from.unwrap_or(Address::zero());
		Ok(EthTransaction {
			nonce: request.nonce.unwrap_or_else(|| client.latest_nonce(&from)),
			action: request.to.map_or(Action::Create, Action::Call),
			gas: request.gas.unwrap_or(U256::from(50_000_000)),
			gas_price: request.gas_price.unwrap_or_else(|| default_gas_price(&*client, &*miner)),
			value: request.value.unwrap_or_else(U256::zero),
			data: request.data.map_or_else(Vec::new, |d| d.to_vec())
		}.fake_sign(from))
	}
}

pub fn pending_logs<M>(miner: &M, filter: &EthcoreFilter) -> Vec<Log> where M: MinerService {
	let receipts = miner.pending_receipts();

	let pending_logs = receipts.into_iter()
		.flat_map(|(hash, r)| r.logs.into_iter().map(|l| (hash.clone(), l)).collect::<Vec<(H256, LogEntry)>>())
		.collect::<Vec<(H256, LogEntry)>>();

	let result = pending_logs.into_iter()
		.filter(|pair| filter.matches(&pair.1))
		.map(|pair| {
			let mut log = Log::from(pair.1);
			log.transaction_hash = Some(pair.0.into());
			log
		})
		.collect();

	result
}

const MAX_QUEUE_SIZE_TO_MINE_ON: usize = 4;	// because uncles go back 6.

impl<C, S: ?Sized, M, EM> EthClient<C, S, M, EM> where
	C: MiningBlockChainClient + 'static,
	S: SyncProvider + 'static,
	M: MinerService + 'static,
	EM: ExternalMinerService + 'static {

	fn active(&self) -> Result<(), Error> {
		// TODO: only call every 30s at most.
		take_weak!(self.client).keep_alive();
		Ok(())
	}
}

#[cfg(windows)]
static SOLC: &'static str = "solc.exe";

#[cfg(not(windows))]
static SOLC: &'static str = "solc";

impl<C, S: ?Sized, M, EM> Eth for EthClient<C, S, M, EM> where
	C: MiningBlockChainClient + 'static,
	S: SyncProvider + 'static,
	M: MinerService + 'static,
	EM: ExternalMinerService + 'static {

	fn protocol_version(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		Ok(Value::String(format!("{}", take_weak!(self.sync).status().protocol_version).to_owned()))
	}

	fn syncing(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		let status = take_weak!(self.sync).status();
		let res = match status.state {
			SyncState::Idle => SyncStatus::None,
			SyncState::Waiting | SyncState::Blocks | SyncState::NewBlocks | SyncState::ChainHead => {
				let current_block = U256::from(take_weak!(self.client).chain_info().best_block_number);
				let highest_block = U256::from(status.highest_block_number.unwrap_or(status.start_block_number));

				if highest_block > current_block + U256::from(6) {
					let info = SyncInfo {
						starting_block: status.start_block_number.into(),
						current_block: current_block.into(),
						highest_block: highest_block.into(),
					};
					SyncStatus::Info(info)
				} else {
					SyncStatus::None
				}
			}
		};
		to_value(&res)
	}

	fn author(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		to_value(&RpcH160::from(take_weak!(self.miner).author()))
	}

	fn is_mining(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		to_value(&(take_weak!(self.miner).is_sealing()))
	}

	fn hashrate(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		to_value(&RpcU256::from(self.external_miner.hashrate()))
	}

	fn gas_price(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		let (client, miner) = (take_weak!(self.client), take_weak!(self.miner));
		to_value(&RpcU256::from(default_gas_price(&*client, &*miner)))
	}

	fn accounts(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		let store = take_weak!(self.accounts);
		let accounts = try!(store.accounts().map_err(|e| errors::internal("Could not fetch accounts.", e)));
		to_value(&accounts.into_iter().map(Into::into).collect::<Vec<RpcH160>>())
	}

	fn block_number(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		to_value(&RpcU256::from(take_weak!(self.client).chain_info().best_block_number))
	}

	fn balance(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_second(params)
			.and_then(|(address, block_number,)| {
				let address: Address = RpcH160::into(address);
				match block_number {
					BlockNumber::Pending => to_value(&RpcU256::from(take_weak!(self.miner).balance(&*take_weak!(self.client), &address))),
					id => match take_weak!(self.client).balance(&address, id.into()) {
						Some(balance) => to_value(&RpcU256::from(balance)),
						None => Err(errors::state_pruned()),
					}
				}
			})
	}

	fn storage_at(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_third::<RpcH160, RpcU256>(params)
			.and_then(|(address, position, block_number,)| {
				let address: Address = RpcH160::into(address);
				let position: U256 = RpcU256::into(position);
				match block_number {
					BlockNumber::Pending => to_value(&RpcU256::from(take_weak!(self.miner).storage_at(&*take_weak!(self.client), &address, &H256::from(position)))),
					id => match take_weak!(self.client).storage_at(&address, &H256::from(position), id.into()) {
						Some(s) => to_value(&RpcH256::from(s)),
						None => Err(errors::state_pruned()),
					}
				}
			})

	}

	fn transaction_count(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_second(params)
			.and_then(|(address, block_number,)| {
				let address: Address = RpcH160::into(address);
				match block_number {
					BlockNumber::Pending => to_value(&RpcU256::from(take_weak!(self.miner).nonce(&*take_weak!(self.client), &address))),
					id => match take_weak!(self.client).nonce(&address, id.into()) {
						Some(nonce) => to_value(&RpcU256::from(nonce)),
						None => Err(errors::state_pruned()),
					}
				}
			})
	}

	fn block_transaction_count_by_hash(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256,)>(params)
			.and_then(|(hash,)| // match
				take_weak!(self.client).block(BlockID::Hash(hash.into()))
					.map_or(Ok(Value::Null), |bytes| to_value(&RpcU256::from(BlockView::new(&bytes).transactions_count()))))
	}

	fn block_transaction_count_by_number(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(BlockNumber,)>(params)
			.and_then(|(block_number,)| match block_number {
				BlockNumber::Pending => to_value(
					&RpcU256::from(take_weak!(self.miner).status().transactions_in_pending_block)
				),
				_ => take_weak!(self.client).block(block_number.into())
						.map_or(Ok(Value::Null), |bytes| to_value(&RpcU256::from(BlockView::new(&bytes).transactions_count())))
			})
	}

	fn block_uncles_count_by_hash(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256,)>(params)
			.and_then(|(hash,)|
				take_weak!(self.client).block(BlockID::Hash(hash.into()))
					.map_or(Ok(Value::Null), |bytes| to_value(&RpcU256::from(BlockView::new(&bytes).uncles_count()))))
	}

	fn block_uncles_count_by_number(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(BlockNumber,)>(params)
			.and_then(|(block_number,)| match block_number {
				BlockNumber::Pending => to_value(&RpcU256::from(0)),
				_ => take_weak!(self.client).block(block_number.into())
						.map_or(Ok(Value::Null), |bytes| to_value(&RpcU256::from(BlockView::new(&bytes).uncles_count())))
			})
	}

	fn code_at(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_second(params)
			.and_then(|(address, block_number,)| {
				let address: Address = RpcH160::into(address);
				match block_number {
					BlockNumber::Pending => to_value(&take_weak!(self.miner).code(&*take_weak!(self.client), &address).map_or_else(Bytes::default, Bytes::new)),
					_ => match take_weak!(self.client).code(&address, block_number.into()) {
						Some(code) => to_value(&code.map_or_else(Bytes::default, Bytes::new)),
						None => Err(errors::state_pruned()),
					},
				}
			})
	}

	fn block_by_hash(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256, bool)>(params)
			.and_then(|(hash, include_txs)| self.block(BlockID::Hash(hash.into()), include_txs))
	}

	fn block_by_number(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(BlockNumber, bool)>(params)
			.and_then(|(number, include_txs)| self.block(number.into(), include_txs))
	}

	fn transaction_by_hash(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256,)>(params)
			.and_then(|(hash,)| {
				let miner = take_weak!(self.miner);
				let hash: H256 = hash.into();
				match miner.transaction(&hash) {
					Some(pending_tx) => to_value(&Transaction::from(pending_tx)),
					None => self.transaction(TransactionID::Hash(hash))
				}
			})
	}

	fn transaction_by_block_hash_and_index(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256, Index)>(params)
			.and_then(|(hash, index)| self.transaction(TransactionID::Location(BlockID::Hash(hash.into()), index.value())))
	}

	fn transaction_by_block_number_and_index(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(BlockNumber, Index)>(params)
			.and_then(|(number, index)| self.transaction(TransactionID::Location(number.into(), index.value())))
	}

	fn transaction_receipt(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256,)>(params)
			.and_then(|(hash,)| {
				let miner = take_weak!(self.miner);
				let hash: H256 = hash.into();
				match (miner.pending_receipt(&hash), self.options.allow_pending_receipt_query) {
					(Some(receipt), true) => to_value(&Receipt::from(receipt)),
					_ => {
						let client = take_weak!(self.client);
						let receipt = client.transaction_receipt(TransactionID::Hash(hash));
						to_value(&receipt.map(Receipt::from))
					}
				}
			})
	}

	fn uncle_by_block_hash_and_index(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH256, Index)>(params)
			.and_then(|(hash, index)| self.uncle(UncleID { block: BlockID::Hash(hash.into()), position: index.value() }))
	}

	fn uncle_by_block_number_and_index(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(BlockNumber, Index)>(params)
			.and_then(|(number, index)| self.uncle(UncleID { block: number.into(), position: index.value() }))
	}

	fn compilers(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		try!(expect_no_params(params));

		let mut compilers = vec![];
		if Command::new(SOLC).output().is_ok() {
			compilers.push("solidity".to_owned())
		}
		to_value(&compilers)
	}

	fn logs(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(Filter,)>(params)
			.and_then(|(filter,)| {
				let include_pending = filter.to_block == Some(BlockNumber::Pending);
				let filter: EthcoreFilter = filter.into();
				let mut logs = take_weak!(self.client).logs(filter.clone())
					.into_iter()
					.map(From::from)
					.collect::<Vec<Log>>();

				if include_pending {
					let pending = pending_logs(&*take_weak!(self.miner), &filter);
					logs.extend(pending);
				}

				to_value(&logs)
			})
	}

	fn work(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		let (no_new_work_timeout,) = from_params::<(u64,)>(params).unwrap_or((0,));

		let client = take_weak!(self.client);
		// check if we're still syncing and return empty strings in that case
		{
			//TODO: check if initial sync is complete here
			//let sync = take_weak!(self.sync);
			if /*sync.status().state != SyncState::Idle ||*/ client.queue_info().total_queue_size() > MAX_QUEUE_SIZE_TO_MINE_ON {
				trace!(target: "miner", "Syncing. Cannot give any work.");
				return Err(errors::no_work());
			}

			// Otherwise spin until our submitted block has been included.
			let timeout = Instant::now() + Duration::from_millis(1000);
			while Instant::now() < timeout && client.queue_info().total_queue_size() > 0 {
				thread::sleep(Duration::from_millis(1));
			}
		}

		let miner = take_weak!(self.miner);
		if miner.author().is_zero() {
			warn!(target: "miner", "Cannot give work package - no author is configured. Use --author to configure!");
			return Err(errors::no_author())
		}
		miner.map_sealing_work(&*client, |b| {
			let pow_hash = b.hash();
			let target = Ethash::difficulty_to_boundary(b.block().header().difficulty());
			let seed_hash = self.seed_compute.lock().get_seedhash(b.block().header().number());

			if no_new_work_timeout > 0 && b.block().header().timestamp() + no_new_work_timeout < get_time().sec as u64 {
				Err(errors::no_new_work())
			} else if self.options.send_block_number_in_get_work {
				let block_number = RpcU256::from(b.block().header().number());
				to_value(&(RpcH256::from(pow_hash), RpcH256::from(seed_hash), RpcH256::from(target), block_number))
			} else {
				to_value(&(RpcH256::from(pow_hash), RpcH256::from(seed_hash), RpcH256::from(target)))
			}
		}).unwrap_or(Err(Error::internal_error()))	// no work found.
	}

	fn submit_work(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcH64, RpcH256, RpcH256)>(params).and_then(|(nonce, pow_hash, mix_hash)| {
			let nonce: H64 = nonce.into();
			let pow_hash: H256 = pow_hash.into();
			let mix_hash: H256 = mix_hash.into();
			trace!(target: "miner", "submit_work: Decoded: nonce={}, pow_hash={}, mix_hash={}", nonce, pow_hash, mix_hash);
			let miner = take_weak!(self.miner);
			let client = take_weak!(self.client);
			let seal = vec![encode(&mix_hash).to_vec(), encode(&nonce).to_vec()];
			let r = miner.submit_seal(&*client, pow_hash, seal);
			to_value(&r.is_ok())
		})
	}

	fn submit_hashrate(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(RpcU256, RpcH256)>(params).and_then(|(rate, id)| {
			self.external_miner.submit_hashrate(rate.into(), id.into());
			to_value(&true)
		})
	}

	fn send_raw_transaction(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(Bytes, )>(params)
			.and_then(|(raw_transaction, )| {
				let raw_transaction = raw_transaction.to_vec();
				match UntrustedRlp::new(&raw_transaction).as_val() {
					Ok(signed_transaction) => dispatch_transaction(&*take_weak!(self.client), &*take_weak!(self.miner), signed_transaction),
					Err(_) => to_value(&RpcH256::from(H256::from(0))),
				}
		})
	}

	fn call(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_second(params)
			.and_then(|(request, block_number,)| {
				let request = CallRequest::into(request);
				let signed = try!(self.sign_call(request));
				let r = match block_number {
					BlockNumber::Pending => take_weak!(self.miner).call(&*take_weak!(self.client), &signed, Default::default()),
					block_number => take_weak!(self.client).call(&signed, block_number.into(), Default::default()),
				};
				to_value(&r.map(|e| Bytes(e.output)).unwrap_or(Bytes::new(vec![])))
			})
	}

	fn estimate_gas(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params_default_second(params)
			.and_then(|(request, block_number,)| {
				let request = CallRequest::into(request);
				let signed = try!(self.sign_call(request));
				let r = match block_number {
					BlockNumber::Pending => take_weak!(self.miner).call(&*take_weak!(self.client), &signed, Default::default()),
					block => take_weak!(self.client).call(&signed, block.into(), Default::default()),
				};
				to_value(&RpcU256::from(r.map(|res| res.gas_used + res.refunded).unwrap_or(From::from(0))))
			})
	}

	fn compile_lll(&self, _: Params) -> Result<Value, Error> {
		try!(self.active());
		rpc_unimplemented!()
	}

	fn compile_serpent(&self, _: Params) -> Result<Value, Error> {
		try!(self.active());
		rpc_unimplemented!()
	}

	fn compile_solidity(&self, params: Params) -> Result<Value, Error> {
		try!(self.active());
		from_params::<(String, )>(params)
			.and_then(|(code, )| {
				let maybe_child = Command::new(SOLC)
					.arg("--bin")
					.arg("--optimize")
					.stdin(Stdio::piped())
					.stdout(Stdio::piped())
					.stderr(Stdio::null())
					.spawn();

				maybe_child
					.map_err(errors::compilation)
					.and_then(|mut child| {
						try!(child.stdin.as_mut()
							.expect("we called child.stdin(Stdio::piped()) before spawn; qed")
							.write_all(code.as_bytes())
							.map_err(errors::compilation));
						let output = try!(child.wait_with_output().map_err(errors::compilation));

						let s = String::from_utf8_lossy(&output.stdout);
						if let Some(hex) = s.lines().skip_while(|ref l| !l.contains("Binary")).skip(1).next() {
							to_value(&Bytes::new(hex.from_hex().unwrap_or(vec![])))
						} else {
							Err(errors::compilation("Unexpected output."))
						}
					})
			})
	}
}