// 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/>.

//! Test client.

use std::str::FromStr;
use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering as AtomicOrder};
use std::sync::Arc;
use std::collections::{HashMap, BTreeMap};
use std::mem;

use blockchain::{TreeRoute, BlockReceipts};
use bytes::Bytes;
use db::{NUM_COLUMNS, COL_STATE};
use ethcore_miner::pool::VerifiedTransaction;
use ethereum_types::{H256, U256, Address};
use ethkey::{Generator, Random};
use ethtrie;
use hash::keccak;
use itertools::Itertools;
use kvdb::DBValue;
use kvdb_memorydb;
use parking_lot::RwLock;
use rlp::{Rlp, RlpStream};
use rustc_hex::FromHex;
use types::transaction::{self, Transaction, LocalizedTransaction, SignedTransaction, Action};
use types::BlockNumber;
use types::basic_account::BasicAccount;
use types::encoded;
use types::filter::Filter;
use types::header::Header;
use types::log_entry::LocalizedLogEntry;
use types::pruning_info::PruningInfo;
use types::receipt::{Receipt, LocalizedReceipt, TransactionOutcome};
use types::view;
use types::views::BlockView;
use vm::Schedule;

use block::{OpenBlock, SealedBlock, ClosedBlock};
use call_contract::{CallContract, RegistryInfo};
use client::{
	Nonce, Balance, ChainInfo, BlockInfo, ReopenBlock, TransactionInfo,
	PrepareOpenBlock, BlockChainClient, BlockChainInfo, BlockStatus, BlockId, Mode,
	TransactionId, UncleId, TraceId, TraceFilter, LastHashes, CallAnalytics,
	ProvingBlockChainClient, ScheduleInfo, ImportSealedBlock, BroadcastProposalBlock, ImportBlock, StateOrBlock,
	Call, StateClient, EngineInfo, AccountData, BlockChain, BlockProducer, SealedBlockImporter, IoClient,
	BadBlocks
};
use engines::Engine;
use error::{Error, EthcoreResult};
use executed::CallError;
use executive::Executed;
use journaldb;
use miner::{self, Miner, MinerService};
use spec::Spec;
use state::StateInfo;
use state_db::StateDB;
use trace::LocalizedTrace;
use verification::queue::QueueInfo as BlockQueueInfo;
use verification::queue::kind::blocks::Unverified;

/// Test client.
pub struct TestBlockChainClient {
	/// Blocks.
	pub blocks: RwLock<HashMap<H256, Bytes>>,
	/// Mapping of numbers to hashes.
	pub numbers: RwLock<HashMap<usize, H256>>,
	/// Genesis block hash.
	pub genesis_hash: H256,
	/// Last block hash.
	pub last_hash: RwLock<H256>,
	/// Extra data do set for each block
	pub extra_data: Bytes,
	/// Difficulty.
	pub difficulty: RwLock<U256>,
	/// Balances.
	pub balances: RwLock<HashMap<Address, U256>>,
	/// Nonces.
	pub nonces: RwLock<HashMap<Address, U256>>,
	/// Storage.
	pub storage: RwLock<HashMap<(Address, H256), H256>>,
	/// Code.
	pub code: RwLock<HashMap<Address, Bytes>>,
	/// Execution result.
	pub execution_result: RwLock<Option<Result<Executed, CallError>>>,
	/// Transaction receipts.
	pub receipts: RwLock<HashMap<TransactionId, LocalizedReceipt>>,
	/// Logs
	pub logs: RwLock<Vec<LocalizedLogEntry>>,
	/// Should return errors on logs.
	pub error_on_logs: RwLock<Option<BlockId>>,
	/// Block queue size.
	pub queue_size: AtomicUsize,
	/// Miner
	pub miner: Arc<Miner>,
	/// Spec
	pub spec: Spec,
	/// Timestamp assigned to latest sealed block
	pub latest_block_timestamp: RwLock<u64>,
	/// Ancient block info.
	pub ancient_block: RwLock<Option<(H256, u64)>>,
	/// First block info.
	pub first_block: RwLock<Option<(H256, u64)>>,
	/// Traces to return
	pub traces: RwLock<Option<Vec<LocalizedTrace>>>,
	/// Pruning history size to report.
	pub history: RwLock<Option<u64>>,
	/// Is disabled
	pub disabled: AtomicBool,
}

/// Used for generating test client blocks.
#[derive(Clone, Copy)]
pub enum EachBlockWith {
	/// Plain block.
	Nothing,
	/// Block with an uncle.
	Uncle,
	/// Block with a transaction.
	Transaction,
	/// Block with multiple transactions.
	Transactions(usize),
	/// Block with an uncle and transaction.
	UncleAndTransaction
}

impl Default for TestBlockChainClient {
	fn default() -> Self {
		TestBlockChainClient::new()
	}
}

impl TestBlockChainClient {
	/// Creates new test client.
	pub fn new() -> Self {
		Self::new_with_extra_data(Bytes::new())
	}

	/// Creates new test client with specified extra data for each block
	pub fn new_with_extra_data(extra_data: Bytes) -> Self {
		let spec = Spec::new_test();
		TestBlockChainClient::new_with_spec_and_extra(spec, extra_data)
	}

	/// Create test client with custom spec.
	pub fn new_with_spec(spec: Spec) -> Self {
		TestBlockChainClient::new_with_spec_and_extra(spec, Bytes::new())
	}

	/// Create test client with custom spec and extra data.
	pub fn new_with_spec_and_extra(spec: Spec, extra_data: Bytes) -> Self {
		let genesis_block = spec.genesis_block();
		let genesis_hash = spec.genesis_header().hash();

		let mut client = TestBlockChainClient {
			blocks: RwLock::new(HashMap::new()),
			numbers: RwLock::new(HashMap::new()),
			genesis_hash: H256::zero(),
			extra_data: extra_data,
			last_hash: RwLock::new(H256::zero()),
			difficulty: RwLock::new(spec.genesis_header().difficulty().clone()),
			balances: RwLock::new(HashMap::new()),
			nonces: RwLock::new(HashMap::new()),
			storage: RwLock::new(HashMap::new()),
			code: RwLock::new(HashMap::new()),
			execution_result: RwLock::new(None),
			receipts: RwLock::new(HashMap::new()),
			logs: RwLock::new(Vec::new()),
			queue_size: AtomicUsize::new(0),
			miner: Arc::new(Miner::new_for_tests(&spec, None)),
			spec: spec,
			latest_block_timestamp: RwLock::new(10_000_000),
			ancient_block: RwLock::new(None),
			first_block: RwLock::new(None),
			traces: RwLock::new(None),
			history: RwLock::new(None),
			disabled: AtomicBool::new(false),
			error_on_logs: RwLock::new(None),
		};

		// insert genesis hash.
		client.blocks.get_mut().insert(genesis_hash, genesis_block);
		client.numbers.get_mut().insert(0, genesis_hash);
		*client.last_hash.get_mut() = genesis_hash;
		client.genesis_hash = genesis_hash;
		client
	}

	/// Set the transaction receipt result
	pub fn set_transaction_receipt(&self, id: TransactionId, receipt: LocalizedReceipt) {
		self.receipts.write().insert(id, receipt);
	}

	/// Set the execution result.
	pub fn set_execution_result(&self, result: Result<Executed, CallError>) {
		*self.execution_result.write() = Some(result);
	}

	/// Set the balance of account `address` to `balance`.
	pub fn set_balance(&self, address: Address, balance: U256) {
		self.balances.write().insert(address, balance);
	}

	/// Set nonce of account `address` to `nonce`.
	pub fn set_nonce(&self, address: Address, nonce: U256) {
		self.nonces.write().insert(address, nonce);
	}

	/// Set `code` at `address`.
	pub fn set_code(&self, address: Address, code: Bytes) {
		self.code.write().insert(address, code);
	}

	/// Set storage `position` to `value` for account `address`.
	pub fn set_storage(&self, address: Address, position: H256, value: H256) {
		self.storage.write().insert((address, position), value);
	}

	/// Set block queue size for testing
	pub fn set_queue_size(&self, size: usize) {
		self.queue_size.store(size, AtomicOrder::Relaxed);
	}

	/// Set timestamp assigned to latest sealed block
	pub fn set_latest_block_timestamp(&self, ts: u64) {
		*self.latest_block_timestamp.write() = ts;
	}

	/// Set logs to return for each logs call.
	pub fn set_logs(&self, logs: Vec<LocalizedLogEntry>) {
		*self.logs.write() = logs;
	}

	/// Set return errors on logs.
	pub fn set_error_on_logs(&self, val: Option<BlockId>) {
		*self.error_on_logs.write() = val;
	}

	/// Add a block to test client.
	pub fn add_block<F>(&self, with: EachBlockWith, hook: F)
		where F: Fn(Header) -> Header
	{
		let n = self.numbers.read().len();

		let mut header = Header::new();
		header.set_difficulty(From::from(n));
		header.set_parent_hash(self.last_hash.read().clone());
		header.set_number(n as BlockNumber);
		header.set_gas_limit(U256::from(1_000_000));
		header.set_extra_data(self.extra_data.clone());

		header = hook(header);

		let uncles = match with {
			EachBlockWith::Uncle | EachBlockWith::UncleAndTransaction => {
				let mut uncles = RlpStream::new_list(1);
				let mut uncle_header = Header::new();
				uncle_header.set_difficulty(From::from(n));
				uncle_header.set_parent_hash(self.last_hash.read().clone());
				uncle_header.set_number(n as BlockNumber);
				uncles.append(&uncle_header);
				header.set_uncles_hash(keccak(uncles.as_raw()));
				uncles
			},
			_ => RlpStream::new_list(0)
		};
		let txs = match with {
			EachBlockWith::Transaction | EachBlockWith::UncleAndTransaction | EachBlockWith::Transactions(_) => {
				let num_transactions = match with {
					EachBlockWith::Transactions(num) => num,
					_ => 1,
				};
				let mut txs = RlpStream::new_list(num_transactions);
				let keypair = Random.generate().unwrap();
				let mut nonce = U256::zero();

				for _ in 0..num_transactions {
					// Update nonces value
					let tx = Transaction {
						action: Action::Create,
						value: U256::from(100),
						data: "3331600055".from_hex().unwrap(),
						gas: U256::from(100_000),
						gas_price: U256::from(200_000_000_000u64),
						nonce: nonce
					};
					let signed_tx = tx.sign(keypair.secret(), None);
					txs.append(&signed_tx);
					nonce += U256::one();
				}

				self.nonces.write().insert(keypair.address(), nonce);
				txs.out()
			},
			_ => ::rlp::EMPTY_LIST_RLP.to_vec()
		};

		let mut rlp = RlpStream::new_list(3);
		rlp.append(&header);
		rlp.append_raw(&txs, 1);
		rlp.append_raw(uncles.as_raw(), 1);
		let unverified = Unverified::from_rlp(rlp.out()).unwrap();
		self.import_block(unverified).unwrap();
	}

	/// Add a sequence of blocks to test client.
	pub fn add_blocks(&self, count: usize, with: EachBlockWith) {
		for _ in 0..count {
			self.add_block(with, |header| header);
		}
	}

	/// Make a bad block by setting invalid parent hash.
	pub fn corrupt_block_parent(&self, n: BlockNumber) {
		let hash = self.block_hash(BlockId::Number(n)).unwrap();
		let mut header: Header = self.block_header(BlockId::Number(n)).unwrap().decode().expect("decoding failed");
		header.set_parent_hash(H256::from_low_u64_be(42));
		let mut rlp = RlpStream::new_list(3);
		rlp.append(&header);
		rlp.append_raw(&::rlp::NULL_RLP, 1);
		rlp.append_raw(&::rlp::NULL_RLP, 1);
		self.blocks.write().insert(hash, rlp.out());
	}

	/// Get block hash with `delta` as offset from the most recent blocks.
	pub fn block_hash_delta_minus(&mut self, delta: usize) -> H256 {
		let blocks_read = self.numbers.read();
		let index = blocks_read.len() - delta;
		blocks_read[&index].clone()
	}

	fn block_hash(&self, id: BlockId) -> Option<H256> {
		match id {
			BlockId::Hash(hash) => Some(hash),
			BlockId::Number(n) => self.numbers.read().get(&(n as usize)).cloned(),
			BlockId::Earliest => self.numbers.read().get(&0).cloned(),
			BlockId::Latest => self.numbers.read().get(&(self.numbers.read().len() - 1)).cloned()
		}
	}

	/// Inserts a transaction with given gas price to miners transactions queue.
	pub fn insert_transaction_with_gas_price_to_queue(&self, gas_price: U256) -> H256 {
		let keypair = Random.generate().unwrap();
		let tx = Transaction {
			action: Action::Create,
			value: U256::from(100),
			data: "3331600055".from_hex().unwrap(),
			gas: U256::from(100_000),
			gas_price: gas_price,
			nonce: U256::zero()
		};
		let signed_tx = tx.sign(keypair.secret(), None);
		self.set_balance(signed_tx.sender(), 10_000_000_000_000_000_000u64.into());
		let hash = signed_tx.hash();
		let res = self.miner.import_external_transactions(self, vec![signed_tx.into()]);
		let res = res.into_iter().next().unwrap();
		assert!(res.is_ok());
		hash
	}

	/// Inserts a transaction to miners transactions queue.
	pub fn insert_transaction_to_queue(&self) -> H256 {
		self.insert_transaction_with_gas_price_to_queue(U256::from(20_000_000_000u64))
	}

	/// Set reported history size.
	pub fn set_history(&self, h: Option<u64>) {
		*self.history.write() = h;
	}

	/// Returns true if the client has been disabled.
	pub fn is_disabled(&self) -> bool {
		self.disabled.load(AtomicOrder::Relaxed)
	}
}

pub fn get_temp_state_db() -> StateDB {
	let db = kvdb_memorydb::create(NUM_COLUMNS.unwrap_or(0));
	let journal_db = journaldb::new(Arc::new(db), journaldb::Algorithm::EarlyMerge, COL_STATE);
	StateDB::new(journal_db, 1024 * 1024)
}

impl ReopenBlock for TestBlockChainClient {
	fn reopen_block(&self, block: ClosedBlock) -> OpenBlock {
		block.reopen(&*self.spec.engine)
	}
}

impl PrepareOpenBlock for TestBlockChainClient {
	fn prepare_open_block(&self, author: Address, gas_range_target: (U256, U256), extra_data: Bytes) -> Result<OpenBlock, Error> {
		let engine = &*self.spec.engine;
		let genesis_header = self.spec.genesis_header();
		let db = self.spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();

		let last_hashes = vec![genesis_header.hash()];
		let mut open_block = OpenBlock::new(
			engine,
			Default::default(),
			false,
			db,
			&genesis_header,
			Arc::new(last_hashes),
			author,
			gas_range_target,
			extra_data,
			false,
			None,
		)?;
		// TODO [todr] Override timestamp for predictability
		open_block.set_timestamp(*self.latest_block_timestamp.read());
		Ok(open_block)
	}
}

impl ScheduleInfo for TestBlockChainClient {
	fn latest_schedule(&self) -> Schedule {
		Schedule::new_post_eip150(24576, true, true, true)
	}
}

impl ImportSealedBlock for TestBlockChainClient {
	fn import_sealed_block(&self, _block: SealedBlock) -> EthcoreResult<H256> {
		Ok(H256::zero())
	}
}

impl BlockProducer for TestBlockChainClient {}

impl BroadcastProposalBlock for TestBlockChainClient {
	fn broadcast_proposal_block(&self, _block: SealedBlock) {}
}

impl SealedBlockImporter for TestBlockChainClient {}

impl ::miner::TransactionVerifierClient for TestBlockChainClient {}
impl ::miner::BlockChainClient for TestBlockChainClient {}

impl Nonce for TestBlockChainClient {
	fn nonce(&self, address: &Address, id: BlockId) -> Option<U256> {
		match id {
			BlockId::Latest => Some(self.nonces.read().get(address).cloned().unwrap_or(self.spec.params().account_start_nonce)),
			_ => None,
		}
	}

	fn latest_nonce(&self, address: &Address) -> U256 {
		self.nonce(address, BlockId::Latest).unwrap()
	}
}

impl Balance for TestBlockChainClient {
	fn balance(&self, address: &Address, state: StateOrBlock) -> Option<U256> {
		match state {
			StateOrBlock::Block(BlockId::Latest) | StateOrBlock::State(_) => Some(self.balances.read().get(address).cloned().unwrap_or_else(U256::zero)),
			_ => None,
		}
	}

	fn latest_balance(&self, address: &Address) -> U256 {
		self.balance(address, BlockId::Latest.into()).unwrap()
	}
}

impl AccountData for TestBlockChainClient {}

impl ChainInfo for TestBlockChainClient {
	fn chain_info(&self) -> BlockChainInfo {
		let number = self.blocks.read().len() as BlockNumber - 1;
		BlockChainInfo {
			total_difficulty: *self.difficulty.read(),
			pending_total_difficulty: *self.difficulty.read(),
			genesis_hash: self.genesis_hash.clone(),
			best_block_hash: self.last_hash.read().clone(),
			best_block_number: number,
			best_block_timestamp: number,
			first_block_hash: self.first_block.read().as_ref().map(|x| x.0),
			first_block_number: self.first_block.read().as_ref().map(|x| x.1),
			ancient_block_hash: self.ancient_block.read().as_ref().map(|x| x.0),
			ancient_block_number: self.ancient_block.read().as_ref().map(|x| x.1)
		}
	}
}

impl BlockInfo for TestBlockChainClient {
	fn block_header(&self, id: BlockId) -> Option<encoded::Header> {
		self.block_hash(id)
			.and_then(|hash| self.blocks.read().get(&hash).map(|r| view!(BlockView, r).header_rlp().as_raw().to_vec()))
			.map(encoded::Header::new)
	}

	fn best_block_header(&self) -> Header {
		self.block_header(BlockId::Hash(self.chain_info().best_block_hash))
			.expect("Best block always has header.")
			.decode()
			.expect("decoding failed")
	}

	fn block(&self, id: BlockId) -> Option<encoded::Block> {
		self.block_hash(id)
			.and_then(|hash| self.blocks.read().get(&hash).cloned())
			.map(encoded::Block::new)
	}

	fn code_hash(&self, address: &Address, id: BlockId) -> Option<H256> {
		match id {
			BlockId::Latest => self.code.read().get(address).map(|c| keccak(&c)),
			_ => None,
		}
	}
}

impl CallContract for TestBlockChainClient {
	fn call_contract(&self, _id: BlockId, _address: Address, _data: Bytes) -> Result<Bytes, String> { Ok(vec![]) }
}

impl TransactionInfo for TestBlockChainClient {
	fn transaction_block(&self, _id: TransactionId) -> Option<H256> {
		None	// Simple default.
	}
}

impl BlockChain for TestBlockChainClient {}

impl RegistryInfo for TestBlockChainClient {
	fn registry_address(&self, _name: String, _block: BlockId) -> Option<Address> { None }
}

impl ImportBlock for TestBlockChainClient {
	fn import_block(&self, unverified: Unverified) -> EthcoreResult<H256> {
		let header = unverified.header;
		let h = header.hash();
		let number: usize = header.number() as usize;
		if number > self.blocks.read().len() {
			panic!("Unexpected block number. Expected {}, got {}", self.blocks.read().len(), number);
		}
		if number > 0 {
			match self.blocks.read().get(header.parent_hash()) {
				Some(parent) => {
					let parent = view!(BlockView, parent).header();
					if parent.number() != (header.number() - 1) {
						panic!("Unexpected block parent");
					}
				},
				None => {
					panic!("Unknown block parent {:?} for block {}", header.parent_hash(), number);
				}
			}
		}
		let len = self.numbers.read().len();
		if number == len {
			{
				let mut difficulty = self.difficulty.write();
				*difficulty = *difficulty + header.difficulty().clone();
			}
			mem::replace(&mut *self.last_hash.write(), h.clone());
			self.blocks.write().insert(h.clone(), unverified.bytes);
			self.numbers.write().insert(number, h.clone());
			let mut parent_hash = header.parent_hash().clone();
			if number > 0 {
				let mut n = number - 1;
				while n > 0 && self.numbers.read()[&n] != parent_hash {
					*self.numbers.write().get_mut(&n).unwrap() = parent_hash.clone();
					n -= 1;
					parent_hash = view!(BlockView, &self.blocks.read()[&parent_hash]).header().parent_hash().clone();
				}
			}
		}
		else {
			self.blocks.write().insert(h.clone(), unverified.bytes);
		}
		Ok(h)
	}
}

impl Call for TestBlockChainClient {
	// State will not be used by test client anyway, since all methods that accept state are mocked
	type State = ();

	fn call(&self, _t: &SignedTransaction, _analytics: CallAnalytics, _state: &mut Self::State, _header: &Header) -> Result<Executed, CallError> {
		self.execution_result.read().clone().unwrap()
	}

	fn call_many(&self, txs: &[(SignedTransaction, CallAnalytics)], state: &mut Self::State, header: &Header) -> Result<Vec<Executed>, CallError> {
		let mut res = Vec::with_capacity(txs.len());
		for &(ref tx, analytics) in txs {
			res.push(self.call(tx, analytics, state, header)?);
		}
		Ok(res)
	}

	fn estimate_gas(&self, _t: &SignedTransaction, _state: &Self::State, _header: &Header) -> Result<U256, CallError> {
		Ok(21000.into())
	}
}

impl StateInfo for () {
	fn nonce(&self, _address: &Address) -> ethtrie::Result<U256> { unimplemented!() }
	fn balance(&self, _address: &Address) -> ethtrie::Result<U256> { unimplemented!() }
	fn storage_at(&self, _address: &Address, _key: &H256) -> ethtrie::Result<H256> { unimplemented!() }
	fn code(&self, _address: &Address) -> ethtrie::Result<Option<Arc<Bytes>>> { unimplemented!() }
}

impl StateClient for TestBlockChainClient {
	// State will not be used by test client anyway, since all methods that accept state are mocked
	type State = ();

	fn latest_state(&self) -> Self::State {
		()
	}

	fn state_at(&self, _id: BlockId) -> Option<Self::State> {
		Some(())
	}
}

impl EngineInfo for TestBlockChainClient {
	fn engine(&self) -> &dyn Engine {
		unimplemented!()
	}
}

impl BadBlocks for TestBlockChainClient {
	fn bad_blocks(&self) -> Vec<(Unverified, String)> {
		vec![
			(Unverified {
				header: Default::default(),
				transactions: vec![],
				uncles: vec![],
				bytes: vec![1, 2, 3],
			}, "Invalid block".into())
		]
	}
}

impl BlockChainClient for TestBlockChainClient {
	fn replay(&self, _id: TransactionId, _analytics: CallAnalytics) -> Result<Executed, CallError> {
		self.execution_result.read().clone().unwrap()
	}

	fn queue_info(&self) -> BlockQueueInfo {
		BlockQueueInfo {
			verified_queue_size: self.queue_size.load(AtomicOrder::Relaxed),
			unverified_queue_size: 0,
			verifying_queue_size: 0,
			max_queue_size: 0,
			max_mem_use: 0,
			mem_used: 0,
		}
	}

	fn replay_block_transactions(&self, _block: BlockId, _analytics: CallAnalytics) -> Result<Box<dyn Iterator<Item = (H256, Executed)>>, CallError> {
		Ok(Box::new(
			self.traces
				.read()
				.clone()
				.unwrap()
				.into_iter()
				.map(|t| t.transaction_hash.unwrap_or_default())
				.zip(self.execution_result.read().clone().unwrap().into_iter())
		))
	}

	fn block_total_difficulty(&self, _id: BlockId) -> Option<U256> {
		Some(U256::zero())
	}

	fn block_hash(&self, id: BlockId) -> Option<H256> {
		Self::block_hash(self, id)
	}

	fn storage_root(&self, _address: &Address, _id: BlockId) -> Option<H256> {
		None
	}

	fn code(&self, address: &Address, state: StateOrBlock) -> Option<Option<Bytes>> {
		match state {
			StateOrBlock::Block(BlockId::Latest) => Some(self.code.read().get(address).cloned()),
			_ => None,
		}
	}

	fn storage_at(&self, address: &Address, position: &H256, state: StateOrBlock) -> Option<H256> {
		match state {
			StateOrBlock::Block(BlockId::Latest) =>
				Some(self.storage.read().get(&(address.clone(), position.clone())).cloned().unwrap_or_default()),
			_ => None,
		}
	}

	fn list_accounts(&self, _id: BlockId, _after: Option<&Address>, _count: u64) -> Option<Vec<Address>> {
		None
	}

	fn list_storage(&self, _id: BlockId, _account: &Address, _after: Option<&H256>, _count: u64) -> Option<Vec<H256>> {
		None
	}
	fn transaction(&self, _id: TransactionId) -> Option<LocalizedTransaction> {
		None	// Simple default.
	}

	fn uncle(&self, _id: UncleId) -> Option<encoded::Header> {
		None	// Simple default.
	}

	fn uncle_extra_info(&self, _id: UncleId) -> Option<BTreeMap<String, String>> {
		None
	}

	fn transaction_receipt(&self, id: TransactionId) -> Option<LocalizedReceipt> {
		self.receipts.read().get(&id).cloned()
	}

	fn localized_block_receipts(&self, _id: BlockId) -> Option<Vec<LocalizedReceipt>> {
		Some(self.receipts.read().values().cloned().collect())
	}

	fn logs(&self, filter: Filter) -> Result<Vec<LocalizedLogEntry>, BlockId> {
		match self.error_on_logs.read().as_ref() {
			Some(id) => return Err(id.clone()),
			None => (),
		}

		let mut logs = self.logs.read().clone();
		let len = logs.len();
		Ok(match filter.limit {
			Some(limit) if limit <= len => logs.split_off(len - limit),
			_ => logs,
		})
	}

	fn last_hashes(&self) -> LastHashes {
		unimplemented!();
	}

	fn block_number(&self, id: BlockId) -> Option<BlockNumber> {
		match id {
			BlockId::Number(number) => Some(number),
			BlockId::Earliest => Some(0),
			BlockId::Latest => Some(self.chain_info().best_block_number),
			BlockId::Hash(ref h) =>
				self.numbers.read().iter().find(|&(_, hash)| hash == h).map(|e| *e.0 as u64)
		}
	}

	fn block_body(&self, id: BlockId) -> Option<encoded::Body> {
		self.block_hash(id).and_then(|hash| self.blocks.read().get(&hash).map(|r| {
			let block = view!(BlockView, r);
			let mut stream = RlpStream::new_list(2);
			stream.append_raw(block.transactions_rlp().as_raw(), 1);
			stream.append_raw(block.uncles_rlp().as_raw(), 1);
			encoded::Body::new(stream.out())
		}))
	}

	fn block_extra_info(&self, id: BlockId) -> Option<BTreeMap<String, String>> {
		self.block(id)
			.map(|block| block.view().header())
			.map(|header| self.spec.engine.extra_info(&header))
	}

	fn block_status(&self, id: BlockId) -> BlockStatus {
		match id {
			BlockId::Number(number) if (number as usize) < self.blocks.read().len() => BlockStatus::InChain,
			BlockId::Hash(ref hash) if self.blocks.read().get(hash).is_some() => BlockStatus::InChain,
			BlockId::Latest | BlockId::Earliest => BlockStatus::InChain,
			_ => BlockStatus::Unknown,
		}
	}

	// works only if blocks are one after another 1 -> 2 -> 3
	fn tree_route(&self, from: &H256, to: &H256) -> Option<TreeRoute> {
		Some(TreeRoute {
			ancestor: H256::zero(),
			index: 0,
			blocks: {
				let numbers_read = self.numbers.read();
				let mut adding = false;

				let mut blocks = Vec::new();
				for (_, hash) in numbers_read.iter().sorted_by(|tuple1, tuple2| tuple1.0.cmp(tuple2.0)) {
					if hash == to {
						if adding {
							blocks.push(hash.clone());
						}
						adding = false;
						break;
					}
					if hash == from {
						adding = true;
					}
					if adding {
						blocks.push(hash.clone());
					}
				}
				if adding { Vec::new() } else { blocks }
			},
			is_from_route_finalized: false,
		})
	}

	fn find_uncles(&self, _hash: &H256) -> Option<Vec<H256>> {
		None
	}

	// TODO: returns just hashes instead of node state rlp(?)
	fn state_data(&self, hash: &H256) -> Option<Bytes> {
		// starts with 'f' ?
		if *hash > H256::from_str("f000000000000000000000000000000000000000000000000000000000000000").unwrap() {
			let mut rlp = RlpStream::new();
			rlp.append(&hash.clone());
			return Some(rlp.out());
		}
		None
	}

	fn block_receipts(&self, hash: &H256) -> Option<BlockReceipts> {
		// starts with 'f' ?
		if *hash > H256::from_str("f000000000000000000000000000000000000000000000000000000000000000").unwrap() {
			let receipt = BlockReceipts::new(vec![Receipt::new(
				TransactionOutcome::StateRoot(H256::zero()),
				U256::zero(),
				vec![])]);
			return Some(receipt);
		}
		None
	}

	fn clear_queue(&self) {
	}

	fn filter_traces(&self, _filter: TraceFilter) -> Option<Vec<LocalizedTrace>> {
		self.traces.read().clone()
	}

	fn trace(&self, _trace: TraceId) -> Option<LocalizedTrace> {
		self.traces.read().clone().and_then(|vec| vec.into_iter().next())
	}

	fn transaction_traces(&self, _trace: TransactionId) -> Option<Vec<LocalizedTrace>> {
		self.traces.read().clone()
	}

	fn block_traces(&self, _trace: BlockId) -> Option<Vec<LocalizedTrace>> {
		self.traces.read().clone()
	}

	fn transactions_to_propagate(&self) -> Vec<Arc<VerifiedTransaction>> {
		self.miner.ready_transactions(self, 4096, miner::PendingOrdering::Priority)
	}

	fn signing_chain_id(&self) -> Option<u64> { None }

	fn mode(&self) -> Mode { Mode::Active }

	fn set_mode(&self, _: Mode) { unimplemented!(); }

	fn spec_name(&self) -> String { "foundation".into() }

	fn set_spec_name(&self, _: String) -> Result<(), ()> { unimplemented!(); }

	fn disable(&self) { self.disabled.store(true, AtomicOrder::Relaxed); }

	fn pruning_info(&self) -> PruningInfo {
		let best_num = self.chain_info().best_block_number;
		PruningInfo {
			earliest_chain: 1,
			earliest_state: self.history.read().as_ref().map(|x| best_num - x).unwrap_or(0),
		}
	}

	fn transact_contract(&self, address: Address, data: Bytes) -> Result<(), transaction::Error> {
		let transaction = Transaction {
			nonce: self.latest_nonce(&self.miner.authoring_params().author),
			action: Action::Call(address),
			gas: self.spec.gas_limit,
			gas_price: U256::zero(),
			value: U256::default(),
			data: data,
		};
		let chain_id = Some(self.spec.chain_id());
		let sig = self.spec.engine.sign(transaction.hash(chain_id)).unwrap();
		let signed = SignedTransaction::new(transaction.with_signature(sig, chain_id)).unwrap();
		self.miner.import_own_transaction(self, signed.into())
	}

	fn registrar_address(&self) -> Option<Address> { None }
}

impl IoClient for TestBlockChainClient {
	fn queue_transactions(&self, transactions: Vec<Bytes>, _peer_id: usize) {
		// import right here
		let txs = transactions.into_iter().filter_map(|bytes| Rlp::new(&bytes).as_val().ok()).collect();
		self.miner.import_external_transactions(self, txs);
	}

	fn queue_ancient_block(&self, unverified: Unverified, _r: Bytes) -> EthcoreResult<H256> {
		self.import_block(unverified)
	}

	fn queue_consensus_message(&self, message: Bytes) {
		self.spec.engine.handle_message(&message).unwrap();
	}
}

impl ProvingBlockChainClient for TestBlockChainClient {
	fn prove_storage(&self, _: H256, _: H256, _: BlockId) -> Option<(Vec<Bytes>, H256)> {
		None
	}

	fn prove_account(&self, _: H256, _: BlockId) -> Option<(Vec<Bytes>, BasicAccount)> {
		None
	}

	fn prove_transaction(&self, _: SignedTransaction, _: BlockId) -> Option<(Bytes, Vec<DBValue>)> {
		None
	}

	fn epoch_signal(&self, _: H256) -> Option<Vec<u8>> {
		None
	}
}

impl super::traits::EngineClient for TestBlockChainClient {
	fn update_sealing(&self) {
		self.miner.update_sealing(self)
	}

	fn submit_seal(&self, block_hash: H256, seal: Vec<Bytes>) {
		let import = self.miner.submit_seal(block_hash, seal).and_then(|block| self.import_sealed_block(block));
		if let Err(err) = import {
			warn!(target: "poa", "Wrong internal seal submission! {:?}", err);
		}
	}

	fn broadcast_consensus_message(&self, _message: Bytes) {}

	fn epoch_transition_for(&self, _block_hash: H256) -> Option<::engines::EpochTransition> {
		None
	}

	fn as_full_client(&self) -> Option<&dyn BlockChainClient> { Some(self) }

	fn block_number(&self, id: BlockId) -> Option<BlockNumber> {
		BlockChainClient::block_number(self, id)
	}

	fn block_header(&self, id: BlockId) -> Option<encoded::Header> {
		BlockChainClient::block_header(self, id)
	}
}