// Copyright 2015-2017 Parity Technologies (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 interface for the light client.

// TODO: remove when complete.
#![allow(unused_imports, unused_variables)]

use std::sync::Arc;

use jsonrpc_core::Error;
use jsonrpc_macros::Trailing;

use light::cache::Cache as LightDataCache;
use light::client::Client as LightClient;
use light::{cht, TransactionQueue};
use light::on_demand::{request, OnDemand};

use ethcore::account_provider::{AccountProvider, DappId};
use ethcore::basic_account::BasicAccount;
use ethcore::encoded;
use ethcore::executed::{Executed, ExecutionError};
use ethcore::ids::BlockId;
use ethcore::transaction::{Action, SignedTransaction, Transaction as EthTransaction};
use ethsync::LightSync;
use rlp::{UntrustedRlp, View};
use util::sha3::{SHA3_NULL_RLP, SHA3_EMPTY_LIST_RLP};
use util::{RwLock, Mutex, Uint, U256};

use futures::{future, Future, BoxFuture, IntoFuture};
use futures::sync::oneshot;

use v1::helpers::{CallRequest as CRequest, errors, limit_logs, dispatch};
use v1::helpers::block_import::is_major_importing;
use v1::traits::Eth;
use v1::types::{
	RichBlock, Block, BlockTransactions, BlockNumber, Bytes, SyncStatus, SyncInfo,
	Transaction, CallRequest, Index, Filter, Log, Receipt, Work,
	H64 as RpcH64, H256 as RpcH256, H160 as RpcH160, U256 as RpcU256,
};
use v1::metadata::Metadata;

use util::Address;

/// Light client `ETH` RPC.
pub struct EthClient {
	sync: Arc<LightSync>,
	client: Arc<LightClient>,
	on_demand: Arc<OnDemand>,
	transaction_queue: Arc<RwLock<TransactionQueue>>,
	accounts: Arc<AccountProvider>,
	cache: Arc<Mutex<LightDataCache>>,
}

// helper for internal error: on demand sender cancelled.
fn err_premature_cancel(_cancel: oneshot::Canceled) -> Error {
	errors::internal("on-demand sender prematurely cancelled", "")
}

type ExecutionResult = Result<Executed, ExecutionError>;

impl EthClient {
	/// Create a new `EthClient` with a handle to the light sync instance, client,
	/// and on-demand request service, which is assumed to be attached as a handler.
	pub fn new(
		sync: Arc<LightSync>,
		client: Arc<LightClient>,
		on_demand: Arc<OnDemand>,
		transaction_queue: Arc<RwLock<TransactionQueue>>,
		accounts: Arc<AccountProvider>,
		cache: Arc<Mutex<LightDataCache>>,
	) -> Self {
		EthClient {
			sync: sync,
			client: client,
			on_demand: on_demand,
			transaction_queue: transaction_queue,
			accounts: accounts,
			cache: cache,
		}
	}

	/// Get a block header from the on demand service or client, or error.
	fn header(&self, id: BlockId) -> BoxFuture<Option<encoded::Header>, Error> {
		if let Some(h) = self.client.block_header(id) {
			return future::ok(Some(h)).boxed()
		}

		let maybe_future = match id {
			BlockId::Number(n) => {
				let cht_root = cht::block_to_cht_number(n).and_then(|cn| self.client.cht_root(cn as usize));
				match cht_root {
					None => return future::ok(None).boxed(),
					Some(root) => {
						let req = request::HeaderByNumber::new(n, root)
							.expect("only fails for 0; client always stores genesis; client already queried; qed");

						self.sync.with_context(|ctx|
							self.on_demand.header_by_number(ctx, req)
								.map(Some)
								.map_err(err_premature_cancel)
								.boxed()
						)
					}
				}
			}
			BlockId::Hash(h) => {
				self.sync.with_context(|ctx|
					self.on_demand.header_by_hash(ctx, request::HeaderByHash(h))
						.then(|res| future::done(match res {
							Ok(h) => Ok(Some(h)),
							Err(e) => Err(err_premature_cancel(e)),
						}))
						.boxed()
				)
			}
			_ => None, // latest, earliest, and pending will have all already returned.
		};

		match maybe_future {
			Some(recv) => recv,
			None => future::err(errors::network_disabled()).boxed()
		}
	}

	// helper for getting account info at a given block.
	fn account(&self, address: Address, id: BlockId) -> BoxFuture<Option<BasicAccount>, Error> {
		let (sync, on_demand) = (self.sync.clone(), self.on_demand.clone());

		self.header(id).and_then(move |header| {
			let header = match header {
				None => return future::ok(None).boxed(),
				Some(hdr) => hdr,
			};

			sync.with_context(|ctx| on_demand.account(ctx, request::Account {
				header: header,
				address: address,
			}).map(Some))
				.map(|x| x.map_err(err_premature_cancel).boxed())
				.unwrap_or_else(|| future::err(errors::network_disabled()).boxed())
		}).boxed()
	}

	// helper for getting proved execution.
	fn proved_execution(&self, req: CallRequest, num: Trailing<BlockNumber>) -> BoxFuture<ExecutionResult, Error> {
		const DEFAULT_GAS_PRICE: U256 = U256([0, 0, 0, 21_000_000]);


		let (sync, on_demand, client) = (self.sync.clone(), self.on_demand.clone(), self.client.clone());
		let req: CRequest = req.into();
		let id = num.0.into();

		let from = req.from.unwrap_or(Address::zero());
		let nonce_fut = match req.nonce {
			Some(nonce) => future::ok(Some(nonce)).boxed(),
			None => self.account(from, id).map(|acc| acc.map(|a| a.nonce)).boxed(),
		};

		let gas_price_fut = match req.gas_price {
			Some(price) => future::ok(price).boxed(),
			None => dispatch::fetch_gas_price_corpus(
				self.sync.clone(),
				self.client.clone(),
				self.on_demand.clone(),
				self.cache.clone(),
			).map(|corp| match corp.median() {
				Some(median) => *median,
				None => DEFAULT_GAS_PRICE,
			}).boxed()
		};

		// if nonce resolves, this should too since it'll be in the LRU-cache.
		let header_fut = self.header(id);

		// fetch missing transaction fields from the network.
		nonce_fut.join(gas_price_fut).and_then(move |(nonce, gas_price)| {
			let action = req.to.map_or(Action::Create, Action::Call);
			let gas = req.gas.unwrap_or(U256::from(10_000_000)); // better gas amount?
			let value = req.value.unwrap_or_else(U256::zero);
			let data = req.data.map_or_else(Vec::new, |d| d.to_vec());

			future::done(match nonce {
				Some(n) => Ok(EthTransaction {
					nonce: n,
					action: action,
					gas: gas,
					gas_price: gas_price,
					value: value,
					data: data,
				}.fake_sign(from)),
				None => Err(errors::unknown_block()),
			})
		}).join(header_fut).and_then(move |(tx, hdr)| {
			// then request proved execution.
			// TODO: get last-hashes from network.
			let (env_info, hdr) = match (client.env_info(id), hdr) {
				(Some(env_info), Some(hdr)) => (env_info, hdr),
				_ => return future::err(errors::unknown_block()).boxed(),
			};
			let request = request::TransactionProof {
				tx: tx,
				header: hdr,
				env_info: env_info,
				engine: client.engine().clone(),
			};

			let proved_future = sync.with_context(move |ctx| {
				on_demand.transaction_proof(ctx, request).map_err(err_premature_cancel).boxed()
			});

			match proved_future {
				Some(fut) => fut.boxed(),
				None => future::err(errors::network_disabled()).boxed(),
			}
		}).boxed()
	}
}

impl Eth for EthClient {
	type Metadata = Metadata;

	fn protocol_version(&self) -> Result<String, Error> {
		Ok(format!("{}", ::light::net::MAX_PROTOCOL_VERSION))
	}

	fn syncing(&self) -> Result<SyncStatus, Error> {
		rpc_unimplemented!()
	}

	fn author(&self, _meta: Self::Metadata) -> BoxFuture<RpcH160, Error> {
		future::ok(Default::default()).boxed()
	}

	fn is_mining(&self) -> Result<bool, Error> {
		Ok(false)
	}

	fn hashrate(&self) -> Result<RpcU256, Error> {
		Ok(Default::default())
	}

	fn gas_price(&self) -> Result<RpcU256, Error> {
		Ok(Default::default())
	}

	fn accounts(&self, meta: Metadata) -> BoxFuture<Vec<RpcH160>, Error> {
		let dapp: DappId = meta.dapp_id().into();

		let accounts = self.accounts
			.note_dapp_used(dapp.clone())
			.and_then(|_| self.accounts.dapp_addresses(dapp))
			.map_err(|e| errors::account("Could not fetch accounts.", e))
			.map(|accs| accs.into_iter().map(Into::<RpcH160>::into).collect());

		future::done(accounts).boxed()
	}

	fn block_number(&self) -> Result<RpcU256, Error> {
		Ok(self.client.chain_info().best_block_number.into())
	}

	fn balance(&self, address: RpcH160, num: Trailing<BlockNumber>) -> BoxFuture<RpcU256, Error> {
		self.account(address.into(), num.0.into())
			.map(|acc| acc.map_or(0.into(), |a| a.balance).into()).boxed()
	}

	fn storage_at(&self, _address: RpcH160, _key: RpcU256, _num: Trailing<BlockNumber>) -> BoxFuture<RpcH256, Error> {
		future::err(errors::unimplemented(None)).boxed()
	}

	fn block_by_hash(&self, hash: RpcH256, include_txs: bool) -> BoxFuture<Option<RichBlock>, Error> {
		future::err(errors::unimplemented(None)).boxed()
	}

	fn block_by_number(&self, num: BlockNumber, include_txs: bool) -> BoxFuture<Option<RichBlock>, Error> {
		future::err(errors::unimplemented(None)).boxed()
	}

	fn transaction_count(&self, address: RpcH160, num: Trailing<BlockNumber>) -> BoxFuture<RpcU256, Error> {
		self.account(address.into(), num.0.into())
			.map(|acc| acc.map_or(0.into(), |a| a.nonce).into()).boxed()
	}

	fn block_transaction_count_by_hash(&self, hash: RpcH256) -> BoxFuture<Option<RpcU256>, Error> {
		let (sync, on_demand) = (self.sync.clone(), self.on_demand.clone());

		self.header(BlockId::Hash(hash.into())).and_then(move |hdr| {
			let hdr = match hdr {
				None => return future::ok(None).boxed(),
				Some(hdr) => hdr,
			};

			if hdr.transactions_root() == SHA3_NULL_RLP {
				future::ok(Some(U256::from(0).into())).boxed()
			} else {
				sync.with_context(|ctx| on_demand.block(ctx, request::Body::new(hdr)))
					.map(|x| x.map(|b| Some(U256::from(b.transactions_count()).into())))
					.map(|x| x.map_err(err_premature_cancel).boxed())
					.unwrap_or_else(|| future::err(errors::network_disabled()).boxed())
			}
		}).boxed()
	}

	fn block_transaction_count_by_number(&self, num: BlockNumber) -> BoxFuture<Option<RpcU256>, Error> {
		let (sync, on_demand) = (self.sync.clone(), self.on_demand.clone());

		self.header(num.into()).and_then(move |hdr| {
			let hdr = match hdr {
				None => return future::ok(None).boxed(),
				Some(hdr) => hdr,
			};

			if hdr.transactions_root() == SHA3_NULL_RLP {
				future::ok(Some(U256::from(0).into())).boxed()
			} else {
				sync.with_context(|ctx| on_demand.block(ctx, request::Body::new(hdr)))
					.map(|x| x.map(|b| Some(U256::from(b.transactions_count()).into())))
					.map(|x| x.map_err(err_premature_cancel).boxed())
					.unwrap_or_else(|| future::err(errors::network_disabled()).boxed())
			}
		}).boxed()
	}

	fn block_uncles_count_by_hash(&self, hash: RpcH256) -> BoxFuture<Option<RpcU256>, Error> {
		let (sync, on_demand) = (self.sync.clone(), self.on_demand.clone());

		self.header(BlockId::Hash(hash.into())).and_then(move |hdr| {
			let hdr = match hdr {
				None => return future::ok(None).boxed(),
				Some(hdr) => hdr,
			};

			if hdr.uncles_hash() == SHA3_EMPTY_LIST_RLP {
				future::ok(Some(U256::from(0).into())).boxed()
			} else {
				sync.with_context(|ctx| on_demand.block(ctx, request::Body::new(hdr)))
					.map(|x| x.map(|b| Some(U256::from(b.uncles_count()).into())))
					.map(|x| x.map_err(err_premature_cancel).boxed())
					.unwrap_or_else(|| future::err(errors::network_disabled()).boxed())
			}
		}).boxed()
	}

	fn block_uncles_count_by_number(&self, num: BlockNumber) -> BoxFuture<Option<RpcU256>, Error> {
		let (sync, on_demand) = (self.sync.clone(), self.on_demand.clone());

		self.header(num.into()).and_then(move |hdr| {
			let hdr = match hdr {
				None => return future::ok(None).boxed(),
				Some(hdr) => hdr,
			};

			if hdr.uncles_hash() == SHA3_EMPTY_LIST_RLP {
				future::ok(Some(U256::from(0).into())).boxed()
			} else {
				sync.with_context(|ctx| on_demand.block(ctx, request::Body::new(hdr)))
					.map(|x| x.map(|b| Some(U256::from(b.uncles_count()).into())))
					.map(|x| x.map_err(err_premature_cancel).boxed())
					.unwrap_or_else(|| future::err(errors::network_disabled()).boxed())
			}
		}).boxed()
	}

	fn code_at(&self, address: RpcH160, num: Trailing<BlockNumber>) -> BoxFuture<Bytes, Error> {
		future::err(errors::unimplemented(None)).boxed()
	}

	fn send_raw_transaction(&self, raw: Bytes) -> Result<RpcH256, Error> {
		let best_header = self.client.best_block_header().decode();

		UntrustedRlp::new(&raw.into_vec()).as_val()
			.map_err(errors::from_rlp_error)
			.and_then(|tx| {
				self.client.engine().verify_transaction_basic(&tx, &best_header)
					.map_err(errors::from_transaction_error)?;

				let signed = SignedTransaction::new(tx).map_err(errors::from_transaction_error)?;
				let hash = signed.hash();

				self.transaction_queue.write().import(signed.into())
					.map(|_| hash)
					.map_err(Into::into)
					.map_err(errors::from_transaction_error)
			})
			.map(Into::into)
	}

	fn submit_transaction(&self, raw: Bytes) -> Result<RpcH256, Error> {
		self.send_raw_transaction(raw)
	}

	fn call(&self, req: CallRequest, num: Trailing<BlockNumber>) -> BoxFuture<Bytes, Error> {
		self.proved_execution(req, num).and_then(|res| {
			match res {
				Ok(exec) => Ok(exec.output.into()),
				Err(e) => Err(errors::execution(e)),
			}
		}).boxed()
	}

	fn estimate_gas(&self, req: CallRequest, num: Trailing<BlockNumber>) -> BoxFuture<RpcU256, Error> {
		// TODO: binary chop for more accurate estimates.
		self.proved_execution(req, num).and_then(|res| {
			match res {
				Ok(exec) => Ok((exec.refunded + exec.gas_used).into()),
				Err(e) => Err(errors::execution(e)),
			}
		}).boxed()
	}

	fn transaction_by_hash(&self, hash: RpcH256) -> Result<Option<Transaction>, Error> {
		Err(errors::unimplemented(None))
	}

	fn transaction_by_block_hash_and_index(&self, hash: RpcH256, idx: Index) -> Result<Option<Transaction>, Error> {
		Err(errors::unimplemented(None))
	}

	fn transaction_by_block_number_and_index(&self, num: BlockNumber, idx: Index) -> Result<Option<Transaction>, Error> {
		Err(errors::unimplemented(None))
	}

	fn transaction_receipt(&self, hash: RpcH256) -> Result<Option<Receipt>, Error> {
		Err(errors::unimplemented(None))
	}

	fn uncle_by_block_hash_and_index(&self, hash: RpcH256, idx: Index) -> Result<Option<RichBlock>, Error> {
		Err(errors::unimplemented(None))
	}

	fn uncle_by_block_number_and_index(&self, num: BlockNumber, idx: Index) -> Result<Option<RichBlock>, Error> {
		Err(errors::unimplemented(None))
	}

	fn compilers(&self) -> Result<Vec<String>, Error> {
		Err(errors::deprecated("Compilation functionality is deprecated.".to_string()))

	}

	fn compile_lll(&self, _: String) -> Result<Bytes, Error> {
		Err(errors::deprecated("Compilation of LLL via RPC is deprecated".to_string()))
	}

	fn compile_serpent(&self, _: String) -> Result<Bytes, Error> {
		Err(errors::deprecated("Compilation of Serpent via RPC is deprecated".to_string()))
	}

	fn compile_solidity(&self, _: String) -> Result<Bytes, Error> {
		Err(errors::deprecated("Compilation of Solidity via RPC is deprecated".to_string()))
	}

	fn logs(&self, _filter: Filter) -> Result<Vec<Log>, Error> {
		Err(errors::unimplemented(None))
	}

	fn work(&self, _timeout: Trailing<u64>) -> Result<Work, Error> {
		Err(errors::unimplemented(None))
	}

	fn submit_work(&self, _nonce: RpcH64, _pow_hash: RpcH256, _mix_hash: RpcH256) -> Result<bool, Error> {
		Err(errors::unimplemented(None))
	}

	fn submit_hashrate(&self, _rate: RpcU256, _id: RpcH256) -> Result<bool, Error> {
		Err(errors::unimplemented(None))
	}
}