// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum 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.

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

/// Validator set maintained in a contract, updated using `getValidators` method.
/// It can also report validators for misbehaviour with two levels: `reportMalicious` and `reportBenign`.
use std::sync::Weak;

use bytes::Bytes;
use ethereum_types::{Address, H256, U256};
use machine::{AuxiliaryData, Call, EthereumMachine};
use parking_lot::RwLock;
use types::{header::Header, ids::BlockId, transaction, BlockNumber};

use client::{traits::TransactionRequest, EngineClient};

use error::Error as EthcoreError;

use super::{safe_contract::ValidatorSafeContract, SimpleList, SystemCall, ValidatorSet};

use_contract!(validator_report, "res/contracts/validator_report.json");

/// A validator contract with reporting.
pub struct ValidatorContract {
    contract_address: Address,
    validators: ValidatorSafeContract,
    client: RwLock<Option<Weak<dyn EngineClient>>>, // TODO [keorn]: remove
    posdao_transition: Option<BlockNumber>,
}

impl ValidatorContract {
    pub fn new(contract_address: Address, posdao_transition: Option<BlockNumber>) -> Self {
        ValidatorContract {
            contract_address,
            validators: ValidatorSafeContract::new(contract_address, posdao_transition),
            client: RwLock::new(None),
            posdao_transition,
        }
    }

    fn transact(
        &self,
        data: Bytes,
        gas_price: Option<U256>,
        client: &dyn EngineClient,
    ) -> Result<(), String> {
        let full_client = client.as_full_client().ok_or("No full client!")?;
        let tx_request = TransactionRequest::call(self.contract_address, data).gas_price(gas_price);
        match full_client.transact(tx_request) {
            Ok(()) | Err(transaction::Error::AlreadyImported) => Ok(()),
            Err(e) => Err(e.to_string())?,
        }
    }

    fn do_report_malicious(
        &self,
        address: &Address,
        block: BlockNumber,
        proof: Bytes,
    ) -> Result<(), EthcoreError> {
        let client = self
            .client
            .read()
            .as_ref()
            .and_then(Weak::upgrade)
            .ok_or("No client!")?;
        let latest = client
            .block_header(BlockId::Latest)
            .ok_or("No latest block!")?;
        if !self.contains(&latest.parent_hash(), address) {
            warn!(target: "engine", "Not reporting {} on block {}: Not a validator", address, block);
            return Ok(());
        }
        let data =
            validator_report::functions::report_malicious::encode_input(*address, block, proof);
        self.validators
            .enqueue_report(*address, block, data.clone());
        let gas_price = self.report_gas_price(latest.number());
        self.transact(data, gas_price, &*client)?;
        warn!(target: "engine", "Reported malicious validator {} at block {}", address, block);
        Ok(())
    }

    fn do_report_benign(&self, address: &Address, block: BlockNumber) -> Result<(), EthcoreError> {
        let client = self
            .client
            .read()
            .as_ref()
            .and_then(Weak::upgrade)
            .ok_or("No client!")?;
        let latest = client
            .block_header(BlockId::Latest)
            .ok_or("No latest block!")?;
        let data = validator_report::functions::report_benign::encode_input(*address, block);
        let gas_price = self.report_gas_price(latest.number());
        self.transact(data, gas_price, &*client)?;
        warn!(target: "engine", "Benign report for validator {} at block {}", address, block);
        Ok(())
    }

    /// Returns the gas price for report transactions.
    ///
    /// After `posdaoTransition`, this is zero. Otherwise it is the default (`None`).
    fn report_gas_price(&self, block: BlockNumber) -> Option<U256> {
        if self.posdao_transition? <= block {
            Some(0.into())
        } else {
            None
        }
    }
}

impl ValidatorSet for ValidatorContract {
    fn default_caller(&self, id: ::types::ids::BlockId) -> Box<Call> {
        self.validators.default_caller(id)
    }

    fn generate_engine_transactions(
        &self,
        first: bool,
        header: &Header,
        call: &mut SystemCall,
    ) -> Result<Vec<(Address, Bytes)>, EthcoreError> {
        self.validators
            .generate_engine_transactions(first, header, call)
    }

    fn on_close_block(&self, header: &Header, address: &Address) -> Result<(), EthcoreError> {
        self.validators.on_close_block(header, address)
    }

    fn on_epoch_begin(
        &self,
        first: bool,
        header: &Header,
        call: &mut SystemCall,
    ) -> Result<(), ::error::Error> {
        self.validators.on_epoch_begin(first, header, call)
    }

    fn genesis_epoch_data(&self, header: &Header, call: &Call) -> Result<Vec<u8>, String> {
        self.validators.genesis_epoch_data(header, call)
    }

    fn is_epoch_end(&self, first: bool, chain_head: &Header) -> Option<Vec<u8>> {
        self.validators.is_epoch_end(first, chain_head)
    }

    fn signals_epoch_end(
        &self,
        first: bool,
        header: &Header,
        aux: AuxiliaryData,
    ) -> ::engines::EpochChange<EthereumMachine> {
        self.validators.signals_epoch_end(first, header, aux)
    }

    fn epoch_set(
        &self,
        first: bool,
        machine: &EthereumMachine,
        number: BlockNumber,
        proof: &[u8],
    ) -> Result<(SimpleList, Option<H256>), ::error::Error> {
        self.validators.epoch_set(first, machine, number, proof)
    }

    fn contains_with_caller(&self, bh: &H256, address: &Address, caller: &Call) -> bool {
        self.validators.contains_with_caller(bh, address, caller)
    }

    fn get_with_caller(&self, bh: &H256, nonce: usize, caller: &Call) -> Address {
        self.validators.get_with_caller(bh, nonce, caller)
    }

    fn count_with_caller(&self, bh: &H256, caller: &Call) -> usize {
        self.validators.count_with_caller(bh, caller)
    }

    fn report_malicious(
        &self,
        address: &Address,
        _set_block: BlockNumber,
        block: BlockNumber,
        proof: Bytes,
    ) {
        if let Err(s) = self.do_report_malicious(address, block, proof) {
            warn!(target: "engine", "Validator {} could not be reported ({}) on block {}", address, s, block);
        }
    }

    fn report_benign(&self, address: &Address, _set_block: BlockNumber, block: BlockNumber) {
        if let Err(s) = self.do_report_benign(address, block) {
            warn!(target: "engine", "Validator {} could not be reported ({}) on block {}", address, s, block);
        }
    }

    fn register_client(&self, client: Weak<dyn EngineClient>) {
        self.validators.register_client(client.clone());
        *self.client.write() = Some(client);
    }
}

#[cfg(test)]
mod tests {
    use super::{super::ValidatorSet, ValidatorContract};
    use accounts::AccountProvider;
    use bytes::ToPretty;
    use call_contract::CallContract;
    use client::{traits::TransactionRequest, BlockChainClient, BlockInfo, ChainInfo};
    use ethabi::FunctionOutputDecoder;
    use ethereum_types::{Address, H520};
    use hash::keccak;
    use miner::{self, MinerService};
    use rlp::encode;
    use rustc_hex::FromHex;
    use spec::Spec;
    use std::sync::Arc;
    use test_helpers::generate_dummy_client_with_spec;
    use types::{header::Header, ids::BlockId};

    #[test]
    fn fetches_validators() {
        let client = generate_dummy_client_with_spec(Spec::new_validator_contract);
        let addr: Address = "0000000000000000000000000000000000000005".parse().unwrap();
        let vc = Arc::new(ValidatorContract::new(addr, None));
        vc.register_client(Arc::downgrade(&client) as _);
        let last_hash = client.best_block_header().hash();
        assert!(vc.contains(
            &last_hash,
            &"7d577a597b2742b498cb5cf0c26cdcd726d39e6e"
                .parse::<Address>()
                .unwrap()
        ));
        assert!(vc.contains(
            &last_hash,
            &"82a978b3f5962a5b0957d9ee9eef472ee55b42f1"
                .parse::<Address>()
                .unwrap()
        ));
    }

    #[test]
    fn reports_validators() {
        let tap = Arc::new(AccountProvider::transient_provider());
        let v1 = tap.insert_account(keccak("1").into(), &"".into()).unwrap();
        let client = generate_dummy_client_with_spec(Spec::new_validator_contract);
        client
            .engine()
            .register_client(Arc::downgrade(&client) as _);
        let validator_contract = "0000000000000000000000000000000000000005"
            .parse::<Address>()
            .unwrap();

        // Make sure reporting can be done.
        client
            .miner()
            .set_gas_range_target((1_000_000.into(), 1_000_000.into()));
        let signer = Box::new((tap.clone(), v1, "".into()));
        client.miner().set_author(miner::Author::Sealer(signer));

        // Check a block that is a bit in future, reject it but don't report the validator.
        let mut header = Header::default();
        let seal = vec![encode(&4u8), encode(&(H520::default().as_bytes()))];
        header.set_seal(seal);
        header.set_author(v1);
        header.set_number(2);
        header.set_parent_hash(client.chain_info().best_block_hash);
        assert!(client.engine().verify_block_external(&header).is_err());
        client.engine().step();
        assert_eq!(client.chain_info().best_block_number, 0);
        // `reportBenign` when the designated proposer releases block from the future (bad clock).
        assert!(client.engine().verify_block_basic(&header).is_err());

        // Now create one that is more in future. That one should be rejected and validator should be reported.
        let mut header = Header::default();
        let seal = vec![encode(&8u8), encode(&(H520::default().as_bytes()))];
        header.set_seal(seal);
        header.set_author(v1);
        header.set_number(2);
        header.set_parent_hash(client.chain_info().best_block_hash);
        // `reportBenign` when the designated proposer releases block from the future (bad clock).
        assert!(client.engine().verify_block_basic(&header).is_err());
        // Seal a block.
        client.engine().step();
        assert_eq!(client.chain_info().best_block_number, 1);
        // Check if the unresponsive validator is `disliked`. "d8f2e0bf" accesses the field `disliked`..
        assert_eq!(
            client
                .call_contract(
                    BlockId::Latest,
                    validator_contract,
                    "d8f2e0bf".from_hex().unwrap()
                )
                .unwrap()
                .to_hex(),
            "0000000000000000000000007d577a597b2742b498cb5cf0c26cdcd726d39e6e"
        );
        // Simulate a misbehaving validator by handling a double proposal.
        let header = client.best_block_header();
        assert!(client
            .engine()
            .verify_block_family(&header, &header)
            .is_err());
        // Seal a block.
        client.engine().step();
        client.engine().step();
        assert_eq!(client.chain_info().best_block_number, 2);
        let (data, decoder) =
            super::validator_report::functions::malice_reported_for_block::call(v1, 1);
        let reported_enc = client
            .call_contract(BlockId::Latest, validator_contract, data)
            .expect("call failed");
        assert_ne!(
            Vec::<Address>::new(),
            decoder.decode(&reported_enc).expect("decoding failed")
        );

        // Check if misbehaving validator was removed.

        client
            .transact(TransactionRequest::call(
                Default::default(),
                Default::default(),
            ))
            .unwrap();
        client.engine().step();
        client.engine().step();
        assert_eq!(client.chain_info().best_block_number, 2);
    }
}
