//! Optimism's payload builder implementation.

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#![cfg_attr(all(not(test), feature = "optimism"), warn(unused_crate_dependencies))]
#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]

#[cfg(feature = "optimism")]
pub use builder::*;

pub mod error;

#[cfg(feature = "optimism")]
mod builder {
    use crate::error::OptimismPayloadBuilderError;
    use reth_basic_payload_builder::*;
    use reth_payload_builder::{
        error::PayloadBuilderError, EthBuiltPayload, OptimismPayloadBuilderAttributes,
    };
    use reth_primitives::{
        constants::{BEACON_NONCE, EMPTY_RECEIPTS, EMPTY_TRANSACTIONS},
        eip4844::calculate_excess_blob_gas,
        proofs,
        revm::env::tx_env_with_recovered,
        Block, Hardfork, Header, IntoRecoveredTransaction, Receipt, Receipts, TxType,
        EMPTY_OMMER_ROOT_HASH, U256,
    };
    use reth_provider::{BundleStateWithReceipts, StateProviderFactory};
    use reth_revm::database::StateProviderDatabase;
    use reth_transaction_pool::{BestTransactionsAttributes, TransactionPool};
    use revm::{
        db::states::bundle_state::BundleRetention,
        primitives::{EVMError, EnvWithHandlerCfg, InvalidTransaction, ResultAndState},
        DatabaseCommit, State,
    };
    use tracing::{debug, trace, warn};

    /// Optimism's payload builder
    #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
    #[non_exhaustive]
    pub struct OptimismPayloadBuilder {
        /// The rollup's compute pending block configuration option.
        // TODO(clabby): Implement this feature.
        compute_pending_block: bool,
    }

    impl OptimismPayloadBuilder {
        /// Sets the rollup's compute pending block configuration option.
        pub fn set_compute_pending_block(mut self, compute_pending_block: bool) -> Self {
            self.compute_pending_block = compute_pending_block;
            self
        }

        /// Enables the rollup's compute pending block configuration option.
        pub fn compute_pending_block(self) -> Self {
            self.set_compute_pending_block(true)
        }

        /// Returns the rollup's compute pending block configuration option.
        pub fn is_compute_pending_block(&self) -> bool {
            self.compute_pending_block
        }
    }

    /// Implementation of the [PayloadBuilder] trait for [OptimismPayloadBuilder].
    impl<Pool, Client> PayloadBuilder<Pool, Client> for OptimismPayloadBuilder
    where
        Client: StateProviderFactory,
        Pool: TransactionPool,
    {
        type Attributes = OptimismPayloadBuilderAttributes;
        type BuiltPayload = EthBuiltPayload;

        fn try_build(
            &self,
            args: BuildArguments<Pool, Client, OptimismPayloadBuilderAttributes, EthBuiltPayload>,
        ) -> Result<BuildOutcome<EthBuiltPayload>, PayloadBuilderError> {
            optimism_payload_builder(args, self.compute_pending_block)
        }

        fn on_missing_payload(
            &self,
            args: BuildArguments<Pool, Client, OptimismPayloadBuilderAttributes, EthBuiltPayload>,
        ) -> Option<EthBuiltPayload> {
            // In Optimism, the PayloadAttributes can specify a `no_tx_pool` option that implies we
            // should not pull transactions from the tx pool. In this case, we build the payload
            // upfront with the list of transactions sent in the attributes without caring about
            // the results of the polling job, if a best payload has not already been built.
            if args.config.attributes.no_tx_pool {
                if let Ok(BuildOutcome::Better { payload, .. }) = self.try_build(args) {
                    trace!(target: "payload_builder", "[OPTIMISM] Forced best payload");
                    return Some(payload)
                }
            }

            None
        }

        fn build_empty_payload(
            client: &Client,
            config: PayloadConfig<Self::Attributes>,
        ) -> Result<EthBuiltPayload, PayloadBuilderError> {
            let extra_data = config.extra_data();
            let PayloadConfig {
                initialized_block_env,
                parent_block,
                attributes,
                chain_spec,
                initialized_cfg,
                ..
            } = config;

            debug!(target: "payload_builder", parent_hash = ?parent_block.hash(), parent_number = parent_block.number, "building empty payload");

            let state = client.state_by_block_hash(parent_block.hash()).map_err(|err| {
                warn!(target: "payload_builder", parent_hash=%parent_block.hash(), %err, "failed to get state for empty payload");
                err
            })?;
            let mut db = State::builder()
                .with_database_boxed(Box::new(StateProviderDatabase::new(&state)))
                .with_bundle_update()
                .build();

            let base_fee = initialized_block_env.basefee.to::<u64>();
            let block_number = initialized_block_env.number.to::<u64>();
            let block_gas_limit: u64 =
                initialized_block_env.gas_limit.try_into().unwrap_or(u64::MAX);

            // apply eip-4788 pre block contract call
            pre_block_beacon_root_contract_call(
                &mut db,
                &chain_spec,
                block_number,
                &initialized_cfg,
                &initialized_block_env,
                &attributes,
            ).map_err(|err| {
                warn!(target: "payload_builder", parent_hash=%parent_block.hash(), %err, "failed to apply beacon root contract call for empty payload");
                err
            })?;

            let WithdrawalsOutcome { withdrawals_root, withdrawals } =
                commit_withdrawals(&mut db, &chain_spec, attributes.payload_attributes.timestamp, attributes.payload_attributes.withdrawals.clone()).map_err(|err| {
                    warn!(target: "payload_builder", parent_hash=%parent_block.hash(), %err, "failed to commit withdrawals for empty payload");
                    err
                })?;

            // merge all transitions into bundle state, this would apply the withdrawal balance
            // changes and 4788 contract call
            db.merge_transitions(BundleRetention::PlainState);

            // calculate the state root
            let bundle_state =
                BundleStateWithReceipts::new(db.take_bundle(), Receipts::new(), block_number);
            let state_root = state.state_root(&bundle_state).map_err(|err| {
                warn!(target: "payload_builder", parent_hash=%parent_block.hash(), %err, "failed to calculate state root for empty payload");
                err
            })?;

            let mut excess_blob_gas = None;
            let mut blob_gas_used = None;

            if chain_spec.is_cancun_active_at_timestamp(attributes.payload_attributes.timestamp) {
                excess_blob_gas = if chain_spec
                    .is_cancun_active_at_timestamp(parent_block.timestamp)
                {
                    let parent_excess_blob_gas = parent_block.excess_blob_gas.unwrap_or_default();
                    let parent_blob_gas_used = parent_block.blob_gas_used.unwrap_or_default();
                    Some(calculate_excess_blob_gas(parent_excess_blob_gas, parent_blob_gas_used))
                } else {
                    // for the first post-fork block, both parent.blob_gas_used and
                    // parent.excess_blob_gas are evaluated as 0
                    Some(calculate_excess_blob_gas(0, 0))
                };

                blob_gas_used = Some(0);
            }

            let header = Header {
                parent_hash: parent_block.hash(),
                ommers_hash: EMPTY_OMMER_ROOT_HASH,
                beneficiary: initialized_block_env.coinbase,
                state_root,
                transactions_root: EMPTY_TRANSACTIONS,
                withdrawals_root,
                receipts_root: EMPTY_RECEIPTS,
                logs_bloom: Default::default(),
                timestamp: attributes.payload_attributes.timestamp,
                mix_hash: attributes.payload_attributes.prev_randao,
                nonce: BEACON_NONCE,
                base_fee_per_gas: Some(base_fee),
                number: parent_block.number + 1,
                gas_limit: block_gas_limit,
                difficulty: U256::ZERO,
                gas_used: 0,
                extra_data,
                blob_gas_used,
                excess_blob_gas,
                parent_beacon_block_root: attributes.payload_attributes.parent_beacon_block_root,
            };

            let block = Block { header, body: vec![], ommers: vec![], withdrawals };
            let sealed_block = block.seal_slow();

            Ok(EthBuiltPayload::new(
                attributes.payload_attributes.payload_id(),
                sealed_block,
                U256::ZERO,
            ))
        }
    }

    /// Constructs an Ethereum transaction payload from the transactions sent through the
    /// Payload attributes by the sequencer. If the `no_tx_pool` argument is passed in
    /// the payload attributes, the transaction pool will be ignored and the only transactions
    /// included in the payload will be those sent through the attributes.
    ///
    /// Given build arguments including an Ethereum client, transaction pool,
    /// and configuration, this function creates a transaction payload. Returns
    /// a result indicating success with the payload or an error in case of failure.
    #[inline]
    pub(crate) fn optimism_payload_builder<Pool, Client>(
        args: BuildArguments<Pool, Client, OptimismPayloadBuilderAttributes, EthBuiltPayload>,
        _compute_pending_block: bool,
    ) -> Result<BuildOutcome<EthBuiltPayload>, PayloadBuilderError>
    where
        Client: StateProviderFactory,
        Pool: TransactionPool,
    {
        let BuildArguments { client, pool, mut cached_reads, config, cancel, best_payload } = args;

        let state_provider = client.state_by_block_hash(config.parent_block.hash())?;
        let state = StateProviderDatabase::new(&state_provider);
        let mut db = State::builder()
            .with_database_ref(cached_reads.as_db(&state))
            .with_bundle_update()
            .build();
        let extra_data = config.extra_data();
        let PayloadConfig {
            initialized_block_env,
            initialized_cfg,
            parent_block,
            attributes,
            chain_spec,
            ..
        } = config;

        debug!(target: "payload_builder", id=%attributes.payload_attributes.payload_id(), parent_hash = ?parent_block.hash(), parent_number = parent_block.number, "building new payload");
        let mut cumulative_gas_used = 0;
        let block_gas_limit: u64 = attributes
            .gas_limit
            .unwrap_or(initialized_block_env.gas_limit.try_into().unwrap_or(u64::MAX));
        let base_fee = initialized_block_env.basefee.to::<u64>();

        let mut executed_txs = Vec::new();
        let mut best_txs = pool.best_transactions_with_attributes(BestTransactionsAttributes::new(
            base_fee,
            initialized_block_env.get_blob_gasprice().map(|gasprice| gasprice as u64),
        ));

        let mut total_fees = U256::ZERO;

        let block_number = initialized_block_env.number.to::<u64>();

        let is_regolith = chain_spec.is_fork_active_at_timestamp(
            Hardfork::Regolith,
            attributes.payload_attributes.timestamp,
        );

        // apply eip-4788 pre block contract call
        pre_block_beacon_root_contract_call(
            &mut db,
            &chain_spec,
            block_number,
            &initialized_cfg,
            &initialized_block_env,
            &attributes,
        )?;

        // Ensure that the create2deployer is force-deployed at the canyon transition. Optimism
        // blocks will always have at least a single transaction in them (the L1 info transaction),
        // so we can safely assume that this will always be triggered upon the transition and that
        // the above check for empty blocks will never be hit on OP chains.
        reth_revm::optimism::ensure_create2_deployer(
            chain_spec.clone(),
            attributes.payload_attributes.timestamp,
            &mut db,
        )
        .map_err(|_| {
            PayloadBuilderError::other(OptimismPayloadBuilderError::ForceCreate2DeployerFail)
        })?;

        let mut receipts = Vec::new();
        for sequencer_tx in &attributes.transactions {
            // Check if the job was cancelled, if so we can exit early.
            if cancel.is_cancelled() {
                return Ok(BuildOutcome::Cancelled)
            }

            // A sequencer's block should never contain blob transactions.
            if matches!(sequencer_tx.tx_type(), TxType::EIP4844) {
                return Err(PayloadBuilderError::other(
                    OptimismPayloadBuilderError::BlobTransactionRejected,
                ))
            }

            // Convert the transaction to a [TransactionSignedEcRecovered]. This is
            // purely for the purposes of utilizing the [tx_env_with_recovered] function.
            // Deposit transactions do not have signatures, so if the tx is a deposit, this
            // will just pull in its `from` address.
            let sequencer_tx = sequencer_tx.clone().try_into_ecrecovered().map_err(|_| {
                PayloadBuilderError::other(OptimismPayloadBuilderError::TransactionEcRecoverFailed)
            })?;

            // Cache the depositor account prior to the state transition for the deposit nonce.
            //
            // Note that this *only* needs to be done post-regolith hardfork, as deposit nonces
            // were not introduced in Bedrock. In addition, regular transactions don't have deposit
            // nonces, so we don't need to touch the DB for those.
            let depositor = (is_regolith && sequencer_tx.is_deposit())
                .then(|| {
                    db.load_cache_account(sequencer_tx.signer())
                        .map(|acc| acc.account_info().unwrap_or_default())
                })
                .transpose()
                .map_err(|_| {
                    PayloadBuilderError::other(OptimismPayloadBuilderError::AccountLoadFailed(
                        sequencer_tx.signer(),
                    ))
                })?;

            let mut evm = revm::Evm::builder()
                .with_db(&mut db)
                .with_env_with_handler_cfg(EnvWithHandlerCfg::new_with_cfg_env(
                    initialized_cfg.clone(),
                    initialized_block_env.clone(),
                    tx_env_with_recovered(&sequencer_tx),
                ))
                .build();

            let ResultAndState { result, state } = match evm.transact() {
                Ok(res) => res,
                Err(err) => {
                    match err {
                        EVMError::Transaction(err) => {
                            trace!(target: "payload_builder", %err, ?sequencer_tx, "Error in sequencer transaction, skipping.");
                            continue
                        }
                        err => {
                            // this is an error that we should treat as fatal for this attempt
                            return Err(PayloadBuilderError::EvmExecutionError(err))
                        }
                    }
                }
            };

            // to realease the db reference drop evm.
            drop(evm);
            // commit changes
            db.commit(state);

            let gas_used = result.gas_used();

            // add gas used by the transaction to cumulative gas used, before creating the receipt
            cumulative_gas_used += gas_used;

            // Push transaction changeset and calculate header bloom filter for receipt.
            receipts.push(Some(Receipt {
                tx_type: sequencer_tx.tx_type(),
                success: result.is_success(),
                cumulative_gas_used,
                logs: result.logs().into_iter().map(Into::into).collect(),
                deposit_nonce: depositor.map(|account| account.nonce),
                // The deposit receipt version was introduced in Canyon to indicate an update to how
                // receipt hashes should be computed when set. The state transition process
                // ensures this is only set for post-Canyon deposit transactions.
                deposit_receipt_version: chain_spec
                    .is_fork_active_at_timestamp(
                        Hardfork::Canyon,
                        attributes.payload_attributes.timestamp,
                    )
                    .then_some(1),
            }));

            // append transaction to the list of executed transactions
            executed_txs.push(sequencer_tx.into_signed());
        }

        if !attributes.no_tx_pool {
            while let Some(pool_tx) = best_txs.next() {
                // ensure we still have capacity for this transaction
                if cumulative_gas_used + pool_tx.gas_limit() > block_gas_limit {
                    // we can't fit this transaction into the block, so we need to mark it as
                    // invalid which also removes all dependent transaction from
                    // the iterator before we can continue
                    best_txs.mark_invalid(&pool_tx);
                    continue
                }

                // A sequencer's block should never contain blob transactions.
                if pool_tx.tx_type() == TxType::EIP4844 as u8 {
                    return Err(PayloadBuilderError::other(
                        OptimismPayloadBuilderError::BlobTransactionRejected,
                    ))
                }

                // check if the job was cancelled, if so we can exit early
                if cancel.is_cancelled() {
                    return Ok(BuildOutcome::Cancelled)
                }

                // convert tx to a signed transaction
                let tx = pool_tx.to_recovered_transaction();

                // Configure the environment for the block.
                let mut evm = revm::Evm::builder()
                    .with_db(&mut db)
                    .with_env_with_handler_cfg(EnvWithHandlerCfg::new_with_cfg_env(
                        initialized_cfg.clone(),
                        initialized_block_env.clone(),
                        tx_env_with_recovered(&tx),
                    ))
                    .build();

                let ResultAndState { result, state } = match evm.transact() {
                    Ok(res) => res,
                    Err(err) => {
                        match err {
                            EVMError::Transaction(err) => {
                                if matches!(err, InvalidTransaction::NonceTooLow { .. }) {
                                    // if the nonce is too low, we can skip this transaction
                                    trace!(target: "payload_builder", %err, ?tx, "skipping nonce too low transaction");
                                } else {
                                    // if the transaction is invalid, we can skip it and all of its
                                    // descendants
                                    trace!(target: "payload_builder", %err, ?tx, "skipping invalid transaction and its descendants");
                                    best_txs.mark_invalid(&pool_tx);
                                }

                                continue
                            }
                            err => {
                                // this is an error that we should treat as fatal for this attempt
                                return Err(PayloadBuilderError::EvmExecutionError(err))
                            }
                        }
                    }
                };
                // drop evm so db is released.
                drop(evm);
                // commit changes
                db.commit(state);

                let gas_used = result.gas_used();

                // add gas used by the transaction to cumulative gas used, before creating the
                // receipt
                cumulative_gas_used += gas_used;

                // Push transaction changeset and calculate header bloom filter for receipt.
                receipts.push(Some(Receipt {
                    tx_type: tx.tx_type(),
                    success: result.is_success(),
                    cumulative_gas_used,
                    logs: result.logs().into_iter().map(Into::into).collect(),
                    deposit_nonce: None,
                    deposit_receipt_version: None,
                }));

                // update add to total fees
                let miner_fee = tx
                    .effective_tip_per_gas(Some(base_fee))
                    .expect("fee is always valid; execution succeeded");
                total_fees += U256::from(miner_fee) * U256::from(gas_used);

                // append transaction to the list of executed transactions
                executed_txs.push(tx.into_signed());
            }
        }

        // check if we have a better block
        if !is_better_payload(best_payload.as_ref(), total_fees) {
            // can skip building the block
            return Ok(BuildOutcome::Aborted { fees: total_fees, cached_reads })
        }

        let WithdrawalsOutcome { withdrawals_root, withdrawals } = commit_withdrawals(
            &mut db,
            &chain_spec,
            attributes.payload_attributes.timestamp,
            attributes.payload_attributes.withdrawals,
        )?;

        // merge all transitions into bundle state, this would apply the withdrawal balance changes
        // and 4788 contract call
        db.merge_transitions(BundleRetention::PlainState);

        let bundle = BundleStateWithReceipts::new(
            db.take_bundle(),
            Receipts::from_vec(vec![receipts]),
            block_number,
        );
        let receipts_root = bundle
            .optimism_receipts_root_slow(
                block_number,
                chain_spec.as_ref(),
                attributes.payload_attributes.timestamp,
            )
            .expect("Number is in range");
        let logs_bloom = bundle.block_logs_bloom(block_number).expect("Number is in range");

        // calculate the state root
        let state_root = state_provider.state_root(&bundle)?;

        // create the block header
        let transactions_root = proofs::calculate_transaction_root(&executed_txs);

        // initialize empty blob sidecars. There are no blob transactions on L2.
        let blob_sidecars = Vec::new();
        let mut excess_blob_gas = None;
        let mut blob_gas_used = None;

        // only determine cancun fields when active
        if chain_spec.is_cancun_active_at_timestamp(attributes.payload_attributes.timestamp) {
            excess_blob_gas = if chain_spec.is_cancun_active_at_timestamp(parent_block.timestamp) {
                let parent_excess_blob_gas = parent_block.excess_blob_gas.unwrap_or_default();
                let parent_blob_gas_used = parent_block.blob_gas_used.unwrap_or_default();
                Some(calculate_excess_blob_gas(parent_excess_blob_gas, parent_blob_gas_used))
            } else {
                // for the first post-fork block, both parent.blob_gas_used and
                // parent.excess_blob_gas are evaluated as 0
                Some(calculate_excess_blob_gas(0, 0))
            };

            blob_gas_used = Some(0);
        }

        let header = Header {
            parent_hash: parent_block.hash(),
            ommers_hash: EMPTY_OMMER_ROOT_HASH,
            beneficiary: initialized_block_env.coinbase,
            state_root,
            transactions_root,
            receipts_root,
            withdrawals_root,
            logs_bloom,
            timestamp: attributes.payload_attributes.timestamp,
            mix_hash: attributes.payload_attributes.prev_randao,
            nonce: BEACON_NONCE,
            base_fee_per_gas: Some(base_fee),
            number: parent_block.number + 1,
            gas_limit: block_gas_limit,
            difficulty: U256::ZERO,
            gas_used: cumulative_gas_used,
            extra_data,
            parent_beacon_block_root: attributes.payload_attributes.parent_beacon_block_root,
            blob_gas_used,
            excess_blob_gas,
        };

        // seal the block
        let block = Block { header, body: executed_txs, ommers: vec![], withdrawals };

        let sealed_block = block.seal_slow();
        debug!(target: "payload_builder", ?sealed_block, "sealed built block");

        let mut payload =
            EthBuiltPayload::new(attributes.payload_attributes.id, sealed_block, total_fees);

        // extend the payload with the blob sidecars from the executed txs
        payload.extend_sidecars(blob_sidecars);

        Ok(BuildOutcome::Better { payload, cached_reads })
    }
}