#![allow(deprecated)]

use crate::{
    blobstore::BlobStoreError,
    error::PoolResult,
    pool::{state::SubPool, BestTransactionFilter, TransactionEvents},
    validate::ValidPoolTransaction,
    AllTransactionsEvents,
};
use futures_util::{ready, Stream};
use reth_eth_wire_types::HandleMempoolData;
use reth_primitives::{
    kzg::KzgSettings, transaction::TryFromRecoveredTransactionError, AccessList, Address,
    BlobTransactionSidecar, BlobTransactionValidationError, FromRecoveredPooledTransaction,
    IntoRecoveredTransaction, PooledTransactionsElement, PooledTransactionsElementEcRecovered,
    SealedBlock, Transaction, TransactionSignedEcRecovered, TryFromRecoveredTransaction, TxHash,
    TxKind, B256, EIP1559_TX_TYPE_ID, EIP4844_TX_TYPE_ID, U256,
};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use std::{
    collections::{HashMap, HashSet},
    fmt,
    future::Future,
    pin::Pin,
    sync::Arc,
    task::{Context, Poll},
};
use tokio::sync::mpsc::Receiver;

/// The `PeerId` type.
pub type PeerId = reth_primitives::B512;

/// General purpose abstraction of a transaction-pool.
///
/// This is intended to be used by API-consumers such as RPC that need inject new incoming,
/// unverified transactions. And by block production that needs to get transactions to execute in a
/// new block.
///
/// Note: This requires `Clone` for convenience, since it is assumed that this will be implemented
/// for a wrapped `Arc` type, see also [`Pool`](crate::Pool).
#[auto_impl::auto_impl(Arc)]
pub trait TransactionPool: Send + Sync + Clone {
    /// The transaction type of the pool
    type Transaction: PoolTransaction;

    /// Returns stats about the pool and all sub-pools.
    fn pool_size(&self) -> PoolSize;

    /// Returns the block the pool is currently tracking.
    ///
    /// This tracks the block that the pool has last seen.
    fn block_info(&self) -> BlockInfo;

    /// Imports an _external_ transaction.
    ///
    /// This is intended to be used by the network to insert incoming transactions received over the
    /// p2p network.
    ///
    /// Consumer: P2P
    fn add_external_transaction(
        &self,
        transaction: Self::Transaction,
    ) -> impl Future<Output = PoolResult<TxHash>> + Send {
        self.add_transaction(TransactionOrigin::External, transaction)
    }

    /// Imports all _external_ transactions
    ///
    ///
    /// Consumer: Utility
    fn add_external_transactions(
        &self,
        transactions: Vec<Self::Transaction>,
    ) -> impl Future<Output = Vec<PoolResult<TxHash>>> + Send {
        self.add_transactions(TransactionOrigin::External, transactions)
    }

    /// Adds an _unvalidated_ transaction into the pool and subscribe to state changes.
    ///
    /// This is the same as [TransactionPool::add_transaction] but returns an event stream for the
    /// given transaction.
    ///
    /// Consumer: Custom
    fn add_transaction_and_subscribe(
        &self,
        origin: TransactionOrigin,
        transaction: Self::Transaction,
    ) -> impl Future<Output = PoolResult<TransactionEvents>> + Send;

    /// Adds an _unvalidated_ transaction into the pool.
    ///
    /// Consumer: RPC
    fn add_transaction(
        &self,
        origin: TransactionOrigin,
        transaction: Self::Transaction,
    ) -> impl Future<Output = PoolResult<TxHash>> + Send;

    /// Adds the given _unvalidated_ transaction into the pool.
    ///
    /// Returns a list of results.
    ///
    /// Consumer: RPC
    fn add_transactions(
        &self,
        origin: TransactionOrigin,
        transactions: Vec<Self::Transaction>,
    ) -> impl Future<Output = Vec<PoolResult<TxHash>>> + Send;

    /// Returns a new transaction change event stream for the given transaction.
    ///
    /// Returns `None` if the transaction is not in the pool.
    fn transaction_event_listener(&self, tx_hash: TxHash) -> Option<TransactionEvents>;

    /// Returns a new transaction change event stream for _all_ transactions in the pool.
    fn all_transactions_event_listener(&self) -> AllTransactionsEvents<Self::Transaction>;

    /// Returns a new Stream that yields transactions hashes for new __pending__ transactions
    /// inserted into the pool that are allowed to be propagated.
    ///
    /// Note: This is intended for networking and will __only__ yield transactions that are allowed
    /// to be propagated over the network, see also [TransactionListenerKind].
    ///
    /// Consumer: RPC/P2P
    fn pending_transactions_listener(&self) -> Receiver<TxHash> {
        self.pending_transactions_listener_for(TransactionListenerKind::PropagateOnly)
    }

    /// Returns a new [Receiver] that yields transactions hashes for new __pending__ transactions
    /// inserted into the pending pool depending on the given [TransactionListenerKind] argument.
    fn pending_transactions_listener_for(&self, kind: TransactionListenerKind) -> Receiver<TxHash>;

    /// Returns a new stream that yields new valid transactions added to the pool.
    fn new_transactions_listener(&self) -> Receiver<NewTransactionEvent<Self::Transaction>> {
        self.new_transactions_listener_for(TransactionListenerKind::PropagateOnly)
    }

    /// Returns a new [Receiver] that yields blob "sidecars" (blobs w/ assoc. kzg
    /// commitments/proofs) for eip-4844 transactions inserted into the pool
    fn blob_transaction_sidecars_listener(&self) -> Receiver<NewBlobSidecar>;

    /// Returns a new stream that yields new valid transactions added to the pool
    /// depending on the given [TransactionListenerKind] argument.
    fn new_transactions_listener_for(
        &self,
        kind: TransactionListenerKind,
    ) -> Receiver<NewTransactionEvent<Self::Transaction>>;

    /// Returns a new Stream that yields new transactions added to the pending sub-pool.
    ///
    /// This is a convenience wrapper around [Self::new_transactions_listener] that filters for
    /// [SubPool::Pending](crate::SubPool).
    fn new_pending_pool_transactions_listener(
        &self,
    ) -> NewSubpoolTransactionStream<Self::Transaction> {
        NewSubpoolTransactionStream::new(
            self.new_transactions_listener_for(TransactionListenerKind::PropagateOnly),
            SubPool::Pending,
        )
    }

    /// Returns a new Stream that yields new transactions added to the basefee sub-pool.
    ///
    /// This is a convenience wrapper around [Self::new_transactions_listener] that filters for
    /// [SubPool::BaseFee](crate::SubPool).
    fn new_basefee_pool_transactions_listener(
        &self,
    ) -> NewSubpoolTransactionStream<Self::Transaction> {
        NewSubpoolTransactionStream::new(self.new_transactions_listener(), SubPool::BaseFee)
    }

    /// Returns a new Stream that yields new transactions added to the queued-pool.
    ///
    /// This is a convenience wrapper around [Self::new_transactions_listener] that filters for
    /// [SubPool::Queued](crate::SubPool).
    fn new_queued_transactions_listener(&self) -> NewSubpoolTransactionStream<Self::Transaction> {
        NewSubpoolTransactionStream::new(self.new_transactions_listener(), SubPool::Queued)
    }

    /// Returns the _hashes_ of all transactions in the pool.
    ///
    /// Note: This returns a `Vec` but should guarantee that all hashes are unique.
    ///
    /// Consumer: P2P
    fn pooled_transaction_hashes(&self) -> Vec<TxHash>;

    /// Returns only the first `max` hashes of transactions in the pool.
    ///
    /// Consumer: P2P
    fn pooled_transaction_hashes_max(&self, max: usize) -> Vec<TxHash>;

    /// Returns the _full_ transaction objects all transactions in the pool.
    ///
    /// This is intended to be used by the network for the initial exchange of pooled transaction
    /// _hashes_
    ///
    /// Note: This returns a `Vec` but should guarantee that all transactions are unique.
    ///
    /// Caution: In case of blob transactions, this does not include the sidecar.
    ///
    /// Consumer: P2P
    fn pooled_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns only the first `max` transactions in the pool.
    ///
    /// Consumer: P2P
    fn pooled_transactions_max(
        &self,
        max: usize,
    ) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns converted [PooledTransactionsElement] for the given transaction hashes.
    ///
    /// This adheres to the expected behavior of
    /// [`GetPooledTransactions`](https://github.com/ethereum/devp2p/blob/master/caps/eth.md#getpooledtransactions-0x09):
    ///
    /// The transactions must be in same order as in the request, but it is OK to skip transactions
    /// which are not available.
    ///
    /// If the transaction is a blob transaction, the sidecar will be included.
    ///
    /// Consumer: P2P
    fn get_pooled_transaction_elements(
        &self,
        tx_hashes: Vec<TxHash>,
        limit: GetPooledTransactionLimit,
    ) -> Vec<PooledTransactionsElement>;

    /// Returns converted [PooledTransactionsElement] for the given transaction hash.
    ///
    /// This adheres to the expected behavior of
    /// [`GetPooledTransactions`](https://github.com/ethereum/devp2p/blob/master/caps/eth.md#getpooledtransactions-0x09):
    ///
    /// If the transaction is a blob transaction, the sidecar will be included.
    ///
    /// Consumer: P2P
    fn get_pooled_transaction_element(&self, tx_hash: TxHash) -> Option<PooledTransactionsElement>;

    /// Returns an iterator that yields transactions that are ready for block production.
    ///
    /// Consumer: Block production
    fn best_transactions(
        &self,
    ) -> Box<dyn BestTransactions<Item = Arc<ValidPoolTransaction<Self::Transaction>>>>;

    /// Returns an iterator that yields transactions that are ready for block production with the
    /// given base fee.
    ///
    /// Consumer: Block production
    #[deprecated(note = "Use best_transactions_with_attributes instead.")]
    fn best_transactions_with_base_fee(
        &self,
        base_fee: u64,
    ) -> Box<dyn BestTransactions<Item = Arc<ValidPoolTransaction<Self::Transaction>>>>;

    /// Returns an iterator that yields transactions that are ready for block production with the
    /// given base fee and optional blob fee attributes.
    ///
    /// Consumer: Block production
    fn best_transactions_with_attributes(
        &self,
        best_transactions_attributes: BestTransactionsAttributes,
    ) -> Box<dyn BestTransactions<Item = Arc<ValidPoolTransaction<Self::Transaction>>>>;

    /// Returns all transactions that can be included in the next block.
    ///
    /// This is primarily used for the `txpool_` RPC namespace:
    /// <https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-txpool> which distinguishes
    /// between `pending` and `queued` transactions, where `pending` are transactions ready for
    /// inclusion in the next block and `queued` are transactions that are ready for inclusion in
    /// future blocks.
    ///
    /// Consumer: RPC
    fn pending_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns all transactions that can be included in _future_ blocks.
    ///
    /// This and [Self::pending_transactions] are mutually exclusive.
    ///
    /// Consumer: RPC
    fn queued_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns all transactions that are currently in the pool grouped by whether they are ready
    /// for inclusion in the next block or not.
    ///
    /// This is primarily used for the `txpool_` namespace: <https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-txpool>
    ///
    /// Consumer: RPC
    fn all_transactions(&self) -> AllPoolTransactions<Self::Transaction>;

    /// Removes all transactions corresponding to the given hashes.
    ///
    /// Also removes all _dependent_ transactions.
    ///
    /// Consumer: Utility
    fn remove_transactions(
        &self,
        hashes: Vec<TxHash>,
    ) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Retains only those hashes that are unknown to the pool.
    /// In other words, removes all transactions from the given set that are currently present in
    /// the pool. Returns hashes already known to the pool.
    ///
    /// Consumer: P2P
    fn retain_unknown<A>(&self, announcement: &mut A)
    where
        A: HandleMempoolData;

    /// Returns if the transaction for the given hash is already included in this pool.
    fn contains(&self, tx_hash: &TxHash) -> bool {
        self.get(tx_hash).is_some()
    }

    /// Returns the transaction for the given hash.
    fn get(&self, tx_hash: &TxHash) -> Option<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns all transactions objects for the given hashes.
    ///
    /// Caution: This in case of blob transactions, this does not include the sidecar.
    fn get_all(&self, txs: Vec<TxHash>) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Notify the pool about transactions that are propagated to peers.
    ///
    /// Consumer: P2P
    fn on_propagated(&self, txs: PropagatedTransactions);

    /// Returns all transactions sent by a given user
    fn get_transactions_by_sender(
        &self,
        sender: Address,
    ) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns a transaction sent by a given user with a given nonce
    fn get_transactions_by_sender_and_nonce(
        &self,
        sender: Address,
        nonce: u64,
    ) -> Option<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns all transactions that where submitted with the given [TransactionOrigin]
    fn get_transactions_by_origin(
        &self,
        origin: TransactionOrigin,
    ) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>>;

    /// Returns all transactions that where submitted as [TransactionOrigin::Local]
    fn get_local_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>> {
        self.get_transactions_by_origin(TransactionOrigin::Local)
    }

    /// Returns all transactions that where submitted as [TransactionOrigin::Private]
    fn get_private_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>> {
        self.get_transactions_by_origin(TransactionOrigin::Private)
    }

    /// Returns all transactions that where submitted as [TransactionOrigin::External]
    fn get_external_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>> {
        self.get_transactions_by_origin(TransactionOrigin::External)
    }

    /// Returns a set of all senders of transactions in the pool
    fn unique_senders(&self) -> HashSet<Address>;

    /// Returns the [BlobTransactionSidecar] for the given transaction hash if it exists in the blob
    /// store.
    fn get_blob(&self, tx_hash: TxHash) -> Result<Option<BlobTransactionSidecar>, BlobStoreError>;

    /// Returns all [BlobTransactionSidecar] for the given transaction hashes if they exists in the
    /// blob store.
    ///
    /// This only returns the blobs that were found in the store.
    /// If there's no blob it will not be returned.
    fn get_all_blobs(
        &self,
        tx_hashes: Vec<TxHash>,
    ) -> Result<Vec<(TxHash, BlobTransactionSidecar)>, BlobStoreError>;

    /// Returns the exact [BlobTransactionSidecar] for the given transaction hashes in the order
    /// they were requested.
    ///
    /// Returns an error if any of the blobs are not found in the blob store.
    fn get_all_blobs_exact(
        &self,
        tx_hashes: Vec<TxHash>,
    ) -> Result<Vec<BlobTransactionSidecar>, BlobStoreError>;
}

/// Extension for [TransactionPool] trait that allows to set the current block info.
#[auto_impl::auto_impl(Arc)]
pub trait TransactionPoolExt: TransactionPool {
    /// Sets the current block info for the pool.
    fn set_block_info(&self, info: BlockInfo);

    /// Event listener for when the pool needs to be updated.
    ///
    /// Implementers need to update the pool accordingly:
    ///
    /// ## Fee changes
    ///
    /// The [CanonicalStateUpdate] includes the base and blob fee of the pending block, which
    /// affects the dynamic fee requirement of pending transactions in the pool.
    ///
    /// ## EIP-4844 Blob transactions
    ///
    /// Mined blob transactions need to be removed from the pool, but from the pool only. The blob
    /// sidecar must not be removed from the blob store. Only after a blob transaction is
    /// finalized, its sidecar is removed from the blob store. This ensures that in case of a reorg,
    /// the sidecar is still available.
    fn on_canonical_state_change(&self, update: CanonicalStateUpdate<'_>);

    /// Updates the accounts in the pool
    fn update_accounts(&self, accounts: Vec<ChangedAccount>);

    /// Deletes the blob sidecar for the given transaction from the blob store
    fn delete_blob(&self, tx: B256);

    /// Deletes multiple blob sidecars from the blob store
    fn delete_blobs(&self, txs: Vec<B256>);

    /// Maintenance function to cleanup blobs that are no longer needed.
    fn cleanup_blobs(&self);
}

/// Determines what kind of new transactions should be emitted by a stream of transactions.
///
/// This gives control whether to include transactions that are allowed to be propagated.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum TransactionListenerKind {
    /// Any new pending transactions
    All,
    /// Only transactions that are allowed to be propagated.
    ///
    /// See also [`ValidPoolTransaction`]
    PropagateOnly,
}

impl TransactionListenerKind {
    /// Returns true if we're only interested in transactions that are allowed to be propagated.
    #[inline]
    pub const fn is_propagate_only(&self) -> bool {
        matches!(self, Self::PropagateOnly)
    }
}

/// A Helper type that bundles all transactions in the pool.
#[derive(Debug, Clone)]
pub struct AllPoolTransactions<T: PoolTransaction> {
    /// Transactions that are ready for inclusion in the next block.
    pub pending: Vec<Arc<ValidPoolTransaction<T>>>,
    /// Transactions that are ready for inclusion in _future_ blocks, but are currently parked,
    /// because they depend on other transactions that are not yet included in the pool (nonce gap)
    /// or otherwise blocked.
    pub queued: Vec<Arc<ValidPoolTransaction<T>>>,
}

// === impl AllPoolTransactions ===

impl<T: PoolTransaction> AllPoolTransactions<T> {
    /// Returns an iterator over all pending [`TransactionSignedEcRecovered`] transactions.
    pub fn pending_recovered(&self) -> impl Iterator<Item = TransactionSignedEcRecovered> + '_ {
        self.pending.iter().map(|tx| tx.transaction.to_recovered_transaction())
    }

    /// Returns an iterator over all queued [`TransactionSignedEcRecovered`] transactions.
    pub fn queued_recovered(&self) -> impl Iterator<Item = TransactionSignedEcRecovered> + '_ {
        self.queued.iter().map(|tx| tx.transaction.to_recovered_transaction())
    }
}

impl<T: PoolTransaction> Default for AllPoolTransactions<T> {
    fn default() -> Self {
        Self { pending: Default::default(), queued: Default::default() }
    }
}

/// Represents a transaction that was propagated over the network.
#[derive(Debug, Clone, Eq, PartialEq, Default)]
pub struct PropagatedTransactions(pub HashMap<TxHash, Vec<PropagateKind>>);

/// Represents how a transaction was propagated over the network.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum PropagateKind {
    /// The full transaction object was sent to the peer.
    ///
    /// This is equivalent to the `Transaction` message
    Full(PeerId),
    /// Only the Hash was propagated to the peer.
    Hash(PeerId),
}

// === impl PropagateKind ===

impl PropagateKind {
    /// Returns the peer the transaction was sent to
    pub const fn peer(&self) -> &PeerId {
        match self {
            Self::Full(peer) | Self::Hash(peer) => peer,
        }
    }
}

impl From<PropagateKind> for PeerId {
    fn from(value: PropagateKind) -> Self {
        match value {
            PropagateKind::Full(peer) | PropagateKind::Hash(peer) => peer,
        }
    }
}

/// Represents a new transaction
#[derive(Debug)]
pub struct NewTransactionEvent<T: PoolTransaction> {
    /// The pool which the transaction was moved to.
    pub subpool: SubPool,
    /// Actual transaction
    pub transaction: Arc<ValidPoolTransaction<T>>,
}

impl<T: PoolTransaction> Clone for NewTransactionEvent<T> {
    fn clone(&self) -> Self {
        Self { subpool: self.subpool, transaction: self.transaction.clone() }
    }
}

/// This type represents a new blob sidecar that has been stored in the transaction pool's
/// blobstore; it includes the `TransactionHash` of the blob transaction along with the assoc.
/// sidecar (blobs, commitments, proofs)
#[derive(Debug, Clone)]
pub struct NewBlobSidecar {
    /// hash of the EIP-4844 transaction.
    pub tx_hash: TxHash,
    /// the blob transaction sidecar.
    pub sidecar: Arc<BlobTransactionSidecar>,
}

/// Where the transaction originates from.
///
/// Depending on where the transaction was picked up, it affects how the transaction is handled
/// internally, e.g. limits for simultaneous transaction of one sender.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum TransactionOrigin {
    /// Transaction is coming from a local source.
    Local,
    /// Transaction has been received externally.
    ///
    /// This is usually considered an "untrusted" source, for example received from another in the
    /// network.
    External,
    /// Transaction is originated locally and is intended to remain private.
    ///
    /// This type of transaction should not be propagated to the network. It's meant for
    /// private usage within the local node only.
    Private,
}

// === impl TransactionOrigin ===

impl TransactionOrigin {
    /// Whether the transaction originates from a local source.
    pub const fn is_local(&self) -> bool {
        matches!(self, Self::Local)
    }

    /// Whether the transaction originates from an external source.
    pub const fn is_external(&self) -> bool {
        matches!(self, Self::External)
    }
    /// Whether the transaction originates from a private source.
    pub const fn is_private(&self) -> bool {
        matches!(self, Self::Private)
    }
}

/// Represents changes after a new canonical block or range of canonical blocks was added to the
/// chain.
///
/// It is expected that this is only used if the added blocks are canonical to the pool's last known
/// block hash. In other words, the first added block of the range must be the child of the last
/// known block hash.
///
/// This is used to update the pool state accordingly.
#[derive(Clone, Debug)]
pub struct CanonicalStateUpdate<'a> {
    /// Hash of the tip block.
    pub new_tip: &'a SealedBlock,
    /// EIP-1559 Base fee of the _next_ (pending) block
    ///
    /// The base fee of a block depends on the utilization of the last block and its base fee.
    pub pending_block_base_fee: u64,
    /// EIP-4844 blob fee of the _next_ (pending) block
    ///
    /// Only after Cancun
    pub pending_block_blob_fee: Option<u128>,
    /// A set of changed accounts across a range of blocks.
    pub changed_accounts: Vec<ChangedAccount>,
    /// All mined transactions in the block range.
    pub mined_transactions: Vec<B256>,
}

impl<'a> CanonicalStateUpdate<'a> {
    /// Returns the number of the tip block.
    pub fn number(&self) -> u64 {
        self.new_tip.number
    }

    /// Returns the hash of the tip block.
    pub const fn hash(&self) -> B256 {
        self.new_tip.hash()
    }

    /// Timestamp of the latest chain update
    pub fn timestamp(&self) -> u64 {
        self.new_tip.timestamp
    }

    /// Returns the block info for the tip block.
    pub fn block_info(&self) -> BlockInfo {
        BlockInfo {
            last_seen_block_hash: self.hash(),
            last_seen_block_number: self.number(),
            pending_basefee: self.pending_block_base_fee,
            pending_blob_fee: self.pending_block_blob_fee,
        }
    }
}

impl fmt::Display for CanonicalStateUpdate<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("CanonicalStateUpdate")
            .field("hash", &self.hash())
            .field("number", &self.number())
            .field("pending_block_base_fee", &self.pending_block_base_fee)
            .field("pending_block_blob_fee", &self.pending_block_blob_fee)
            .field("changed_accounts", &self.changed_accounts.len())
            .field("mined_transactions", &self.mined_transactions.len())
            .finish()
    }
}

/// Represents a changed account
#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
pub struct ChangedAccount {
    /// The address of the account.
    pub address: Address,
    /// Account nonce.
    pub nonce: u64,
    /// Account balance.
    pub balance: U256,
}

// === impl ChangedAccount ===

impl ChangedAccount {
    /// Creates a new `ChangedAccount` with the given address and 0 balance and nonce.
    pub(crate) const fn empty(address: Address) -> Self {
        Self { address, nonce: 0, balance: U256::ZERO }
    }
}

/// An `Iterator` that only returns transactions that are ready to be executed.
///
/// This makes no assumptions about the order of the transactions, but expects that _all_
/// transactions are valid (no nonce gaps.) for the tracked state of the pool.
///
/// Note: this iterator will always return the best transaction that it currently knows.
/// There is no guarantee transactions will be returned sequentially in decreasing
/// priority order.
pub trait BestTransactions: Iterator + Send {
    /// Mark the transaction as invalid.
    ///
    /// Implementers must ensure all subsequent transaction _don't_ depend on this transaction.
    /// In other words, this must remove the given transaction _and_ drain all transaction that
    /// depend on it.
    fn mark_invalid(&mut self, transaction: &Self::Item);

    /// An iterator may be able to receive additional pending transactions that weren't present it
    /// the pool when it was created.
    ///
    /// This ensures that iterator will return the best transaction that it currently knows and not
    /// listen to pool updates.
    fn no_updates(&mut self);

    /// Skip all blob transactions.
    ///
    /// There's only limited blob space available in a block, once exhausted, EIP-4844 transactions
    /// can no longer be included.
    ///
    /// If called then the iterator will no longer yield blob transactions.
    ///
    /// Note: this will also exclude any transactions that depend on blob transactions.
    fn skip_blobs(&mut self);

    /// Controls whether the iterator skips blob transactions or not.
    ///
    /// If set to true, no blob transactions will be returned.
    fn set_skip_blobs(&mut self, skip_blobs: bool);

    /// Creates an iterator which uses a closure to determine if a transaction should be yielded.
    ///
    /// Given an element the closure must return true or false. The returned iterator will yield
    /// only the elements for which the closure returns true.
    ///
    /// Descendant transactions will be skipped.
    fn filter<P>(self, predicate: P) -> BestTransactionFilter<Self, P>
    where
        P: FnMut(&Self::Item) -> bool,
        Self: Sized,
    {
        BestTransactionFilter::new(self, predicate)
    }
}

/// A no-op implementation that yields no transactions.
impl<T> BestTransactions for std::iter::Empty<T> {
    fn mark_invalid(&mut self, _tx: &T) {}

    fn no_updates(&mut self) {}

    fn skip_blobs(&mut self) {}

    fn set_skip_blobs(&mut self, _skip_blobs: bool) {}
}

/// A Helper type that bundles best transactions attributes together.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub struct BestTransactionsAttributes {
    /// The base fee attribute for best transactions.
    pub basefee: u64,
    /// The blob fee attribute for best transactions.
    pub blob_fee: Option<u64>,
}

// === impl BestTransactionsAttributes ===

impl BestTransactionsAttributes {
    /// Creates a new `BestTransactionsAttributes` with the given basefee and blob fee.
    pub const fn new(basefee: u64, blob_fee: Option<u64>) -> Self {
        Self { basefee, blob_fee }
    }

    /// Creates a new `BestTransactionsAttributes` with the given basefee.
    pub const fn base_fee(basefee: u64) -> Self {
        Self::new(basefee, None)
    }

    /// Sets the given blob fee.
    pub const fn with_blob_fee(mut self, blob_fee: u64) -> Self {
        self.blob_fee = Some(blob_fee);
        self
    }
}

/// Trait for transaction types used inside the pool
pub trait PoolTransaction:
    fmt::Debug
    + Send
    + Sync
    + FromRecoveredPooledTransaction
    + TryFromRecoveredTransaction
    + IntoRecoveredTransaction
{
    /// Hash of the transaction.
    fn hash(&self) -> &TxHash;

    /// The Sender of the transaction.
    fn sender(&self) -> Address;

    /// Returns the nonce for this transaction.
    fn nonce(&self) -> u64;

    /// Returns the cost that this transaction is allowed to consume:
    ///
    /// For EIP-1559 transactions: `max_fee_per_gas * gas_limit + tx_value`.
    /// For legacy transactions: `gas_price * gas_limit + tx_value`.
    /// For EIP-4844 blob transactions: `max_fee_per_gas * gas_limit + tx_value +
    /// max_blob_fee_per_gas * blob_gas_used`.
    fn cost(&self) -> U256;

    /// Amount of gas that should be used in executing this transaction. This is paid up-front.
    fn gas_limit(&self) -> u64;

    /// Returns the EIP-1559 the maximum fee per gas the caller is willing to pay.
    ///
    /// For legacy transactions this is `gas_price`.
    ///
    /// This is also commonly referred to as the "Gas Fee Cap" (`GasFeeCap`).
    fn max_fee_per_gas(&self) -> u128;

    /// Returns the `access_list` for the particular transaction type.
    /// For Legacy transactions, returns default.
    fn access_list(&self) -> Option<&AccessList>;

    /// Returns the EIP-1559 Priority fee the caller is paying to the block author.
    ///
    /// This will return `None` for non-EIP1559 transactions
    fn max_priority_fee_per_gas(&self) -> Option<u128>;

    /// Returns the EIP-4844 max fee per data gas
    ///
    /// This will return `None` for non-EIP4844 transactions
    fn max_fee_per_blob_gas(&self) -> Option<u128>;

    /// Returns the effective tip for this transaction.
    ///
    /// For EIP-1559 transactions: `min(max_fee_per_gas - base_fee, max_priority_fee_per_gas)`.
    /// For legacy transactions: `gas_price - base_fee`.
    fn effective_tip_per_gas(&self, base_fee: u64) -> Option<u128>;

    /// Returns the max priority fee per gas if the transaction is an EIP-1559 transaction, and
    /// otherwise returns the gas price.
    fn priority_fee_or_price(&self) -> u128;

    /// Returns the transaction's [`TxKind`], which is the address of the recipient or
    /// [`TxKind::Create`] if the transaction is a contract creation.
    fn kind(&self) -> TxKind;

    /// Returns the recipient of the transaction if it is not a [`TxKind::Create`]
    /// transaction.
    fn to(&self) -> Option<Address> {
        self.kind().to().copied()
    }

    /// Returns the input data of this transaction.
    fn input(&self) -> &[u8];

    /// Returns a measurement of the heap usage of this type and all its internals.
    fn size(&self) -> usize;

    /// Returns the transaction type
    fn tx_type(&self) -> u8;

    /// Returns true if the transaction is an EIP-1559 transaction.
    fn is_eip1559(&self) -> bool {
        self.tx_type() == EIP1559_TX_TYPE_ID
    }

    /// Returns true if the transaction is an EIP-4844 transaction.
    fn is_eip4844(&self) -> bool {
        self.tx_type() == EIP4844_TX_TYPE_ID
    }

    /// Returns the length of the rlp encoded transaction object
    ///
    /// Note: Implementations should cache this value.
    fn encoded_length(&self) -> usize;

    /// Returns `chain_id`
    fn chain_id(&self) -> Option<u64>;
}

/// An extension trait that provides additional interfaces for the
/// [`EthTransactionValidator`](crate::EthTransactionValidator).
pub trait EthPoolTransaction: PoolTransaction {
    /// Extracts the blob sidecar from the transaction.
    fn take_blob(&mut self) -> EthBlobTransactionSidecar;

    /// Returns the number of blobs this transaction has.
    fn blob_count(&self) -> usize;

    /// Validates the blob sidecar of the transaction with the given settings.
    fn validate_blob(
        &self,
        blob: &BlobTransactionSidecar,
        settings: &KzgSettings,
    ) -> Result<(), BlobTransactionValidationError>;
}

/// The default [`PoolTransaction`] for the [Pool](crate::Pool) for Ethereum.
///
/// This type is essentially a wrapper around [`TransactionSignedEcRecovered`] with additional
/// fields derived from the transaction that are frequently used by the pools for ordering.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct EthPooledTransaction {
    /// `EcRecovered` transaction info
    pub(crate) transaction: TransactionSignedEcRecovered,

    /// For EIP-1559 transactions: `max_fee_per_gas * gas_limit + tx_value`.
    /// For legacy transactions: `gas_price * gas_limit + tx_value`.
    /// For EIP-4844 blob transactions: `max_fee_per_gas * gas_limit + tx_value +
    /// max_blob_fee_per_gas * blob_gas_used`.
    pub(crate) cost: U256,

    /// This is the RLP length of the transaction, computed when the transaction is added to the
    /// pool.
    pub(crate) encoded_length: usize,

    /// The blob side car for this transaction
    pub(crate) blob_sidecar: EthBlobTransactionSidecar,
}

/// Represents the blob sidecar of the [`EthPooledTransaction`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum EthBlobTransactionSidecar {
    /// This transaction does not have a blob sidecar
    None,
    /// This transaction has a blob sidecar (EIP-4844) but it is missing
    ///
    /// It was either extracted after being inserted into the pool or re-injected after reorg
    /// without the blob sidecar
    Missing,
    /// The eip-4844 transaction was pulled from the network and still has its blob sidecar
    Present(BlobTransactionSidecar),
}

impl EthBlobTransactionSidecar {
    /// Returns the blob sidecar if it is present
    pub const fn maybe_sidecar(&self) -> Option<&BlobTransactionSidecar> {
        match self {
            Self::Present(sidecar) => Some(sidecar),
            _ => None,
        }
    }
}

impl EthPooledTransaction {
    /// Create new instance of [Self].
    ///
    /// Caution: In case of blob transactions, this does marks the blob sidecar as
    /// [`EthBlobTransactionSidecar::Missing`]
    pub fn new(transaction: TransactionSignedEcRecovered, encoded_length: usize) -> Self {
        let mut blob_sidecar = EthBlobTransactionSidecar::None;

        #[allow(unreachable_patterns)]
        let gas_cost = match &transaction.transaction {
            Transaction::Legacy(t) => {
                U256::from(t.gas_price).saturating_mul(U256::from(t.gas_limit))
            }
            Transaction::Eip2930(t) => {
                U256::from(t.gas_price).saturating_mul(U256::from(t.gas_limit))
            }
            Transaction::Eip1559(t) => {
                U256::from(t.max_fee_per_gas).saturating_mul(U256::from(t.gas_limit))
            }
            Transaction::Eip4844(t) => {
                blob_sidecar = EthBlobTransactionSidecar::Missing;
                U256::from(t.max_fee_per_gas).saturating_mul(U256::from(t.gas_limit))
            }
            _ => U256::ZERO,
        };
        let mut cost = transaction.value();
        cost = cost.saturating_add(gas_cost);

        if let Some(blob_tx) = transaction.as_eip4844() {
            // Add max blob cost using saturating math to avoid overflow
            cost = cost.saturating_add(U256::from(
                blob_tx.max_fee_per_blob_gas.saturating_mul(blob_tx.blob_gas() as u128),
            ));
        }

        Self { transaction, cost, encoded_length, blob_sidecar }
    }

    /// Return the reference to the underlying transaction.
    pub const fn transaction(&self) -> &TransactionSignedEcRecovered {
        &self.transaction
    }
}

/// Conversion from the network transaction type to the pool transaction type.
impl From<PooledTransactionsElementEcRecovered> for EthPooledTransaction {
    fn from(tx: PooledTransactionsElementEcRecovered) -> Self {
        let encoded_length = tx.length_without_header();
        let (tx, signer) = tx.into_components();
        match tx {
            PooledTransactionsElement::BlobTransaction(tx) => {
                // include the blob sidecar
                let (tx, blob) = tx.into_parts();
                let tx = TransactionSignedEcRecovered::from_signed_transaction(tx, signer);
                let mut pooled = Self::new(tx, encoded_length);
                pooled.blob_sidecar = EthBlobTransactionSidecar::Present(blob);
                pooled
            }
            tx => {
                // no blob sidecar
                Self::new(tx.into_ecrecovered_transaction(signer), encoded_length)
            }
        }
    }
}

impl PoolTransaction for EthPooledTransaction {
    /// Returns hash of the transaction.
    fn hash(&self) -> &TxHash {
        self.transaction.hash_ref()
    }

    /// Returns the Sender of the transaction.
    fn sender(&self) -> Address {
        self.transaction.signer()
    }

    /// Returns the nonce for this transaction.
    fn nonce(&self) -> u64 {
        self.transaction.nonce()
    }

    /// Returns the cost that this transaction is allowed to consume:
    ///
    /// For EIP-1559 transactions: `max_fee_per_gas * gas_limit + tx_value`.
    /// For legacy transactions: `gas_price * gas_limit + tx_value`.
    /// For EIP-4844 blob transactions: `max_fee_per_gas * gas_limit + tx_value +
    /// max_blob_fee_per_gas * blob_gas_used`.
    fn cost(&self) -> U256 {
        self.cost
    }

    /// Amount of gas that should be used in executing this transaction. This is paid up-front.
    fn gas_limit(&self) -> u64 {
        self.transaction.gas_limit()
    }

    /// Returns the EIP-1559 Max base fee the caller is willing to pay.
    ///
    /// For legacy transactions this is `gas_price`.
    ///
    /// This is also commonly referred to as the "Gas Fee Cap" (`GasFeeCap`).
    fn max_fee_per_gas(&self) -> u128 {
        #[allow(unreachable_patterns)]
        match &self.transaction.transaction {
            Transaction::Legacy(tx) => tx.gas_price,
            Transaction::Eip2930(tx) => tx.gas_price,
            Transaction::Eip1559(tx) => tx.max_fee_per_gas,
            Transaction::Eip4844(tx) => tx.max_fee_per_gas,
            _ => 0,
        }
    }

    fn access_list(&self) -> Option<&AccessList> {
        self.transaction.access_list()
    }

    /// Returns the EIP-1559 Priority fee the caller is paying to the block author.
    ///
    /// This will return `None` for non-EIP1559 transactions
    fn max_priority_fee_per_gas(&self) -> Option<u128> {
        #[allow(unreachable_patterns, clippy::match_same_arms)]
        match &self.transaction.transaction {
            Transaction::Legacy(_) | Transaction::Eip2930(_) => None,
            Transaction::Eip1559(tx) => Some(tx.max_priority_fee_per_gas),
            Transaction::Eip4844(tx) => Some(tx.max_priority_fee_per_gas),
            _ => None,
        }
    }

    fn max_fee_per_blob_gas(&self) -> Option<u128> {
        self.transaction.max_fee_per_blob_gas()
    }

    /// Returns the effective tip for this transaction.
    ///
    /// For EIP-1559 transactions: `min(max_fee_per_gas - base_fee, max_priority_fee_per_gas)`.
    /// For legacy transactions: `gas_price - base_fee`.
    fn effective_tip_per_gas(&self, base_fee: u64) -> Option<u128> {
        self.transaction.effective_tip_per_gas(Some(base_fee))
    }

    /// Returns the max priority fee per gas if the transaction is an EIP-1559 transaction, and
    /// otherwise returns the gas price.
    fn priority_fee_or_price(&self) -> u128 {
        self.transaction.priority_fee_or_price()
    }

    /// Returns the transaction's [`TxKind`], which is the address of the recipient or
    /// [`TxKind::Create`] if the transaction is a contract creation.
    fn kind(&self) -> TxKind {
        self.transaction.kind()
    }

    fn input(&self) -> &[u8] {
        self.transaction.input().as_ref()
    }

    /// Returns a measurement of the heap usage of this type and all its internals.
    fn size(&self) -> usize {
        self.transaction.transaction.input().len()
    }

    /// Returns the transaction type
    fn tx_type(&self) -> u8 {
        self.transaction.tx_type().into()
    }

    /// Returns the length of the rlp encoded object
    fn encoded_length(&self) -> usize {
        self.encoded_length
    }

    /// Returns `chain_id`
    fn chain_id(&self) -> Option<u64> {
        self.transaction.chain_id()
    }
}

impl EthPoolTransaction for EthPooledTransaction {
    fn take_blob(&mut self) -> EthBlobTransactionSidecar {
        if self.is_eip4844() {
            std::mem::replace(&mut self.blob_sidecar, EthBlobTransactionSidecar::Missing)
        } else {
            EthBlobTransactionSidecar::None
        }
    }

    fn blob_count(&self) -> usize {
        match &self.transaction.transaction {
            Transaction::Eip4844(tx) => tx.blob_versioned_hashes.len(),
            _ => 0,
        }
    }

    fn validate_blob(
        &self,
        sidecar: &BlobTransactionSidecar,
        settings: &KzgSettings,
    ) -> Result<(), BlobTransactionValidationError> {
        match &self.transaction.transaction {
            Transaction::Eip4844(tx) => tx.validate_blob(sidecar, settings),
            _ => Err(BlobTransactionValidationError::NotBlobTransaction(self.tx_type())),
        }
    }
}

impl TryFromRecoveredTransaction for EthPooledTransaction {
    type Error = TryFromRecoveredTransactionError;

    fn try_from_recovered_transaction(
        tx: TransactionSignedEcRecovered,
    ) -> Result<Self, Self::Error> {
        // ensure we can handle the transaction type and its format
        match tx.tx_type() as u8 {
            0..=EIP1559_TX_TYPE_ID => {
                // supported
            }
            EIP4844_TX_TYPE_ID => {
                // doesn't have a blob sidecar
                return Err(TryFromRecoveredTransactionError::BlobSidecarMissing)
            }
            unsupported => {
                // unsupported transaction type
                return Err(TryFromRecoveredTransactionError::UnsupportedTransactionType(
                    unsupported,
                ))
            }
        };

        let encoded_length = tx.length_without_header();
        let transaction = Self::new(tx, encoded_length);
        Ok(transaction)
    }
}

impl FromRecoveredPooledTransaction for EthPooledTransaction {
    fn from_recovered_pooled_transaction(tx: PooledTransactionsElementEcRecovered) -> Self {
        Self::from(tx)
    }
}

impl IntoRecoveredTransaction for EthPooledTransaction {
    fn to_recovered_transaction(&self) -> TransactionSignedEcRecovered {
        self.transaction.clone()
    }
}

/// Represents the current status of the pool.
#[derive(Debug, Clone, Copy, Default)]
pub struct PoolSize {
    /// Number of transactions in the _pending_ sub-pool.
    pub pending: usize,
    /// Reported size of transactions in the _pending_ sub-pool.
    pub pending_size: usize,
    /// Number of transactions in the _blob_ pool.
    pub blob: usize,
    /// Reported size of transactions in the _blob_ pool.
    pub blob_size: usize,
    /// Number of transactions in the _basefee_ pool.
    pub basefee: usize,
    /// Reported size of transactions in the _basefee_ sub-pool.
    pub basefee_size: usize,
    /// Number of transactions in the _queued_ sub-pool.
    pub queued: usize,
    /// Reported size of transactions in the _queued_ sub-pool.
    pub queued_size: usize,
    /// Number of all transactions of all sub-pools
    ///
    /// Note: this is the sum of ```pending + basefee + queued```
    pub total: usize,
}

// === impl PoolSize ===

impl PoolSize {
    /// Asserts that the invariants of the pool size are met.
    #[cfg(test)]
    pub(crate) fn assert_invariants(&self) {
        assert_eq!(self.total, self.pending + self.basefee + self.queued + self.blob);
    }
}

/// Represents the current status of the pool.
#[derive(Default, Debug, Clone, Copy, Eq, PartialEq)]
pub struct BlockInfo {
    /// Hash for the currently tracked block.
    pub last_seen_block_hash: B256,
    /// Current the currently tracked block.
    pub last_seen_block_number: u64,
    /// Currently enforced base fee: the threshold for the basefee sub-pool.
    ///
    /// Note: this is the derived base fee of the _next_ block that builds on the block the pool is
    /// currently tracking.
    pub pending_basefee: u64,
    /// Currently enforced blob fee: the threshold for eip-4844 blob transactions.
    ///
    /// Note: this is the derived blob fee of the _next_ block that builds on the block the pool is
    /// currently tracking
    pub pending_blob_fee: Option<u128>,
}

/// The limit to enforce for [`TransactionPool::get_pooled_transaction_elements`].
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum GetPooledTransactionLimit {
    /// No limit, return all transactions.
    None,
    /// Enforce a size limit on the returned transactions, for example 2MB
    ResponseSizeSoftLimit(usize),
}

impl GetPooledTransactionLimit {
    /// Returns true if the given size exceeds the limit.
    #[inline]
    pub const fn exceeds(&self, size: usize) -> bool {
        match self {
            Self::None => false,
            Self::ResponseSizeSoftLimit(limit) => size > *limit,
        }
    }
}

/// A Stream that yields full transactions the subpool
#[must_use = "streams do nothing unless polled"]
#[derive(Debug)]
pub struct NewSubpoolTransactionStream<Tx: PoolTransaction> {
    st: Receiver<NewTransactionEvent<Tx>>,
    subpool: SubPool,
}

// === impl NewSubpoolTransactionStream ===

impl<Tx: PoolTransaction> NewSubpoolTransactionStream<Tx> {
    /// Create a new stream that yields full transactions from the subpool
    pub const fn new(st: Receiver<NewTransactionEvent<Tx>>, subpool: SubPool) -> Self {
        Self { st, subpool }
    }

    /// Tries to receive the next value for this stream.
    pub fn try_recv(
        &mut self,
    ) -> Result<NewTransactionEvent<Tx>, tokio::sync::mpsc::error::TryRecvError> {
        loop {
            match self.st.try_recv() {
                Ok(event) => {
                    if event.subpool == self.subpool {
                        return Ok(event)
                    }
                }
                Err(e) => return Err(e),
            }
        }
    }
}

impl<Tx: PoolTransaction> Stream for NewSubpoolTransactionStream<Tx> {
    type Item = NewTransactionEvent<Tx>;

    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        loop {
            match ready!(self.st.poll_recv(cx)) {
                Some(event) => {
                    if event.subpool == self.subpool {
                        return Poll::Ready(Some(event))
                    }
                }
                None => return Poll::Ready(None),
            }
        }
    }
}
