//! Transaction validation abstractions.

use crate::{
    error::PoolError,
    identifier::{SenderId, TransactionId},
    traits::PoolTransaction,
};
use reth_primitives::{rpc::Address, BlockID, TxHash, U256};
use std::{fmt, time::Instant};

/// A Result type returned after checking a transaction's validity.
pub enum TransactionValidationOutcome<T: PoolTransaction> {
    /// Transaction successfully validated
    Valid {
        /// Balance of the sender at the current point.
        balance: U256,
        /// current nonce of the sender
        state_nonce: u64,
        /// Validated transaction.
        transaction: T,
    },
    /// The transaction is considered invalid indefinitely.
    Invalid(T, PoolError),
}

/// Provides support for validating transaction at any given state of the chain
#[async_trait::async_trait]
pub trait TransactionValidator: Send + Sync + 'static {
    /// The transaction type to validate.
    type Transaction: PoolTransaction;

    /// Validates the transaction and returns a validated outcome
    ///
    /// This is used by the transaction-pool check the transaction's validity against the state of
    /// the given block hash.
    ///
    /// This is supposed to extend the `transaction` with its id in the graph of
    /// transactions for the sender.
    async fn validate_transaction(
        &self,
        _transaction: Self::Transaction,
    ) -> TransactionValidationOutcome<Self::Transaction>;
}

/// A valida transaction in the pool.
pub struct ValidPoolTransaction<T: PoolTransaction> {
    /// The transaction
    pub transaction: T,
    /// The identifier for this transaction.
    pub transaction_id: TransactionId,
    /// Whether to propagate the transaction.
    pub propagate: bool,
    /// Whether the tx is from a local source.
    pub is_local: bool,
    /// Total cost of the transaction: `feeCap x gasLimit + transferred_value`.
    pub cost: U256,
    /// Timestamp when this was added to the pool.
    pub timestamp: Instant,
}

// === impl ValidPoolTransaction ===

impl<T: PoolTransaction> ValidPoolTransaction<T> {
    /// Returns the hash of the transaction.
    pub fn hash(&self) -> &TxHash {
        self.transaction.hash()
    }

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

    /// Returns the internal identifier for the sender of this transaction
    pub(crate) fn sender_id(&self) -> SenderId {
        self.transaction_id.sender
    }

    /// Returns the internal identifier for this transaction.
    pub(crate) fn id(&self) -> &TransactionId {
        &self.transaction_id
    }

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

    /// Returns the EIP-1559 Max base fee the caller is willing to pay.
    pub fn max_fee_per_gas(&self) -> Option<U256> {
        self.transaction.max_fee_per_gas()
    }

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

    /// Returns true if this transaction is underpriced compared to the other.
    pub(crate) fn is_underpriced(&self, other: &Self) -> bool {
        self.transaction.effective_gas_price() <= other.transaction.effective_gas_price()
    }
}

#[cfg(test)]
impl<T: PoolTransaction + Clone> Clone for ValidPoolTransaction<T> {
    fn clone(&self) -> Self {
        Self {
            transaction: self.transaction.clone(),
            transaction_id: self.transaction_id,
            propagate: self.propagate,
            is_local: self.is_local,
            cost: self.cost,
            timestamp: self.timestamp,
        }
    }
}

impl<T: PoolTransaction> fmt::Debug for ValidPoolTransaction<T> {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(fmt, "Transaction {{ ")?;
        write!(fmt, "hash: {:?}, ", &self.transaction.hash())?;
        write!(fmt, "provides: {:?}, ", &self.transaction_id)?;
        write!(fmt, "raw tx: {:?}", &self.transaction)?;
        write!(fmt, "}}")?;
        Ok(())
    }
}