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// Copyright 2020 Parity Technologies
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use crate::error::Error;
use std::{
	fmt::{Debug, LowerHex},
	sync::Arc,
};

/// Transaction pool listener.
///
/// Listener is being notified about status of every transaction in the pool.
pub trait Listener<T> {
	/// The transaction has been successfully added to the pool.
	/// If second argument is `Some` the transaction has took place of some other transaction
	/// which was already in pool.
	/// NOTE: You won't be notified about drop of `old` transaction separately.
	fn added(&mut self, _tx: &Arc<T>, _old: Option<&Arc<T>>) {}

	/// The transaction was rejected from the pool.
	/// It means that it was too cheap to replace any transaction already in the pool.
	fn rejected<H: Debug + LowerHex>(&mut self, _tx: &Arc<T>, _reason: &Error<H>) {}

	/// The transaction was pushed out from the pool because of the limit.
	fn dropped(&mut self, _tx: &Arc<T>, _by: Option<&T>) {}

	/// The transaction was marked as invalid by executor.
	fn invalid(&mut self, _tx: &Arc<T>) {}

	/// The transaction has been canceled.
	fn canceled(&mut self, _tx: &Arc<T>) {}

	/// The transaction has been culled from the pool.
	fn culled(&mut self, _tx: &Arc<T>) {}
}

/// A no-op implementation of `Listener`.
#[derive(Debug)]
pub struct NoopListener;
impl<T> Listener<T> for NoopListener {}

impl<T, A, B> Listener<T> for (A, B)
where
	A: Listener<T>,
	B: Listener<T>,
{
	fn added(&mut self, tx: &Arc<T>, old: Option<&Arc<T>>) {
		self.0.added(tx, old);
		self.1.added(tx, old);
	}

	fn rejected<H: Debug + LowerHex>(&mut self, tx: &Arc<T>, reason: &Error<H>) {
		self.0.rejected(tx, reason);
		self.1.rejected(tx, reason);
	}

	fn dropped(&mut self, tx: &Arc<T>, by: Option<&T>) {
		self.0.dropped(tx, by);
		self.1.dropped(tx, by);
	}

	fn invalid(&mut self, tx: &Arc<T>) {
		self.0.invalid(tx);
		self.1.invalid(tx);
	}

	fn canceled(&mut self, tx: &Arc<T>) {
		self.0.canceled(tx);
		self.1.canceled(tx);
	}

	fn culled(&mut self, tx: &Arc<T>) {
		self.0.culled(tx);
		self.1.culled(tx);
	}
}