// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity 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.

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

//! Local Transactions List.

use std::sync::Arc;

use ethereum_types::H256;
use linked_hash_map::LinkedHashMap;
use pool::VerifiedTransaction as Transaction;
use txpool::{self, VerifiedTransaction};

/// Status of local transaction.
/// Can indicate that the transaction is currently part of the queue (`Pending/Future`)
/// or gives a reason why the transaction was removed.
#[derive(Debug, PartialEq, Clone)]
pub enum Status {
	/// The transaction is currently in the transaction queue.
	Pending(Arc<Transaction>),
	/// Transaction is already mined.
	Mined(Arc<Transaction>),
	/// Transaction is dropped because of limit
	Dropped(Arc<Transaction>),
	/// Replaced because of higher gas price of another transaction.
	Replaced {
		/// Replaced transaction
		old: Arc<Transaction>,
		/// Transaction that replaced this one.
		new: Arc<Transaction>,
	},
	/// Transaction was never accepted to the queue.
	/// It means that it was too cheap to replace any transaction already in the pool.
	Rejected(Arc<Transaction>, String),
	/// Transaction is invalid.
	Invalid(Arc<Transaction>),
	/// Transaction was canceled.
	Canceled(Arc<Transaction>),
}

impl Status {
	fn is_pending(&self) -> bool {
		match *self {
			Status::Pending(_) => true,
			_ => false,
		}
	}
}

/// Keeps track of local transactions that are in the queue or were mined/dropped recently.
#[derive(Debug)]
pub struct LocalTransactionsList {
	max_old: usize,
	transactions: LinkedHashMap<H256, Status>,
	pending: usize,
}

impl Default for LocalTransactionsList {
	fn default() -> Self {
		Self::new(10)
	}
}

impl LocalTransactionsList {
	/// Create a new list of local transactions.
	pub fn new(max_old: usize) -> Self {
		LocalTransactionsList {
			max_old,
			transactions: Default::default(),
			pending: 0,
		}
	}

	/// Returns true if the transaction is already in local transactions.
	pub fn contains(&self, hash: &H256) -> bool {
		self.transactions.contains_key(hash)
	}

	/// Return a map of all currently stored transactions.
	pub fn all_transactions(&self) -> &LinkedHashMap<H256, Status> {
		&self.transactions
	}

	/// Returns true if there are pending local transactions.
	pub fn has_pending(&self) -> bool {
		self.pending > 0
	}

	fn clear_old(&mut self) {
		let number_of_old = self.transactions.len() - self.pending;
		if self.max_old >= number_of_old {
			return;
		}

		let to_remove: Vec<_> = self.transactions
			.iter()
			.filter(|&(_, status)| !status.is_pending())
			.map(|(hash, _)| *hash)
			.take(number_of_old - self.max_old)
			.collect();

		for hash in to_remove {
			self.transactions.remove(&hash);
		}
	}

	fn insert(&mut self, hash: H256, status: Status) {
		let result = self.transactions.insert(hash, status);
		if let Some(old) = result {
			if old.is_pending() {
				self.pending -= 1;
			}
		}
	}
}

impl txpool::Listener<Transaction> for LocalTransactionsList {
	fn added(&mut self, tx: &Arc<Transaction>, old: Option<&Arc<Transaction>>) {
		if !tx.priority().is_local() {
			return;
		}

		debug!(target: "own_tx", "Imported to the pool (hash {:?})", tx.hash());
		self.clear_old();
		self.insert(*tx.hash(), Status::Pending(tx.clone()));
		self.pending += 1;

		if let Some(old) = old {
			if self.transactions.contains_key(old.hash()) {
				self.insert(*old.hash(), Status::Replaced {
					old: old.clone(),
					new: tx.clone(),
				});
			}
		}
	}

	fn rejected(&mut self, tx: &Arc<Transaction>, reason: &txpool::ErrorKind) {
		if !tx.priority().is_local() {
			return;
		}

		debug!(target: "own_tx", "Transaction rejected (hash {:?}). {}", tx.hash(), reason);
		self.insert(*tx.hash(), Status::Rejected(tx.clone(), format!("{}", reason)));
		self.clear_old();
	}

	fn dropped(&mut self, tx: &Arc<Transaction>, new: Option<&Transaction>) {
		if !tx.priority().is_local() {
			return;
		}

		match new {
			Some(new) => warn!(target: "own_tx", "Transaction pushed out because of limit (hash {:?}, replacement: {:?})", tx.hash(), new.hash()),
			None => warn!(target: "own_tx", "Transaction dropped because of limit (hash: {:?})", tx.hash()),
		}
		self.insert(*tx.hash(), Status::Dropped(tx.clone()));
		self.clear_old();
	}

	fn invalid(&mut self, tx: &Arc<Transaction>) {
		if !tx.priority().is_local() {
			return;
		}

		warn!(target: "own_tx", "Transaction marked invalid (hash {:?})", tx.hash());
		self.insert(*tx.hash(), Status::Invalid(tx.clone()));
		self.clear_old();
	}

	fn canceled(&mut self, tx: &Arc<Transaction>) {
		if !tx.priority().is_local() {
			return;
		}

		warn!(target: "own_tx", "Transaction canceled (hash {:?})", tx.hash());
		self.insert(*tx.hash(), Status::Canceled(tx.clone()));
		self.clear_old();
	}

	/// The transaction has been mined.
	fn mined(&mut self, tx: &Arc<Transaction>) {
		if !tx.priority().is_local() {
			return;
		}

		info!(target: "own_tx", "Transaction mined (hash {:?})", tx.hash());
		self.insert(*tx.hash(), Status::Mined(tx.clone()));
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use ethereum_types::U256;
	use ethkey::{Random, Generator};
	use transaction;
	use txpool::Listener;

	use pool;

	#[test]
	fn should_add_transaction_as_pending() {
		// given
		let mut list = LocalTransactionsList::default();
		let tx1 = new_tx(10);
		let tx2 = new_tx(20);

		// when
		list.added(&tx1, None);
		list.added(&tx2, None);

		// then
		assert!(list.contains(tx1.hash()));
		assert!(list.contains(tx2.hash()));
		let statuses = list.all_transactions().values().cloned().collect::<Vec<Status>>();
		assert_eq!(statuses, vec![Status::Pending(tx1), Status::Pending(tx2)]);
	}

	#[test]
	fn should_clear_old_transactions() {
		// given
		let mut list = LocalTransactionsList::new(1);
		let tx1 = new_tx(10);
		let tx2 = new_tx(50);
		let tx3 = new_tx(51);

		list.added(&tx1, None);
		list.invalid(&tx1);
		list.dropped(&tx2, None);
		assert!(!list.contains(tx1.hash()));
		assert!(list.contains(tx2.hash()));
		assert!(!list.contains(tx3.hash()));

		// when
		list.added(&tx3, Some(&tx1));

		// then
		assert!(!list.contains(tx1.hash()));
		assert!(list.contains(tx2.hash()));
		assert!(list.contains(tx3.hash()));
	}

	fn new_tx<T: Into<U256>>(nonce: T) -> Arc<Transaction> {
		let keypair = Random.generate().unwrap();
		let signed = transaction::Transaction {
			action: transaction::Action::Create,
			value: U256::from(100),
			data: Default::default(),
			gas: U256::from(10),
			gas_price: U256::from(1245),
			nonce: nonce.into(),
		}.sign(keypair.secret(), None);

		let mut tx = Transaction::from_pending_block_transaction(signed);
		tx.priority = pool::Priority::Local;

		Arc::new(tx)
	}
}