// Copyright 2021 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot 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.

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

//! The monitor command.

use crate::{prelude::*, rpc_helpers::*, signer::Signer, Error, MonitorConfig, SharedConfig};
use codec::Encode;
use jsonrpsee::{
	rpc_params,
	types::{traits::SubscriptionClient, Subscription},
	ws_client::WsClient,
};

use sc_transaction_pool_api::TransactionStatus;
use sp_core::storage::StorageKey;

/// Ensure that now is the signed phase.
async fn ensure_signed_phase<T: EPM::Config, B: BlockT>(
	client: &WsClient,
	at: B::Hash,
) -> Result<(), Error<T>> {
	let key = StorageKey(EPM::CurrentPhase::<T>::hashed_key().to_vec());
	let phase = get_storage::<EPM::Phase<BlockNumber>>(client, rpc_params! {key, at})
		.await
		.map_err::<Error<T>, _>(Into::into)?
		.unwrap_or_default();

	if phase.is_signed() {
		Ok(())
	} else {
		Err(Error::IncorrectPhase)
	}
}

/// Ensure that our current `us` have not submitted anything previously.
async fn ensure_no_previous_solution<
	T: EPM::Config + frame_system::Config<AccountId = AccountId>,
	B: BlockT,
>(
	ext: &mut Ext,
	us: &AccountId,
) -> Result<(), Error<T>> {
	use EPM::signed::SignedSubmissions;
	ext.execute_with(|| {
		if <SignedSubmissions<T>>::get().iter().any(|ss| &ss.who == us) {
			Err(Error::AlreadySubmitted)
		} else {
			Ok(())
		}
	})
}

macro_rules! monitor_cmd_for { ($runtime:tt) => { paste::paste! {
	/// The monitor command.
	pub(crate) async fn [<monitor_cmd_ $runtime>](
		client: &WsClient,
		shared: SharedConfig,
		config: MonitorConfig,
		signer: Signer,
	) -> Result<(), Error<$crate::[<$runtime _runtime_exports>]::Runtime>> {
		use $crate::[<$runtime _runtime_exports>]::*;

		let (sub, unsub) = if config.listen == "head" {
			("chain_subscribeNewHeads", "chain_unsubscribeNewHeads")
		} else {
			("chain_subscribeFinalizedHeads", "chain_unsubscribeFinalizedHeads")
		};

		loop {
			log::info!(target: LOG_TARGET, "subscribing to {:?} / {:?}", sub, unsub);
			let mut subscription: Subscription<Header> = client
				.subscribe(&sub, None, &unsub)
				.await
				.unwrap();

			while let Some(now) = subscription.next().await? {
				let hash = now.hash();
				log::trace!(target: LOG_TARGET, "new event at #{:?} ({:?})", now.number, hash);

				// if the runtime version has changed, terminate.
				crate::check_versions::<Runtime>(client).await?;

				// we prefer doing this check before fetching anything into a remote-ext.
				if ensure_signed_phase::<Runtime, Block>(client, hash).await.is_err() {
					log::debug!(target: LOG_TARGET, "phase closed, not interested in this block at all.");
					continue;
				};

				// grab an externalities without staking, just the election snapshot.
				let mut ext = crate::create_election_ext::<Runtime, Block>(
					shared.uri.clone(),
					Some(hash),
					vec![],
				).await?;

				if ensure_no_previous_solution::<Runtime, Block>(&mut ext, &signer.account).await.is_err() {
					log::debug!(target: LOG_TARGET, "We already have a solution in this phase, skipping.");
					continue;
				}

				// mine a solution, and run feasibility check on it as well.
				let (raw_solution, witness) = crate::mine_with::<Runtime>(&config.solver, &mut ext, true)?;
				log::info!(target: LOG_TARGET, "mined solution with {:?}", &raw_solution.score);

				let nonce = crate::get_account_info::<Runtime>(client, &signer.account, Some(hash))
					.await?
					.map(|i| i.nonce)
					.expect(crate::signer::SIGNER_ACCOUNT_WILL_EXIST);
				let tip = 0 as Balance;
				let period = <Runtime as frame_system::Config>::BlockHashCount::get() / 2;
				let current_block = now.number.saturating_sub(1);
				let era = sp_runtime::generic::Era::mortal(period.into(), current_block.into());
				log::trace!(
					target: LOG_TARGET, "transaction mortality: {:?} -> {:?}",
					era.birth(current_block.into()),
					era.death(current_block.into()),
				);
				let extrinsic = ext.execute_with(|| create_uxt(raw_solution, witness, signer.clone(), nonce, tip, era));
				let bytes = sp_core::Bytes(extrinsic.encode());

				let mut tx_subscription: Subscription<
					TransactionStatus<<Block as BlockT>::Hash, <Block as BlockT>::Hash>
				> = match client
					.subscribe(&"author_submitAndWatchExtrinsic", rpc_params! { bytes }, "author_unwatchExtrinsic")
					.await
				{
					Ok(sub) => sub,
					Err(why) => {
					// This usually happens when we've been busy with mining for a few blocks, and
					// now we're receiving the subscriptions of blocks in which we were busy. In
					// these blocks, we still don't have a solution, so we re-compute a new solution
					// and submit it with an outdated `Nonce`, which yields most often `Stale`
					// error. NOTE: to improve this overall, and to be able to introduce an array of
					// other fancy features, we should make this multi-threaded and do the
					// computation outside of this callback.
						log::warn!(target: LOG_TARGET, "failing to submit a transaction {:?}. continuing...", why);
						continue
					}
				};

				while let Some(status_update) = tx_subscription.next().await? {
					log::trace!(target: LOG_TARGET, "status update {:?}", status_update);
					match status_update {
						TransactionStatus::Ready | TransactionStatus::Broadcast(_) | TransactionStatus::Future => continue,
						TransactionStatus::InBlock(hash) => {
							log::info!(target: LOG_TARGET, "included at {:?}", hash);
							let key = StorageKey(frame_support::storage::storage_prefix(b"System",b"Events").to_vec());
							let events = get_storage::<Vec<frame_system::EventRecord<Event, <Block as BlockT>::Hash>>,
							>(client, rpc_params!{ key, hash }).await?.unwrap_or_default();
							log::info!(target: LOG_TARGET, "events at inclusion {:?}", events);
						}
						TransactionStatus::Retracted(hash) => {
							log::info!(target: LOG_TARGET, "Retracted at {:?}", hash);
						}
						TransactionStatus::Finalized(hash) => {
							log::info!(target: LOG_TARGET, "Finalized at {:?}", hash);
							break
						}
						_ => {
							log::warn!(target: LOG_TARGET, "Stopping listen due to other status {:?}", status_update);
							break
						}
					}
				};
			}

			log::warn!(target: LOG_TARGET, "subscription to {} terminated. Retrying..", sub)
		}
	}
}}}

monitor_cmd_for!(polkadot);
monitor_cmd_for!(kusama);
monitor_cmd_for!(westend);