// Copyright (C) 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.

//! A module exporting runtime API implementation functions for all runtime APIs using `v5`
//! primitives.
//!
//! Runtimes implementing the v2 runtime API are recommended to forward directly to these
//! functions.

use crate::{
	configuration, disputes, dmp, hrmp, inclusion, initializer, paras, paras_inherent, scheduler,
	session_info, shared,
};
use frame_system::pallet_prelude::*;
use primitives::{
	slashing, AuthorityDiscoveryId, CandidateEvent, CandidateHash, CommittedCandidateReceipt,
	CoreIndex, CoreOccupied, CoreState, DisputeState, ExecutorParams, GroupIndex,
	GroupRotationInfo, Hash, Id as ParaId, InboundDownwardMessage, InboundHrmpMessage,
	OccupiedCore, OccupiedCoreAssumption, PersistedValidationData, PvfCheckStatement,
	ScrapedOnChainVotes, SessionIndex, SessionInfo, ValidationCode, ValidationCodeHash,
	ValidatorId, ValidatorIndex, ValidatorSignature,
};
use sp_runtime::traits::One;
use sp_std::{collections::btree_map::BTreeMap, prelude::*};

/// Implementation for the `validators` function of the runtime API.
pub fn validators<T: initializer::Config>() -> Vec<ValidatorId> {
	<shared::Pallet<T>>::active_validator_keys()
}

/// Implementation for the `validator_groups` function of the runtime API.
pub fn validator_groups<T: initializer::Config>(
) -> (Vec<Vec<ValidatorIndex>>, GroupRotationInfo<BlockNumberFor<T>>) {
	let now = <frame_system::Pallet<T>>::block_number() + One::one();

	let groups = <scheduler::Pallet<T>>::validator_groups();
	let rotation_info = <scheduler::Pallet<T>>::group_rotation_info(now);

	(groups, rotation_info)
}

/// Implementation for the `availability_cores` function of the runtime API.
pub fn availability_cores<T: initializer::Config>() -> Vec<CoreState<T::Hash, BlockNumberFor<T>>> {
	let cores = <scheduler::Pallet<T>>::availability_cores();
	let config = <configuration::Pallet<T>>::config();
	let now = <frame_system::Pallet<T>>::block_number() + One::one();
	let rotation_info = <scheduler::Pallet<T>>::group_rotation_info(now);

	let time_out_at = |backed_in_number, availability_period| {
		let time_out_at = backed_in_number + availability_period;

		let current_window = rotation_info.last_rotation_at() + availability_period;
		let next_rotation = rotation_info.next_rotation_at();

		// If we are within `period` blocks of rotation, timeouts are being checked
		// actively. We could even time out this block.
		if time_out_at < current_window {
			time_out_at
		} else if time_out_at <= next_rotation {
			// Otherwise, it will time out at the sooner of the next rotation
			next_rotation
		} else {
			// or the scheduled time-out. This is by definition within `period` blocks
			// of `next_rotation` and is thus a valid timeout block.
			time_out_at
		}
	};

	let group_responsible_for =
		|backed_in_number, core_index| match <scheduler::Pallet<T>>::group_assigned_to_core(
			core_index,
			backed_in_number,
		) {
			Some(g) => g,
			None => {
				log::warn!(
					target: "runtime::polkadot-api::v2",
					"Could not determine the group responsible for core extracted \
					from list of cores for some prior block in same session",
				);

				GroupIndex(0)
			},
		};

	let mut core_states: Vec<_> = cores
		.into_iter()
		.enumerate()
		.map(|(i, core)| match core {
			CoreOccupied::Paras(entry) => {
				let pending_availability =
					<inclusion::Pallet<T>>::pending_availability(entry.para_id())
						.expect("Occupied core always has pending availability; qed");

				let backed_in_number = *pending_availability.backed_in_number();
				CoreState::Occupied(OccupiedCore {
					next_up_on_available: <scheduler::Pallet<T>>::next_up_on_available(CoreIndex(
						i as u32,
					)),
					occupied_since: backed_in_number,
					time_out_at: time_out_at(backed_in_number, config.paras_availability_period),
					next_up_on_time_out: <scheduler::Pallet<T>>::next_up_on_time_out(CoreIndex(
						i as u32,
					)),
					availability: pending_availability.availability_votes().clone(),
					group_responsible: group_responsible_for(
						backed_in_number,
						pending_availability.core_occupied(),
					),
					candidate_hash: pending_availability.candidate_hash(),
					candidate_descriptor: pending_availability.candidate_descriptor().clone(),
				})
			},
			CoreOccupied::Free => CoreState::Free,
		})
		.collect();

	// This will overwrite only `Free` cores if the scheduler module is working as intended.
	for scheduled in <scheduler::Pallet<T>>::scheduled_claimqueue() {
		core_states[scheduled.core.0 as usize] = CoreState::Scheduled(primitives::ScheduledCore {
			para_id: scheduled.paras_entry.para_id(),
			collator: None,
		});
	}

	core_states
}

/// Returns current block number being processed and the corresponding root hash.
fn current_relay_parent<T: frame_system::Config>(
) -> (BlockNumberFor<T>, <T as frame_system::Config>::Hash) {
	use parity_scale_codec::Decode as _;
	let state_version = <frame_system::Pallet<T>>::runtime_version().state_version();
	let relay_parent_number = <frame_system::Pallet<T>>::block_number();
	let relay_parent_storage_root = T::Hash::decode(&mut &sp_io::storage::root(state_version)[..])
		.expect("storage root must decode to the Hash type; qed");
	(relay_parent_number, relay_parent_storage_root)
}

fn with_assumption<Config, T, F>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
	build: F,
) -> Option<T>
where
	Config: inclusion::Config,
	F: FnOnce() -> Option<T>,
{
	match assumption {
		OccupiedCoreAssumption::Included => {
			<inclusion::Pallet<Config>>::force_enact(para_id);
			build()
		},
		OccupiedCoreAssumption::TimedOut => build(),
		OccupiedCoreAssumption::Free => {
			if <inclusion::Pallet<Config>>::pending_availability(para_id).is_some() {
				None
			} else {
				build()
			}
		},
	}
}

/// Implementation for the `persisted_validation_data` function of the runtime API.
pub fn persisted_validation_data<T: initializer::Config>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<PersistedValidationData<T::Hash, BlockNumberFor<T>>> {
	let (relay_parent_number, relay_parent_storage_root) = current_relay_parent::<T>();
	with_assumption::<T, _, _>(para_id, assumption, || {
		crate::util::make_persisted_validation_data::<T>(
			para_id,
			relay_parent_number,
			relay_parent_storage_root,
		)
	})
}

/// Implementation for the `assumed_validation_data` function of the runtime API.
pub fn assumed_validation_data<T: initializer::Config>(
	para_id: ParaId,
	expected_persisted_validation_data_hash: Hash,
) -> Option<(PersistedValidationData<T::Hash, BlockNumberFor<T>>, ValidationCodeHash)> {
	let (relay_parent_number, relay_parent_storage_root) = current_relay_parent::<T>();
	// This closure obtains the `persisted_validation_data` for the given `para_id` and matches
	// its hash against an expected one.
	let make_validation_data = || {
		crate::util::make_persisted_validation_data::<T>(
			para_id,
			relay_parent_number,
			relay_parent_storage_root,
		)
		.filter(|validation_data| validation_data.hash() == expected_persisted_validation_data_hash)
	};

	let persisted_validation_data = make_validation_data().or_else(|| {
		// Try again with force enacting the core. This check only makes sense if
		// the core is occupied.
		<inclusion::Pallet<T>>::pending_availability(para_id).and_then(|_| {
			<inclusion::Pallet<T>>::force_enact(para_id);
			make_validation_data()
		})
	});
	// If we were successful, also query current validation code hash.
	persisted_validation_data.zip(<paras::Pallet<T>>::current_code_hash(&para_id))
}

/// Implementation for the `check_validation_outputs` function of the runtime API.
pub fn check_validation_outputs<T: initializer::Config>(
	para_id: ParaId,
	outputs: primitives::CandidateCommitments,
) -> bool {
	let relay_parent_number = <frame_system::Pallet<T>>::block_number();
	<inclusion::Pallet<T>>::check_validation_outputs_for_runtime_api(
		para_id,
		relay_parent_number,
		outputs,
	)
}

/// Implementation for the `session_index_for_child` function of the runtime API.
pub fn session_index_for_child<T: initializer::Config>() -> SessionIndex {
	// Just returns the session index from `inclusion`. Runtime APIs follow
	// initialization so the initializer will have applied any pending session change
	// which is expected at the child of the block whose context the runtime API was invoked
	// in.
	//
	// Incidentally, this is also the rationale for why it is OK to query validators or
	// occupied cores or etc. and expect the correct response "for child".
	<shared::Pallet<T>>::session_index()
}

/// Implementation for the `AuthorityDiscoveryApi::authorities()` function of the runtime API.
/// It is a heavy call, but currently only used for authority discovery, so it is fine.
/// Gets next, current and some historical authority ids using `session_info` module.
pub fn relevant_authority_ids<T: initializer::Config + pallet_authority_discovery::Config>(
) -> Vec<AuthorityDiscoveryId> {
	let current_session_index = session_index_for_child::<T>();
	let earliest_stored_session = <session_info::Pallet<T>>::earliest_stored_session();

	// Due to `max_validators`, the `SessionInfo` stores only the validators who are actively
	// selected to participate in parachain consensus. We'd like all authorities for the current
	// and next sessions to be used in authority-discovery. The two sets likely have large overlap.
	let mut authority_ids = <pallet_authority_discovery::Pallet<T>>::current_authorities().to_vec();
	authority_ids.extend(<pallet_authority_discovery::Pallet<T>>::next_authorities().to_vec());

	// Due to disputes, we'd like to remain connected to authorities of the previous few sessions.
	// For this, we don't need anyone other than the validators actively participating in consensus.
	for session_index in earliest_stored_session..current_session_index {
		let info = <session_info::Pallet<T>>::session_info(session_index);
		if let Some(mut info) = info {
			authority_ids.append(&mut info.discovery_keys);
		}
	}

	authority_ids.sort();
	authority_ids.dedup();

	authority_ids
}

/// Implementation for the `validation_code` function of the runtime API.
pub fn validation_code<T: initializer::Config>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<ValidationCode> {
	with_assumption::<T, _, _>(para_id, assumption, || <paras::Pallet<T>>::current_code(&para_id))
}

/// Implementation for the `candidate_pending_availability` function of the runtime API.
pub fn candidate_pending_availability<T: initializer::Config>(
	para_id: ParaId,
) -> Option<CommittedCandidateReceipt<T::Hash>> {
	<inclusion::Pallet<T>>::candidate_pending_availability(para_id)
}

/// Implementation for the `candidate_events` function of the runtime API.
// NOTE: this runs without block initialization, as it accesses events.
// this means it can run in a different session than other runtime APIs at the same block.
pub fn candidate_events<T, F>(extract_event: F) -> Vec<CandidateEvent<T::Hash>>
where
	T: initializer::Config,
	F: Fn(<T as frame_system::Config>::RuntimeEvent) -> Option<inclusion::Event<T>>,
{
	use inclusion::Event as RawEvent;

	<frame_system::Pallet<T>>::read_events_no_consensus()
		.into_iter()
		.filter_map(|record| extract_event(record.event))
		.filter_map(|event| {
			Some(match event {
				RawEvent::<T>::CandidateBacked(c, h, core, group) =>
					CandidateEvent::CandidateBacked(c, h, core, group),
				RawEvent::<T>::CandidateIncluded(c, h, core, group) =>
					CandidateEvent::CandidateIncluded(c, h, core, group),
				RawEvent::<T>::CandidateTimedOut(c, h, core) =>
					CandidateEvent::CandidateTimedOut(c, h, core),
				// Not needed for candidate events.
				RawEvent::<T>::UpwardMessagesReceived { .. } => return None,
				RawEvent::<T>::__Ignore(_, _) => unreachable!("__Ignore cannot be used"),
			})
		})
		.collect()
}

/// Get the session info for the given session, if stored.
pub fn session_info<T: session_info::Config>(index: SessionIndex) -> Option<SessionInfo> {
	<session_info::Pallet<T>>::session_info(index)
}

/// Implementation for the `dmq_contents` function of the runtime API.
pub fn dmq_contents<T: dmp::Config>(
	recipient: ParaId,
) -> Vec<InboundDownwardMessage<BlockNumberFor<T>>> {
	<dmp::Pallet<T>>::dmq_contents(recipient)
}

/// Implementation for the `inbound_hrmp_channels_contents` function of the runtime API.
pub fn inbound_hrmp_channels_contents<T: hrmp::Config>(
	recipient: ParaId,
) -> BTreeMap<ParaId, Vec<InboundHrmpMessage<BlockNumberFor<T>>>> {
	<hrmp::Pallet<T>>::inbound_hrmp_channels_contents(recipient)
}

/// Implementation for the `validation_code_by_hash` function of the runtime API.
pub fn validation_code_by_hash<T: paras::Config>(
	hash: ValidationCodeHash,
) -> Option<ValidationCode> {
	<paras::Pallet<T>>::code_by_hash(hash)
}

/// Disputes imported via means of on-chain imports.
pub fn on_chain_votes<T: paras_inherent::Config>() -> Option<ScrapedOnChainVotes<T::Hash>> {
	<paras_inherent::Pallet<T>>::on_chain_votes()
}

/// Submits an PVF pre-checking vote.
pub fn submit_pvf_check_statement<T: paras::Config>(
	stmt: PvfCheckStatement,
	signature: ValidatorSignature,
) {
	<paras::Pallet<T>>::submit_pvf_check_statement(stmt, signature)
}

/// Returns the list of all PVF code hashes that require pre-checking.
pub fn pvfs_require_precheck<T: paras::Config>() -> Vec<ValidationCodeHash> {
	<paras::Pallet<T>>::pvfs_require_precheck()
}

/// Returns the validation code hash for the given parachain making the given
/// `OccupiedCoreAssumption`.
pub fn validation_code_hash<T>(
	para_id: ParaId,
	assumption: OccupiedCoreAssumption,
) -> Option<ValidationCodeHash>
where
	T: inclusion::Config,
{
	with_assumption::<T, _, _>(para_id, assumption, || {
		<paras::Pallet<T>>::current_code_hash(&para_id)
	})
}

/// Implementation for `get_session_disputes` function from the runtime API
pub fn get_session_disputes<T: disputes::Config>(
) -> Vec<(SessionIndex, CandidateHash, DisputeState<BlockNumberFor<T>>)> {
	<disputes::Pallet<T>>::disputes()
}

/// Get session executor parameter set
pub fn session_executor_params<T: session_info::Config>(
	session_index: SessionIndex,
) -> Option<ExecutorParams> {
	// This is to bootstrap the storage working around the runtime migration issue:
	// https://github.com/paritytech/substrate/issues/9997
	// After the bootstrap is complete (no less than 7 session passed with the runtime)
	// this code should be replaced with a pure
	// <session_info::Pallet<T>>::session_executor_params(session_index) call.
	match <session_info::Pallet<T>>::session_executor_params(session_index) {
		Some(ep) => Some(ep),
		None => Some(ExecutorParams::default()),
	}
}

/// Implementation of `unapplied_slashes` runtime API
pub fn unapplied_slashes<T: disputes::slashing::Config>(
) -> Vec<(SessionIndex, CandidateHash, slashing::PendingSlashes)> {
	<disputes::slashing::Pallet<T>>::unapplied_slashes()
}

/// Implementation of `submit_report_dispute_lost` runtime API
pub fn submit_unsigned_slashing_report<T: disputes::slashing::Config>(
	dispute_proof: slashing::DisputeProof,
	key_ownership_proof: slashing::OpaqueKeyOwnershipProof,
) -> Option<()> {
	let key_ownership_proof = key_ownership_proof.decode()?;

	<disputes::slashing::Pallet<T>>::submit_unsigned_slashing_report(
		dispute_proof,
		key_ownership_proof,
	)
}