// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! Runtime configuration for MessageQueue pallet
use codec::{Decode, Encode, MaxEncodedLen};
use cumulus_primitives_core::{AggregateMessageOrigin as CumulusAggregateMessageOrigin, ParaId};
use frame_support::{
	traits::{ProcessMessage, ProcessMessageError, QueueFootprint, QueuePausedQuery},
	weights::WeightMeter,
};
use pallet_message_queue::OnQueueChanged;
use scale_info::TypeInfo;
use snowbridge_core::ChannelId;
use sp_std::{marker::PhantomData, prelude::*};
use xcm::v4::{Junction, Location};

/// The aggregate origin of an inbound message.
/// This is specialized for BridgeHub, as the snowbridge-outbound-queue-pallet is also using
/// the shared MessageQueue pallet.
#[derive(Encode, Decode, Copy, MaxEncodedLen, Clone, Eq, PartialEq, TypeInfo, Debug)]
pub enum AggregateMessageOrigin {
	/// The message came from the para-chain itself.
	Here,
	/// The message came from the relay-chain.
	///
	/// This is used by the DMP queue.
	Parent,
	/// The message came from a sibling para-chain.
	///
	/// This is used by the HRMP queue.
	Sibling(ParaId),
	/// The message came from a snowbridge channel.
	///
	/// This is used by Snowbridge inbound queue.
	Snowbridge(ChannelId),
}

impl From<AggregateMessageOrigin> for Location {
	fn from(origin: AggregateMessageOrigin) -> Self {
		use AggregateMessageOrigin::*;
		match origin {
			Here => Location::here(),
			Parent => Location::parent(),
			Sibling(id) => Location::new(1, Junction::Parachain(id.into())),
			// NOTE: We don't need this conversion for Snowbridge. However we have to
			// implement it anyway as xcm_builder::ProcessXcmMessage requires it.
			Snowbridge(_) => Location::default(),
		}
	}
}

impl From<CumulusAggregateMessageOrigin> for AggregateMessageOrigin {
	fn from(origin: CumulusAggregateMessageOrigin) -> Self {
		match origin {
			CumulusAggregateMessageOrigin::Here => Self::Here,
			CumulusAggregateMessageOrigin::Parent => Self::Parent,
			CumulusAggregateMessageOrigin::Sibling(id) => Self::Sibling(id),
		}
	}
}

#[cfg(feature = "runtime-benchmarks")]
impl From<u32> for AggregateMessageOrigin {
	fn from(x: u32) -> Self {
		match x {
			0 => Self::Here,
			1 => Self::Parent,
			p => Self::Sibling(ParaId::from(p)),
		}
	}
}

/// Routes messages to either the XCMP or Snowbridge processor.
pub struct BridgeHubMessageRouter<XcmpProcessor, SnowbridgeProcessor>(
	PhantomData<(XcmpProcessor, SnowbridgeProcessor)>,
)
where
	XcmpProcessor: ProcessMessage<Origin = AggregateMessageOrigin>,
	SnowbridgeProcessor: ProcessMessage<Origin = AggregateMessageOrigin>;

impl<XcmpProcessor, SnowbridgeProcessor> ProcessMessage
	for BridgeHubMessageRouter<XcmpProcessor, SnowbridgeProcessor>
where
	XcmpProcessor: ProcessMessage<Origin = AggregateMessageOrigin>,
	SnowbridgeProcessor: ProcessMessage<Origin = AggregateMessageOrigin>,
{
	type Origin = AggregateMessageOrigin;

	fn process_message(
		message: &[u8],
		origin: Self::Origin,
		meter: &mut WeightMeter,
		id: &mut [u8; 32],
	) -> Result<bool, ProcessMessageError> {
		use AggregateMessageOrigin::*;
		match origin {
			Here | Parent | Sibling(_) =>
				XcmpProcessor::process_message(message, origin, meter, id),
			Snowbridge(_) => SnowbridgeProcessor::process_message(message, origin, meter, id),
		}
	}
}

/// Narrow the scope of the `Inner` query from `AggregateMessageOrigin` to `ParaId`.
///
/// All non-`Sibling` variants will be ignored.
pub struct NarrowOriginToSibling<Inner>(PhantomData<Inner>);
impl<Inner: QueuePausedQuery<ParaId>> QueuePausedQuery<AggregateMessageOrigin>
	for NarrowOriginToSibling<Inner>
{
	fn is_paused(origin: &AggregateMessageOrigin) -> bool {
		match origin {
			AggregateMessageOrigin::Sibling(id) => Inner::is_paused(id),
			_ => false,
		}
	}
}

impl<Inner: OnQueueChanged<ParaId>> OnQueueChanged<AggregateMessageOrigin>
	for NarrowOriginToSibling<Inner>
{
	fn on_queue_changed(origin: AggregateMessageOrigin, fp: QueueFootprint) {
		if let AggregateMessageOrigin::Sibling(id) = origin {
			Inner::on_queue_changed(id, fp)
		}
	}
}

/// Convert a sibling `ParaId` to an `AggregateMessageOrigin`.
pub struct ParaIdToSibling;
impl sp_runtime::traits::Convert<ParaId, AggregateMessageOrigin> for ParaIdToSibling {
	fn convert(para_id: ParaId) -> AggregateMessageOrigin {
		AggregateMessageOrigin::Sibling(para_id)
	}
}