// Copyright 2020 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/>.

//! Various implementations for `ConvertOrigin`.

use sp_std::{marker::PhantomData, convert::TryInto};
use xcm::v0::{MultiLocation, OriginKind, NetworkId, Junction, BodyId, BodyPart};
use xcm_executor::traits::{Convert, ConvertOrigin};
use frame_support::traits::{EnsureOrigin, Get, OriginTrait, GetBacking};
use frame_system::RawOrigin as SystemRawOrigin;
use polkadot_parachain::primitives::IsSystem;

/// Sovereign accounts use the system's `Signed` origin with an account ID derived from the `LocationConverter`.
pub struct SovereignSignedViaLocation<LocationConverter, Origin>(
	PhantomData<(LocationConverter, Origin)>
);
impl<
	LocationConverter: Convert<MultiLocation, Origin::AccountId>,
	Origin: OriginTrait,
> ConvertOrigin<Origin> for SovereignSignedViaLocation<LocationConverter, Origin> where Origin::AccountId: Clone {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		if let OriginKind::SovereignAccount = kind {
			let location = LocationConverter::convert(origin)?;
			Ok(Origin::signed(location).into())
		} else {
			Err(origin)
		}
	}
}

pub struct ParentAsSuperuser<Origin>(PhantomData<Origin>);
impl<
	Origin: OriginTrait,
> ConvertOrigin<Origin> for ParentAsSuperuser<Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Superuser, MultiLocation::X1(Junction::Parent)) =>
				Ok(Origin::root()),
			(_, origin) => Err(origin),
		}
	}
}

pub struct ChildSystemParachainAsSuperuser<ParaId, Origin>(PhantomData<(ParaId, Origin)>);
impl<
	ParaId: IsSystem + From<u32>,
	Origin: OriginTrait,
> ConvertOrigin<Origin> for ChildSystemParachainAsSuperuser<ParaId, Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Superuser, MultiLocation::X1(Junction::Parachain(id)))
			if ParaId::from(id).is_system() =>
				Ok(Origin::root()),
			(_, origin) => Err(origin),
		}
	}
}

pub struct SiblingSystemParachainAsSuperuser<ParaId, Origin>(PhantomData<(ParaId, Origin)>);
impl<
	ParaId: IsSystem + From<u32>,
	Origin: OriginTrait
> ConvertOrigin<Origin> for SiblingSystemParachainAsSuperuser<ParaId, Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Superuser, MultiLocation::X2(Junction::Parent, Junction::Parachain(id)))
			if ParaId::from(id).is_system() =>
				Ok(Origin::root()),
			(_, origin) => Err(origin),
		}
	}
}

pub struct ChildParachainAsNative<ParachainOrigin, Origin>(
	PhantomData<(ParachainOrigin, Origin)>
);
impl<
	ParachainOrigin: From<u32>,
	Origin: From<ParachainOrigin>,
> ConvertOrigin<Origin> for ChildParachainAsNative<ParachainOrigin, Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Native, MultiLocation::X1(Junction::Parachain(id)))
			=> Ok(Origin::from(ParachainOrigin::from(id))),
			(_, origin) => Err(origin),
		}
	}
}

pub struct SiblingParachainAsNative<ParachainOrigin, Origin>(
	PhantomData<(ParachainOrigin, Origin)>
);
impl<
	ParachainOrigin: From<u32>,
	Origin: From<ParachainOrigin>,
> ConvertOrigin<Origin> for SiblingParachainAsNative<ParachainOrigin, Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Native, MultiLocation::X2(Junction::Parent, Junction::Parachain(id)))
			=> Ok(Origin::from(ParachainOrigin::from(id))),
			(_, origin) => Err(origin),
		}
	}
}

// Our Relay-chain has a native origin given by the `Get`ter.
pub struct RelayChainAsNative<RelayOrigin, Origin>(
	PhantomData<(RelayOrigin, Origin)>
);
impl<
	RelayOrigin: Get<Origin>,
	Origin,
> ConvertOrigin<Origin> for RelayChainAsNative<RelayOrigin, Origin> {
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Native, MultiLocation::X1(Junction::Parent)) => Ok(RelayOrigin::get()),
			(_, origin) => Err(origin),
		}
	}
}

pub struct SignedAccountId32AsNative<Network, Origin>(
	PhantomData<(Network, Origin)>
);
impl<
	Network: Get<NetworkId>,
	Origin: OriginTrait,
> ConvertOrigin<Origin> for SignedAccountId32AsNative<Network, Origin> where
	Origin::AccountId: From<[u8; 32]>,
{
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Native, MultiLocation::X1(Junction::AccountId32 { id, network }))
			if matches!(network, NetworkId::Any) || network == Network::get()
			=> Ok(Origin::signed(id.into())),
			(_, origin) => Err(origin),
		}
	}
}

pub struct SignedAccountKey20AsNative<Network, Origin>(
	PhantomData<(Network, Origin)>
);
impl<
	Network: Get<NetworkId>,
	Origin: OriginTrait
> ConvertOrigin<Origin> for SignedAccountKey20AsNative<Network, Origin> where
	Origin::AccountId: From<[u8; 20]>,
{
	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
		match (kind, origin) {
			(OriginKind::Native, MultiLocation::X1(Junction::AccountKey20 { key, network }))
				if matches!(network, NetworkId::Any) || network == Network::get() =>
			{
				Ok(Origin::signed(key.into()))
			}
			(_, origin) => Err(origin),
		}
	}
}

/// EnsureOrigin barrier to convert from dispatch origin to XCM origin, if one exists.
pub struct EnsureXcmOrigin<Origin, Conversion>(PhantomData<(Origin, Conversion)>);
impl<
	Origin: OriginTrait + Clone,
	Conversion: Convert<Origin, MultiLocation>,
> EnsureOrigin<Origin> for EnsureXcmOrigin<Origin, Conversion> where
	Origin::PalletsOrigin: PartialEq,
{
	type Success = MultiLocation;
	fn try_origin(o: Origin) -> Result<Self::Success, Origin> {
		let o = match Conversion::convert(o) {
			Ok(location) => return Ok(location),
			Err(o) => o,
		};
		// We institute a root fallback so root can always represent the context. This
		// guarantees that `successful_origin` will work.
		if o.caller() == Origin::root().caller() {
			Ok(MultiLocation::Null)
		} else {
			Err(o)
		}
	}

	#[cfg(feature = "runtime-benchmarks")]
	fn successful_origin() -> Origin {
		Origin::root()
	}
}

/// `Convert` implementation to convert from some a `Signed` (system) `Origin` into an `AccountId32`.
///
/// Typically used when configuring `pallet-xcm` for allowing normal accounts to dispatch an XCM from an `AccountId32`
/// origin.
pub struct SignedToAccountId32<Origin, AccountId, Network>(
	PhantomData<(Origin, AccountId, Network)>
);
impl<
	Origin: OriginTrait + Clone,
	AccountId: Into<[u8; 32]>,
	Network: Get<NetworkId>,
> Convert<Origin, MultiLocation> for SignedToAccountId32<Origin, AccountId, Network> where
	Origin::PalletsOrigin: From<SystemRawOrigin<AccountId>> +
	TryInto<SystemRawOrigin<AccountId>, Error=Origin::PalletsOrigin>
{
	fn convert(o: Origin) -> Result<MultiLocation, Origin> {
		o.try_with_caller(|caller| match caller.try_into() {
			Ok(SystemRawOrigin::Signed(who)) =>
				Ok(Junction::AccountId32 { network: Network::get(), id: who.into() }.into()),
			Ok(other) => Err(other.into()),
			Err(other) => Err(other),
		})
	}
}

/// `Convert` implementation to convert from some an origin which implements `Backing` into a corresponding `Plurality`
/// MultiLocation.
///
/// Typically used when configuring `pallet-xcm` for allowing a collective's Origin to dispatch an XCM from a
/// `Plurality` origin.
pub struct BackingToPlurality<Origin, COrigin, Body>(
	PhantomData<(Origin, COrigin, Body)>
);
impl<
	Origin: OriginTrait + Clone,
	COrigin: GetBacking,
	Body: Get<BodyId>,
> Convert<Origin, MultiLocation> for BackingToPlurality<Origin, COrigin, Body> where
	Origin::PalletsOrigin: From<COrigin> +
	TryInto<COrigin, Error=Origin::PalletsOrigin>
{
	fn convert(o: Origin) -> Result<MultiLocation, Origin> {
		o.try_with_caller(|caller| match caller.try_into() {
			Ok(co) => match co.get_backing() {
				Some(backing) => Ok(Junction::Plurality {
					id: Body::get(),
					part: BodyPart::Fraction { nom: backing.approvals, denom: backing.eligible },
				}.into()),
				None => Err(co.into()),
			}
			Err(other) => Err(other),
		})
	}
}