From 4d4853ab9cb3fb0924b9e7e8bc778a715a96f061 Mon Sep 17 00:00:00 2001
From: Frederik Gartenmeister <mustermeiszer@posteo.de>
Date: Wed, 6 Dec 2023 13:21:48 +0100
Subject: [PATCH] feat: Enable ecosystem wide compatible account derivation

---
 primitives/src/lib.rs      | 159 +++++++++++++++++++++++++++++++++++++
 runtime/hydradx/src/xcm.rs |   2 +
 2 files changed, 161 insertions(+)

diff --git a/primitives/src/lib.rs b/primitives/src/lib.rs
index 9fe493c72..cd6c2a70c 100644
--- a/primitives/src/lib.rs
+++ b/primitives/src/lib.rs
@@ -75,3 +75,162 @@ pub type Header = generic::Header<BlockNumber, BlakeTwo256>;
 
 /// Block type.
 pub type Block = generic::Block<Header, UncheckedExtrinsic>;
+
+
+pub mod xcm {
+	use codec::{Compact, Encode};
+	use sp_io::hashing::blake2_256;
+	use sp_std::{borrow::Borrow, marker::PhantomData, vec::Vec};
+	use xcm::prelude::{
+		AccountId32, AccountKey20, Here, MultiLocation, PalletInstance, Parachain, X1,
+	};
+	use xcm_executor::traits::Convert;
+
+	/// NOTE: Copied from <https://github.com/moonbeam-foundation/polkadot/blob/d83bb6cc7d7c93ead2fd3cafce0e268fd3f6b9bc/xcm/xcm-builder/src/location_conversion.rs#L25C1-L68C2>
+	///
+	/// temporary struct that mimics the behavior of the upstream type that we
+	/// will move to once we update this repository to Polkadot 0.9.43+.
+	pub struct HashedDescriptionDescribeFamilyAllTerminal<AccountId>(PhantomData<AccountId>);
+	impl<AccountId: From<[u8; 32]> + Clone> HashedDescriptionDescribeFamilyAllTerminal<AccountId> {
+		fn describe_location_suffix(l: &MultiLocation) -> Result<Vec<u8>, ()> {
+			match (l.parents, &l.interior) {
+				(0, Here) => Ok(Vec::new()),
+				(0, X1(PalletInstance(i))) => {
+					Ok((b"Pallet", Compact::<u32>::from(*i as u32)).encode())
+				}
+				(0, X1(AccountId32 { id, .. })) => Ok((b"AccountId32", id).encode()),
+				(0, X1(AccountKey20 { key, .. })) => Ok((b"AccountKey20", key).encode()),
+				_ => Err(()),
+			}
+		}
+	}
+
+	impl<AccountId: From<[u8; 32]> + Clone> Convert<MultiLocation, AccountId>
+	for HashedDescriptionDescribeFamilyAllTerminal<AccountId>
+	{
+		fn convert_ref(location: impl Borrow<MultiLocation>) -> Result<AccountId, ()> {
+			let l = location.borrow();
+			let to_hash = match (l.parents, l.interior.first()) {
+				(0, Some(Parachain(index))) => {
+					let tail = l.interior.split_first().0;
+					let interior = Self::describe_location_suffix(&tail.into())?;
+					(b"ChildChain", Compact::<u32>::from(*index), interior).encode()
+				}
+				(1, Some(Parachain(index))) => {
+					let tail = l.interior.split_first().0;
+					let interior = Self::describe_location_suffix(&tail.into())?;
+					(b"SiblingChain", Compact::<u32>::from(*index), interior).encode()
+				}
+				(1, _) => {
+					let tail = l.interior.into();
+					let interior = Self::describe_location_suffix(&tail)?;
+					(b"ParentChain", interior).encode()
+				}
+				_ => return Err(()),
+			};
+			Ok(blake2_256(&to_hash).into())
+		}
+
+		fn reverse_ref(_: impl Borrow<AccountId>) -> Result<MultiLocation, ()> {
+			Err(())
+		}
+	}
+
+	#[test]
+	fn test_hashed_family_all_terminal_converter() {
+		use xcm::prelude::X2;
+
+		type Converter<AccountId> = HashedDescriptionDescribeFamilyAllTerminal<AccountId>;
+
+		assert_eq!(
+			[
+				129, 211, 14, 6, 146, 54, 225, 200, 135, 103, 248, 244, 125, 112, 53, 133, 91, 42,
+				215, 236, 154, 199, 191, 208, 110, 148, 223, 55, 92, 216, 250, 34
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 0,
+				interior: X2(
+					Parachain(1),
+					AccountId32 {
+						network: None,
+						id: [0u8; 32]
+					}
+				),
+			})
+				.unwrap()
+		);
+		assert_eq!(
+			[
+				17, 142, 105, 253, 199, 34, 43, 136, 155, 48, 12, 137, 155, 219, 155, 110, 93, 181,
+				93, 252, 124, 60, 250, 195, 229, 86, 31, 220, 121, 111, 254, 252
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 1,
+				interior: X2(
+					Parachain(1),
+					AccountId32 {
+						network: None,
+						id: [0u8; 32]
+					}
+				),
+			})
+				.unwrap()
+		);
+		assert_eq!(
+			[
+				237, 65, 190, 49, 53, 182, 196, 183, 151, 24, 214, 23, 72, 244, 235, 87, 187, 67,
+				52, 122, 195, 192, 10, 58, 253, 49, 0, 112, 175, 224, 125, 66
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 0,
+				interior: X2(
+					Parachain(1),
+					AccountKey20 {
+						network: None,
+						key: [0u8; 20]
+					}
+				),
+			})
+				.unwrap()
+		);
+		assert_eq!(
+			[
+				226, 225, 225, 162, 254, 156, 113, 95, 68, 155, 160, 118, 126, 18, 166, 132, 144,
+				19, 8, 204, 228, 112, 164, 189, 179, 124, 249, 1, 168, 110, 151, 50
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 1,
+				interior: X2(
+					Parachain(1),
+					AccountKey20 {
+						network: None,
+						key: [0u8; 20]
+					}
+				),
+			})
+				.unwrap()
+		);
+		assert_eq!(
+			[
+				254, 186, 179, 229, 13, 24, 84, 36, 84, 35, 64, 95, 114, 136, 62, 69, 247, 74, 215,
+				104, 121, 114, 53, 6, 124, 46, 42, 245, 121, 197, 12, 208
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 1,
+				interior: X2(Parachain(2), PalletInstance(3)),
+			})
+				.unwrap()
+		);
+		assert_eq!(
+			[
+				217, 56, 0, 36, 228, 154, 250, 26, 200, 156, 1, 39, 254, 162, 16, 187, 107, 67, 27,
+				16, 218, 254, 250, 184, 6, 27, 216, 138, 194, 93, 23, 165
+			],
+			Converter::<[u8; 32]>::convert(MultiLocation {
+				parents: 1,
+				interior: Here,
+			})
+				.unwrap()
+		);
+	}
+}
diff --git a/runtime/hydradx/src/xcm.rs b/runtime/hydradx/src/xcm.rs
index 9fd85919b..6555b731d 100644
--- a/runtime/hydradx/src/xcm.rs
+++ b/runtime/hydradx/src/xcm.rs
@@ -306,6 +306,8 @@ pub type LocationToAccountId = (
 	SiblingParachainConvertsVia<Sibling, AccountId>,
 	// Straight up local `AccountId32` origins just alias directly to `AccountId`.
 	AccountId32Aliases<RelayNetwork, AccountId>,
+	// Generate remote accounts according to polkadot standards
+	primitives::xcm::HashedDescriptionDescribeFamilyAllTerminal<AccountId>,
 );
 
 parameter_types! {