Preparing light client structure [v2] (#150)

* light client structure + remote call requests

substrate/polkadot/api/src/light.rs

@@ -0,0 +1,106 @@
+// Copyright 2017 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/>.
+
+//! Strongly typed API for light Polkadot client.
+
+use std::sync::Arc;
+use client::backend::{Backend, RemoteBackend};
+use client::{Client, CallExecutor};
+use codec::Slicable;
+use state_machine;
+use primitives::{AccountId, BlockId, Hash, Index, SessionKey, Timestamp};
+use primitives::parachain::{DutyRoster, CandidateReceipt, Id as ParaId};
+use runtime::{Block, UncheckedExtrinsic};
+use full::CheckedId;
+use {PolkadotApi, RemotePolkadotApi, BlockBuilder, CheckedBlockId, Result, ErrorKind};
+
+/// Remote polkadot API implementation.
+pub struct RemotePolkadotApiWrapper<B: Backend, E: CallExecutor>(pub Arc<Client<B, E>>);
+
+/// Block builder for light client.
+pub struct LightBlockBuilder;
+
+impl<B: Backend, E: CallExecutor> PolkadotApi for RemotePolkadotApiWrapper<B, E>
+	where ::client::error::Error: From<<<B as Backend>::State as state_machine::backend::Backend>::Error>
+{
+	type CheckedBlockId = CheckedId;
+	type BlockBuilder = LightBlockBuilder;
+
+	fn check_id(&self, id: BlockId) -> Result<CheckedId> {
+		Ok(CheckedId(id))
+	}
+
+	fn session_keys(&self, at: &CheckedId) -> Result<Vec<SessionKey>> {
+		self.0.executor().call(at.block_id(), "authorities", &[])
+			.and_then(|r| Vec::<SessionKey>::decode(&mut &r.return_data[..])
+				.ok_or("error decoding session keys".into()))
+			.map_err(Into::into)
+	}
+
+	fn validators(&self, _at: &CheckedId) -> Result<Vec<AccountId>> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn random_seed(&self, _at: &Self::CheckedBlockId) -> Result<Hash> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn duty_roster(&self, _at: &CheckedId) -> Result<DutyRoster> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn timestamp(&self, _at: &CheckedId) -> Result<Timestamp> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn evaluate_block(&self, _at: &CheckedId, _block: Block) -> Result<bool> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn index(&self, _at: &CheckedId, _account: AccountId) -> Result<Index> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn active_parachains(&self, _at: &Self::CheckedBlockId) -> Result<Vec<ParaId>> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn parachain_code(&self, _at: &Self::CheckedBlockId, _parachain: ParaId) -> Result<Option<Vec<u8>>> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn parachain_head(&self, _at: &Self::CheckedBlockId, _parachain: ParaId) -> Result<Option<Vec<u8>>> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn build_block(&self, _parent: &CheckedId, _timestamp: Timestamp, _parachains: Vec<CandidateReceipt>) -> Result<Self::BlockBuilder> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+}
+
+impl<B: RemoteBackend, E: CallExecutor> RemotePolkadotApi for RemotePolkadotApiWrapper<B, E>
+	where ::client::error::Error: From<<<B as Backend>::State as state_machine::backend::Backend>::Error>
+{}
+
+impl BlockBuilder for LightBlockBuilder {
+	fn push_extrinsic(&mut self, _extrinsic: UncheckedExtrinsic) -> Result<()> {
+		Err(ErrorKind::UnknownRuntime.into())
+	}
+
+	fn bake(self) -> Block {
+		unimplemented!()
+	}
+}