Add an RPC method for calling a contract. (#3563)

* Sketch

* Some work on docs.

* Doc improvements.

* More docs.

* Some more docs.

* Yet another comment.

* Bump impl_version.

* Accept the block hash

* Use NumberOrHex

* Update node/rpc/src/contracts.rs

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Move rpc/primitives

substrate/node/runtime/src/lib.rs

@@ -27,7 +27,7 @@ use support::{
 use primitives::u32_trait::{_1, _2, _3, _4};
 use node_primitives::{
 	AccountId, AccountIndex, Balance, BlockNumber, Hash, Index,
-	Moment, Signature,
+	Moment, Signature, ContractExecResult,
 };
 use babe::{AuthorityId as BabeId};
 use grandpa::fg_primitives::{self, ScheduledChange};
@@ -83,7 +83,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
 	spec_version: 156,
-	impl_version: 157,
+	impl_version: 158,
 	apis: RUNTIME_API_VERSIONS,
 };
 
@@ -654,6 +654,31 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl node_primitives::ContractsApi<Block> for Runtime {
+		fn call(
+			origin: AccountId,
+			dest: AccountId,
+			value: Balance,
+			gas_limit: u64,
+			input_data: Vec<u8>,
+		) -> ContractExecResult {
+			let exec_result = Contracts::bare_call(
+				origin,
+				dest.into(),
+				value,
+				gas_limit,
+				input_data,
+			);
+			match exec_result {
+				Ok(v) => ContractExecResult::Success {
+					status: v.status,
+					data: v.data,
+				},
+				Err(_) => ContractExecResult::Error,
+			}
+		}
+	}
+
 	impl substrate_session::SessionKeys<Block> for Runtime {
 		fn generate_session_keys(seed: Option<Vec<u8>>) -> Vec<u8> {
 			let seed = seed.as_ref().map(|s| rstd::str::from_utf8(&s).expect("Seed is an utf8 string"));