// This file is part of Substrate.

// Copyright (C) 2019-2020 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.

//! RPC interface for the transaction payment module.

use std::sync::Arc;
use codec::{Codec, Decode};
use sp_blockchain::HeaderBackend;
use jsonrpc_core::{Error as RpcError, ErrorCode, Result};
use jsonrpc_derive::rpc;
use sp_runtime::{generic::BlockId, traits::{Block as BlockT, MaybeDisplay, MaybeFromStr}};
use sp_api::ProvideRuntimeApi;
use sp_core::Bytes;
use pallet_transaction_payment_rpc_runtime_api::RuntimeDispatchInfo;
pub use pallet_transaction_payment_rpc_runtime_api::TransactionPaymentApi as TransactionPaymentRuntimeApi;
pub use self::gen_client::Client as TransactionPaymentClient;

#[rpc]
pub trait TransactionPaymentApi<BlockHash, ResponseType> {
	#[rpc(name = "payment_queryInfo")]
	fn query_info(
		&self,
		encoded_xt: Bytes,
		at: Option<BlockHash>
	) -> Result<ResponseType>;
}

/// A struct that implements the [`TransactionPaymentApi`].
pub struct TransactionPayment<C, P> {
	client: Arc<C>,
	_marker: std::marker::PhantomData<P>,
}

impl<C, P> TransactionPayment<C, P> {
	/// Create new `TransactionPayment` with the given reference to the client.
	pub fn new(client: Arc<C>) -> Self {
		TransactionPayment { client, _marker: Default::default() }
	}
}

/// Error type of this RPC api.
pub enum Error {
	/// The transaction was not decodable.
	DecodeError,
	/// The call to runtime failed.
	RuntimeError,
}

impl From<Error> for i64 {
	fn from(e: Error) -> i64 {
		match e {
			Error::RuntimeError => 1,
			Error::DecodeError => 2,
		}
	}
}

impl<C, Block, Balance> TransactionPaymentApi<<Block as BlockT>::Hash, RuntimeDispatchInfo<Balance>>
	for TransactionPayment<C, Block>
where
	Block: BlockT,
	C: 'static + ProvideRuntimeApi<Block> + HeaderBackend<Block>,
	C::Api: TransactionPaymentRuntimeApi<Block, Balance>,
	Balance: Codec + MaybeDisplay + MaybeFromStr,
{
	fn query_info(
		&self,
		encoded_xt: Bytes,
		at: Option<<Block as BlockT>::Hash>
	) -> Result<RuntimeDispatchInfo<Balance>> {
		let api = self.client.runtime_api();
		let at = BlockId::hash(at.unwrap_or_else(||
			// If the block hash is not supplied assume the best block.
			self.client.info().best_hash
		));

		let encoded_len = encoded_xt.len() as u32;

		let uxt: Block::Extrinsic = Decode::decode(&mut &*encoded_xt).map_err(|e| RpcError {
			code: ErrorCode::ServerError(Error::DecodeError.into()),
			message: "Unable to query dispatch info.".into(),
			data: Some(format!("{:?}", e).into()),
		})?;
		api.query_info(&at, uxt, encoded_len).map_err(|e| RpcError {
			code: ErrorCode::ServerError(Error::RuntimeError.into()),
			message: "Unable to query dispatch info.".into(),
			data: Some(format!("{:?}", e).into()),
		})
	}
}
