// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
// This file is part of Frontier.
//
// Copyright (c) 2022 Parity Technologies (UK) Ltd.
//
// This program 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.
//
// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

use std::sync::Arc;

use ethereum::TransactionV2 as EthereumTransaction;
use ethereum_types::{H256, U256, U64};
use jsonrpsee::core::RpcResult;
// Substrate
use sc_client_api::backend::{Backend, StorageProvider};
use sc_transaction_pool::ChainApi;
use sc_transaction_pool_api::InPoolTransaction;
use sp_api::{ApiExt, ProvideRuntimeApi};
use sp_blockchain::HeaderBackend;
use sp_core::hashing::keccak_256;
use sp_runtime::traits::Block as BlockT;
// Frontier
use fc_rpc_core::types::*;
use fp_rpc::EthereumRuntimeRPCApi;

use crate::{
	eth::{transaction_build, BlockInfo, Eth},
	frontier_backend_client, internal_err,
};

impl<B, C, P, CT, BE, A, CIDP, EC> Eth<B, C, P, CT, BE, A, CIDP, EC>
where
	B: BlockT,
	C: ProvideRuntimeApi<B>,
	C::Api: EthereumRuntimeRPCApi<B>,
	C: HeaderBackend<B> + StorageProvider<B, BE> + 'static,
	BE: Backend<B> + 'static,
	A: ChainApi<Block = B>,
{
	pub async fn transaction_by_hash(&self, hash: H256) -> RpcResult<Option<Transaction>> {
		let client = Arc::clone(&self.client);
		let backend = Arc::clone(&self.backend);
		let graph = Arc::clone(&self.graph);

		let (eth_block_hash, index) = match frontier_backend_client::load_transactions::<B, C>(
			client.as_ref(),
			backend.as_ref(),
			hash,
			true,
		)
		.await
		.map_err(|err| internal_err(format!("{:?}", err)))?
		{
			Some((eth_block_hash, index)) => (eth_block_hash, index as usize),
			None => {
				let api = client.runtime_api();
				let best_block = client.info().best_hash;

				let api_version = if let Ok(Some(api_version)) =
					api.api_version::<dyn EthereumRuntimeRPCApi<B>>(best_block)
				{
					api_version
				} else {
					return Err(internal_err("failed to retrieve Runtime Api version"));
				};
				// If the transaction is not yet mapped in the frontier db,
				// check for it in the transaction pool.
				let mut xts: Vec<<B as BlockT>::Extrinsic> = Vec::new();
				// Collect transactions in the ready validated pool.
				xts.extend(
					graph
						.validated_pool()
						.ready()
						.map(|in_pool_tx| in_pool_tx.data().clone())
						.collect::<Vec<<B as BlockT>::Extrinsic>>(),
				);

				// Collect transactions in the future validated pool.
				xts.extend(
					graph
						.validated_pool()
						.futures()
						.iter()
						.map(|(_hash, extrinsic)| extrinsic.clone())
						.collect::<Vec<<B as BlockT>::Extrinsic>>(),
				);

				let ethereum_transactions: Vec<EthereumTransaction> = if api_version > 1 {
					api.extrinsic_filter(best_block, xts).map_err(|err| {
						internal_err(format!("fetch runtime extrinsic filter failed: {:?}", err))
					})?
				} else {
					#[allow(deprecated)]
					let legacy = api.extrinsic_filter_before_version_2(best_block, xts)
						.map_err(|err| {
							internal_err(format!(
								"fetch runtime extrinsic filter failed: {:?}",
								err
							))
						})?;
					legacy.into_iter().map(|tx| tx.into()).collect()
				};

				for txn in ethereum_transactions {
					let inner_hash = txn.hash();
					if hash == inner_hash {
						return Ok(Some(transaction_build(&txn, None, None, None)));
					}
				}
				// Unknown transaction.
				return Ok(None);
			}
		};

		let BlockInfo {
			block,
			statuses,
			base_fee,
			..
		} = self.block_info_by_eth_block_hash(eth_block_hash).await?;
		match (block, statuses) {
			(Some(block), Some(statuses)) => Ok(Some(transaction_build(
				&block.transactions[index],
				Some(&block),
				Some(&statuses[index]),
				Some(base_fee),
			))),
			_ => Ok(None),
		}
	}

	pub async fn transaction_by_block_hash_and_index(
		&self,
		hash: H256,
		index: Index,
	) -> RpcResult<Option<Transaction>> {
		let index = index.value();
		let BlockInfo {
			block,
			statuses,
			base_fee,
			..
		} = self.block_info_by_eth_block_hash(hash).await?;

		match (block, statuses) {
			(Some(block), Some(statuses)) => {
				if let (Some(transaction), Some(status)) =
					(block.transactions.get(index), statuses.get(index))
				{
					Ok(Some(transaction_build(
						transaction,
						Some(&block),
						Some(status),
						Some(base_fee),
					)))
				} else {
					Err(internal_err(format!("{:?} is out of bounds", index)))
				}
			}
			_ => Ok(None),
		}
	}

	pub async fn transaction_by_block_number_and_index(
		&self,
		number: BlockNumberOrHash,
		index: Index,
	) -> RpcResult<Option<Transaction>> {
		let index = index.value();
		let BlockInfo {
			block,
			statuses,
			base_fee,
			..
		} = self.block_info_by_number(number).await?;

		match (block, statuses) {
			(Some(block), Some(statuses)) => {
				if let (Some(transaction), Some(status)) =
					(block.transactions.get(index), statuses.get(index))
				{
					Ok(Some(transaction_build(
						transaction,
						Some(&block),
						Some(status),
						Some(base_fee),
					)))
				} else {
					Err(internal_err(format!("{:?} is out of bounds", index)))
				}
			}
			_ => Ok(None),
		}
	}

	pub async fn transaction_receipt(
		&self,
		block_info: &BlockInfo<B::Hash>,
		hash: H256,
		index: usize,
	) -> RpcResult<Option<Receipt>> {
		let BlockInfo {
			block,
			receipts,
			statuses,
			substrate_hash,
			..
		} = block_info.clone();
		match (block, statuses, receipts) {
			(Some(block), Some(statuses), Some(receipts)) => {
				let block_hash = H256::from(keccak_256(&rlp::encode(&block.header)));
				let receipt = receipts[index].clone();

				let (logs, logs_bloom, status_code, cumulative_gas_used, gas_used) =
					if !block_info.is_eip1559 {
						// Pre-london frontier update stored receipts require cumulative gas calculation.
						match receipt {
							ethereum::ReceiptV3::Legacy(ref d) => {
								let index = core::cmp::min(receipts.len(), index + 1);
								let cumulative_gas: u32 = receipts[..index]
									.iter()
									.map(|r| match r {
										ethereum::ReceiptV3::Legacy(d) => Ok(d.used_gas.as_u32()),
										_ => Err(internal_err(format!(
											"Unknown receipt for request {}",
											hash
										))),
									})
									.sum::<RpcResult<u32>>()?;
								(
									d.logs.clone(),
									d.logs_bloom,
									d.status_code,
									U256::from(cumulative_gas),
									d.used_gas,
								)
							}
							_ => {
								return Err(internal_err(format!(
									"Unknown receipt for request {}",
									hash
								)))
							}
						}
					} else {
						match receipt {
							ethereum::ReceiptV3::Legacy(ref d)
							| ethereum::ReceiptV3::EIP2930(ref d)
							| ethereum::ReceiptV3::EIP1559(ref d) => {
								let cumulative_gas = d.used_gas;
								let gas_used = if index > 0 {
									let previous_receipt = receipts[index - 1].clone();
									let previous_gas_used = match previous_receipt {
										ethereum::ReceiptV3::Legacy(d)
										| ethereum::ReceiptV3::EIP2930(d)
										| ethereum::ReceiptV3::EIP1559(d) => d.used_gas,
									};
									cumulative_gas.saturating_sub(previous_gas_used)
								} else {
									cumulative_gas
								};
								(
									d.logs.clone(),
									d.logs_bloom,
									d.status_code,
									cumulative_gas,
									gas_used,
								)
							}
						}
					};

				let status = statuses[index].clone();
				let mut cumulative_receipts = receipts;
				cumulative_receipts.truncate((status.transaction_index + 1) as usize);
				let transaction = block.transactions[index].clone();
				let effective_gas_price = match transaction {
					EthereumTransaction::Legacy(t) => t.gas_price,
					EthereumTransaction::EIP2930(t) => t.gas_price,
					EthereumTransaction::EIP1559(t) => {
						let parent_eth_hash = block.header.parent_hash;
						let base_fee_block_substrate_hash = if parent_eth_hash.is_zero() {
							substrate_hash
						} else {
							frontier_backend_client::load_hash::<B, C>(
								self.client.as_ref(),
								self.backend.as_ref(),
								parent_eth_hash,
							)
							.await
							.map_err(|err| internal_err(format!("{:?}", err)))?
							.ok_or(internal_err(
								"Failed to retrieve substrate parent block hash",
							))?
						};

						self.client
							.runtime_api()
							.gas_price(base_fee_block_substrate_hash)
							.unwrap_or_default()
							.checked_add(t.max_priority_fee_per_gas)
							.unwrap_or_else(U256::max_value)
							.min(t.max_fee_per_gas)
					}
				};

				return Ok(Some(Receipt {
					transaction_hash: Some(status.transaction_hash),
					transaction_index: Some(status.transaction_index.into()),
					block_hash: Some(block_hash),
					from: Some(status.from),
					to: status.to,
					block_number: Some(block.header.number),
					cumulative_gas_used,
					gas_used: Some(gas_used),
					contract_address: status.contract_address,
					logs: {
						let mut pre_receipts_log_index = None;
						if cumulative_receipts.len() > 0 {
							cumulative_receipts.truncate(cumulative_receipts.len() - 1);
							pre_receipts_log_index = Some(
								cumulative_receipts
									.iter()
									.map(|r| match r {
										ethereum::ReceiptV3::Legacy(d)
										| ethereum::ReceiptV3::EIP2930(d)
										| ethereum::ReceiptV3::EIP1559(d) => d.logs.len() as u32,
									})
									.sum::<u32>(),
							);
						}
						logs.iter()
							.enumerate()
							.map(|(i, log)| Log {
								address: log.address,
								topics: log.topics.clone(),
								data: Bytes(log.data.clone()),
								block_hash: Some(block_hash),
								block_number: Some(block.header.number),
								transaction_hash: Some(status.transaction_hash),
								transaction_index: Some(status.transaction_index.into()),
								log_index: Some(U256::from(
									(pre_receipts_log_index.unwrap_or(0)) + i as u32,
								)),
								transaction_log_index: Some(U256::from(i)),
								removed: false,
							})
							.collect()
					},
					status_code: Some(U64::from(status_code)),
					logs_bloom,
					state_root: None,
					effective_gas_price,
					transaction_type: match receipt {
						ethereum::ReceiptV3::Legacy(_) => U256::from(0),
						ethereum::ReceiptV3::EIP2930(_) => U256::from(1),
						ethereum::ReceiptV3::EIP1559(_) => U256::from(2),
					},
				}));
			}
			_ => Ok(None),
		}
	}
}