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// SPDX-License-Identifier: Apache-2.0
// This file is part of Frontier.
//
// Copyright (c) 2020-2022 Parity Technologies (UK) Ltd.
//
// 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.

#![cfg_attr(not(feature = "std"), no_std)]
#![deny(unused_crate_dependencies)]

extern crate alloc;

use alloc::vec::Vec;
use core::cmp::min;

use fp_evm::{ExitError, ExitSucceed, LinearCostPrecompile, PrecompileFailure};

/// The identity precompile.
pub struct Identity;

impl LinearCostPrecompile for Identity {
    const BASE: u64 = 15;
    const WORD: u64 = 3;

    fn execute(input: &[u8], _: u64) -> Result<(ExitSucceed, Vec<u8>), PrecompileFailure> {
        Ok((ExitSucceed::Returned, input.to_vec()))
    }
}

/// The ecrecover precompile.
pub struct ECRecover;

impl LinearCostPrecompile for ECRecover {
    const BASE: u64 = 3000;
    const WORD: u64 = 0;

    fn execute(i: &[u8], _: u64) -> Result<(ExitSucceed, Vec<u8>), PrecompileFailure> {
        let mut input = [0u8; 128];
        input[..min(i.len(), 128)].copy_from_slice(&i[..min(i.len(), 128)]);

        let mut msg = [0u8; 32];
        let mut sig = [0u8; 65];

        msg[0..32].copy_from_slice(&input[0..32]);
        sig[0..32].copy_from_slice(&input[64..96]); // r
        sig[32..64].copy_from_slice(&input[96..128]); // s
        sig[64] = input[63]; // v

        // v can only be 27 or 28 on the full 32 bytes value.
        // https://github.com/ethereum/go-ethereum/blob/a907d7e81aaeea15d80b2d3209ad8e08e3bf49e0/core/vm/contracts.go#L177
        if input[32..63] != [0u8; 31] || ![27, 28].contains(&input[63]) {
            return Ok((ExitSucceed::Returned, [0u8; 0].to_vec()))
        }

        let result = match sp_io::crypto::secp256k1_ecdsa_recover(&sig, &msg) {
            Ok(pubkey) => {
                let mut address = sp_io::hashing::keccak_256(&pubkey);
                address[0..12].copy_from_slice(&[0u8; 12]);
                address.to_vec()
            },
            Err(_) => [0u8; 0].to_vec(),
        };

        Ok((ExitSucceed::Returned, result))
    }
}

/// The ripemd precompile.
pub struct Ripemd160;

impl LinearCostPrecompile for Ripemd160 {
    const BASE: u64 = 600;
    const WORD: u64 = 120;

    fn execute(input: &[u8], _cost: u64) -> Result<(ExitSucceed, Vec<u8>), PrecompileFailure> {
        use ripemd::Digest;

        let mut ret = [0u8; 32];
        ret[12..32].copy_from_slice(&ripemd::Ripemd160::digest(input));
        Ok((ExitSucceed::Returned, ret.to_vec()))
    }
}

/// The sha256 precompile.
pub struct Sha256;

impl LinearCostPrecompile for Sha256 {
    const BASE: u64 = 60;
    const WORD: u64 = 12;

    fn execute(input: &[u8], _cost: u64) -> Result<(ExitSucceed, Vec<u8>), PrecompileFailure> {
        let ret = sp_io::hashing::sha2_256(input);
        Ok((ExitSucceed::Returned, ret.to_vec()))
    }
}

/// The ECRecoverPublicKey precompile.
/// Similar to ECRecover, but returns the pubkey (not the corresponding Ethereum address)
pub struct ECRecoverPublicKey;

impl LinearCostPrecompile for ECRecoverPublicKey {
    const BASE: u64 = 3000;
    const WORD: u64 = 0;

    fn execute(i: &[u8], _: u64) -> Result<(ExitSucceed, Vec<u8>), PrecompileFailure> {
        let mut input = [0u8; 128];
        input[..min(i.len(), 128)].copy_from_slice(&i[..min(i.len(), 128)]);

        let mut msg = [0u8; 32];
        let mut sig = [0u8; 65];

        msg[0..32].copy_from_slice(&input[0..32]);
        sig[0..32].copy_from_slice(&input[64..96]);
        sig[32..64].copy_from_slice(&input[96..128]);
        sig[64] = input[63];

        let pubkey = sp_io::crypto::secp256k1_ecdsa_recover(&sig, &msg).map_err(|_| {
            PrecompileFailure::Error {
                exit_status: ExitError::Other("Public key recover failed".into()),
            }
        })?;

        Ok((ExitSucceed::Returned, pubkey.to_vec()))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use pallet_evm_test_vector_support::test_precompile_test_vectors;

    // TODO: this fails on the test "InvalidHighV-bits-1" where it is expected to return ""
    #[test]
    fn process_consensus_tests_for_ecrecover() -> Result<(), String> {
        test_precompile_test_vectors::<ECRecover>("../testdata/ecRecover.json")?;
        Ok(())
    }

    #[test]
    fn process_consensus_tests_for_sha256() -> Result<(), String> {
        test_precompile_test_vectors::<Sha256>("../testdata/common_sha256.json")?;
        Ok(())
    }

    #[test]
    fn process_consensus_tests_for_ripemd160() -> Result<(), String> {
        test_precompile_test_vectors::<Ripemd160>("../testdata/common_ripemd.json")?;
        Ok(())
    }
}