/*
 * This file is part of the Flowee project
 * Copyright (C) 2009-2010 Satoshi Nakamoto
 * Copyright (C) 2009-2015 The Bitcoin Core developers
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

#ifndef FLOWEE_SCRIPT_SIGCACHE_H
#define FLOWEE_SCRIPT_SIGCACHE_H

#include "script/interpreter.h"
#include <uint256.h>

#include <vector>
#include <cstring>

#include <primitives/Tx.h>

class PublicKey;

/**
 * We're hashing a nonce into the entries themselves, so we don't need extra
 * blinding in the set hash computation.
 *
 * This may exhibit platform endian dependent behavior but because these are
 * nonced hashes (random) and this state is only ever used locally it is safe.
 * All that matters is local consistency.
 */
class SignatureCacheHasher
{
public:
    template <uint8_t hash_select>
    uint32_t operator()(const uint256& key) const
    {
        static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available.");
        uint32_t u;
        std::memcpy(&u, key.begin()+4*hash_select, 4);
        return u;
    }
};

class CachingTransactionSignatureChecker : public TransactionSignatureChecker
{
private:
    bool store;

public:
    CachingTransactionSignatureChecker(const CTransaction* oldTxToIn, const Tx &txIn, unsigned int nInIn, int64_t amount, bool storeIn=true,
                                       const std::vector<Tx::Output> *spentOutputsIn = nullptr)
        : TransactionSignatureChecker(oldTxToIn, txIn, nInIn, amount, spentOutputsIn), store(storeIn) {}

    bool VerifySignature(const std::vector<unsigned char>& vchSig, const PublicKey& vchPubKey, const uint256& sighash, uint32_t flags) const override;
};

void InitSignatureCache();

#endif