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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_POW_H
#define BITCOIN_POW_H
#include <consensus/params.h>
#include <cstdint>
class CBlockHeader;
class CBlockIndex;
class uint256;
class arith_uint256;
/**
* Convert nBits value to target.
*
* @param[in] nBits compact representation of the target
* @param[in] pow_limit PoW limit (consensus parameter)
*
* @return the proof-of-work target or nullopt if the nBits value
* is invalid (due to overflow or exceeding pow_limit)
*/
std::optional<arith_uint256> DeriveTarget(unsigned int nBits, uint256 pow_limit);
unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params&);
unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params&);
/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params&);
bool CheckProofOfWorkImpl(uint256 hash, unsigned int nBits, const Consensus::Params&);
/**
* Return false if the proof-of-work requirement specified by new_nbits at a
* given height is not possible, given the proof-of-work on the prior block as
* specified by old_nbits.
*
* This function only checks that the new value is within a factor of 4 of the
* old value for blocks at the difficulty adjustment interval, and otherwise
* requires the values to be the same.
*
* Always returns true on networks where min difficulty blocks are allowed,
* such as regtest/testnet.
*/
bool PermittedDifficultyTransition(const Consensus::Params& params, int64_t height, uint32_t old_nbits, uint32_t new_nbits);
#endif // BITCOIN_POW_H