// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-2022 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <chain.h>

#include <tinyformat.h>

#include <util/time.h>

std::string CBlockFileInfo::ToString() const

{

    return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));

}

std::string CBlockIndex::ToString() const

{

    return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",

                     pprev, nHeight, hashMerkleRoot.ToString(), GetBlockHash().ToString());

}

void CChain::SetTip(CBlockIndex& block)

{

    CBlockIndex* pindex = █

    vChain.resize(pindex->nHeight + 1);

    while (pindex && vChain[pindex->nHeight] != pindex) {

  Branch (25:12): [True: 692M, False: 6.73M]
  Branch (25:22): [True: 690M, False: 2.22M]

        vChain[pindex->nHeight] = pindex;

        pindex = pindex->pprev;

    }

}

std::vector<uint256> LocatorEntries(const CBlockIndex* index)

{

    int step = 1;

    std::vector<uint256> have;

    if (index == nullptr) return have;

  Branch (35:9): [True: 0, False: 167k]

    have.reserve(32);

    while (index) {

  Branch (38:12): [True: 1.39M, False: 0]

        have.emplace_back(index->GetBlockHash());

        if (index->nHeight == 0) break;

  Branch (40:13): [True: 167k, False: 1.22M]

        // Exponentially larger steps back, plus the genesis block.

        int height = std::max(index->nHeight - step, 0);

        // Use skiplist.

        index = index->GetAncestor(height);

        if (have.size() > 10) step *= 2;

  Branch (45:13): [True: 543k, False: 684k]

    }

    return have;

}

CBlockLocator GetLocator(const CBlockIndex* index)

{

    return CBlockLocator{LocatorEntries(index)};

}

CBlockLocator CChain::GetLocator() const

{

    return ::GetLocator(Tip());

}

const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {

    if (pindex == nullptr) {

  Branch (61:9): [True: 11.0k, False: 4.45M]

        return nullptr;

    }

    if (pindex->nHeight > Height())

  Branch (64:9): [True: 2.23M, False: 2.22M]

        pindex = pindex->GetAncestor(Height());

    while (pindex && !Contains(pindex))

  Branch (66:12): [True: 4.45M, False: 11.0k]
  Branch (66:22): [True: 5.56k, False: 4.44M]

        pindex = pindex->pprev;

    return pindex;

}

CBlockIndex* CChain::FindEarliestAtLeast(int64_t nTime, int height) const

{

    std::pair<int64_t, int> blockparams = std::make_pair(nTime, height);

    std::vector<CBlockIndex*>::const_iterator lower = std::lower_bound(vChain.begin(), vChain.end(), blockparams,

        [](CBlockIndex* pBlock, const std::pair<int64_t, int>& blockparams) -> bool { return pBlock->GetBlockTimeMax() < blockparams.first || pBlock->nHeight < blockparams.second; });

  Branch (75:94): [True: 0, False: 0]
  Branch (75:143): [True: 0, False: 0]

    return (lower == vChain.end() ? nullptr : *lower);

  Branch (76:13): [True: 0, False: 0]

}

/** Turn the lowest '1' bit in the binary representation of a number into a '0'. */

int static inline InvertLowestOne(int n) { return n & (n - 1); }

/** Compute what height to jump back to with the CBlockIndex::pskip pointer. */

int static inline GetSkipHeight(int height) {

    if (height < 2)

  Branch (84:9): [True: 396k, False: 280M]

        return 0;

    // Determine which height to jump back to. Any number strictly lower than height is acceptable,

    // but the following expression seems to perform well in simulations (max 110 steps to go back

    // up to 2**18 blocks).

    return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 : InvertLowestOne(height);

  Branch (90:12): [True: 139M, False: 140M]

}

const CBlockIndex* CBlockIndex::GetAncestor(int height) const

{

    if (height > nHeight || height < 0) {

  Branch (95:9): [True: 1.00M, False: 78.2M]
  Branch (95:29): [True: 46.0M, False: 32.2M]

        return nullptr;

    }

    const CBlockIndex* pindexWalk = this;

    int heightWalk = nHeight;

    while (heightWalk > height) {

  Branch (101:12): [True: 139M, False: 32.2M]

        int heightSkip = GetSkipHeight(heightWalk);

        int heightSkipPrev = GetSkipHeight(heightWalk - 1);

        if (pindexWalk->pskip != nullptr &&

  Branch (104:13): [True: 139M, False: 330]

            (heightSkip == height ||

  Branch (105:14): [True: 3.81M, False: 135M]

             (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&

  Branch (106:15): [True: 63.8M, False: 71.3M]
  Branch (106:40): [True: 11.5M, False: 52.3M]

                                       heightSkipPrev >= height)))) {

  Branch (107:40): [True: 4.05M, False: 7.45M]

            // Only follow pskip if pprev->pskip isn't better than pskip->pprev.

            pindexWalk = pindexWalk->pskip;

            heightWalk = heightSkip;

        } else {

            assert(pindexWalk->pprev);

  Branch (112:13): [True: 75.4M, False: 0]

            pindexWalk = pindexWalk->pprev;

            heightWalk--;

        }

    }

    return pindexWalk;

}

CBlockIndex* CBlockIndex::GetAncestor(int height)

{

    return const_cast<CBlockIndex*>(static_cast<const CBlockIndex*>(this)->GetAncestor(height));

}

void CBlockIndex::BuildSkip()

{

    if (pprev)

  Branch (127:9): [True: 2.23M, False: 0]

        pskip = pprev->GetAncestor(GetSkipHeight(nHeight));

}

arith_uint256 GetBlockProof(const CBlockIndex& block)

{

    arith_uint256 bnTarget;

    bool fNegative;

    bool fOverflow;

    bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);

    if (fNegative || fOverflow || bnTarget == 0)

  Branch (137:9): [True: 0, False: 6.78M]
  Branch (137:22): [True: 0, False: 6.78M]
  Branch (137:35): [True: 0, False: 6.78M]

        return 0;

    // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256

    // as it's too large for an arith_uint256. However, as 2**256 is at least as large

    // as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,

    // or ~bnTarget / (bnTarget+1) + 1.

    return (~bnTarget / (bnTarget + 1)) + 1;

}

int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)

{

    arith_uint256 r;

    int sign = 1;

    if (to.nChainWork > from.nChainWork) {

  Branch (150:9): [True: 502, False: 87]

        r = to.nChainWork - from.nChainWork;

    } else {

        r = from.nChainWork - to.nChainWork;

        sign = -1;

    }

    r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);

    if (r.bits() > 63) {

  Branch (157:9): [True: 0, False: 589]

        return sign * std::numeric_limits<int64_t>::max();

    }

    return sign * int64_t(r.GetLow64());

}

/** Find the last common ancestor two blocks have.

 *  Both pa and pb must be non-nullptr. */

const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {

    if (pa->nHeight > pb->nHeight) {

  Branch (166:9): [True: 0, False: 18.7M]

        pa = pa->GetAncestor(pb->nHeight);

    } else if (pb->nHeight > pa->nHeight) {

  Branch (168:16): [True: 380k, False: 18.3M]

        pb = pb->GetAncestor(pa->nHeight);

    }

    while (pa != pb && pa && pb) {

  Branch (172:12): [True: 4.69k, False: 18.7M]
  Branch (172:24): [True: 4.69k, False: 0]
  Branch (172:30): [True: 4.69k, False: 0]

        pa = pa->pprev;

        pb = pb->pprev;

    }

    // Eventually all chain branches meet at the genesis block.

    assert(pa == pb);

  Branch (178:5): [True: 18.7M, False: 0]

    return pa;

}