uint64_t CWallet::GetStakeWeight() const
{
    // Choose coins to use
    int64_t nBalance = GetBalance();

    if (nBalance <= nReserveBalance)
        return 0;

    vector<const CWalletTx*> vwtxPrev;

    set<pair<const CWalletTx*,unsigned int> > setCoins;
    int64_t nValueIn = 0;

    if (!SelectCoinsForStaking(nBalance - nReserveBalance, GetTime(), setCoins, nValueIn))
        return 0;

    if (setCoins.empty())
        return 0;

    uint64_t nWeight = 0;

    int64_t nCurrentTime = GetTime();
    CTxDB txdb("r");

    LOCK2(cs_main, cs_wallet);
    int nStakeMinConfirmations = 0;

    nStakeMinConfirmations = 1440;


    BOOST_FOREACH(PAIRTYPE(const CWalletTx*, unsigned int) pcoin, setCoins)
    {
        CTxIndex txindex;
        if (pcoin.first->GetDepthInMainChain() >= nStakeMinConfirmations)
            nWeight += pcoin.first->vout[pcoin.second].nValue;
    }

    return nWeight;
}

// ppcoin: total coin age spent in transaction, in the unit of coin-days.
// Only those coins meeting minimum age requirement counts. As those
// transactions not in main chain are not currently indexed so we
// might not find out about their coin age. Older transactions are 
// guaranteed to be in main chain by sync-checkpoint. This rule is
// introduced to help nodes establish a consistent view of the coin
// age (trust score) of competing branches.
bool CTransaction::GetCoinAge(CTxDB& txdb, const CBlockIndex* pindexPrev, uint64_t& nCoinAge) const
{
    CBigNum bnCentSecond = 0;  // coin age in the unit of cent-seconds
    nCoinAge = 0;
    int nStakeMinConfirmations = 0;

    if (IsCoinBase())
        return true;

    BOOST_FOREACH(const CTxIn& txin, vin)
    {
        // First try finding the previous transaction in database
        CTransaction txPrev;
        CTxIndex txindex;
        if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
            continue;  // previous transaction not in main chain
        if (nTime < txPrev.nTime)
            return false;  // Transaction timestamp violation

        int nSpendDepth;
        
		nStakeMinConfirmations = 1440;


        if (IsConfirmedInNPrevBlocks(txindex, pindexPrev, nStakeMinConfirmations - 1, nSpendDepth))
        {
            LogPrint("coinage", "coin age skip nSpendDepth=%d\n", nSpendDepth + 1);
            continue; // only count coins meeting min confirmations requirement
        }

        int64_t nValueIn = txPrev.vout[txin.prevout.n].nValue;
        bnCentSecond += CBigNum(nValueIn) * (nTime-txPrev.nTime) / CENT;

        LogPrint("coinage", "coin age nValueIn=%d nTimeDiff=%d bnCentSecond=%s\n", nValueIn, nTime - txPrev.nTime, bnCentSecond.ToString());
    }

    CBigNum bnCoinDay = bnCentSecond * CENT / COIN / (24 * 60 * 60);
    LogPrint("coinage", "coin age bnCoinDay=%s\n", bnCoinDay.ToString());
    nCoinAge = bnCoinDay.getuint64();
    return true;
}

void CWallet::AvailableCoinsForStaking(vector<COutput>& vCoins, unsigned int nSpendTime) const
{
    vCoins.clear();

    {
        LOCK2(cs_main, cs_wallet);
        int nStakeMinConfirmations = 0;
        for (map<uint256, CWalletTx>::const_iterator it = mapWallet.begin(); it != mapWallet.end(); ++it)
        {
            const CWalletTx* pcoin = &(*it).second;

            int nDepth = pcoin->GetDepthInMainChain();
            if (nDepth < 1)
                continue;


            nStakeMinConfirmations = 1440;


            if (nDepth < nStakeMinConfirmations)
            {
                continue;
            }    
            else
            {
            // Filtering by tx timestamp instead of block timestamp may give false positives but never false negatives
            if (pcoin->nTime + nStakeMinAge > nSpendTime)
               continue;
            }
            
            if (pcoin->GetBlocksToMaturity() > 0)
                continue;

            for (unsigned int i = 0; i < pcoin->vout.size(); i++)
                if (!(pcoin->IsSpent(i)) && IsMine(pcoin->vout[i]) && pcoin->vout[i].nValue >= nMinimumInputValue)
                    vCoins.push_back(COutput(pcoin, i, nDepth, true));
        }
    }
}