text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2012 The Bitcoin developers
  // Copyright (c) 2013 The UperCoin developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "txdb.h"
  #include "miner.h"
  #include "kernel.h"
  
  using namespace std;
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // BitcoinMiner
  //
  
  int64_t nReserveBalance = 0;
  static unsigned int nMaxStakeSearchInterval = 60;
  uint64_t nStakeInputsMapSize = 0;
  
  int static FormatHashBlocks(void* pbuffer, unsigned int len)
  {
      unsigned char* pdata = (unsigned char*)pbuffer;
      unsigned int blocks = 1 + ((len + 8) / 64);
      unsigned char* pend = pdata + 64 * blocks;
      memset(pdata + len, 0, 64 * blocks - len);
      pdata[len] = 0x80;
      unsigned int bits = len * 8;
      pend[-1] = (bits >> 0) & 0xff;
      pend[-2] = (bits >> 8) & 0xff;
      pend[-3] = (bits >> 16) & 0xff;
      pend[-4] = (bits >> 24) & 0xff;
      return blocks;
  }
  
  static const unsigned int pSHA256InitState[8] =
  {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
  
  void SHA256Transform(void* pstate, void* pinput, const void* pinit)
  {
      SHA256_CTX ctx;
      unsigned char data[64];
  
      SHA256_Init(&ctx);
  
      for (int i = 0; i < 16; i++)
          ((uint32_t*)data)[i] = ByteReverse(((uint32_t*)pinput)[i]);
  
      for (int i = 0; i < 8; i++)
          ctx.h[i] = ((uint32_t*)pinit)[i];
  
      SHA256_Update(&ctx, data, sizeof(data));
      for (int i = 0; i < 8; i++)
          ((uint32_t*)pstate)[i] = ctx.h[i];
  }
  
  // Some explaining would be appreciated
  class COrphan
  {
  public:
      CTransaction* ptx;
      set<uint256> setDependsOn;
      double dPriority;
      double dFeePerKb;
  
      COrphan(CTransaction* ptxIn)
      {
          ptx = ptxIn;
          dPriority = dFeePerKb = 0;
      }
  
      void print() const
      {
          printf("COrphan(hash=%s, dPriority=%.1f, dFeePerKb=%.1f)\n",
                 ptx->GetHash().ToString().substr(0,10).c_str(), dPriority, dFeePerKb);
          BOOST_FOREACH(uint256 hash, setDependsOn)
              printf("   setDependsOn %s\n", hash.ToString().substr(0,10).c_str());
      }
  };
  
  
  uint64_t nLastBlockTx = 0;
  uint64_t nLastBlockSize = 0;
  uint32_t nLastCoinStakeSearchInterval = 0;
   
  // We want to sort transactions by priority and fee, so:
  typedef boost::tuple<double, double, CTransaction*> TxPriority;
  class TxPriorityCompare
  {
      bool byFee;
  public:
      TxPriorityCompare(bool _byFee) : byFee(_byFee) { }
      bool operator()(const TxPriority& a, const TxPriority& b)
      {
          if (byFee)
          {
              if (a.get<1>() == b.get<1>())
                  return a.get<0>() < b.get<0>();
              return a.get<1>() < b.get<1>();
          }
          else
          {
              if (a.get<0>() == b.get<0>())
                  return a.get<1>() < b.get<1>();
              return a.get<0>() < b.get<0>();
          }
      }
  };
  
  // CreateNewBlock: create new block (without proof-of-work/with provided coinstake)
  CBlock* CreateNewBlock(CWallet* pwallet, CTransaction *txCoinStake)
  {
      bool fProofOfStake = txCoinStake != NULL;
  
      // Create new block
      auto_ptr<CBlock> pblock(new CBlock());
      if (!pblock.get())
          return NULL;
  
      // Create coinbase tx
      CTransaction txCoinBase;
      txCoinBase.vin.resize(1);
      txCoinBase.vin[0].prevout.SetNull();
      txCoinBase.vout.resize(1);
  
      if (!fProofOfStake)
      {
          CReserveKey reservekey(pwallet);
          txCoinBase.vout[0].scriptPubKey.SetDestination(reservekey.GetReservedKey().GetID());
  
          // Add our coinbase tx as first transaction
          pblock->vtx.push_back(txCoinBase);
      }
      else
      {
          // Coinbase output must be empty for Proof-of-Stake block
          txCoinBase.vout[0].SetEmpty();
  
          // Syncronize timestamps
          pblock->nTime = txCoinBase.nTime = txCoinStake->nTime;
  
          // Add coinbase and coinstake transactions
          pblock->vtx.push_back(txCoinBase);
          pblock->vtx.push_back(*txCoinStake);
      }
  
      // Largest block you're willing to create:
      unsigned int nBlockMaxSize = GetArg("-blockmaxsize", MAX_BLOCK_SIZE_GEN/2);
      // Limit to betweeen 1K and MAX_BLOCK_SIZE-1K for sanity:
      nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SIZE-1000), nBlockMaxSize));
  
      // How much of the block should be dedicated to high-priority transactions,
      // included regardless of the fees they pay
      unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", 27000);
      nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
  
      // Minimum block size you want to create; block will be filled with free transactions
      // until there are no more or the block reaches this size:
      unsigned int nBlockMinSize = GetArg("-blockminsize", 0);
      nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
  
      // Fee-per-kilobyte amount considered the same as "free"
      // Be careful setting this: if you set it to zero then
      // a transaction spammer can cheaply fill blocks using
      // 1-satoshi-fee transactions. It should be set above the real
      // cost to you of processing a transaction.
      int64_t nMinTxFee = MIN_TX_FEE;
      if (mapArgs.count("-mintxfee"))
          ParseMoney(mapArgs["-mintxfee"], nMinTxFee);
  
      CBlockIndex* pindexPrev = pindexBest;
  
      pblock->nBits = GetNextTargetRequired(pindexPrev, fProofOfStake);
  
      // Collect memory pool transactions into the block
      int64_t nFees = 0;
      {
          LOCK2(cs_main, mempool.cs);
          CBlockIndex* pindexPrev = pindexBest;
          CTxDB txdb("r");
  
          // Priority order to process transactions
          list<COrphan> vOrphan; // list memory doesn't move
          map<uint256, vector<COrphan*> > mapDependers;
  
          // This vector will be sorted into a priority queue:
          vector<TxPriority> vecPriority;
          vecPriority.reserve(mempool.mapTx.size());
          for (map<uint256, CTransaction>::iterator mi = mempool.mapTx.begin(); mi != mempool.mapTx.end(); ++mi)
          {
              CTransaction& tx = (*mi).second;
              if (tx.IsCoinBase() || tx.IsCoinStake() || !tx.IsFinal())
                  continue;
  
              COrphan* porphan = NULL;
              double dPriority = 0;
              int64_t nTotalIn = 0;
              bool fMissingInputs = false;
              BOOST_FOREACH(const CTxIn& txin, tx.vin)
              {
                  // Read prev transaction
                  CTransaction txPrev;
                  CTxIndex txindex;
                  if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))
                  {
                      // This should never happen; all transactions in the memory
                      // pool should connect to either transactions in the chain
                      // or other transactions in the memory pool.
                      if (!mempool.mapTx.count(txin.prevout.hash))
                      {
                          printf("ERROR: mempool transaction missing input\n");
                          if (fDebug) assert("mempool transaction missing input" == 0);
                          fMissingInputs = true;
                          if (porphan)
                              vOrphan.pop_back();
                          break;
                      }
  
                      // Has to wait for dependencies
                      if (!porphan)
                      {
                          // Use list for automatic deletion
                          vOrphan.push_back(COrphan(&tx));
                          porphan = &vOrphan.back();
                      }
                      mapDependers[txin.prevout.hash].push_back(porphan);
                      porphan->setDependsOn.insert(txin.prevout.hash);
                      nTotalIn += mempool.mapTx[txin.prevout.hash].vout[txin.prevout.n].nValue;
                      continue;
                  }
                  int64_t nValueIn = txPrev.vout[txin.prevout.n].nValue;
                  nTotalIn += nValueIn;
  
                  int nConf = txindex.GetDepthInMainChain();
                  dPriority += (double)nValueIn * nConf;
              }
              if (fMissingInputs) continue;
  
              // Priority is sum(valuein * age) / txsize
              unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
              dPriority /= nTxSize;
  
              // This is a more accurate fee-per-kilobyte than is used by the client code, because the
              // client code rounds up the size to the nearest 1K. That's good, because it gives an
              // incentive to create smaller transactions.
              double dFeePerKb =  double(nTotalIn-tx.GetValueOut()) / (double(nTxSize)/1000.0);
  
              if (porphan)
              {
                  porphan->dPriority = dPriority;
                  porphan->dFeePerKb = dFeePerKb;
              }
              else
                  vecPriority.push_back(TxPriority(dPriority, dFeePerKb, &(*mi).second));
          }
  
          // Collect transactions into block
          map<uint256, CTxIndex> mapTestPool;
          uint64_t nBlockSize = 1000;
          uint64_t nBlockTx = 0;
          int nBlockSigOps = 100;
          bool fSortedByFee = (nBlockPrioritySize <= 0);
  
          TxPriorityCompare comparer(fSortedByFee);
          std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
  
          while (!vecPriority.empty())
          {
              // Take highest priority transaction off the priority queue:
              double dPriority = vecPriority.front().get<0>();
              double dFeePerKb = vecPriority.front().get<1>();
              CTransaction& tx = *(vecPriority.front().get<2>());
  
              std::pop_heap(vecPriority.begin(), vecPriority.end(), comparer);
              vecPriority.pop_back();
  
              // Size limits
              unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
              if (nBlockSize + nTxSize >= nBlockMaxSize)
                  continue;
  
              // Legacy limits on sigOps:
              unsigned int nTxSigOps = tx.GetLegacySigOpCount();
              if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                  continue;
  
              // Timestamp limit
              if (tx.nTime > GetAdjustedTime() || (fProofOfStake && tx.nTime > txCoinStake->nTime))
                  continue;
  
              // Simplify transaction fee - allow free = false
              int64_t nMinFee = tx.GetMinFee(nBlockSize, true, GMF_BLOCK, nTxSize);
  
              // Skip free transactions if we're past the minimum block size:
              if (fSortedByFee && (dFeePerKb < nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
                  continue;
  
              // Prioritize by fee once past the priority size or we run out of high-priority
              // transactions:
              if (!fSortedByFee &&
                  ((nBlockSize + nTxSize >= nBlockPrioritySize) || (dPriority < COIN * 144 / 250)))
              {
                  fSortedByFee = true;
                  comparer = TxPriorityCompare(fSortedByFee);
                  std::make_heap(vecPriority.begin(), vecPriority.end(), comparer);
              }
  
              // Connecting shouldn't fail due to dependency on other memory pool transactions
              // because we're already processing them in order of dependency
              map<uint256, CTxIndex> mapTestPoolTmp(mapTestPool);
              MapPrevTx mapInputs;
              bool fInvalid;
              if (!tx.FetchInputs(txdb, mapTestPoolTmp, false, true, mapInputs, fInvalid))
                  continue;
  
              int64_t nTxFees = tx.GetValueIn(mapInputs)-tx.GetValueOut();
              if (nTxFees < nMinFee)
                  continue;
  
              nTxSigOps += tx.GetP2SHSigOpCount(mapInputs);
              if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                  continue;
  
              if (!tx.ConnectInputs(txdb, mapInputs, mapTestPoolTmp, CDiskTxPos(1,1,1), pindexPrev, false, true, true, MANDATORY_SCRIPT_VERIFY_FLAGS))
                  continue;
              mapTestPoolTmp[tx.GetHash()] = CTxIndex(CDiskTxPos(1,1,1), tx.vout.size());
              swap(mapTestPool, mapTestPoolTmp);
  
              // Added
              pblock->vtx.push_back(tx);
              nBlockSize += nTxSize;
              ++nBlockTx;
              nBlockSigOps += nTxSigOps;
              nFees += nTxFees;
  
              if (fDebug && GetBoolArg("-printpriority"))
              {
                  printf("priority %.1f feeperkb %.1f txid %s\n",
                         dPriority, dFeePerKb, tx.GetHash().ToString().c_str());
              }
  
              // Add transactions that depend on this one to the priority queue
              uint256 hash = tx.GetHash();
              if (mapDependers.count(hash))
              {
                  BOOST_FOREACH(COrphan* porphan, mapDependers[hash])
                  {
                      if (!porphan->setDependsOn.empty())
                      {
                          porphan->setDependsOn.erase(hash);
                          if (porphan->setDependsOn.empty())
                          {
                              vecPriority.push_back(TxPriority(porphan->dPriority, porphan->dFeePerKb, porphan->ptx));
                              std::push_heap(vecPriority.begin(), vecPriority.end(), comparer);
                          }
                      }
                  }
              }
          }
  
          nLastBlockTx = nBlockTx;
          nLastBlockSize = nBlockSize;
  
          if (!fProofOfStake)
          {
              pblock->vtx[0].vout[0].nValue = GetProofOfWorkReward(pblock->nBits, nFees);
  
              if (fDebug)
                  printf("CreateNewBlock(): PoW reward %" PRIu64 "\n", pblock->vtx[0].vout[0].nValue);
          }
  
          if (fDebug && GetBoolArg("-printpriority"))
              printf("CreateNewBlock(): total size %" PRIu64 "\n", nBlockSize);
  
          // Fill in header
          pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
          if (!fProofOfStake)
          {
              pblock->nTime          = max(pindexPrev->GetMedianTimePast()+1, pblock->GetMaxTransactionTime());
              pblock->nTime          = max(pblock->GetBlockTime(), PastDrift(pindexPrev->GetBlockTime()));
              pblock->UpdateTime(pindexPrev);
          }
          pblock->nNonce         = 0;
      }
  
      return pblock.release();
  }
  
  
  void IncrementExtraNonce(CBlock* pblock, CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
  {
      // Update nExtraNonce
      static uint256 hashPrevBlock;
      if (hashPrevBlock != pblock->hashPrevBlock)
      {
          nExtraNonce = 0;
          hashPrevBlock = pblock->hashPrevBlock;
      }
      ++nExtraNonce;
  
      unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
      pblock->vtx[0].vin[0].scriptSig = (CScript() << nHeight << CBigNum(nExtraNonce)) + COINBASE_FLAGS;
      assert(pblock->vtx[0].vin[0].scriptSig.size() <= 100);
  
      pblock->hashMerkleRoot = pblock->BuildMerkleTree();
  }
  
  
  void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash1)
  {
      //
      // Pre-build hash buffers
      //
      struct
      {
          struct unnamed2
          {
              int nVersion;
              uint256 hashPrevBlock;
              uint256 hashMerkleRoot;
              unsigned int nTime;
              unsigned int nBits;
              unsigned int nNonce;
          }
          block;
          unsigned char pchPadding0[64];
          uint256 hash1;
          unsigned char pchPadding1[64];
      }
      tmp;
      memset(&tmp, 0, sizeof(tmp));
  
      tmp.block.nVersion       = pblock->nVersion;
      tmp.block.hashPrevBlock  = pblock->hashPrevBlock;
      tmp.block.hashMerkleRoot = pblock->hashMerkleRoot;
      tmp.block.nTime          = pblock->nTime;
      tmp.block.nBits          = pblock->nBits;
      tmp.block.nNonce         = pblock->nNonce;
  
      FormatHashBlocks(&tmp.block, sizeof(tmp.block));
      FormatHashBlocks(&tmp.hash1, sizeof(tmp.hash1));
  
      // Byte swap all the input buffer
      for (unsigned int i = 0; i < sizeof(tmp)/4; i++)
          ((unsigned int*)&tmp)[i] = ByteReverse(((unsigned int*)&tmp)[i]);
  
      // Precalc the first half of the first hash, which stays constant
      SHA256Transform(pmidstate, &tmp.block, pSHA256InitState);
  
      memcpy(pdata, &tmp.block, 128);
      memcpy(phash1, &tmp.hash1, 64);
  }
  
  
  bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
  {
      uint256 hashBlock = pblock->GetHash();
      uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
  
      if(!pblock->IsProofOfWork())
          return error("CheckWork() : %s is not a proof-of-work block", hashBlock.GetHex().c_str());
  
      if (hashBlock > hashTarget)
          return error("CheckWork() : proof-of-work not meeting target");
  
      //// debug print
      printf("CheckWork() : new proof-of-work block found  \n  hash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), hashTarget.GetHex().c_str());
      pblock->print();
      printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());
  
      // Found a solution
      {
          LOCK(cs_main);
          if (pblock->hashPrevBlock != hashBestChain)
              return error("CheckWork() : generated block is stale");
  
          // Remove key from key pool
          reservekey.KeepKey();
  
          // Track how many getdata requests this block gets
          {
              LOCK(wallet.cs_wallet);
              wallet.mapRequestCount[hashBlock] = 0;
          }
  
          // Process this block the same as if we had received it from another node
          if (!ProcessBlock(NULL, pblock))
              return error("CheckWork() : ProcessBlock, block not accepted");
      }
  
      return true;
  }
  
  bool CheckStake(CBlock* pblock, CWallet& wallet)
  {
      uint256 proofHash = 0, hashTarget = 0;
      uint256 hashBlock = pblock->GetHash();
  
      if(!pblock->IsProofOfStake())
          return error("CheckStake() : %s is not a proof-of-stake block", hashBlock.GetHex().c_str());
  
      // verify hash target and signature of coinstake tx
      if (!CheckProofOfStake(pblock->vtx[1], pblock->nBits, proofHash, hashTarget))
          return error("CheckStake() : proof-of-stake checking failed");
  
      //// debug print
      printf("CheckStake() : new proof-of-stake block found  \n  hash: %s \nproofhash: %s  \ntarget: %s\n", hashBlock.GetHex().c_str(), proofHash.GetHex().c_str(), hashTarget.GetHex().c_str());
      pblock->print();
      printf("out %s\n", FormatMoney(pblock->vtx[1].GetValueOut()).c_str());
  
      // Found a solution
      {
          LOCK(cs_main);
          if (pblock->hashPrevBlock != hashBestChain)
              return error("CheckStake() : generated block is stale");
  
          // Track how many getdata requests this block gets
          {
              LOCK(wallet.cs_wallet);
              wallet.mapRequestCount[hashBlock] = 0;
          }
  
          // Process this block the same as if we had received it from another node
          if (!ProcessBlock(NULL, pblock))
              return error("CheckStake() : ProcessBlock, block not accepted");
      }
  
      return true;
  }
  
  // Precalculated SHA256 contexts and metadata
  // (txid, vout.n) => (SHA256_CTX, (tx.nTime, nAmount))
  typedef std::map<std::pair<uint256, unsigned int>, std::pair<SHA256_CTX, std::pair<uint32_t, uint64_t> > > MidstateMap;
  
  // Fill the inputs map with precalculated states and metadata
  bool FillMap(CWallet *pwallet, uint32_t nUpperTime, MidstateMap &inputsMap)
  {
      // Choose coins to use
      int64_t nBalance = pwallet->GetBalance();
  
      if (nBalance <= nReserveBalance)
          return false;
  
      uint32_t nTime = GetAdjustedTime();
  
      CTxDB txdb("r");
      {
          LOCK2(cs_main, pwallet->cs_wallet);
  
          CoinsSet setCoins;
          int64_t nValueIn = 0;
          if (!pwallet->SelectCoinsSimple(nBalance - nReserveBalance, MIN_TX_FEE, MAX_MONEY, nUpperTime, nCoinbaseMaturity * 10, setCoins, nValueIn))
              return error("FillMap() : SelectCoinsSimple failed");
  
          if (setCoins.empty())
              return false;
  
          CBlock block;
          CTxIndex txindex;
  
          for(CoinsSet::const_iterator pcoin = setCoins.begin(); pcoin != setCoins.end(); pcoin++)
          {
              pair<uint256, uint32_t> key = make_pair(pcoin->first->GetHash(), pcoin->second);
  
              // Skip existent inputs
              if (inputsMap.find(key) != inputsMap.end())
                  continue;
  
              // Trying to parse scriptPubKey
              txnouttype whichType;
              vector<valtype> vSolutions;
              if (!Solver(pcoin->first->vout[pcoin->second].scriptPubKey, whichType, vSolutions))
                  continue;
  
              // Only support pay to public key and pay to address
              if (whichType != TX_PUBKEY && whichType != TX_PUBKEYHASH)
                  continue;
  
              // Load transaction index item
              if (!txdb.ReadTxIndex(pcoin->first->GetHash(), txindex))
                  continue;
  
              // Read block header
              if (!block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
                  continue;
  
              // Only load coins meeting min age requirement
              if (nStakeMinAge + block.nTime > nTime - nMaxStakeSearchInterval)
                  continue;
  
              uint64_t nStakeModifier = 0;
              if (!GetKernelStakeModifier(block.GetHash(), nStakeModifier))
                  continue;
  
              SHA256_CTX ctx;
              // Calculate midstate using (modifier, block time, tx offset, tx time, output number)
              GetKernelMidstate(nStakeModifier, block.nTime, txindex.pos.nTxPos - txindex.pos.nBlockPos, pcoin->first->nTime, pcoin->second, ctx);
  
              // (txid, vout.n) => (SHA256_CTX, (tx.nTime, nAmount))
              inputsMap[key] = make_pair(ctx, make_pair(pcoin->first->nTime, pcoin->first->vout[pcoin->second].nValue));
          }
  
          nStakeInputsMapSize = inputsMap.size();
  
          if (fDebug)
              printf("Stake miner: map of %" PRIu64 " precalculated contexts has been created\n", nStakeInputsMapSize);
      }
  
      return true;
  }
  
  // Scan inputs map in order to find a solution
  bool ScanMap(const MidstateMap &inputsMap, uint32_t nBits, MidstateMap::key_type &LuckyInput, std::pair<uint256, uint32_t> &solution)
  {
      static uint32_t nLastCoinStakeSearchTime = GetAdjustedTime(); // startup timestamp
      uint32_t nSearchTime = GetAdjustedTime();
  
      if (inputsMap.size() > 0 && nSearchTime > nLastCoinStakeSearchTime)
      {
          // Scanning interval (begintime, endtime)
          std::pair<uint32_t, uint32_t> interval;
  
          interval.first = nSearchTime;
          interval.second = nSearchTime - min(nSearchTime-nLastCoinStakeSearchTime, nMaxStakeSearchInterval);
  
          // (txid, nout) => (SHA256_CTX, (tx.nTime, nAmount))
          for(MidstateMap::const_iterator input = inputsMap.begin(); input != inputsMap.end(); input++)
          {
              SHA256_CTX ctx = input->second.first;
  
              // scan(State, Bits, Time, Amount, ...)
              if (ScanMidstateBackward(ctx, nBits, input->second.second.first, input->second.second.second, interval, solution))
              {
                  // Solution found
                  LuckyInput = input->first; // (txid, nout)
  
                  return true;
              }
          }
  
          // Inputs map iteration can be big enough to consume few seconds while scanning.
          // We're using dynamical calculation of scanning interval in order to compensate this delay.
          nLastCoinStakeSearchInterval = nSearchTime - nLastCoinStakeSearchTime;
          nLastCoinStakeSearchTime = nSearchTime;
      }
  
      // No solutions were found
      return false;
  }
  
  void StakeMiner(CWallet *pwallet)
  {
      SetThreadPriority(THREAD_PRIORITY_LOWEST);
  
      // Make this thread recognisable as the mining thread
      RenameThread("upercoin-miner");
  
      MidstateMap inputsMap;
      if (!FillMap(pwallet, GetAdjustedTime(), inputsMap))
          return;
  
      bool fTrySync = true;
  
      CBlockIndex* pindexPrev = pindexBest;
      uint32_t nBits = GetNextTargetRequired(pindexPrev, true);
  
      while (true)
      {
          if (fShutdown)
              return;
  
          while (pwallet->IsLocked())
          {
              Sleep(1000);
              if (fShutdown)
                  return;
          }
  
          while (vNodes.empty() || IsInitialBlockDownload())
          {
              fTrySync = true;
  
              Sleep(1000);
              if (fShutdown)
                  return;
          }
  
          if (fTrySync)
          {
              fTrySync = false;
              if (vNodes.size() < 3 || nBestHeight < GetNumBlocksOfPeers())
              {
                  Sleep(1000);
                  continue;
              }
          }
  
          MidstateMap::key_type LuckyInput;
          std::pair<uint256, uint32_t> solution;
  
          if (ScanMap(inputsMap, nBits, LuckyInput, solution))
          {
              SetThreadPriority(THREAD_PRIORITY_NORMAL);
  
              // Remove lucky input from the map
              inputsMap.erase(inputsMap.find(LuckyInput));
  
              CKey key;
              CTransaction txCoinStake;
  
              // Create new coinstake transaction
              if (!pwallet->CreateCoinStake(LuckyInput.first, LuckyInput.second, solution.second, nBits, txCoinStake, key))
              {
                  string strMessage = _("Warning: Unable to create coinstake transaction, see debug.log for the details. Mining thread has been stopped.");
                  strMiscWarning = strMessage;
                  printf("*** %s\n", strMessage.c_str());
  
                  return;
              }
  
              // Now we have new coinstake, it's time to create the block ...
              CBlock* pblock;
              pblock = CreateNewBlock(pwallet, &txCoinStake);
              if (!pblock)
              {
                  string strMessage = _("Warning: Unable to allocate memory for the new block object. Mining thread has been stopped.");
                  strMiscWarning = strMessage;
                  printf("*** %s\n", strMessage.c_str());
  
                  return;
              }
  
              unsigned int nExtraNonce = 0;
              IncrementExtraNonce(pblock, pindexPrev, nExtraNonce);
  
              // ... and sign it
              if (!key.Sign(pblock->GetHash(), pblock->vchBlockSig))
              {
                  string strMessage = _("Warning: Proof-of-Stake miner is unable to sign the block (locked wallet?). Mining thread has been stopped.");
                  strMiscWarning = strMessage;
                  printf("*** %s\n", strMessage.c_str());
  
                  return;
              }
  
              CheckStake(pblock, *pwallet);
              SetThreadPriority(THREAD_PRIORITY_LOWEST);
              Sleep(500);
          }
  
          if (pindexPrev != pindexBest)
          {
              // The best block has been changed, we need to refill the map
              if (FillMap(pwallet, GetAdjustedTime(), inputsMap))
              {
                  pindexPrev = pindexBest;
                  nBits = GetNextTargetRequired(pindexPrev, true);
              }
              else
              {
                  // Clear existent data if FillMap failed
                  inputsMap.clear();
              }
          }
  
          Sleep(500);
  
          continue;
      }
  }
  