// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or https://www.opensource.org/licenses/mit-license.php .

#ifndef BITCOIN_TXMEMPOOL_H
#define BITCOIN_TXMEMPOOL_H

#include <list>

#include "amount.h"
#include "coins.h"
#include "primitives/transaction.h"
#include "sync.h"

#undef foreach
#include "boost/multi_index_container.hpp"
#include "boost/multi_index/ordered_index.hpp"

class CAutoFile;

inline double AllowFreeThreshold()
{
    return COIN * 144 / 250;
}

inline bool AllowFree(double dPriority)
{
    // Large (in bytes) low-priority (new, small-coin) transactions
    // need a fee.
    return dPriority > AllowFreeThreshold();
}

/** Fake height value used in CCoins to signify they are only in the memory pool (since 0.8) */
static const unsigned int MEMPOOL_HEIGHT = 0x7FFFFFFF;

/**
 * CTxMemPool stores these:
 */
class CTxMemPoolEntry
{
private:
    CTransaction tx;
    CAmount nFee;              //!< Cached to avoid expensive parent-transaction lookups
    size_t nTxSize;            //!< ... and avoid recomputing tx size
    size_t nModSize;           //!< ... and modified size for priority
    size_t nUsageSize;         //!< ... and total memory usage
    CFeeRate feeRate;          //!< ... and fee per kB
    int64_t nTime;             //!< Local time when entering the mempool
    double dPriority;          //!< Priority when entering the mempool
    unsigned int nHeight;      //!< Chain height when entering the mempool
    bool hadNoDependencies;    //!< Not dependent on any other txs when it entered the mempool
    bool spendsCoinbase;       //!< keep track of transactions that spend a coinbase
    uint32_t nBranchId;        //!< Branch ID this transaction is known to commit to, cached for efficiency

public:
    CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
                    int64_t _nTime, double _dPriority, unsigned int _nHeight,
                    bool poolHasNoInputsOf, bool spendsCoinbase, uint32_t nBranchId);
    CTxMemPoolEntry();
    CTxMemPoolEntry(const CTxMemPoolEntry& other);

    const CTransaction& GetTx() const { return this->tx; }
    double GetPriority(unsigned int currentHeight) const;
    CAmount GetFee() const { return nFee; }
    CFeeRate GetFeeRate() const { return feeRate; }
    size_t GetTxSize() const { return nTxSize; }
    int64_t GetTime() const { return nTime; }
    unsigned int GetHeight() const { return nHeight; }
    bool WasClearAtEntry() const { return hadNoDependencies; }
    size_t DynamicMemoryUsage() const { return nUsageSize; }

    bool GetSpendsCoinbase() const { return spendsCoinbase; }
    uint32_t GetValidatedBranchId() const { return nBranchId; }
};

// extracts a TxMemPoolEntry's transaction hash
struct mempoolentry_txid
{
    typedef uint256 result_type;
    result_type operator() (const CTxMemPoolEntry &entry) const
    {
        return entry.GetTx().GetHash();
    }
};

class CompareTxMemPoolEntryByFee
{
public:
    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b)
    {
        if (a.GetFeeRate() == b.GetFeeRate())
            return a.GetTime() < b.GetTime();
        return a.GetFeeRate() > b.GetFeeRate();
    }
};

class CBlockPolicyEstimator;

/** An inpoint - a combination of a transaction and an index n into its vin */
class CInPoint
{
public:
    const CTransaction* ptx;
    uint32_t n;

    CInPoint() { SetNull(); }
    CInPoint(const CTransaction* ptxIn, uint32_t nIn) { ptx = ptxIn; n = nIn; }
    void SetNull() { ptx = NULL; n = (uint32_t) -1; }
    bool IsNull() const { return (ptx == NULL && n == (uint32_t) -1); }
    size_t DynamicMemoryUsage() const { return 0; }
};

/**
 * CTxMemPool stores valid-according-to-the-current-best-chain
 * transactions that may be included in the next block.
 *
 * Transactions are added when they are seen on the network
 * (or created by the local node), but not all transactions seen
 * are added to the pool: if a new transaction double-spends
 * an input of a transaction in the pool, it is dropped,
 * as are non-standard transactions.
 */
class CTxMemPool
{
private:
    uint32_t nCheckFrequency; //!< Value n means that n times in 2^32 we check.
    unsigned int nTransactionsUpdated;
    CBlockPolicyEstimator* minerPolicyEstimator;

    uint64_t totalTxSize = 0;  //!< sum of all mempool tx' byte sizes
    uint64_t cachedInnerUsage; //!< sum of dynamic memory usage of all the map elements (NOT the maps themselves)

    std::map<uint256, const CTransaction*> mapSproutNullifiers;
    std::map<uint256, const CTransaction*> mapSaplingNullifiers;

    void checkNullifiers(ShieldedType type) const;
    
public:
    typedef boost::multi_index_container<
        CTxMemPoolEntry,
        boost::multi_index::indexed_by<
            // sorted by txid
            boost::multi_index::ordered_unique<mempoolentry_txid>,
            // sorted by fee rate
            boost::multi_index::ordered_non_unique<
                boost::multi_index::identity<CTxMemPoolEntry>,
                CompareTxMemPoolEntryByFee
            >
        >
    > indexed_transaction_set;

    mutable CCriticalSection cs;
    indexed_transaction_set mapTx;
    std::map<COutPoint, CInPoint> mapNextTx;
    std::map<uint256, std::pair<double, CAmount> > mapDeltas;

    CTxMemPool(const CFeeRate& _minRelayFee);
    ~CTxMemPool();

    /**
     * If sanity-checking is turned on, check makes sure the pool is
     * consistent (does not contain two transactions that spend the same inputs,
     * all inputs are in the mapNextTx array). If sanity-checking is turned off,
     * check does nothing.
     */
    void check(const CCoinsViewCache *pcoins) const;
    void setSanityCheck(double dFrequency = 1.0) { nCheckFrequency = static_cast<uint32_t>(dFrequency * 4294967295.0); }

    bool addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry, bool fCurrentEstimate = true);
    void remove(const CTransaction &tx, std::list<CTransaction>& removed, bool fRecursive = false);
    void removeWithAnchor(const uint256 &invalidRoot, ShieldedType type);
    void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
    void removeConflicts(const CTransaction &tx, std::list<CTransaction>& removed);
    void removeExpired(unsigned int nBlockHeight);
    void removeForBlock(const std::vector<CTransaction>& vtx, unsigned int nBlockHeight,
                        std::list<CTransaction>& conflicts, bool fCurrentEstimate = true);
    void removeWithoutBranchId(uint32_t nMemPoolBranchId);
    void clear();
    void queryHashes(std::vector<uint256>& vtxid);
    void pruneSpent(const uint256& hash, CCoins &coins);
    unsigned int GetTransactionsUpdated() const;
    void AddTransactionsUpdated(unsigned int n);
    /**
     * Check that none of this transactions inputs are in the mempool, and thus
     * the tx is not dependent on other mempool transactions to be included in a block.
     */
    bool HasNoInputsOf(const CTransaction& tx) const;

    /** Affect CreateNewBlock prioritisation of transactions */
    void PrioritiseTransaction(const uint256 hash, const std::string strHash, double dPriorityDelta, const CAmount& nFeeDelta);
    void ApplyDeltas(const uint256 hash, double &dPriorityDelta, CAmount &nFeeDelta);
    void ClearPrioritisation(const uint256 hash);

    bool nullifierExists(const uint256& nullifier, ShieldedType type) const;

    unsigned long size()
    {
        LOCK(cs);
        return mapTx.size();
    }

    uint64_t GetTotalTxSize()
    {
        LOCK(cs);
        return totalTxSize;
    }

    bool exists(uint256 hash) const
    {
        LOCK(cs);
        return (mapTx.count(hash) != 0);
    }

    bool lookup(uint256 hash, CTransaction& result) const;

    /** Estimate fee rate needed to get into the next nBlocks */
    CFeeRate estimateFee(int nBlocks) const;

    /** Estimate priority needed to get into the next nBlocks */
    double estimatePriority(int nBlocks) const;
    
    /** Write/Read estimates to disk */
    bool WriteFeeEstimates(CAutoFile& fileout) const;
    bool ReadFeeEstimates(CAutoFile& filein);

    size_t DynamicMemoryUsage() const;

    /** Return nCheckFrequency */
    uint32_t GetCheckFrequency() const {
        return nCheckFrequency;
    }
};

/** 
 * CCoinsView that brings transactions from a memorypool into view.
 * It does not check for spendings by memory pool transactions.
 */
class CCoinsViewMemPool : public CCoinsViewBacked
{
protected:
    CTxMemPool &mempool;

public:
    CCoinsViewMemPool(CCoinsView *baseIn, CTxMemPool &mempoolIn);
    bool GetNullifier(const uint256 &txid, ShieldedType type) const;
    bool GetCoins(const uint256 &txid, CCoins &coins) const;
    bool HaveCoins(const uint256 &txid) const;
};

#endif // BITCOIN_TXMEMPOOL_H