// Copyright (c) 2018 The Zcash developers
// Copyright (c) 2016-2020 The Hush developers
// Distributed under the GPLv3 software license, see the accompanying
// file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html

#ifndef TRANSACTION_BUILDER_H
#define TRANSACTION_BUILDER_H

#include "consensus/params.h"
#include "keystore.h"
#include "primitives/transaction.h"
#include "script/script.h"
#include "script/standard.h"
#include "uint256.h"
#include "zcash/Address.hpp"
#include "zcash/IncrementalMerkleTree.hpp"
#include "zcash/Note.hpp"
#include "zcash/NoteEncryption.hpp"

#include <boost/optional.hpp>

struct SpendDescriptionInfo {
    libzcash::SaplingExpandedSpendingKey expsk;
    libzcash::SaplingNote note;
    uint256 alpha;
    uint256 anchor;
    SaplingWitness witness;

    SpendDescriptionInfo(
        libzcash::SaplingExpandedSpendingKey expsk,
        libzcash::SaplingNote note,
        uint256 anchor,
        SaplingWitness witness);
};

struct OutputDescriptionInfo {
    uint256 ovk;
    libzcash::SaplingNote note;
    std::array<unsigned char, ZC_MEMO_SIZE> memo;

    OutputDescriptionInfo(
        uint256 ovk,
        libzcash::SaplingNote note,
        std::array<unsigned char, ZC_MEMO_SIZE> memo) : ovk(ovk), note(note), memo(memo) {}
};

struct TransparentInputInfo {
    CScript scriptPubKey;
    CAmount value;

    TransparentInputInfo(
        CScript scriptPubKey,
        CAmount value) : scriptPubKey(scriptPubKey), value(value) {}
};

class TransactionBuilder
{
private:
    Consensus::Params consensusParams;
    int nHeight;
    const CKeyStore* keystore;
    CMutableTransaction mtx;
    CAmount fee = 10000;

    std::vector<SpendDescriptionInfo> spends;
    std::vector<OutputDescriptionInfo> outputs;
    std::vector<TransparentInputInfo> tIns;

    boost::optional<std::pair<uint256, libzcash::SaplingPaymentAddress>> zChangeAddr;
    boost::optional<CTxDestination> tChangeAddr;
    boost::optional<CScript> opReturn;

    bool AddOpRetLast(CScript &s);

public:
    TransactionBuilder() {}
    TransactionBuilder(const Consensus::Params& consensusParams, int nHeight, CKeyStore* keyStore = nullptr);

    void SetFee(CAmount fee);

    // Returns false if the anchor does not match the anchor used by
    // previously-added Sapling spends.
    bool AddSaplingSpend(
        libzcash::SaplingExpandedSpendingKey expsk,
        libzcash::SaplingNote note,
        uint256 anchor,
        SaplingWitness witness);

    void AddSaplingOutput(
        uint256 ovk,
        libzcash::SaplingPaymentAddress to,
        CAmount value,
        std::array<unsigned char, ZC_MEMO_SIZE> memo = {{0}});

    // Assumes that the value correctly corresponds to the provided UTXO.
    void AddTransparentInput(COutPoint utxo, CScript scriptPubKey, CAmount value, uint32_t nSequence = 0xffffffff);

    bool AddTransparentOutput(CTxDestination& to, CAmount value);

    void AddOpRet(CScript &s);

    bool AddOpRetLast();

    void SendChangeTo(libzcash::SaplingPaymentAddress changeAddr, uint256 ovk);

    bool SendChangeTo(CTxDestination& changeAddr);

    void SetLockTime(uint32_t time) { this->mtx.nLockTime = time; }

    boost::optional<CTransaction> Build();
};

#endif /* TRANSACTION_BUILDER_H */