// Copyright (c) 2021-present 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 <wallet/transaction.h>

#include <consensus/validation.h>

#include <interfaces/chain.h>

using interfaces::FoundBlock;

namespace wallet {

bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const

{

        CMutableTransaction tx1 {*this->GetTx()};

        CMutableTransaction tx2 {*_tx.GetTx()};

        for (auto& txin : tx1.vin) {

            txin.scriptSig = CScript();

            txin.scriptWitness.SetNull();

        }

        for (auto& txin : tx2.vin) {

            txin.scriptSig = CScript();

            txin.scriptWitness.SetNull();

        }

        return CTransaction(tx1) == CTransaction(tx2);

}

bool CWalletTx::InMempool() const

{

    return state<TxStateInMempool>();

}

int64_t CWalletTx::GetTxTime() const

{

    int64_t n = nTimeSmart;

    return n ? n : nTimeReceived;

}

void CWalletTx::updateState(interfaces::Chain& chain)

{

    bool active;

    auto lookup_block = [&](const uint256& hash, int& height, TxState& state) {

        // If tx block (or conflicting block) was reorged out of chain

        // while the wallet was shutdown, change tx status to UNCONFIRMED

        // and reset block height, hash, and index. ABANDONED tx don't have

        // associated blocks and don't need to be updated. The case where a

        // transaction was reorged out while online and then reconfirmed

        // while offline is covered by the rescan logic.

        if (!chain.findBlock(hash, FoundBlock().inActiveChain(active).height(height)) || !active) {

            state = TxStateInactive{};

        }

    };

    if (auto* conf = state<TxStateConfirmed>()) {

        lookup_block(conf->confirmed_block_hash, conf->confirmed_block_height, m_state);

    } else if (auto* conf = state<TxStateBlockConflicted>()) {

        lookup_block(conf->conflicting_block_hash, conf->conflicting_block_height, m_state);

    }

    // If the above downgraded a previously-confirmed witness variant back to unconfirmed,

    // the canonical choice is no longer pinned by confirmation. Re-apply the least-weight rule.

    if (!isConfirmed()) RecomputeCanonical();

}

bool CWalletTx::Update(CTransactionRef new_tx, const TxState& new_state)

{

    Assert(new_tx);

    if (!Assume(GetHash() == new_tx->GetHash())) {

        return false;

    }

    bool ret = false;

    const auto& [tx_pair, inserted] = m_txs.emplace(new_tx->GetWitnessHash(), std::move(new_tx));

    if (inserted) {

        ret = true;

    }

    const auto& [wtxid, tx] = *tx_pair;

    if (new_state.index() != m_state.index()) {

        m_state = new_state;

        if (state<TxStateConfirmed>()) {

            m_canonical_wtxid = wtxid;

        }

        ret = true;

    } else {

        assert(TxStateSerializedIndex(m_state) == TxStateSerializedIndex(new_state));

        assert(TxStateSerializedBlockHash(m_state) == TxStateSerializedBlockHash(new_state));

    }

    // While unconfirmed, derive the canonical variant from all known variants

    if (!isConfirmed()) {

        const Wtxid prev_canonical = m_canonical_wtxid;

        RecomputeCanonical();

        if (m_canonical_wtxid != prev_canonical) {

            ret = true;

        }

    }

    return ret;

}

void CWalletTx::RecomputeCanonical()

{

    // Recompute the canonical variant among the witness variants. They share

    // the txid but differ in the wtxid. Prefer variant with witness data and

    // the least weight.

    Assert(!m_txs.empty());

    // Returns true if 'a' should be preferred over 'b'

    auto is_better = [](const CTransactionRef& a, const CTransactionRef& b) {

        // A witnessed variant always beats a witnessless one

        if (a->HasWitness() != b->HasWitness()) return a->HasWitness();

        // Otherwise the lighter one wins

        return GetTransactionWeight(*a) < GetTransactionWeight(*b);

    };

    auto it = m_txs.begin();

    auto best_wtxid = it->first;

    const CTransactionRef* best = &it->second;

    it = std::next(it);

    for (; it != m_txs.end(); it = std::next(it)) {

        if (is_better(it->second, *best)) {

            best = &it->second;

            best_wtxid = it->first;

        }

    }

    m_canonical_wtxid = best_wtxid;

}

} // namespace wallet