// Copyright (c) 2017-2022 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 <common/system.h>

#include <consensus/validation.h>

#include <interfaces/chain.h>

#include <node/types.h>

#include <policy/fees.h>

#include <policy/policy.h>

#include <util/moneystr.h>

#include <util/rbf.h>

#include <util/translation.h>

#include <wallet/coincontrol.h>

#include <wallet/feebumper.h>

#include <wallet/fees.h>

#include <wallet/receive.h>

#include <wallet/spend.h>

#include <wallet/wallet.h>

namespace wallet {

//! Check whether transaction has descendant in wallet or mempool, or has been

//! mined, or conflicts with a mined transaction. Return a feebumper::Result.

static feebumper::Result PreconditionChecks(const CWallet& wallet, const CWalletTx& wtx, bool require_mine, std::vector<bilingual_str>& errors) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)

{

    if (wallet.HasWalletSpend(wtx.tx)) {

        errors.push_back(Untranslated("Transaction has descendants in the wallet"));

        return feebumper::Result::INVALID_PARAMETER;

    }

    {

        if (wallet.chain().hasDescendantsInMempool(wtx.GetHash())) {

            errors.push_back(Untranslated("Transaction has descendants in the mempool"));

            return feebumper::Result::INVALID_PARAMETER;

        }

    }

    if (wallet.GetTxDepthInMainChain(wtx) != 0) {

        errors.push_back(Untranslated("Transaction has been mined, or is conflicted with a mined transaction"));

        return feebumper::Result::WALLET_ERROR;

    }

    if (!SignalsOptInRBF(*wtx.tx)) {

        errors.push_back(Untranslated("Transaction is not BIP 125 replaceable"));

        return feebumper::Result::WALLET_ERROR;

    }

    if (wtx.mapValue.count("replaced_by_txid")) {

        errors.push_back(strprintf(Untranslated("Cannot bump transaction %s which was already bumped by transaction %s"), wtx.GetHash().ToString(), wtx.mapValue.at("replaced_by_txid")));

        return feebumper::Result::WALLET_ERROR;

    }

    if (require_mine) {

        // check that original tx consists entirely of our inputs

        // if not, we can't bump the fee, because the wallet has no way of knowing the value of the other inputs (thus the fee)

        isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;

        if (!AllInputsMine(wallet, *wtx.tx, filter)) {

            errors.push_back(Untranslated("Transaction contains inputs that don't belong to this wallet"));

            return feebumper::Result::WALLET_ERROR;

        }

    }

    return feebumper::Result::OK;

}

//! Check if the user provided a valid feeRate

static feebumper::Result CheckFeeRate(const CWallet& wallet, const CMutableTransaction& mtx, const CFeeRate& newFeerate, const int64_t maxTxSize, CAmount old_fee, std::vector<bilingual_str>& errors)

{

    // check that fee rate is higher than mempool's minimum fee

    // (no point in bumping fee if we know that the new tx won't be accepted to the mempool)

    // This may occur if the user set fee_rate or paytxfee too low, if fallbackfee is too low, or, perhaps,

    // in a rare situation where the mempool minimum fee increased significantly since the fee estimation just a

    // moment earlier. In this case, we report an error to the user, who may adjust the fee.

    CFeeRate minMempoolFeeRate = wallet.chain().mempoolMinFee();

    if (newFeerate.GetFeePerK() < minMempoolFeeRate.GetFeePerK()) {

        errors.push_back(strprintf(

            Untranslated("New fee rate (%s) is lower than the minimum fee rate (%s) to get into the mempool -- "),

            FormatMoney(newFeerate.GetFeePerK()),

            FormatMoney(minMempoolFeeRate.GetFeePerK())));

        return feebumper::Result::WALLET_ERROR;

    }

    std::vector<COutPoint> reused_inputs;

    reused_inputs.reserve(mtx.vin.size());

    for (const CTxIn& txin : mtx.vin) {

        reused_inputs.push_back(txin.prevout);

    }

    std::optional<CAmount> combined_bump_fee = wallet.chain().calculateCombinedBumpFee(reused_inputs, newFeerate);

    if (!combined_bump_fee.has_value()) {

        errors.push_back(strprintf(Untranslated("Failed to calculate bump fees, because unconfirmed UTXOs depend on enormous cluster of unconfirmed transactions.")));

    }

    CAmount new_total_fee = newFeerate.GetFee(maxTxSize) + combined_bump_fee.value();

    CFeeRate incrementalRelayFee = wallet.chain().relayIncrementalFee();

    // Min total fee is old fee + relay fee

    CAmount minTotalFee = old_fee + incrementalRelayFee.GetFee(maxTxSize);

    if (new_total_fee < minTotalFee) {

        errors.push_back(strprintf(Untranslated("Insufficient total fee %s, must be at least %s (oldFee %s + incrementalFee %s)"),

            FormatMoney(new_total_fee), FormatMoney(minTotalFee), FormatMoney(old_fee), FormatMoney(incrementalRelayFee.GetFee(maxTxSize))));

        return feebumper::Result::INVALID_PARAMETER;

    }

    CAmount requiredFee = GetRequiredFee(wallet, maxTxSize);

    if (new_total_fee < requiredFee) {

        errors.push_back(strprintf(Untranslated("Insufficient total fee (cannot be less than required fee %s)"),

            FormatMoney(requiredFee)));

        return feebumper::Result::INVALID_PARAMETER;

    }

    // Check that in all cases the new fee doesn't violate maxTxFee

    const CAmount max_tx_fee = wallet.m_default_max_tx_fee;

    if (new_total_fee > max_tx_fee) {

        errors.push_back(strprintf(Untranslated("Specified or calculated fee %s is too high (cannot be higher than -maxtxfee %s)"),

            FormatMoney(new_total_fee), FormatMoney(max_tx_fee)));

        return feebumper::Result::WALLET_ERROR;

    }

    return feebumper::Result::OK;

}

static CFeeRate EstimateFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CAmount old_fee, const CCoinControl& coin_control)

{

    // Get the fee rate of the original transaction. This is calculated from

    // the tx fee/vsize, so it may have been rounded down. Add 1 satoshi to the

    // result.

    int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));

    CFeeRate feerate(old_fee, txSize);

    feerate += CFeeRate(1);

    // The node has a configurable incremental relay fee. Increment the fee by

    // the minimum of that and the wallet's conservative

    // WALLET_INCREMENTAL_RELAY_FEE value to future proof against changes to

    // network wide policy for incremental relay fee that our node may not be

    // aware of. This ensures we're over the required relay fee rate

    // (Rule 4).  The replacement tx will be at least as large as the

    // original tx, so the total fee will be greater (Rule 3)

    CFeeRate node_incremental_relay_fee = wallet.chain().relayIncrementalFee();

    CFeeRate wallet_incremental_relay_fee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);

    feerate += std::max(node_incremental_relay_fee, wallet_incremental_relay_fee);

    // Fee rate must also be at least the wallet's GetMinimumFeeRate

    CFeeRate min_feerate(GetMinimumFeeRate(wallet, coin_control, /*feeCalc=*/nullptr));

    // Set the required fee rate for the replacement transaction in coin control.

    return std::max(feerate, min_feerate);

}

namespace feebumper {

bool TransactionCanBeBumped(const CWallet& wallet, const uint256& txid)

{

    LOCK(wallet.cs_wallet);

    const CWalletTx* wtx = wallet.GetWalletTx(txid);

    if (wtx == nullptr) return false;

    std::vector<bilingual_str> errors_dummy;

    feebumper::Result res = PreconditionChecks(wallet, *wtx, /* require_mine=*/ true, errors_dummy);

    return res == feebumper::Result::OK;

}

Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCoinControl& coin_control, std::vector<bilingual_str>& errors,

                                 CAmount& old_fee, CAmount& new_fee, CMutableTransaction& mtx, bool require_mine, const std::vector<CTxOut>& outputs, std::optional<uint32_t> original_change_index)

{

    // For now, cannot specify both new outputs to use and an output index to send change

    if (!outputs.empty() && original_change_index.has_value()) {

        errors.push_back(Untranslated("The options 'outputs' and 'original_change_index' are incompatible. You can only either specify a new set of outputs, or designate a change output to be recycled."));

        return Result::INVALID_PARAMETER;

    }

    // We are going to modify coin control later, copy to reuse

    CCoinControl new_coin_control(coin_control);

    LOCK(wallet.cs_wallet);

    errors.clear();

    auto it = wallet.mapWallet.find(txid);

    if (it == wallet.mapWallet.end()) {

        errors.push_back(Untranslated("Invalid or non-wallet transaction id"));

        return Result::INVALID_ADDRESS_OR_KEY;

    }

    const CWalletTx& wtx = it->second;

    // Make sure that original_change_index is valid

    if (original_change_index.has_value() && original_change_index.value() >= wtx.tx->vout.size()) {

        errors.push_back(Untranslated("Change position is out of range"));

        return Result::INVALID_PARAMETER;

    }

    // Retrieve all of the UTXOs and add them to coin control

    // While we're here, calculate the input amount

    std::map<COutPoint, Coin> coins;

    CAmount input_value = 0;

    std::vector<CTxOut> spent_outputs;

    for (const CTxIn& txin : wtx.tx->vin) {

        coins[txin.prevout]; // Create empty map entry keyed by prevout.

    }

    wallet.chain().findCoins(coins);

    for (const CTxIn& txin : wtx.tx->vin) {

        const Coin& coin = coins.at(txin.prevout);

        if (coin.out.IsNull()) {

            errors.push_back(Untranslated(strprintf("%s:%u is already spent", txin.prevout.hash.GetHex(), txin.prevout.n)));

            return Result::MISC_ERROR;

        }

        PreselectedInput& preset_txin = new_coin_control.Select(txin.prevout);

        if (!wallet.IsMine(txin.prevout)) {

            preset_txin.SetTxOut(coin.out);

        }

        input_value += coin.out.nValue;

        spent_outputs.push_back(coin.out);

    }

    // Figure out if we need to compute the input weight, and do so if necessary

    PrecomputedTransactionData txdata;

    txdata.Init(*wtx.tx, std::move(spent_outputs), /* force=*/ true);

    for (unsigned int i = 0; i < wtx.tx->vin.size(); ++i) {

        const CTxIn& txin = wtx.tx->vin.at(i);

        const Coin& coin = coins.at(txin.prevout);

        if (new_coin_control.IsExternalSelected(txin.prevout)) {

            // For external inputs, we estimate the size using the size of this input

            int64_t input_weight = GetTransactionInputWeight(txin);

            // Because signatures can have different sizes, we need to figure out all of the

            // signature sizes and replace them with the max sized signature.

            // In order to do this, we verify the script with a special SignatureChecker which

            // will observe the signatures verified and record their sizes.

            SignatureWeights weights;

            TransactionSignatureChecker tx_checker(wtx.tx.get(), i, coin.out.nValue, txdata, MissingDataBehavior::FAIL);

            SignatureWeightChecker size_checker(weights, tx_checker);

            VerifyScript(txin.scriptSig, coin.out.scriptPubKey, &txin.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, size_checker);

            // Add the difference between max and current to input_weight so that it represents the largest the input could be

            input_weight += weights.GetWeightDiffToMax();

            new_coin_control.SetInputWeight(txin.prevout, input_weight);

        }

    }

    Result result = PreconditionChecks(wallet, wtx, require_mine, errors);

    if (result != Result::OK) {

        return result;

    }

    // Calculate the old output amount.

    CAmount output_value = 0;

    for (const auto& old_output : wtx.tx->vout) {

        output_value += old_output.nValue;

    }

    old_fee = input_value - output_value;

    // Fill in recipients (and preserve a single change key if there

    // is one). If outputs vector is non-empty, replace original

    // outputs with its contents, otherwise use original outputs.

    std::vector<CRecipient> recipients;

    CAmount new_outputs_value = 0;

    const auto& txouts = outputs.empty() ? wtx.tx->vout : outputs;

    for (size_t i = 0; i < txouts.size(); ++i) {

        const CTxOut& output = txouts.at(i);

        CTxDestination dest;

        ExtractDestination(output.scriptPubKey, dest);

        if (original_change_index.has_value() ?  original_change_index.value() == i : OutputIsChange(wallet, output)) {

            new_coin_control.destChange = dest;

        } else {

            CRecipient recipient = {dest, output.nValue, false};

            recipients.push_back(recipient);

        }

        new_outputs_value += output.nValue;

    }

    // If no recipients, means that we are sending coins to a change address

    if (recipients.empty()) {

        // Just as a sanity check, ensure that the change address exist

        if (std::get_if<CNoDestination>(&new_coin_control.destChange)) {

            errors.emplace_back(Untranslated("Unable to create transaction. Transaction must have at least one recipient"));

            return Result::INVALID_PARAMETER;

        }

        // Add change as recipient with SFFO flag enabled, so fees are deduced from it.

        // If the output differs from the original tx output (because the user customized it) a new change output will be created.

        recipients.emplace_back(CRecipient{new_coin_control.destChange, new_outputs_value, /*fSubtractFeeFromAmount=*/true});

        new_coin_control.destChange = CNoDestination();

    }

    if (coin_control.m_feerate) {

        // The user provided a feeRate argument.

        // We calculate this here to avoid compiler warning on the cs_wallet lock

        // We need to make a temporary transaction with no input witnesses as the dummy signer expects them to be empty for external inputs

        CMutableTransaction temp_mtx{*wtx.tx};

        for (auto& txin : temp_mtx.vin) {

            txin.scriptSig.clear();

            txin.scriptWitness.SetNull();

        }

        temp_mtx.vout = txouts;

        const int64_t maxTxSize{CalculateMaximumSignedTxSize(CTransaction(temp_mtx), &wallet, &new_coin_control).vsize};

        Result res = CheckFeeRate(wallet, temp_mtx, *new_coin_control.m_feerate, maxTxSize, old_fee, errors);

        if (res != Result::OK) {

            return res;

        }

    } else {

        // The user did not provide a feeRate argument

        new_coin_control.m_feerate = EstimateFeeRate(wallet, wtx, old_fee, new_coin_control);

    }

    // Fill in required inputs we are double-spending(all of them)

    // N.B.: bip125 doesn't require all the inputs in the replaced transaction to be

    // used in the replacement transaction, but it's very important for wallets to make

    // sure that happens. If not, it would be possible to bump a transaction A twice to

    // A2 and A3 where A2 and A3 don't conflict (or alternatively bump A to A2 and A2

    // to A3 where A and A3 don't conflict). If both later get confirmed then the sender

    // has accidentally double paid.

    for (const auto& inputs : wtx.tx->vin) {

        new_coin_control.Select(COutPoint(inputs.prevout));

    }

    new_coin_control.m_allow_other_inputs = true;

    // We cannot source new unconfirmed inputs(bip125 rule 2)

    new_coin_control.m_min_depth = 1;

    auto res = CreateTransaction(wallet, recipients, /*change_pos=*/std::nullopt, new_coin_control, false);

    if (!res) {

        errors.push_back(Untranslated("Unable to create transaction.") + Untranslated(" ") + util::ErrorString(res));

        return Result::WALLET_ERROR;

    }

    const auto& txr = *res;

    // Write back new fee if successful

    new_fee = txr.fee;

    // Write back transaction

    mtx = CMutableTransaction(*txr.tx);

    return Result::OK;

}

bool SignTransaction(CWallet& wallet, CMutableTransaction& mtx) {

    LOCK(wallet.cs_wallet);

    if (wallet.IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER)) {

        // Make a blank psbt

        PartiallySignedTransaction psbtx(mtx);

        // First fill transaction with our data without signing,

        // so external signers are not asked to sign more than once.

        bool complete;

        wallet.FillPSBT(psbtx, complete, SIGHASH_ALL, false /* sign */, true /* bip32derivs */);

        auto err{wallet.FillPSBT(psbtx, complete, SIGHASH_ALL, true /* sign */, false  /* bip32derivs */)};

        if (err) return false;

        complete = FinalizeAndExtractPSBT(psbtx, mtx);

        return complete;

    } else {

        return wallet.SignTransaction(mtx);

    }

}

Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<bilingual_str>& errors, uint256& bumped_txid)

{

    LOCK(wallet.cs_wallet);

    if (!errors.empty()) {

        return Result::MISC_ERROR;

    }

    auto it = txid.IsNull() ? wallet.mapWallet.end() : wallet.mapWallet.find(txid);

    if (it == wallet.mapWallet.end()) {

        errors.push_back(Untranslated("Invalid or non-wallet transaction id"));

        return Result::MISC_ERROR;

    }

    const CWalletTx& oldWtx = it->second;

    // make sure the transaction still has no descendants and hasn't been mined in the meantime

    Result result = PreconditionChecks(wallet, oldWtx, /* require_mine=*/ false, errors);

    if (result != Result::OK) {

        return result;

    }

    // commit/broadcast the tx

    CTransactionRef tx = MakeTransactionRef(std::move(mtx));

    mapValue_t mapValue = oldWtx.mapValue;

    mapValue["replaces_txid"] = oldWtx.GetHash().ToString();

    wallet.CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm);

    // mark the original tx as bumped

    bumped_txid = tx->GetHash();

    if (!wallet.MarkReplaced(oldWtx.GetHash(), bumped_txid)) {

        errors.push_back(Untranslated("Created new bumpfee transaction but could not mark the original transaction as replaced"));

    }

    return Result::OK;

}

} // namespace feebumper

} // namespace wallet