// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-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/fees.h>

#include <policy/feerate.h>

#include <util/fees.h>

#include <wallet/coincontrol.h>

#include <wallet/wallet.h>

#include <optional>

namespace wallet {

CAmount GetRequiredFee(const CWallet& wallet, unsigned int nTxBytes)

{

    return GetRequiredFeeRate(wallet).GetFee(static_cast<int32_t>(nTxBytes));

}

CAmount GetMinimumFee(const MinimumFeeRateResult& min_fee_rate, unsigned int nTxBytes)

{

    return min_fee_rate.fee_rate.GetFee(static_cast<int32_t>(nTxBytes));

}

CFeeRate GetRequiredFeeRate(const CWallet& wallet)

{

    return std::max(wallet.m_min_fee, wallet.chain().relayMinFee());

}

MinimumFeeRateResult GetMinimumFeeRate(const CWallet& wallet, const CCoinControl& coin_control)

{

    /* User control of how to calculate fee uses the following parameter precedence:

       1. coin_control.m_feerate

       2. coin_control.m_confirm_target

       3. m_confirm_target (user-set member variable of wallet)

       The first parameter that is set is used.

    */

    if (coin_control.m_feerate) { // 1.

        CFeeRate fee_rate{*coin_control.m_feerate};

        // Allow to override automatic min/max check over coin control instance

        if (coin_control.fOverrideFeeRate) return {fee_rate, FeeReason::USER_SPECIFIED, std::nullopt};

        CFeeRate required_feerate = GetRequiredFeeRate(wallet);

        if (required_feerate > fee_rate) return {required_feerate, FeeReason::REQUIRED, std::nullopt};

        return {fee_rate, FeeReason::USER_SPECIFIED, std::nullopt};

    }

    // We will use smart fee estimation

    unsigned int target = coin_control.m_confirm_target ? *coin_control.m_confirm_target : wallet.m_confirm_target;

    // By default estimates are economical iff we are signaling opt-in-RBF

    bool conservative_estimate = !coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf);

    // Allow to override the default fee estimate mode over the CoinControl instance

    if (coin_control.m_fee_mode == FeeEstimateMode::CONSERVATIVE)

        conservative_estimate = true;

    else if (coin_control.m_fee_mode == FeeEstimateMode::ECONOMICAL)

        conservative_estimate = false;

    const auto fee_estimation_res = wallet.chain().getFeeRateEstimate(target, conservative_estimate);

    const FeeRateEstimation& estimation{FeeRateEstimationRef(fee_estimation_res)};

    CFeeRate fee_rate{estimation.feerate};

    FeeReason fee_reason{FeeReason::FEE_RATE_ESTIMATOR};

    // Only fee rate estimator results have a returned target.

    std::optional<int> returned_target{estimation.returned_target};

    if (fee_rate == CFeeRate(0)) {

        // if we don't have enough data for getFeeRateEstimate, then use fallback fee

        fee_rate = wallet.m_fallback_fee;

        fee_reason = FeeReason::FALLBACK;

        returned_target = std::nullopt;

        // directly return if fallback fee is disabled (feerate 0 == disabled)

        if (wallet.m_fallback_fee == CFeeRate(0)) return {fee_rate, FeeReason::FALLBACK, std::nullopt};

    }

    // Obey mempool min fee when using smart fee estimation or fallback fee

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

    if (fee_rate < min_mempool_feerate) {

        fee_rate = min_mempool_feerate;

        fee_reason = FeeReason::MEMPOOL_MIN;

        returned_target = std::nullopt;

    }

    CFeeRate required_feerate = GetRequiredFeeRate(wallet);

    if (required_feerate > fee_rate) return {required_feerate, FeeReason::REQUIRED, std::nullopt};

    return {fee_rate, fee_reason, returned_target};

}

CFeeRate GetDiscardRate(const CWallet& wallet)

{

    unsigned int highest_target = wallet.chain().maximumFeeEstimationTargetBlocks();

    const auto res = wallet.chain().getFeeRateEstimate(highest_target, /*conservative=*/false);

    auto discard_rate = res ? CFeeRate(res->feerate) : CFeeRate(0);

    // Don't let discard_rate be greater than longest possible fee estimate if we get a valid fee estimate

    discard_rate = (discard_rate == CFeeRate(0)) ? wallet.m_discard_rate : std::min(discard_rate, wallet.m_discard_rate);

    // Discard rate must be at least dust relay feerate

    discard_rate = std::max(discard_rate, wallet.chain().relayDustFee());

    return discard_rate;

}

} // namespace wallet