// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-2022 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 <wallet/fees.h>

#include <wallet/coincontrol.h>

#include <wallet/wallet.h>

namespace wallet {

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

{

    return GetRequiredFeeRate(wallet).GetFee(nTxBytes);

}

CAmount GetMinimumFee(const CWallet& wallet, unsigned int nTxBytes, const CCoinControl& coin_control, FeeCalculation* feeCalc)

{

    return GetMinimumFeeRate(wallet, coin_control, feeCalc).GetFee(nTxBytes);

}

CFeeRate GetRequiredFeeRate(const CWallet& wallet)

{

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

}

CFeeRate GetMinimumFeeRate(const CWallet& wallet, const CCoinControl& coin_control, FeeCalculation* feeCalc)

{

    /* 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_pay_tx_fee (user-set member variable of wallet)

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

       The first parameter that is set is used.

    */

    CFeeRate feerate_needed;

    if (coin_control.m_feerate) { // 1.

        feerate_needed = *(coin_control.m_feerate);

        if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;

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

        if (coin_control.fOverrideFeeRate) return feerate_needed;

    }

    else if (!coin_control.m_confirm_target && wallet.m_pay_tx_fee != CFeeRate(0)) { // 3. TODO: remove magic value of 0 for wallet member m_pay_tx_fee

        feerate_needed = wallet.m_pay_tx_fee;

        if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;

    }

    else { // 2. or 4.

        // 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;

        feerate_needed = wallet.chain().estimateSmartFee(target, conservative_estimate, feeCalc);

        if (feerate_needed == CFeeRate(0)) {

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

            feerate_needed = wallet.m_fallback_fee;

            if (feeCalc) feeCalc->reason = FeeReason::FALLBACK;

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

            if (wallet.m_fallback_fee == CFeeRate(0)) return feerate_needed;

        }

        // Obey mempool min fee when using smart fee estimation

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

        if (feerate_needed < min_mempool_feerate) {

            feerate_needed = min_mempool_feerate;

            if (feeCalc) feeCalc->reason = FeeReason::MEMPOOL_MIN;

        }

    }

    // prevent user from paying a fee below the required fee rate

    CFeeRate required_feerate = GetRequiredFeeRate(wallet);

    if (required_feerate > feerate_needed) {

        feerate_needed = required_feerate;

        if (feeCalc) feeCalc->reason = FeeReason::REQUIRED;

    }

    return feerate_needed;

}

CFeeRate GetDiscardRate(const CWallet& wallet)

{

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

    CFeeRate discard_rate = wallet.chain().estimateSmartFee(highest_target, /*conservative=*/false);

    // 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