Token-2022 스왑의 전송 수수료

use spl_token_2022::extension::transfer_fee::TransferFeeConfig;
use spl_token_2022::extension::StateWithExtensions;

let mint_data = ...;
let state = StateWithExtensions::<Mint>::unpack(&mint_data)?;
let config = state.get_extension::<TransferFeeConfig>()?;

let epoch = Clock::get()?.epoch;
let fee_bp = config.get_epoch_fee(epoch).transfer_fee_basis_points;
let max_fee = u64::from(config.get_epoch_fee(epoch).maximum_fee);

let fee = (amount as u128 * fee_bp as u128 / 10_000).min(max_fee as u128) as u64;

import { getTransferFeeConfig, getTransferFeeAmount } from "@solana/spl-token";

const config = getTransferFeeConfig(mintAccount);
const currentEpochFee = config.olderTransferFee.epoch <= currentEpoch
  ? config.newerTransferFee
  : config.olderTransferFee;

const rate   = currentEpochFee.transferFeeBasisPoints;
const maxFee = currentEpochFee.maximumFee;
const fee    = Math.min(Math.floor(amount * rate / 10_000), Number(maxFee));

transfer_fee_in  = min(amount_in · f_in / 10_000, max_in)
vault_received   = amount_in − transfer_fee_in

pool_fee         = ceil(vault_received · f_pool / 1_000_000)
amount_after     = vault_received − pool_fee
amount_out_gross = y · amount_after / (x + amount_after)

transfer_fee_out = min(amount_out_gross · f_out / 10_000, max_out)
user_receives    = amount_out_gross − transfer_fee_out

# 사용자가 전송 수수료 후 amount_out_exact를 받기를 원함
amount_out_gross = amount_out_exact + transfer_fee_out_for(amount_out_exact)

# 그런 다음 CPMM 정확한 출력에 대해 amount_after를 풀기:
amount_after     = ceil(x · amount_out_gross / (y − amount_out_gross))

# 그런 다음 풀 수수료 추가:
vault_received   = ceil(amount_after · 1_000_000 / (1_000_000 − f_pool))

# 그런 다음 입금 전송 수수료 추가:
amount_in = ceil(vault_received · 10_000 / (10_000 − f_in))
# (또는 반복 — 아래 수수료 상한 엣지 케이스 참조)

transfer_fee_in = min(1_000 · 100 / 10_000, 10_000)  = 10     // 1%, 상한 훨씬 아래
vault_received  = 1_000 − 10 = 990

pool_fee        = ceil(990 · 2_500 / 1_000_000)  = 3    // 0.25%
amount_after    = 990 − 3 = 987

amount_out_gross = 1_000_000 · 987 / (1_000_000 + 987)  ≈ 986.03