103 lines
3.4 KiB
Python
103 lines
3.4 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass
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from datetime import datetime, timezone
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from decimal import Decimal, ROUND_UP
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from src.application.contracts import ICache, ILogger
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from src.application.domain.exceptions import OrderTotalOutOfRangeException, ServiceUnavailableException
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_MIN_USDT_AMOUNT: Decimal = Decimal('1')
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_FEE_TIERS: tuple[tuple[Decimal, Decimal, Decimal, bool, bool], ...] = (
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(Decimal('0.08'), Decimal('0'), Decimal('30000'), True, True),
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(Decimal('0.06'), Decimal('30000'), Decimal('100000'), False, True),
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(Decimal('0.04'), Decimal('30000'), Decimal('600000'), False, True),
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)
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def _total_in_bracket(
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total: Decimal,
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lo: Decimal,
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hi: Decimal,
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*,
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lo_inclusive: bool,
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hi_inclusive: bool,
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) -> bool:
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if lo_inclusive:
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ok_lo = total >= lo
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else:
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ok_lo = total > lo
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if hi_inclusive:
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ok_hi = total <= hi
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else:
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ok_hi = total < hi
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return ok_lo and ok_hi
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@dataclass(slots=True)
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class PaymentQuote:
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usdt_amount: Decimal
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usdt_exchange_rate: Decimal
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gas_fee: Decimal
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service_fee: Decimal
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total_price: Decimal
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service_fee_rate: Decimal
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created_at: datetime
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class PaymentQuoteService:
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def __init__(self, *, remote_cache: ICache, logger: ILogger):
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self._remote_cache = remote_cache
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self._logger = logger
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async def get_quote(self, usdt_amount: Decimal) -> PaymentQuote:
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if usdt_amount < _MIN_USDT_AMOUNT:
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raise OrderTotalOutOfRangeException(
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message='Order total is below minimum allowed amount',
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)
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rate_raw = await self._remote_cache.hget('tradex:rub:rate', 'value')
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gas_raw = await self._remote_cache.hget('gwei:eth:last', 'normal_rub')
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self._logger.info(f'Actual market values: rate={rate_raw}, gas={gas_raw}')
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if rate_raw is None:
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self._logger.error('Exchange rate unavailable')
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raise ServiceUnavailableException(message='Exchange rate unavailable')
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if gas_raw is None:
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self._logger.error('Exchange gas unavailable')
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raise ServiceUnavailableException(message='Exchange gas unavailable')
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gas_fee = Decimal(gas_raw).quantize(Decimal('0.00'), rounding=ROUND_UP)
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usdt_exchange_rate = Decimal(rate_raw).quantize(Decimal('0.00'), rounding=ROUND_UP)
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base_rub = usdt_amount * usdt_exchange_rate
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chosen_rate: Decimal | None = None
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service_fee: Decimal | None = None
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total_price: Decimal | None = None
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for fee_rate, lo, hi, li, ri in _FEE_TIERS:
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sf = (base_rub * fee_rate).quantize(Decimal('0.01'))
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tp = (base_rub + sf + gas_fee).quantize(Decimal('0.01'))
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if _total_in_bracket(tp, lo, hi, lo_inclusive=li, hi_inclusive=ri):
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chosen_rate = fee_rate
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service_fee = sf
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total_price = tp
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break
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if chosen_rate is None or service_fee is None or total_price is None:
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raise OrderTotalOutOfRangeException(
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message='Order total exceeds maximum allowed amount',
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)
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return PaymentQuote(
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usdt_amount=usdt_amount,
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usdt_exchange_rate=usdt_exchange_rate,
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gas_fee=gas_fee,
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service_fee=service_fee,
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total_price=total_price,
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service_fee_rate=chosen_rate,
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created_at=datetime.now(timezone.utc),
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)
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