from __future__ import annotations
from dataclasses import dataclass
from datetime import datetime,timezone
from decimal import Decimal,ROUND_UP
from src.application.contracts import ICache,ILogger
from src.application.domain.exceptions import ServiceUnavailableException
from src.infrastructure.config import settings


@dataclass(slots=True)
class PaymentQuote:
    usdt_amount: Decimal
    usdt_exchange_rate: Decimal
    gas_fee: Decimal
    service_fee: Decimal
    total_price: Decimal
    service_fee_rate: Decimal
    created_at: datetime


class PaymentQuoteService:
    def __init__(self, *, remote_cache: ICache, logger: ILogger):
        self._remote_cache = remote_cache
        self._logger = logger


    async def get_quote(self, usdt_amount: Decimal) -> PaymentQuote:
        rate_raw = await self._remote_cache.hget('tradex:rub:rate','value')
        gas_raw = await self._remote_cache.hget('gwei:eth:last','normal_rub')
        self._logger.info(f'Actual market values: rate={rate_raw}, gas={gas_raw}')

        if rate_raw is None:
            self._logger.error('Exchange rate unavailable')
            raise ServiceUnavailableException(message='Exchange rate unavailable')

        if gas_raw is None:
            self._logger.error('Exchange gas unavailable')
            raise ServiceUnavailableException(message='Exchange gas unavailable')

        gas_fee = Decimal(gas_raw).quantize(Decimal('0.00'), rounding=ROUND_UP)
        usdt_exchange_rate = Decimal(rate_raw).quantize(Decimal('0.00'), rounding=ROUND_UP)
        service_fee = (usdt_amount * usdt_exchange_rate * settings.PAYMENT_SERVICE_FEE_RATE).quantize(Decimal('0.01'))
        total_price = (usdt_amount * usdt_exchange_rate + service_fee + gas_fee).quantize(Decimal('0.01'))

        return PaymentQuote(
            usdt_amount=usdt_amount,
            usdt_exchange_rate=usdt_exchange_rate,
            gas_fee=gas_fee,
            service_fee=service_fee,
            total_price=total_price,
            service_fee_rate=settings.PAYMENT_SERVICE_FEE_RATE,
            created_at=datetime.now(timezone.utc),
        )