from __future__ import annotations

from collections.abc import Sequence
from datetime import date
from decimal import Decimal

from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db.models import Currency, FundingRate
from app.repositories._upsert import insert_for


class FundingRateRepository:
    def __init__(self, session: AsyncSession) -> None:
        self.session = session

    async def effective_on(
        self, portfolio_id: int, currency_id: int, on_date: date
    ) -> FundingRate | None:
        """Ставка, действующая на дату: последняя запись с effective_from <= даты."""
        result = await self.session.execute(
            select(FundingRate)
            .where(
                FundingRate.portfolio_id == portfolio_id,
                FundingRate.currency_id == currency_id,
                FundingRate.effective_from <= on_date,
            )
            .order_by(FundingRate.effective_from.desc())
            .limit(1)
        )
        return result.scalar_one_or_none()

    async def upsert(
        self,
        *,
        portfolio_id: int,
        currency_id: int,
        effective_from: date,
        rate: Decimal,
        user: str,
    ) -> None:
        stmt = insert_for(self.session, FundingRate.__table__).values(
            portfolio_id=portfolio_id,
            currency_id=currency_id,
            effective_from=effective_from,
            rate=rate,
            created_by=user,
            updated_by=user,
        )
        stmt = stmt.on_conflict_do_update(
            index_elements=["portfolio_id", "currency_id", "effective_from"],
            set_={
                "rate": stmt.excluded.rate,
                "updated_at": func.now(),
                "updated_by": user,
            },
        )
        await self.session.execute(stmt)

    async def list_for_portfolio(
        self, portfolio_id: int
    ) -> Sequence[tuple[FundingRate, str]]:
        """(ставка, код валюты), новые сверху."""
        result = await self.session.execute(
            select(FundingRate, Currency.code)
            .join(Currency, Currency.id == FundingRate.currency_id)
            .where(FundingRate.portfolio_id == portfolio_id)
            .order_by(FundingRate.effective_from.desc(), Currency.code)
        )
        return result.tuples().all()