"""fin_holdings 持仓仓储：按客户（+状态）查持仓、申购加仓 upsert、赎回减仓。"""
from __future__ import annotations

from decimal import Decimal

from sqlalchemy import case, select, update
from sqlalchemy.dialects.mysql import insert as mysql_insert

from model.fin_holdings import FinHoldings
from repositories.base import BaseRepository


class FinHoldingsRepo(BaseRepository):
    model = FinHoldings

    async def list_by_customer(
        self, customer_id: int, status: str | None = None
    ) -> list[FinHoldings]:
        """按客户 ID 查持仓，可按状态过滤（status=None 表示不过滤）。"""
        stmt = select(FinHoldings).where(FinHoldings.customer_id == customer_id)
        if status is not None:
            stmt = stmt.where(FinHoldings.status == status)
        stmt = stmt.order_by(FinHoldings.id)
        return list((await self.db.scalars(stmt)).all())

    async def get_by_customer_product(
        self, customer_id: int, product_id: int
    ) -> FinHoldings | None:
        return await self.db.scalar(
            select(FinHoldings).where(
                FinHoldings.customer_id == customer_id,
                FinHoldings.product_id == product_id,
            )
        )

    async def upsert(
        self, customer_id: int, product_id: int, add_shares: Decimal, add_cost: Decimal
    ) -> None:
        """申购加仓：有则加份额/成本，无则新增（靠 uk_customer_product 唯一键）。不 commit。"""
        stmt = mysql_insert(FinHoldings).values(
            customer_id=customer_id,
            product_id=product_id,
            shares=add_shares,
            cost_amount=add_cost,
        )
        stmt = stmt.on_duplicate_key_update(
            shares=FinHoldings.shares + add_shares,
            cost_amount=FinHoldings.cost_amount + add_cost,
        )
        await self.db.execute(stmt)

    async def redeem(
        self, customer_id: int, product_id: int, redeem_shares: Decimal
    ) -> bool:
        """赎回减仓：shares -= redeem_shares，份额归 0 时状态置'已清仓'。

        持仓份额不足（含无持仓、shares=0）时不动作，返回 False。
        不 commit，由 service 层事务统一提交，保证「减仓 + 入账」原子性。
        """
        result = await self.db.execute(
            update(FinHoldings)
            .where(
                FinHoldings.customer_id == customer_id,
                FinHoldings.product_id == product_id,
                FinHoldings.shares >= redeem_shares,
            )
            .values(
                shares=FinHoldings.shares - redeem_shares,
                status=case(
                    (FinHoldings.shares - redeem_shares == 0, "已清仓"),
                    else_=FinHoldings.status,
                ),
            )
        )
        return result.rowcount > 0