"""回款数据访问：回款行与关联引用（业务号/发货单号/发货日）。

只读写数据并 flush；commit/rollback 与业务异常一律在 service 层。

- 列表与详情统一 join 出 ``business_no / shipment_no / ship_date``，
  ship_date 供 service 按 ``formula.payment_days`` 派生回款天数 —— 关联
  引用经本层查询一次供给，service 不再对发货单二次查询
- shipment_id 是手动指定（可空），发货单关联一律 outerjoin
"""

from datetime import date

from sqlalchemy import Select, func, select
from sqlalchemy.orm import Session

from app.models import Business, Receipt, Shipment
from app.schemas.receipt import ReceiptQuery


def get_by_id(session: Session, receipt_id: int) -> Receipt | None:
    """按主键取回款行（供摘要预取与状态判定；不锁行，写保护锚在业务行）。"""
    return session.get(Receipt, receipt_id)


def get_with_refs(
    session: Session, receipt_id: int
) -> tuple[Receipt, str, str | None, date | None] | None:
    """回款行 + 业务号 + 发货单号 + 发货日（DTO 与 payment_days 派生共用）。

    business 主表为 inner join（FK NOT NULL，业务与回款同存亡）；发货单
    可未指定，outerjoin 后 shipment_no / ship_date 可能为 None。
    """
    row = session.execute(
        select(Receipt, Business.business_no, Shipment.shipment_no, Shipment.ship_date)
        .join(Business, Business.id == Receipt.business_id)
        .outerjoin(Shipment, Shipment.id == Receipt.shipment_id)
        .where(Receipt.id == receipt_id)
    ).first()
    return row


def get_shipment(session: Session, shipment_id: int) -> Shipment | None:
    """按主键取发货单（同业务强校验的只读预查；FK RESTRICT 为最终防线）。"""
    return session.get(Shipment, shipment_id)


def _apply_filters(stmt: Select, query: ReceiptQuery) -> Select:
    """回款列表的筛选条件（全部落在 Receipt 自身列上）。"""
    if query.business_id is not None:
        stmt = stmt.where(Receipt.business_id == query.business_id)
    if query.date_from is not None:
        stmt = stmt.where(Receipt.receipt_date >= query.date_from)
    if query.date_to is not None:
        stmt = stmt.where(Receipt.receipt_date <= query.date_to)
    if query.is_barter is not None:
        stmt = stmt.where(Receipt.is_barter == query.is_barter)
    # settlement_status 是 M3 核算防重锚点（需规 2.3.3），必须保持具名字段
    if query.settlement_status is not None:
        stmt = stmt.where(Receipt.settlement_status == query.settlement_status)
    if query.confirmation_status is not None:
        stmt = stmt.where(Receipt.confirmation_status == query.confirmation_status)
    return stmt


def list_receipts(
    session: Session, query: ReceiptQuery
) -> list[tuple[Receipt, str, str | None, date | None]]:
    """分页查询回款（附业务号/发货单号/发货日），按 id 倒序。"""
    stmt = _apply_filters(
        select(Receipt, Business.business_no, Shipment.shipment_no, Shipment.ship_date)
        .join(Business, Business.id == Receipt.business_id)
        .outerjoin(Shipment, Shipment.id == Receipt.shipment_id),
        query,
    )
    return list(
        session.execute(
            stmt.order_by(Receipt.id.desc()).offset(query.offset).limit(query.page_size)
        ).all()
    )


def count_receipts(session: Session, query: ReceiptQuery) -> int:
    """回款总数（筛选条件与列表共用同一 apply_filters，防两侧口径漂移）。"""
    stmt = _apply_filters(select(func.count()).select_from(Receipt), query)
    return int(session.execute(stmt).scalar_one())


def create(session: Session, receipt: Receipt) -> Receipt:
    """新增回款行。只 flush 以取得自增 id，编号唯一键冲突由 service 兜底。"""
    session.add(receipt)
    session.flush()
    return receipt


def delete(session: Session, receipt: Receipt) -> None:
    """物理删除回款行（已核算与否的准入判定在 service 层）。"""
    session.delete(receipt)
    session.flush()