"""发货管理业务编排（需求 2.2.2）。

事务边界在本层：repository 只 flush，commit/rollback 只写在这里。

- 行金额（amount）与发货单总金额（total_amount）服务层按 数量×单价 计算
  固化，不信任前端传值；单价可空时行金额记 0（对齐业务明细口径）
- 业务级汇总（发货/运费合计）回写统一收口 ``business_service._recalc_totals``，
  本模块不另写聚合逻辑；发货单 total_amount 由 repository 行 SUM 重算
- **写操作前 FOR UPDATE 锁业务行**（receipt_service 同款写准入）：发货与
  回款并发写同一业务时相互串行化，防 ``_recalc_totals`` 重算互相覆盖
  （丢失更新）；锁序统一「业务行 → 单据编号区间」，与业务/回款同构
- 业务状态门槛：仅执行中（1）业务可写发货单 —— 终态业务的发货单禁改禁删
  （一期保守口径：编辑不影响已核算回款、核算未发生，但会改业务级汇总
  基线，设计未定项待业务确认后可放开终态编辑）
- 删除保护：被回款批次指定（receipts.shipment_id）的发货单禁删，先解除
  回款的批次指定；删除连带明细行并重算业务级汇总
- 编号 SH 生成复用 no_generator.next_no；残余竞态以唯一键（1062）冲突
  重试一次兜底，模式同 business_service.create_business
- 审计：锁行与编号生成放在进入审计前（不产生未提交变更），状态校验在
  审计上下文内，失败也留痕 —— 失败回滚释放已取序号，当日序号空洞无害
  （唯一性不依赖连续）；ship_date 是回款天数基准日，编辑即时生效（M3 按
  编辑后基准日实时派生，无固化快照可漂移）
"""

import logging
from decimal import ROUND_HALF_UP, Decimal

from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import Session

from app.core.constants import (
    ACTION_CREATE,
    ACTION_DELETE,
    ACTION_UPDATE,
    MODULE_SHIPMENT,
    NO_PREFIX_SHIPMENT,
)
from app.core.db_errors import is_duplicate_entry
from app.core.exceptions import BadRequestError, NotFoundError
from app.core.response import PageResult
from app.models import Business, Shipment, ShipmentItem, User
from app.models.business import BUSINESS_STATUS_ACTIVE
from app.repositories import business_repository, shipment_repository
from app.schemas.shipment import (
    ShipmentCreateIn,
    ShipmentDetailOut,
    ShipmentItemIn,
    ShipmentItemOut,
    ShipmentOut,
    ShipmentQuery,
    ShipmentUpdateIn,
)
from app.services import audit_service
from app.services.audit_service import AuditRecord, RequestMeta
from app.services.business_service import _recalc_totals
from app.services.no_generator import next_no

logger = logging.getLogger(__name__)

# 编号唯一键冲突后的重试次数（模式同 business_service._NO_RETRY）
_NO_RETRY = 1


def _to_out(row: tuple[Shipment, str]) -> ShipmentOut:
    """(shipment, business_no) → 响应模型；金额出参 str。"""
    shipment, business_no = row
    return ShipmentOut(
        id=shipment.id,
        shipment_no=shipment.shipment_no,
        business_id=shipment.business_id,
        business_no=business_no,
        ship_date=shipment.ship_date,
        freight_amount=str(shipment.freight_amount),
        total_amount=str(shipment.total_amount),
        remark=shipment.remark,
    )


def _item_to_out(item: ShipmentItem) -> ShipmentItemOut:
    return ShipmentItemOut(
        id=item.id,
        product_id=item.product_id,
        product_name=item.product_name,
        spec_model=item.spec_model,
        unit=item.unit,
        quantity=str(item.quantity),
        sale_price=str(item.sale_price) if item.sale_price is not None else None,
        amount=str(item.amount),
    )


def _amount_or_zero(value: str | None) -> Decimal:
    """可空金额入参转 Decimal，空记 0（运费可缺省的统一归一）。"""
    return Decimal(value) if value is not None else Decimal("0")


def _build_item_rows(items: list[ShipmentItemIn]) -> list[ShipmentItem]:
    """入参明细行转 ORM 行：amount 服务层按 数量×单价 计算固化。

    不信任前端传值（schema 亦无 amount 入参）——单价可空时行金额记 0，
    由用户在编辑中补价后重算；shipment_id 由 replace_items 统一回填。
    乘积显式 quantize 两位固化（模式同 business_service._build_item_rows）：
    数量(2位)×单价(4位) 可产 6 位小数，直写 DECIMAL(14,2) 会被 MySQL
    静默舍入且回显漂移。
    """
    rows: list[ShipmentItem] = []
    for item in items:
        quantity = Decimal(item.quantity)
        sale_price = Decimal(item.sale_price) if item.sale_price is not None else None
        amount = (
            (quantity * sale_price).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
            if sale_price is not None
            else Decimal("0.00")
        )
        rows.append(
            ShipmentItem(
                product_id=item.product_id,
                product_name=item.product_name,
                spec_model=item.spec_model or "",
                unit=item.unit,
                quantity=quantity,
                sale_price=sale_price,
                amount=amount,
            )
        )
    return rows


def _generate_no(session: Session) -> str:
    """生成发货单号（SH 前缀；MAX+FOR UPDATE 与 1062 兜底见 no_generator）。"""
    return next_no(session, model=Shipment, column_name="shipment_no", prefix=NO_PREFIX_SHIPMENT)


def _ensure_business_writable(session: Session, business_id: int, action: str) -> Business:
    """锁业务行并要求状态=1 执行中（新增/编辑/删除共用的写准入）。

    锁在判定之前取：判定结果基于锁定后的行，配合 _recalc_totals 的重算
    同事务提交，并发写不会丢失更新。与 receipt_service._ensure_business_writable
    同构 —— 文案单据名落到发货单（私有函数各自保留，不为一个字符串上提
    公共层）。

    :raises NotFoundError: 业务不存在
    :raises BadRequestError: 业务已完成或已终止
    """
    business = business_repository.get_by_id(session, business_id, for_update=True)
    if business is None:
        raise NotFoundError("业务不存在")
    if business.status != BUSINESS_STATUS_ACTIVE:
        raise BadRequestError(f"业务已完成或已终止，禁止{action}")
    return business


def _is_duplicate_entry(exc: IntegrityError) -> bool:
    """识别 MySQL 唯一键冲突（1062），与 business/receipt_service 同口径。"""
    return is_duplicate_entry(exc)


def list_shipments(session: Session, query: ShipmentQuery) -> PageResult[ShipmentOut]:
    """分页查询发货单（附业务号；business_id 可空=全量，一期按业务维度查看为主）。"""
    rows = shipment_repository.list_shipments(
        session,
        offset=query.offset,
        limit=query.page_size,
        business_id=query.business_id,
        ship_date_from=query.ship_date_from,
        ship_date_to=query.ship_date_to,
    )
    total = shipment_repository.count_shipments(
        session,
        business_id=query.business_id,
        ship_date_from=query.ship_date_from,
        ship_date_to=query.ship_date_to,
    )
    return PageResult[ShipmentOut](
        records=[_to_out(row) for row in rows],
        total=total,
        page_num=query.page_num,
        page_size=query.page_size,
    )


def get_detail(session: Session, shipment_id: int) -> ShipmentDetailOut:
    """发货单详情（附明细行，供编辑抽屉回显）。

    :raises NotFoundError: 发货单不存在
    """
    row = shipment_repository.get_with_business_no(session, shipment_id)
    if row is None:
        raise NotFoundError("发货单不存在")
    out = ShipmentDetailOut(**_to_out(row).model_dump())
    out.items = [
        _item_to_out(item) for item in shipment_repository.list_items(session, shipment_id)
    ]
    return out


def create_shipment(
    session: Session,
    payload: ShipmentCreateIn,
    *,
    operator: User,
    meta: RequestMeta | None = None,
) -> ShipmentOut:
    """新增发货单：锁业务行 → 校验 → 建单 + 明细 + 双重汇总回写，一个事务。

    摘要两号（发货单号/业务号）在进入审计前就绪：业务号取自锁行结果、
    发货单号先行生成（SELECT MAX FOR UPDATE，不产生未提交变更）；状态
    校验在审计上下文内，失败也留痕 —— 失败路径回滚释放已取序号，当日
    序号出现空洞无害（唯一性不依赖连续）。

    :raises NotFoundError: 业务不存在
    :raises BadRequestError: 业务已完成或已终止，禁止新发货
    """
    business = business_repository.get_by_id(session, payload.business_id, for_update=True)
    shipment_no = _generate_no(session)
    with audit_service.audit(
        session,
        operator=operator,
        record=AuditRecord(
            module=MODULE_SHIPMENT,
            action=ACTION_CREATE,
            summary=(
                f"新增发货单 {shipment_no}"
                f"（业务 {business.business_no if business else f'#{payload.business_id}'}，"
                f"明细 {len(payload.items)} 行）"
            ),
            request_data=payload.model_dump(exclude_none=True),
        ),
        meta=meta,
    ):
        # 单号唯一键冲突的重试整体收在审计上下文内（模式同
        # business_service.create_business）：rollback 释放旧锁，重试前重新
        # 锁业务行与生成编号——成功/最终失败各只记一条审计，无递归
        for attempt in range(_NO_RETRY + 1):
            try:
                if business is None:
                    raise NotFoundError("业务不存在")
                if business.status != BUSINESS_STATUS_ACTIVE:
                    raise BadRequestError("业务已完成或已终止，禁止新发货")

                shipment = Shipment(
                    shipment_no=shipment_no,
                    business_id=payload.business_id,
                    ship_date=payload.ship_date,
                    freight_amount=_amount_or_zero(payload.freight_amount),
                    total_amount=Decimal("0"),
                    remark=payload.remark,
                )
                shipment_repository.create(session, shipment)
                shipment_repository.replace_items(
                    session, shipment.id, _build_item_rows(payload.items)
                )
                total = shipment_repository.sum_item_amount(session, shipment.id)
                shipment.total_amount = total if total is not None else Decimal("0")
                _recalc_totals(session, business)
                out = _to_out((shipment, business.business_no))
                new_id, new_no = shipment.id, shipment_no  # 固化：commit 后不碰 ORM
                session.commit()
                break
            except IntegrityError as exc:
                session.rollback()
                if _is_duplicate_entry(exc) and attempt < _NO_RETRY:
                    business = business_repository.get_by_id(
                        session, payload.business_id, for_update=True
                    )
                    shipment_no = _generate_no(session)
                    continue
                raise

        logger.info(
            "新增发货单 | shipment_id=%s | no=%s | business_id=%s",
            new_id,
            new_no,
            payload.business_id,
        )
        return out


def update_shipment(
    session: Session,
    shipment_id: int,
    payload: ShipmentUpdateIn,
    *,
    operator: User,
    meta: RequestMeta | None = None,
) -> ShipmentOut:
    """编辑发货单（明细全量替换）+ 双重汇总回写，一个事务。

    business_id 不在编辑入参内 —— 发货单挂靠的业务创建时定死，改挂会让
    已指定本发货单的回款语义断裂。终态业务的发货单禁改（与回款写准入同
    口径；一期保守处理，设计未定项待业务确认后可放开——发货编辑不影响
    已核算回款，核算未发生，无固化快照可漂移）。

    :raises NotFoundError: 发货单不存在 / 业务不存在
    :raises BadRequestError: 业务已完成或已终止
    """
    shipment = shipment_repository.get_by_id(session, shipment_id)
    with audit_service.audit(
        session,
        operator=operator,
        record=AuditRecord(
            module=MODULE_SHIPMENT,
            action=ACTION_UPDATE,
            summary=f"修改发货单 {shipment.shipment_no if shipment else f'#{shipment_id}'}",
            request_data=payload.model_dump(exclude_none=True),
        ),
        meta=meta,
    ):
        if shipment is None:
            raise NotFoundError("发货单不存在")
        business = _ensure_business_writable(session, shipment.business_id, "编辑发货单")

        shipment.ship_date = payload.ship_date
        shipment.freight_amount = _amount_or_zero(payload.freight_amount)
        shipment.remark = payload.remark
        shipment_repository.replace_items(session, shipment_id, _build_item_rows(payload.items))
        total = shipment_repository.sum_item_amount(session, shipment_id)
        shipment.total_amount = total if total is not None else Decimal("0")
        _recalc_totals(session, business)
        # business_id 创建时定死不可改挂，锁定的 business.business_no 与重查同源
        out = _to_out((shipment, business.business_no))
        shipment_no = shipment.shipment_no
        session.commit()
        # commit 后不再触碰 ORM 属性（audit_service 约定）：单号已固化
        logger.info("修改发货单 | shipment_id=%s | no=%s", shipment_id, shipment_no)
        return out


def delete_shipment(
    session: Session,
    shipment_id: int,
    *,
    operator: User,
    meta: RequestMeta | None = None,
) -> None:
    """删除发货单（物理删除，连带明细行）+ 业务级汇总回写，一个事务。

    被回款批次指定（receipts.shipment_id 引用）→ 400 引导先解除回款的
    批次指定；业务须状态=1 执行中（终态业务的发货单禁删，与回款写准入
    同口径）—— 发货单的运费/金额是业务级汇总与 M3 核算的源数据，终态后
    不得变动。

    :raises NotFoundError: 发货单不存在 / 业务不存在
    :raises BadRequestError: 业务已完成或已终止 / 已被回款批次指定
    """
    shipment = shipment_repository.get_by_id(session, shipment_id)
    with audit_service.audit(
        session,
        operator=operator,
        record=AuditRecord(
            module=MODULE_SHIPMENT,
            action=ACTION_DELETE,
            summary=f"删除发货单 {shipment.shipment_no if shipment else f'#{shipment_id}'}",
        ),
        meta=meta,
    ):
        if shipment is None:
            raise NotFoundError("发货单不存在")
        business = _ensure_business_writable(session, shipment.business_id, "删除发货单")
        if shipment_repository.count_receipt_refs(session, shipment_id):
            raise BadRequestError("已被回款批次指定，请先解除回款的批次指定")

        shipment_no = shipment.shipment_no
        shipment_repository.delete_with_items(session, shipment_id)
        _recalc_totals(session, business)
        session.commit()
        # commit 后不再触碰 ORM 属性（audit_service 约定）：单号已固化
        logger.info("删除发货单 | shipment_id=%s | no=%s", shipment_id, shipment_no)