"""工作台仓储：四区块的只读聚合查询；不 commit、不抛业务异常。

总览只做 SQL 聚合（SUM/COUNT DISTINCT），不复用报表的
``department_summary``——后者会加载整月台账并逐团队查人员，适合报表页，
不适合每次打开工作台。
"""

from datetime import date, datetime

from sqlalchemy import exists, func, or_, select
from sqlalchemy.orm import Session, defer

from app.models import (
    ApprovalOrder,
    Business,
    BusinessRole,
    MonthlySettlement,
    PerformanceLedger,
    Personnel,
    Receipt,
    Shipment,
)
from app.models.approval import (
    APPROVAL_STATUS_PENDING_FINANCE,
    APPROVAL_STATUS_PENDING_LEADER,
)

_ACTIVE_SINGLE = (PerformanceLedger.calc_type == 1, PerformanceLedger.is_active == 1)
_PENDING_STATUSES = (
    APPROVAL_STATUS_PENDING_FINANCE,
    APPROVAL_STATUS_PENDING_LEADER,
)


# ==== 经营绩效总览 ====


def sum_month_performance(session: Session, month: str) -> dict:
    """当月单笔生效行合计与人员数（拆行求和不失真，人数需 DISTINCT）。"""
    return (
        session.execute(
            select(
                func.coalesce(func.sum(PerformanceLedger.performance_amount), 0).label(
                    "performance_total"
                ),
                func.coalesce(func.sum(PerformanceLedger.payable_amount), 0).label("payable_total"),
                func.count(func.distinct(PerformanceLedger.personnel_id)).label("person_count"),
            ).where(
                PerformanceLedger.settlement_month == month,
                *_ACTIVE_SINGLE,
            )
        )
        .mappings()
        .one()
    )


def performance_trend(session: Session, months: list[str]) -> dict[str, object]:
    """近 N 个月绩效合计（按台账归属月）。"""
    rows = session.execute(
        select(
            PerformanceLedger.settlement_month,
            func.coalesce(func.sum(PerformanceLedger.performance_amount), 0),
        )
        .where(
            PerformanceLedger.settlement_month.in_(months),
            *_ACTIVE_SINGLE,
        )
        .group_by(PerformanceLedger.settlement_month)
    ).all()
    return dict(rows)


def receipt_trend(session: Session, *, start_date: date, end_date: date) -> dict[str, object]:
    """近 N 个月回款合计（按到账月，含未核算回款——与台账口径不同，页面注明）。

    过滤走 ``receipt_date`` 原始列范围（可用索引）；``DATE_FORMAT`` 只用于
    分组，不参与 WHERE，避免函数列导致全表扫描。
    """
    month_expr = func.date_format(Receipt.receipt_date, "%Y-%m")
    rows = session.execute(
        select(month_expr, func.coalesce(func.sum(Receipt.amount), 0))
        .where(Receipt.receipt_date >= start_date, Receipt.receipt_date < end_date)
        .group_by(month_expr)
    ).all()
    return dict(rows)


def count_active_managers(session: Session) -> int:
    """在职营销经理数（团队数口径，与部门汇总的团队枚举一致）。"""
    return int(
        session.execute(
            select(func.count())
            .select_from(Personnel)
            .join(BusinessRole, Personnel.business_role_id == BusinessRole.id)
            .where(
                BusinessRole.role_code == "sales_manager",
                Personnel.status == 1,
            )
        ).scalar_one()
    )


def get_month_settlement(session: Session, month: str) -> MonthlySettlement | None:
    """当月月结头（状态与锁定时间角标）。"""
    return session.execute(
        select(MonthlySettlement).where(MonthlySettlement.settlement_month == month)
    ).scalar_one_or_none()


# ==== 待办事项 ====


def list_pending_approvals(
    session: Session, *, statuses: tuple[int, ...], limit: int
) -> list[ApprovalOrder]:
    """待处理审批单（按提交时间升序——最久的排前面）。

    ``statuses`` 由调用方按当前用户角色解析（待我审批），空元组返回空列表。

    排除 snapshot_json 列（快照可达上百 KB，待办只取单号/类型/提交人/时间）。
    """
    if not statuses:
        return []
    return list(
        session.execute(
            select(ApprovalOrder)
            .options(defer(ApprovalOrder.snapshot_json))
            .where(ApprovalOrder.status.in_(statuses))
            .order_by(ApprovalOrder.create_time.asc(), ApprovalOrder.id.asc())
            .limit(limit)
        ).scalars()
    )


def count_pending_approvals(session: Session, *, statuses: tuple[int, ...]) -> int:
    if not statuses:
        return 0
    return int(
        session.execute(
            select(func.count())
            .select_from(ApprovalOrder)
            .where(ApprovalOrder.status.in_(statuses))
        ).scalar_one()
    )


def list_unassigned_receipts(session: Session, *, limit: int) -> list:
    """回款未指定发货批次（shipment_id IS NULL，核算前置缺失）。"""
    return list(
        session.execute(
            select(
                Receipt,
                Business.business_no.label("business_no"),
            )
            .outerjoin(Business, Business.id == Receipt.business_id)
            .where(Receipt.shipment_id.is_(None))
            .order_by(Receipt.receipt_date.asc(), Receipt.id.asc())
            .limit(limit)
        ).all()
    )


def count_unassigned_receipts(session: Session) -> int:
    return int(
        session.execute(
            select(func.count()).select_from(Receipt).where(Receipt.shipment_id.is_(None))
        ).scalar_one()
    )


# ==== 风险预警 ====


def list_overdue_shipments(session: Session, *, cutoff: date, limit: int) -> list:
    """发货后超过阈值且该批次无任何回款的发货单（回款逾期规则）。

    已终止业务（status=3）不再催收，排除在预警之外；业务行缺失时仍保留，
    避免历史脏数据让发货单从预警中静默消失。
    """
    has_receipt = exists().where(Receipt.shipment_id == Shipment.id)
    return list(
        session.execute(
            select(
                Shipment,
                Business.business_no.label("business_no"),
            )
            .outerjoin(Business, Business.id == Shipment.business_id)
            .where(
                Shipment.ship_date <= cutoff,
                ~has_receipt,
                or_(Business.status.is_(None), Business.status != 3),
            )
            .order_by(Shipment.ship_date.asc())
            .limit(limit)
        ).all()
    )


def count_overdue_shipments(session: Session, *, cutoff: date) -> int:
    has_receipt = exists().where(Receipt.shipment_id == Shipment.id)
    return int(
        session.execute(
            select(func.count())
            .select_from(Shipment)
            .outerjoin(Business, Business.id == Shipment.business_id)
            .where(
                Shipment.ship_date <= cutoff,
                ~has_receipt,
                or_(Business.status.is_(None), Business.status != 3),
            )
        ).scalar_one()
    )


def list_overdue_approvals(
    session: Session, *, cutoff: datetime, limit: int
) -> list[ApprovalOrder]:
    """提交后超过阈值仍未处理的审批单（审批超时规则）。

    排除 snapshot_json 列（同待办：预警只用单号/类型/提交人/时间）。
    """
    return list(
        session.execute(
            select(ApprovalOrder)
            .options(defer(ApprovalOrder.snapshot_json))
            .where(
                ApprovalOrder.status.in_(_PENDING_STATUSES),
                ApprovalOrder.create_time < cutoff,
            )
            .order_by(ApprovalOrder.create_time.asc())
            .limit(limit)
        ).scalars()
    )


def count_overdue_approvals(session: Session, *, cutoff: datetime) -> int:
    return int(
        session.execute(
            select(func.count())
            .select_from(ApprovalOrder)
            .where(
                ApprovalOrder.status.in_(_PENDING_STATUSES),
                ApprovalOrder.create_time < cutoff,
            )
        ).scalar_one()
    )