"""计提公式模板数据访问。

本层只 flush 不 commit —— 事务边界由 services 层控制。
"""

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

from app.models import BusinessRole, CalcTemplateDefinition


def get_by_id(session: Session, template_id: int, *, for_update: bool = False) -> CalcTemplateDefinition | None:
    """按主键查询；删除校验走行锁。"""
    if for_update:
        stmt = select(CalcTemplateDefinition).where(CalcTemplateDefinition.id == template_id).with_for_update()
        return session.execute(stmt).scalar_one_or_none()
    return session.get(CalcTemplateDefinition, template_id)


def get_by_code(session: Session, template_code: str) -> CalcTemplateDefinition | None:
    """按编码查询模板。编码是岗位绑定与参数解析的锚点。"""
    stmt = select(CalcTemplateDefinition).where(CalcTemplateDefinition.template_code == template_code)
    return session.execute(stmt).scalar_one_or_none()


def list_all(session: Session) -> list[CalcTemplateDefinition]:
    """全部模板（含停用，供管理列表展示引用状态）。"""
    stmt = select(CalcTemplateDefinition).order_by(
        CalcTemplateDefinition.sort_order, CalcTemplateDefinition.id
    )
    return list(session.execute(stmt).scalars())


def list_active(session: Session) -> list[CalcTemplateDefinition]:
    """启用模板，供岗位表单下拉。"""
    stmt = (
        select(CalcTemplateDefinition)
        .where(CalcTemplateDefinition.status == 1)
        .order_by(CalcTemplateDefinition.sort_order, CalcTemplateDefinition.id)
    )
    return list(session.execute(stmt).scalars())


def count_roles_by_codes(session: Session, codes: list[str]) -> dict[str, int]:
    """批量统计各模板被岗位引用的数量，用于删除保护与列表展示。"""
    if not codes:
        return {}
    rows = session.execute(
        select(BusinessRole.calc_template, func.count(BusinessRole.id))
        .where(BusinessRole.calc_template.in_(codes))
        .group_by(BusinessRole.calc_template)
    ).all()
    return {code: int(count) for code, count in rows}


def create(session: Session, template: CalcTemplateDefinition) -> CalcTemplateDefinition:
    """新增模板。只 flush 以取得自增 id。"""
    session.add(template)
    session.flush()
    return template


def delete(session: Session, template: CalcTemplateDefinition) -> None:
    """删除模板。调用方须先完成保护规则校验。"""
    session.delete(template)
    session.flush()