# dao/stu_dao.py
# 学生信息数据访问层

from typing import List, Optional, Tuple

from sqlalchemy.orm import Session

from dao.advisor_dao import assert_advisor_alive
from dao.cls_mgmt_dao import assert_cls_alive
from dao.exceptions import ConflictError, NotFoundError
from dao.pagination import paginate
from model.stu_model import StuInfo


def assert_stu_alive(db: Session, stu_id: str, detail: Optional[str] = None) -> StuInfo:
    """
    确认学生存在且未删除，否则抛 NotFoundError。
    供成绩、就业模块复用作外键校验。
    """
    stu = db.query(StuInfo).filter(StuInfo.id == stu_id, StuInfo.is_deleted == 0).first()
    if not stu:
        raise NotFoundError(detail or "学生不存在")
    return stu


def list_students(
    db: Session,
    page: int,
    size: int,
    name: Optional[str] = None,
    cls_id: Optional[str] = None,
    state: Optional[str] = None,
) -> Tuple[int, List[StuInfo]]:
    """分页查询未删除的学生，支持按姓名模糊 / 班级 / 状态过滤。"""
    query = db.query(StuInfo).filter(StuInfo.is_deleted == 0)
    if name:
        query = query.filter(StuInfo.name.like(f"%{name}%"))
    if cls_id:
        query = query.filter(StuInfo.cls_id == cls_id)
    if state:
        query = query.filter(StuInfo.state == state)
    return paginate(query, page, size, order_by=StuInfo.id)


def create_student(db: Session, data: dict) -> StuInfo:
    """新增学生：校验学号唯一，且所属班级、顾问（若填写）都存在。"""
    # 学号是主键，已软删除的记录同样占用该学号，所以这里不加 is_deleted 过滤
    if db.query(StuInfo).filter(StuInfo.id == data["id"]).first():
        raise ConflictError("学生编号已存在")

    assert_cls_alive(db, data["cls_id"], "所属班级不存在")
    if data.get("advisor_id"):
        assert_advisor_alive(db, data["advisor_id"], "顾问不存在")

    stu = StuInfo(**data)
    db.add(stu)
    db.commit()
    db.refresh(stu)
    return stu


def update_student(db: Session, stu_id: str, data: dict) -> StuInfo:
    """更新学生：若更换班级 / 顾问需重新校验外键。"""
    stu = assert_stu_alive(db, stu_id, "学生不存在或已删除")

    if data.get("cls_id"):
        assert_cls_alive(db, data["cls_id"], "所属班级不存在")
    if data.get("advisor_id"):
        assert_advisor_alive(db, data["advisor_id"], "顾问不存在")

    for field, value in data.items():
        setattr(stu, field, value)

    db.commit()
    db.refresh(stu)
    return stu


def soft_delete_student(db: Session, stu_id: str) -> None:
    """软删除学生。"""
    stu = assert_stu_alive(db, stu_id, "学生不存在或已删除")
    stu.is_deleted = 1
    db.commit()