import random
from datetime import datetime
from sqlalchemy.orm import Session
from model.wl_teacher_model import Teacher
from scheme.wl_teacher_scheme import TeacherCreate, TeacherUpdate


def generate_teacher_no():
    """生成老师工号：T + 年月日 + 3位随机数，例如 T20260912001"""
    date_str = datetime.now().strftime("%Y%m%d")
    seq = random.randint(1, 999)
    return f"T{date_str}{seq:03d}"

def list_teachers(db: Session):
    """查询全部未删除教师列表"""
    return db.query(Teacher).filter(Teacher.is_deleted == 0).order_by(Teacher.t_id.desc()).all()

def get_teacher_id(db: Session, t_id: int):
    return (db.query(Teacher).filter(Teacher.t_id == t_id, Teacher.is_deleted == 0)
            .first() )

def get_teacher_no(db:Session, t_no: str):
    return(db.query(Teacher).filter(Teacher.t_no == t_no,Teacher.is_deleted == 0)
           .first())


def create_teacher(db: Session, teacher_data: TeacherCreate):
    """创建新老师"""
    # 如果前端没传工号，自动生成
    t_no = teacher_data.t_no or generate_teacher_no()

    # 唯一性校验
    if get_teacher_no(db, t_no):
        raise ValueError("老师编号已存在")

    data = teacher_data.model_dump()
    data["t_no"] = t_no

    db_teacher = Teacher(**data)
    db.add(db_teacher)
    db.commit()
    db.refresh(db_teacher)
    return db_teacher

def update_teacher(db: Session, t_id: int, update_data: TeacherUpdate):
    """修改教师"""
    db_obj = get_teacher_id(db, t_id)
    if not db_obj:
        return None
    # model_dump(exclude_unset=True) 只取前端传过来的字段
    update_dict = update_data.model_dump(exclude_unset=True)
    for k, v in update_dict.items():
        setattr(db_obj, k, v)
    db.commit()
    db.refresh(db_obj)
    return db_obj

def delete_teacher_logic(db: Session, t_id: int):
    """逻辑删除，修改is_deleted=1"""
    db_obj = get_teacher_id(db, t_id)
    if not db_obj:
        return None
    db_obj.is_deleted = 1
    db.commit()
    return db_obj