from sqlalchemy.orm import Session
from sqlalchemy import select, update, delete
from model.wl_score_model import Score
from model.wl_student_model import Student


def get_score(db: Session, stu_id: int, exam_order: int):
    """根据学生id+考试批次查询单条成绩"""
    stmt = select(Score).where(
        Score.stu_id == stu_id,
        Score.exam_order == exam_order
    )
    return db.scalar(stmt)


def get_student_by_id(db: Session, stu_id: int):
    """检测学生是否存在：通过学生id查学生表"""
    return db.scalar(select(Student).where(Student.stu_id == stu_id))


def get_student_by_name(db: Session, stu_name: str):
    """通过学生姓名查询学生"""
    return db.scalar(select(Student).where(Student.stu_name == stu_name))


def list_score_by_stu_id(db: Session, stu_id: int):
    """查询一个学生全部成绩，返回列表"""
    stmt = select(Score).where(Score.stu_id == stu_id)
    return db.scalars(stmt).all()



def create_score(db: Session, stu_id: int, exam_order: int, score: float):
    """
    新增成绩
    返回：成功返回StudentScore对象；检测不通过返回None
    """
    # 1.检测：学生是否真实存在学生表
    stu = get_student_by_id(db, stu_id)
    if not stu:
        print("[检测] 学生表无此学生,stu_id=", stu_id)
        return None

    # 2.检测：该学生该批次成绩是否已经存在（重复新增）
    exist_score = get_score(db, stu_id, exam_order)
    if exist_score:
        print("[检测] 成绩已存在 stu_id=", stu_id, "exam_order=", exam_order)
        return None

    # 3.构建ORM对象插入数据库
    new_score = Score(
        stu_id=stu_id,
        exam_order=exam_order,
        score=score
    )
    db.add(new_score)
    db.commit()
    db.refresh(new_score)
    return new_score



def update_score(db: Session, stu_id: int, exam_order: int, new_score: float):
    """
    更新指定学生指定考试批次的分数
    """
    # 1.检测学生是否存在
    stu = get_student_by_id(db, stu_id)
    if not stu:
        print("[检测] 更新失败：学生不存在")
        return None

    # 2.检测这条成绩记录本身是否存在
    score_obj = get_score(db, stu_id, exam_order)
    if not score_obj:
        print("[检测] 更新失败：该学生该批次成绩记录不存在")
        return None

    # 方案A：直接修改对象属性（推荐）
    score_obj.score = new_score
    db.commit()
    db.refresh(score_obj)
    return score_obj





def delete_score(db: Session, stu_id: int, exam_order: int):
    """删除某个学生某一次考核成绩"""
    # 检测记录是否存在
    score_obj = get_score(db, stu_id, exam_order)
    if not score_obj:
        print("[检测] 删除失败，记录不存在")
        return False

    stmt = delete(Score).where(
        Score.stu_id == stu_id,
        Score.exam_order == exam_order
    )
    db.execute(stmt)
    db.commit()
    return True