from models.student import Student
from sqlalchemy.orm import Session

from schemas.student import Gender


#新建学生
def create_students(d: dict, db: Session):
    stu = Student(**d)

    try:
        db.add(stu)
        #  把 SQL 发给数据库执行
        db.flush()
        # 根据 id 生成学生编号
        if not stu.student_no:
            stu.student_no = f"STU{stu.id:04d}"
        db.commit()
        db.refresh(stu)
        return stu
    except Exception as e:
        db.rollback()
        print(f"插入学生失败: {e}")
        return None

#查询学生是否已经被逻辑删除
def get_student_by_id(student_id: int, db: Session):
    # 同时判断 is_deleted，已经逻辑删除的学生不会被查到
    return db.query(Student).filter(
        Student.id == student_id,
        Student.is_deleted == 0,
    ).first()

#更新学生信息
def update_student(student_id: int, data: dict, db: Session):
    # 第一步：先查询学生
    student = get_student_by_id(student_id, db)

    # 没有查到就返回 None
    if not student:
        return None

    try:
        # 第二步：循环修改前端传来的字段
        # field 是字段名，value 是新的值
        for field, value in data.items():
            setattr(student, field, value)

        # 第三步：提交修改并重新读取数据
        db.commit()
        db.refresh(student)
        return student

    except Exception as e:
        # 修改失败时回滚
        db.rollback()
        print("修改学生失败：", e)
        return False

#允许条件输入的列表查询
def get_students(
    db: Session,
    student_no: str | None = None,
    student_name: str | None = None,
    class_id: int | None = None,
    page: int = 1,
    page_size: int = 10,
    gender: Gender = None,
):
    # 第一步：只查询没有被删除的学生
    query = db.query(Student).filter(Student.is_deleted == 0)

    # 第二步：前端传了哪个条件，就增加哪个条件
    if student_no:
        # 学号使用精确查询
        query = query.filter(Student.student_no == student_no)

    if gender:
        #查询枚举性别
        query = query.filter(Student.gender == gender)

    if student_name:
        # 姓名使用模糊查询，例如“张”可以查到“张三”
        query = query.filter(Student.student_name.like(f"%{student_name}%"))

        # 班级 ID 使用精确查询
    if class_id is not None:
            query = query.filter(Student.class_id == class_id)

    # 分页之前统计符合条件的总条数
    total = query.count()

    #默认按学生id排序
    students = (
        query
        .order_by(Student.id.desc())
        .offset((page - 1) * page_size)
        .limit(page_size)
        .all()
    )
    return total, students

#逻辑删除学生
def delete_student(student_id: int, db: Session):
    # 第一步：查询学生
    student = get_student_by_id(student_id, db)

    if not student:
        return None

    try:
        # 第二步：不真正删除记录，只把删除标记改成 1
        student.is_deleted = 1

        # 第三步：提交修改
        db.commit()
        return student

    except Exception as e:
        # 删除失败时回滚
        db.rollback()
        print("删除学生失败：", e)
        return False