from sqlalchemy.orm import Session
from sqlalchemy.exc import IntegrityError
from dao.advisor import crud
from scheme.advisors import AdvisorIn

# 成功 (数据, None)；失败 (None, "错误码")。

def create_advisor(db:Session,advisor_id:int,advisor_name:str):
    exist=crud.search_advisor(db,advisor_id=advisor_id)
    if exist is not None:
        return None,"DUPLICATE"  #ID主键已被占用
    try:
        advisor = crud.create_advisor(db,advisor_id,advisor_name)
    except IntegrityError:
        db.rollback()
        return None, "DUPLICATE"
    return advisor, None


def update_advisor(db:Session,advisor_id:int,advisor_in:AdvisorIn):
    exist = crud.search_advisor(db,advisor_id=advisor_id)
    if exist is None:
        return None, "NOT_FOUND"
    u_advisor=crud.update_advisor(db,advisor_id=advisor_id,advisor_name=advisor_in.advisor_name)
    if u_advisor is None:
        return None, "NOT_FOUND"      # 查过之后被并发删掉了
    return u_advisor,None


#删除成功返回Advisor ID，删除失败返回None。顾问如连接学生，则拒绝删除。
def delete_advisor(db: Session, advisor_id: int):
    exist = crud.search_advisor(db=db, advisor_id=advisor_id)
    if exist is None:
        return None, "NOT_FOUND"
    # 查一下这个顾问名下有没有学生
    if crud.list_students_of_advisor(db, advisor_id):
        return None, "HAS_STUDENTS"
    result = crud.delete_advisor(db=db, advisor_id=advisor_id)
    if result is None:
        return None, "NOT_FOUND"      # 查过之后被并发删掉了
    return result, None