from fastapi import Query, Depends, HTTPException, APIRouter
from sqlalchemy.orm import Session
from sqlalchemy_fastapi_demo.dao.Score import ScoreDAO
from sqlalchemy_fastapi_demo.database import get_db
from sqlalchemy_fastapi_demo.scheme.Score import ScoreCreate, ScoreUpdate

app_score=APIRouter()

# 查询所有成绩
@app_score.get("/",summary='查询所有成绩')
async def get_scores(
    skip: int = Query(0, ge=0, description="跳过的记录数"),
    limit: int = Query(100, ge=1, le=200, description="返回的最大记录数"),
    db: Session = Depends(get_db)
):
    scores=ScoreDAO.get_all(db, skip=skip, limit=limit)
    return scores

# 查询单个数据
@app_score.get("/{stu_id}/{exam_id}",summary='查询单个成绩')
async def get_score(
        stu_id: int,
        exam_id: int,
        db: Session = Depends(get_db)
):
    score=ScoreDAO.get_by_id(db, stu_id,exam_id)
    if not score:
        raise HTTPException(status_code=404, detail="学生不存在")
    return score

# 创建学生
@app_score.post("/",summary='创建学生成绩')
async def create_scores(
        score:ScoreCreate,
        db: Session = Depends(get_db)
):
    # 检查学生在不在学生表
    existing_foreign_key=ScoreDAO.inspect_stu_id_unq(db, score.stu_id)
    if not existing_foreign_key:
        raise HTTPException(status_code=404, detail="该学生不存在")
    if existing_foreign_key.is_deleted == 1:
        raise HTTPException(status_code=404, detail="该学生不存在")
    # 检查成绩是否已被占用
    existing_score=ScoreDAO.get_by_id(db, score.stu_id,score.exam_id)
    if existing_score:
        raise HTTPException(status_code=400, detail="学生成绩已存在，请勿重复添加")
    new_score=ScoreDAO.post_score(db,score)
    return new_score

# 修改
@app_score.put("/{stu_id}/{exam_id}",summary='修改信息')
async def update_scores(
        stu_id: int,
        exam_id: int,
        score:ScoreUpdate,
        db: Session = Depends(get_db)
):
    # 只允许修改成绩，学生id和考试次序不允许修改，SQLAlchemy不能直接更新联合主键本身
    # 检查成绩是否已存在
    existing_foreign_key = ScoreDAO.inspect_stu_id_unq(db, score.stu_id)
    if not existing_foreign_key:
        raise HTTPException(status_code=404, detail="该学生不存在")
    existing_score=ScoreDAO.get_by_id(db, stu_id,exam_id)
    if not existing_score:
        raise HTTPException(status_code=404, detail="学生成绩不存在")
    # 直接调用DAO更新，只更新score字段
    b = ScoreDAO.put_score(db, stu_id, exam_id, score)
    return b

# 修改成绩：支持修改 stu_id、exam_id、score；原理：删除旧记录，新增新记录
    # stu_id、exam_id是联合主键。MySQL不允许update 直接修改主键字段，SQLAlchemy
    # 底层执行会抛数据库异常。所以采用「删旧、建新」的方案模拟修改

    # 风险大
    # 现在代码：删旧和新增是两次
    # db.commit()。
    # 如果删旧成功，新增中途崩掉，会出现旧数据没了，新数据没加上，数据丢失。

    # 数据库这条记录实际上是新行，不是原来那一行。
    # 如果别的表有外键引用这条成绩记录，这个方案会出问题（旧记录删掉，关联跟着没了）。
# @app_score.put("/{stu_id}/{exam_id}",summary='修改学生成绩(支持修改学生ID、考核序次、分数)')
# async def update_scores(
#         stu_id: int,
#         exam_id: int,
#         score:ScoreUpdate,
#         db: Session = Depends(get_db)
# ):
#     # 1.找到旧记录
#     old_score = ScoreDAO.get_by_id(db, stu_id, exam_id)
#     if not old_score:
#         raise HTTPException(status_code=404, detail="待修改的成绩记录不存在")
#     # 2.确定新值：前端没传的字段，沿用旧记录的值
#     new_stu = score.stu_id if score.stu_id is not None else old_score.stu_id
#     new_exam_id = score.exam_id if score.exam_id is not None else old_score.exam_id
#     new_score_val = score.score if score.score is not None else old_score.score
#     # 3.校验新stu_id学生是否存在
#     if new_stu != old_score.stu_id:
#         stu_obj = ScoreDAO.inspect_stu_id_unq(db, new_stu)
#         if not stu_obj:
#             raise HTTPException(status_code=404, detail="目标学生不存在")
#     # 4.如果新主键组合和旧的不一样，要检查新组合是否冲突
#     if (new_stu, new_exam_id) != (old_score.stu_id, old_score.exam_id):
#         conflict = ScoreDAO.get_by_id(db, new_stu, new_exam_id)
#         if conflict:
#             raise HTTPException(status_code=400, detail="新【学生ID+考核序次】组合已存在，不能使用")
#     # 核心逻辑：删除旧记录，新增一条全新记录
#     # 删除旧数据
#     ScoreDAO.delete_score(db, stu_id, exam_id)
#     # 组装成ScoreCreate对象，调用新增DAO
#     from sqlalchemy_fastapi_demo.scheme.Score import ScoreCreate
#     new_create_data = ScoreCreate(
#         stu_id=new_stu,
#         exam_id=new_exam_id,
#         score=new_score_val
#     )
#     new_db_score = ScoreDAO.post_score(db, new_create_data)
#     return new_db_score



# 删除
@app_score.delete("/{stu_id}/{exam_id}",summary='删除学生成绩')
async def delete_scores(
        stu_id: int,
        exam_id: int,
        db: Session = Depends(get_db)
):
    score=ScoreDAO.delete_score(db, stu_id,exam_id)
    if not score:
        raise HTTPException(status_code=404, detail="学生成绩不存在")
    return {"msg":"删除成功"}