import uuid
from fastapi import APIRouter, Depends, HTTPException,Query
from dao.class_dao import update_class_dao, add_class_dao, get_class_dao
from database import get_db
from model.class_model import StudentClassIntermediate
from schema.class_request import ClassRequest, ClassResponse, TransferRequest
from dao.class_dao import Student_delect_Dao
from datetime import datetime
from model.class_model import Class_info
from sqlalchemy import select, func



class_api = APIRouter()


@class_api.post('',response_model=ClassResponse,summary='班级信息新增接口')
def add_orders(cs:ClassRequest,db=Depends(get_db)):
    d = cs.model_dump()
    r = add_class_dao( o=d,db=db )
    if not r:
        raise HTTPException(status_code=500,detail='服务器繁忙或班级不存在！')
    return ClassResponse(totals=1,data=d)


# @class_api.delete('/{class_name}/')
# def delete_orders(class_name:str,db=Depends(get_db)):
#    rows= delect_class_dao( class_name=class_name,db=db )
#    if  rows:
#        return {'code': 200, 'totals': rows, 'detail': '删除成功'}
#    raise HTTPException(status_code=500,detail='删除异常，稍后操作！')



@class_api.delete("/class_id",summary='班级信息删除接口')
async def delete_student(class_id: str, db= Depends(get_db)):
    target_student =  Student_delect_Dao.soft_delete_student(db, class_id)
    if not target_student:
        raise HTTPException(status_code=404, detail="班级数据不存在或已删除")
    # 直接更新软删除标记为1，完成逻辑删除
    target_student.is_deleted = 1
    r=datetime.now().isoformat()
    db.commit()
    return  ClassResponse(totals=1,data=r)




@class_api.get('',summary='班级信息查询接口')
def get_orders(class_name:str,db=Depends(get_db)):
    r=get_class_dao(class_name,db)
    if r:
         return [{"class_id": i.class_id, 'class_name': i.class_name, "class_code": i.class_code, "tags": i.tags,
                  "status":i.status,'create_time':i.create_time,"update_time": i.update_time} for i in r]
    raise HTTPException(status_code=404,detail='班级不存在！')

@class_api.put('/{class_id}',summary='班级信息更新接口')
def get_orders(order:ClassRequest,class_id:str,db=Depends(get_db)):
    d = order.model_dump(exclude_unset=True)
    r = update_class_dao( class_id=class_id,update_data=d,db=db )
    if not r:
        raise HTTPException(status_code=500, detail='没有更新！')
    return {'code':200,'totals':r,'detail':'更新成功'}


@class_api.get("/classes",summary='班级学生信息分页查询接口')
def get_all_classes_with_student_count(
    page: int = Query(1, ge=1),  #page：页码，默认值为1
    size: int = Query(10, ge=1, le=100), #size：单页返回数据条数，默认值10，约束范围1~100，
    db = Depends(get_db) #db：通过依赖注入的方式获取SQLAlchemy的数据库会话实例
):
    total = db.scalar(select(func.count(Class_info.class_id)).where(Class_info.is_deleted == 0)) #班级表中所有符合条件的主键数量
    offset = (page - 1) * size  #计算分页偏移量

    class_list = db.execute(
        select(
            Class_info.class_name,
            # 直接统计当前班级的学生数量
            (
                select(func.count(StudentClassIntermediate.student_id))
                .where(
                    StudentClassIntermediate.class_id == Class_info.class_id,
                    StudentClassIntermediate.is_deleted == 0
                )
            ).label("student_count")
        )
        .where(Class_info.is_deleted == 0)
        .order_by(Class_info.class_name)
        .offset(offset).limit(size)
    ).mappings().all()

    return {
        "total_classes": total,
        "page": page,
        "size": size,
        "class_list": class_list
    }



# 同步转班接口
@class_api.patch("/students/{student_id}/transfer",summary='学生转班信息查询接口')
def transfer_student(
        student_id: str,
        request: TransferRequest,
        db=Depends(get_db)
):
    target_class_name = request.target_class_name

    # 1. 【关键修改】根据班级名称查找班级ID
    # 注意：这里假设班级名称是唯一的。如果名称不唯一，建议前端传ID或后端增加歧义处理
    target_class_res = db.execute(
        select(Class_info).where(
            Class_info.class_name == target_class_name,
            Class_info.is_deleted == 0
        )
    )
    target_class = target_class_res.scalar_one_or_none()

    if not target_class:
        raise HTTPException(status_code=404, detail=f"未找到名为 '{target_class_name}' 的班级")

    # 获取目标班级的ID，用于后续关联
    target_class_id = target_class.class_id
    # 2. 查询学生当前所在的有效班级关联
    current_link_res = db.execute(
        select(StudentClassIntermediate).where(
            StudentClassIntermediate.student_id == student_id,
            StudentClassIntermediate.is_deleted == 0
        )
    )
    current_link = current_link_res.scalar_one_or_none()

    now = datetime.now()

    # 3. 逻辑处理：如果学生已经在目标班级，直接返回
    if current_link and current_link.class_id == target_class_id:
        return {"message": f"该学生已在 '{target_class_name}' 班级中，无需重复操作"}

    # 4. 逻辑删除原班级关联 (如果存在)
    if current_link:
        current_link.is_deleted = 1  # 标记为已删除
        current_link.update_time = now  # 更新时间
        # 注意：这里不需要 db.add(current_link)，因为它是从 session查出来的对象，修改属性后 commit 即可生效

    # 5. 新增新班级关联记录
    new_link = StudentClassIntermediate(
        id=str(uuid.uuid4())[:8],  # 生成新的主键ID
        class_id=target_class_id,  # 使用刚才查到的目标班级ID
        student_id=student_id,
        is_deleted=0,  # 标记为有效
        create_time=now,
        update_time=now
    )
    db.add(new_link)

    # 6. 提交事务
    db.commit()

    return {
        "message": f"学生 {student_id} 成功转入班级 '{target_class.class_name}'",
        "new_class_id": target_class_id,
        "old_class_id": current_link.class_id if current_link else None
    }