from typing import Optional, Any
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from app.core.biz_exception import NotFoundError
from app.models.troov_session import TroovSession
from app.schemas.troov_session import TroovSessionCreate, TroovSessionUpdate

# 假设你的项目中分页和搜索工具方法路径如下，请根据实际情况调整
from app.utils.pagination import paginate 
from app.utils.search import apply_keyword_search_stmt


class TroovSessionService:

    @staticmethod
    async def add(db: AsyncSession, obj_in: TroovSessionCreate) -> TroovSession:
        # 优化点 1: 使用 model_dump 直接解包，避免手动挨个赋值
        db_obj = TroovSession(**obj_in.model_dump())
        
        # 默认值已经在 schema 中定义了，这里不需要再 obj_in.status or "pending"
        db.add(db_obj)
        await db.commit()
        await db.refresh(db_obj)
        return db_obj

    @staticmethod
    async def pop(db: AsyncSession, slot_date: Optional[str] = None, slot_time: Optional[str] = None) -> TroovSession:
        stmt = select(TroovSession).where(TroovSession.status == "pending")
        if slot_date:
            stmt = stmt.where(TroovSession.slot_date == slot_date)
        if slot_time:
            stmt = stmt.where(TroovSession.slot_time == slot_time)
            
        # 优点保留: 使用 skip_locked=True 完美解决并发争抢问题
        stmt = stmt.order_by(TroovSession.created_at.asc()).limit(1).with_for_update(skip_locked=True)

        result = await db.execute(stmt)
        obj = result.scalar_one_or_none()

        if not obj:
            raise NotFoundError("No pending troov session found")

        obj.status = "booking"
        await db.commit()
        await db.refresh(obj)
        return obj

    @staticmethod
    async def update(db: AsyncSession, session_id: str, obj_in: TroovSessionUpdate) -> TroovSession:
        stmt = select(TroovSession).where(TroovSession.session_id == session_id)
        db_obj = (await db.execute(stmt)).scalar_one_or_none()

        if not db_obj:
            raise NotFoundError("TroovSession not found")

        # 优化点 2: 使用 exclude_unset=True 仅提取客户端真正传入的字段
        update_data = obj_in.model_dump(exclude_unset=True)
        
        # 安全防御: 防止客户端恶意或错误修改主键
        update_data.pop("session_id", None) 

        # 动态赋值，后续 Schema 加字段这里完全不用改代码
        for field, value in update_data.items():
            setattr(db_obj, field, value)

        await db.commit()
        await db.refresh(db_obj)
        return db_obj

    @staticmethod
    async def get_by_session_id(db: AsyncSession, session_id: str) -> Optional[TroovSession]:
        stmt = select(TroovSession).where(TroovSession.session_id == session_id)
        return (await db.execute(stmt)).scalar_one_or_none()

    @staticmethod
    async def list(
        db: AsyncSession, 
        status: Optional[str] = None, 
        keyword: Optional[str] = None, # 新增 keyword 支持
        page: int = 1,                 # 分页库通常 page 从 1 开始
        size: int = 10
    ) -> Any:
        stmt = select(TroovSession)
        
        if status:
            stmt = stmt.where(TroovSession.status == status)

        # 优化点 3: 引入你提供的 apply_keyword_search_stmt 范式
        if keyword:
            stmt = apply_keyword_search_stmt(
                stmt=stmt,
                model=TroovSession,
                keyword=keyword,
                fields=["session_id", "source"] # 根据业务需求定义支持模糊搜索的字段
            )

        stmt = stmt.order_by(TroovSession.created_at.asc())
        
        # 优化点 4: 使用统一的 paginate 方法取代手动 offset 和 limit
        return await paginate(db, stmt, page, size)