# app/services/task_service.py

from typing import List, Optional

from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, update

from app.core.queue_manager import queue_manager
from app.core.biz_exception import NotFoundError
from app.models.task import Task
from app.schemas.task import TaskCreate, TaskUpdate


class TaskService:

    # ======================
    # 创建任务
    # ======================
    @staticmethod
    async def create(db: AsyncSession, obj_in: TaskCreate) -> Task:
        db_obj = Task(
            command=obj_in.command,
            args=obj_in.args,
            status=obj_in.status or 0,
        )
        db.add(db_obj)
        await db.commit()
        await db.refresh(db_obj)
        
        # 👇 只在 READY 状态才入队
        if db_obj.status == 0:
            queue_manager.put(
                queue_name=db_obj.command,
                task_id=db_obj.id,
                priority=0,   # 先用默认优先级
            )
        return db_obj

    # ======================
    # 根据 ID 获取
    # ======================
    @staticmethod
    async def get_by_id(db: AsyncSession, task_id: int) -> Task:
        stmt = select(Task).where(Task.id == task_id)
        obj = (await db.execute(stmt)).scalar_one_or_none()

        if not obj:
            raise NotFoundError("Task not exist")
        return obj

    # ======================
    # 更新任务
    # ======================
    @staticmethod
    async def update(
        db: AsyncSession,
        task_id: int,
        obj_in: TaskUpdate
    ) -> Task:
        stmt = select(Task).where(Task.id == task_id)
        db_obj = (await db.execute(stmt)).scalar_one_or_none()

        if not db_obj:
            raise NotFoundError("Task not exist")

        if obj_in.result is not None:
            db_obj.result = obj_in.result
        if obj_in.status is not None:
            db_obj.status = obj_in.status

        await db.commit()
        await db.refresh(db_obj)
        
        # 👇 核心：从非 READY → READY，才重新入队
        if old_status != 0 and db_obj.status == 0:
            queue_manager.put(
                queue_name=db_obj.command,
                task_id=db_obj.id,
                priority=0,
            )
        return db_obj

    # ======================
    # 获取待处理任务（分页）
    # ======================
    @staticmethod
    async def get_pending(
        db: AsyncSession,
        command: str,
        page: int,
        size: int
    ) -> List[Task]:
        offset = page * size

        stmt = (
            select(Task)
            .where(
                Task.command == command,
                Task.status == 0
            )
            .order_by(Task.create_at.asc())
            .offset(offset)
            .limit(size)
        )

        return (await db.execute(stmt)).scalars().all()