from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from app.core.logger import logger
from app.core.biz_exception import NotFoundError, BizLogicError
from app.core.queue_manager import queue_manager
from app.models.task import Task
from app.models.vas_task import VasTask

class QueueService:
    
    async def rebuild_task_queue(db: AsyncSession, queue_name: str):
        if queue_manager.is_initialized(queue_name):
            return
        
        queue = queue_manager.get_queue(queue_name)
        queue.clear()
        
        stmt = (
            select(Task)
            .where(
                Task.command == queue_name,
                Task.status == 0
            )
        )
        tasks = (await db.execute(stmt)).scalars().all()

        for task in tasks:
            queue_manager.put(
                queue_name=queue_name,
                task_id=task.id,
                priority=0,
            )

        queue_manager.mark_initialized(queue_name)
        logger.info(f"[Queue] rebuilt: {queue_name}")
            
    async def rebuild_vas_task_queue(db: AsyncSession, queue_name: str):
        if queue_manager.is_initialized(queue_name):
            return
        
        queue = queue_manager.get_queue(queue_name)
        queue.clear()
        
        stmt = (
            select(VasTask)
            .where(
                VasTask.routing_key == queue_name,
                VasTask.status == 'pending'
            )
        )
        tasks = (await db.execute(stmt)).scalars().all()

        for task in tasks:
            queue_manager.put(
                queue_name=task.routing_key,
                task_id=task.id,
                priority=task.priority,
            )

        queue_manager.mark_initialized(queue_name)
        logger.info(f"[Queue] rebuilt: {queue_name}")
        
    async def pop_task(db: AsyncSession, queue_name: str):
        """
        从指定队列出队一个任务，并标记为 RUNNING
        """
        await QueueService.rebuild_task_queue(db, queue_name)
        task_id = queue_manager.pop(queue_name)
        if not task_id:
            raise NotFoundError(f'{queue_name} is empty')

        stmt = select(Task).where(Task.id == task_id)
        task = (await db.execute(stmt)).scalar_one_or_none()

        if task.status != 0:
            raise BizLogicError(f'task not READY, skipped')
        
        task.status = 1

        await db.commit()
        await db.refresh(task)

        return task
        
        
    async def pop_vas_task(db: AsyncSession, queue_name: str):
        """
        从指定队列出队一个任务，并标记为 RUNNING
        """
        await QueueService.rebuild_vas_task_queue(db, queue_name)
        task_id = queue_manager.pop(queue_name)
        if not task_id:
            raise NotFoundError(f'{queue_name} is empty')
        
        stmt = select(VasTask).where(VasTask.id == task_id)
        task = (await db.execute(stmt)).scalar_one_or_none()
        
        if task.status != "pending":
            raise BizLogicError(f'task not READY, skipped')
        
        task.status = "running"
        
        await db.commit()
        await db.refresh(task)

        return task
    
    
    async def dump_all():
        return queue_manager.dump_all()