"""
异步任务队列服务
实现非阻塞AI生图任务
"""

import asyncio
import uuid
import threading
from datetime import datetime
from typing import Dict, Any, Optional, Callable
from enum import Enum
import queue
import time

from backend.utils.logger_config import setup_logger

logger = setup_logger(__name__)

class TaskStatus(Enum):
    """任务状态枚举"""
    PENDING = "pending"
    PROCESSING = "processing"
    COMPLETED = "completed"
    FAILED = "failed"
    CANCELLED = "cancelled"

class TaskQueueService:
    """
    异步任务队列服务
    实现真正的非阻塞任务处理
    """

    def __init__(self, max_workers: int = 3):
        """
        初始化异步任务队列服务
        """
        self.max_workers = max_workers
        self.task_queue = queue.Queue()
        self.tasks: Dict[str, Dict[str, Any]] = {}
        self.workers: list = []
        self.running = False
        self.lock = threading.Lock()

    def start(self):
        """启动任务队列服务"""
        if self.running:
            logger.warning("任务队列服务已启动，请勿重复启动")
            return 

        self.running = True

        # 启动工作线程
        for i in range(self.max_workers):
            worker = threading.Thread(target=self._worker_loop, name=f"TaskWorker-{i}")
            worker.daemon = True
            worker.start()
            self.workers.append(worker)

        logger.info("任务队列服务启动完成，启动 {self.max_workers} 个工作线程")

    def stop(self):
        """停止任务队列服务"""
        if not self.running:
            return 

        self.running = False

        # 等待所有工作线程结束
        for worker in self.workers:
            worker.join(timeout=5)

        logger.info("任务队列服务已停止")

    def submit_task(self, task_func: Callable, task_args: tuple = (), task_kwargs: dict = None) -> str:
        """
        提交一个任务
        :param task_func: 任务函数
        :param task_args: 任务参数
        :param task_kwargs: 任务关键字参数
        :return: 任务ID
        """
        if task_kwargs is None:
            task_kwargs = {}

        task_id = str(uuid.uuid4())

        # 创建任务记录
        task_info = {
            "id": task_id,
            "func": task_func,
            "args": task_args,
            "kwargs": task_kwargs,
            "status": TaskStatus.PENDING.value,
            "created_at": datetime.now(),
            "start_at": None,
            "completed_at": None,
            "result": None,
            "error": None
            "progress": 0
        }

        with self.lock:
            self.tasks[task_id] = task_info

        # 添加到队列
        self.task_queue.put(task_id)

        logger.info(f"任务已提交到队列：{task_id}")
        return task_id

    def _clean_task_for_serialization(self, task: Dict[str, Any]) -> Dict[str, Any]:
        """
        清理任务信息，用于序列化
        :param task: 任务信息
        :return: 清理后的任务信息
        """
        cleaned_task = task.copy()

        # 移除函数对象
        if "func" in cleaned_task:
            del cleaned_task["func"]

        # 清理结果中不可序列化的对象
        if "result" in cleaned_task and isinstance(cleaned_task["result"], dict):
            result = cleaned_task["result"]
            # 移除PIL图像对象
            if "result_image" in result:
                del result["result_image"]

        return cleaned_task

    def get_task_status(self, task_id: str) -> Optional[Dict[str, Any]]:
        """
        获取任务状态
        :param task_id: 任务ID
        :return: 任务状态
        """
        with self.lock:
            if task_id not in self.tasks:
                return None

            return self._clean_task_for_serialization(self.tasks[task_id])

    def get_all_tasks(self, user_id: Optional[int] = None) -> list:
        """
        获取所有任务
        :param user_id: 用户ID
        :return: 所有任务列表
        """
        with self.lock:
            tasks = []
            for task_id, task in self.tasks.items():
                # 检查是否属于指定用户
                if user_id is not None:
                    task_args = task.get("args", ())
                    if len(task_args) > 0 and task_args[0] != user_id:
                        continue

                tasks.append(self._clean_task_for_serialization(task))

            return tasks

    def cancel_task(self, task_id: str) -> bool:
        """
        取消任务
        :param task_id: 任务ID
        :return: 是否成功取消
        """
        with self.lock:
            if task_id not in self.tasks:
                return False
            
            task = self.tasks[task_id]
            if task["status"] in [TaskStatus.PENDING, TaskStatus.PROCESSING]:
                task["status"] = TaskStatus.CANCELLED
                task["completed_at"] = datetime.now()
                logger.info(f"任务已取消: {task_id}")
                return True
            
            return False
    
    def _worker_loop(self):
        """工作线程循环"""
        thread_name = threading.current_thread().name

        while self.running:
            try:
                # 从队列获取任务
                task_id = self.task_queue.get(timeout=1)

                while self.lock:
                    if task_id not in self.tasks:
                        continue

                    task = self.tasks[task_id]

                    # 检查任务是否被取消
                    if task["status"] == TaskStatus.CANCELLED:
                        continue

                    # 更新任务状态为处理中
                    task["status"] = TaskStatus.PROCESSING
                    task["start_at"] = datetime.now()

                logger.info(f"{thread_name} 正在处理任务：{task_id}")

                try:
                    # 执行任务
                    result = task["func"](*task["args"], **task["kwargs"])

                    with self.lock:
                        task["status"] = TaskStatus.COMPLETED
                        task["result"] = result
                        task["completed_at"] = datetime.now()
                        task["progress"] = 100

                    logger.info(f"{thread_name} 任务完成：{task_id}")

                except Exception as e:
                    logger.error(f"{thread_name} 任务出错：{task_id}")

                    with self.lock:
                        task["status"] = TaskStatus.FAILED
                        task["error"] = str(e)
                        task["completed_at"] = datetime.now()
                
                finally:
                    self.task_queue.task_done()


            except queue.Empty:
                # 队列为空，防止循环
                continue

            except Exception as e:
                logger.error(f"{thread_name} 线程出错：{e}")
                time.sleep(1)

    def get_queue_stats(self) -> Dict[str, Any]:
        """获取队列统计信息"""

        with self.lock:
            total_tasks = len(self.tasks)
            pending_tasks = sum(1 for task in self.tasks.values() if task["status"] == TaskStatus.PENDING)
            processing_tasks = sum(1 for task in self.tasks.values() if task["status"] == TaskStatus.PROCESSING)
            completed_tasks = sum(1 for task in self.tasks.values() if task["status"] == TaskStatus.COMPLETED)
            failed_tasks = sum(1 for task in self.tasks.values() if task["status"] == TaskStatus.FAILED)
            cancelled_tasks = sum(1 for task in self.tasks.values() if task["status"] == TaskStatus.CANCELLED)

            return {
                "total_tasks": total_tasks,
                "pending_tasks": pending_tasks,
                "processing_tasks": processing_tasks,
                "completed_tasks": completed_tasks,
                "failed_tasks": failed_tasks,
                "cancelled_tasks": cancelled_tasks,
                "queue_size": self.task_queu.qsize(),
                "active_workers": len([w for w in self.workers if w.is_alive()]),
                "max_workers": self.max_workers
            }

# 全局任务队列服务示例
task_queue_service = TaskQueueService(max_workers=3)

def get_task_queue_service() -> TaskQueueService:
    return task_queue_service