# tasks.py
import requests
from datetime import datetime, date

from django.db import transaction, DatabaseError

from .models import Task, TaskDetail,CrawlQueue
from django.utils import timezone
import threading
import time
from celery import shared_task
from selenium_django.settings import CRAWL_API_URL


def safe_dict_get(d, key, default=None):
    """安全获取字典 key"""
    if isinstance(d, dict):
        return d.get(key, default)
    return default

@shared_task(bind=True, queue='crawler', max_retries=3, default_retry_delay=60)
def trigger_task_execution(self, task_id):
    """接收任务 → 入队等待处理"""
    try:
        task = Task.objects.get(id=task_id)
        # 标记为排队状态
        task.status = 'queued'
        task.save(update_fields=['status'])
        print(f"任务 {task_id} 状态更新为 queued")

        # 将任务存入 CrawlQueue
        CrawlQueue.objects.create(
            task=task,
            texts=task.description,
            parse_flag=task.parse_flag,
            limit=task.limit,
            sort_options=[],
            status="pending",
        )
        print(f"任务 {task_id} 已加入爬虫队列")

        # 立即触发队列处理任务
        process_crawl_queue.delay()

    except Task.DoesNotExist:
        print(f"Task {task_id} 不存在")
    except Exception as e:
        print(f"Task {task_id} 入队失败: {e}")
        raise self.retry(exc=e)

@shared_task(bind=True, queue='crawl_worker', max_retries=3, default_retry_delay=60)
def process_crawl_queue(self):
    """
    顺序执行队列任务，确保一个接着一个执行
    """
    item = None
    try:
        # 获取最早 pending 任务（加锁避免并发）
        with transaction.atomic():
            item = (
                CrawlQueue.objects
                .select_for_update(skip_locked=True)
                .filter(status='pending')
                .order_by('created_at')
                .first()
            )
            if not item:
                return "no task"

            # 标记队列和任务状态
            item.status = 'processing'
            item.save(update_fields=['status'])

            task = item.task
            task.status = 'running'
            task.save(update_fields=['status'])

        # 事务之外执行网络请求，减少锁表时间
        payload = {
            "texts": item.texts,
            "parse": item.parse_flag,
            "limit": item.limit,
            "sort": item.sort_options
        }
        print(f"开始请求爬虫 task_id={task.id}")
        resp = requests.post(CRAWL_API_URL, json=payload, timeout=300)
        resp.raise_for_status()
        try:
            data = resp.json()
        except ValueError:
            print(f"Task {task.id} 返回非 JSON 数据: {resp.text[:200]}")
            data = {}

        results = data.get("results", [])
        if not isinstance(results, list):
            results = []

        # 保存结果，事务保护
        with transaction.atomic():
            for idx, r in enumerate(results, start=1):
                TaskDetail.objects.get_or_create(
                    task=task,
                    original_link=r.get("originalLink") or "",
                    defaults={
                        "author": ";".join(r.get("author", [])) if isinstance(r.get("author"), list) else (r.get("author") or ""),
                        "date": str(r.get("date")) if r.get("date") else None,
                        "download": int(r.get("download") or 0),
                        "keywords": ";".join(r.get("keywords", [])) if isinstance(r.get("keywords"), list) else (r.get("keywords") or ""),
                        "pdf_url": r.get("pdfUrl") or "",
                        "parsed_summary": r.get("parsed_summary") or {},
                        "quote": r.get("quote") or "",
                        "site": r.get("site") or "",
                        "source": r.get("source") or "",
                        "summary": r.get("summary") or "",
                        "title": r.get("title") or "",
                    }
                )
                print(f"Task {task.id} 保存第 {idx} 条结果成功")

        # 标记完成
        with transaction.atomic():
            task.status = 'done'
            task.save(update_fields=['status'])
            item.status = 'done'
            item.save(update_fields=['status'])
            print(f"任务 {task.id} 执行完成")

    except requests.RequestException as e:
        print(f"网络请求失败 task_id={item.task.id if item else 'N/A'}: {e}")
        if item:
            with transaction.atomic():
                item.status = 'pending'
                item.save(update_fields=['status'])
        raise self.retry(exc=e)

    except DatabaseError as e:
        print(f"数据库异常 task_id={item.task.id if item else 'N/A'}: {e}")
        raise self.retry(exc=e)

    except Exception as e:
        print(f"任务执行失败 task_id={item.task.id if item else 'N/A'}: {e}")
        if item:
            with transaction.atomic():
                task.status = 'failed'
                task.save(update_fields=['status'])
                item.status = 'failed'
                item.save(update_fields=['status'])
        raise self.retry(exc=e)

    finally:
        # 触发下一个队列任务
        process_crawl_queue.apply_async(countdown=1)