"""回忆录后台任务聚合：debounce 后派发 process_memoir_segments（feature 层）。"""

from __future__ import annotations

from typing import Dict, List

from app.core.logging import get_logger
from app.core.task_tracker import task_tracker

logger = get_logger(__name__)


class BackgroundTaskRunner:
    def __init__(self, debounce_seconds: int = 5) -> None:
        self.debounce_seconds = debounce_seconds
        self._pending: Dict[str, List[str]] = {}
        self._timers: Dict[str, object] = {}

    async def _submit_task(self, user_id: str, segment_ids: List[str]) -> str | None:
        try:
            from app.tasks.memoir_tasks import process_memoir_segments

            result = process_memoir_segments.delay(user_id, segment_ids)
            task_id = result.id
            await task_tracker.add_task(user_id, task_id, "memoir")
            logger.info(
                "已提交 Celery 任务: user_id=%s, task_id=%s, segments=%s",
                user_id,
                task_id,
                len(segment_ids),
            )
            return task_id
        except Exception as e:
            logger.error("提交 Celery 任务失败: %s", e)
            return None

    async def queue_message(self, user_id: str, segment_id: str) -> None:
        import asyncio

        self._pending.setdefault(user_id, []).append(segment_id)
        if user_id in self._timers:
            self._timers[user_id].cancel()

        async def delayed_submit():
            try:
                await asyncio.sleep(self.debounce_seconds)
                segment_ids = self._pending.pop(user_id, [])
                if segment_ids:
                    await self._submit_task(user_id, segment_ids)
            except asyncio.CancelledError:
                pass
            except Exception as e:
                logger.error("延迟提交任务失败: %s", e)

        self._timers[user_id] = asyncio.create_task(delayed_submit())

    async def flush_pending(self, user_id: str) -> str | None:
        if user_id in self._timers:
            self._timers[user_id].cancel()
            del self._timers[user_id]
        segment_ids = self._pending.pop(user_id, [])
        if segment_ids:
            return await self._submit_task(user_id, segment_ids)
        return None