from __future__ import annotations

import json
import logging
from datetime import date, datetime, time, timedelta
from typing import Any, Optional
from urllib.error import HTTPError, URLError
from urllib.parse import urlencode
from urllib.request import Request, urlopen

from app.core.config import Settings
from app.core.timezone import BEIJING_TZ, to_beijing_naive
from app.schemas.agent import SignalItem

logger = logging.getLogger(__name__)


class NewsSearchClient:
    """通过公开技术新闻检索接口采集动态AI新闻候选。"""

    endpoint = "https://hn.algolia.com/api/v1/search_by_date"

    def __init__(self, settings: Settings) -> None:
        self.settings = settings

    def collect_ai_news(self, run_date: date) -> list[SignalItem]:
        # HN Algolia按时间倒序返回技术新闻候选，模型后续只从这些证据里挑选日报条目。
        since = run_date - timedelta(days=self.settings.news_recent_days)
        stories: dict[str, dict[str, Any]] = {}
        for query in self._queries():
            payload = self._search(query=query, since=since, until=run_date)
            for story in payload.get("hits", []):
                url = self._story_url(story)
                object_id = story.get("objectID")
                key = str(object_id or url)
                if isinstance(url, str) and url.startswith("http"):
                    stories[key] = story

        candidates = [self._story_to_signal(story) for story in stories.values()]
        candidates = [candidate for candidate in candidates if candidate is not None]
        candidates.sort(key=lambda item: item.published_at or datetime.min, reverse=True)
        logger.info("news_candidates_collected days=%s items=%s", self.settings.news_recent_days, len(candidates))
        return candidates[: self.settings.news_max_items]

    def _queries(self) -> list[str]:
        # 查询词覆盖模型、Agent、开源AI和融资产品动态，避免单一关键词漏掉日报候选。
        return [
            "AI OR LLM OR agent",
            "large language model",
            "OpenAI Anthropic",
            "AI startup funding",
        ]

    def _search(self, query: str, since: date, until: date) -> dict[str, Any]:
        # search_by_date接口稳定返回最新故事，numericFilters把候选限制在本次日报窗口内。
        start_at = int(datetime.combine(since, time.min, tzinfo=BEIJING_TZ).timestamp())
        end_at = int(datetime.combine(until, time.max, tzinfo=BEIJING_TZ).timestamp())
        params = {
            "query": query,
            "tags": "story",
            "hitsPerPage": str(self.settings.news_search_max_records),
            "numericFilters": f"created_at_i>={start_at},created_at_i<={end_at}",
        }
        url = f"{self.endpoint}?{urlencode(params)}"
        request = Request(url, headers={"User-Agent": "SignalScout"})
        try:
            with urlopen(request, timeout=20) as response:
                body = response.read().decode("utf-8")
        except HTTPError as exc:
            message = exc.read().decode("utf-8", errors="replace")
            raise RuntimeError(f"News search failed: HTTP {exc.code} {message}") from exc
        except URLError as exc:
            raise RuntimeError(f"News search failed: {exc.reason}") from exc
        return json.loads(body)

    def _story_to_signal(self, story: dict[str, Any]) -> Optional[SignalItem]:
        # HN故事先保留标题、链接和互动指标，重要性与摘要由模型最终确定。
        title = story.get("title")
        url = self._story_url(story)
        if not isinstance(title, str) or not isinstance(url, str):
            return None
        author = str(story.get("author") or "unknown")
        points = int(story.get("points") or 0)
        comments = int(story.get("num_comments") or 0)
        published_at = self._parse_hn_date(story.get("created_at"))
        return SignalItem(
            source_type="news",
            topic="AI 新闻候选",
            title=title[:300],
            summary=f"Hacker News 最新技术讨论，作者 {author}，约 {points} points、{comments} 条评论。",
            source_url=url,
            source_name="Hacker News",
            published_at=published_at,
            importance=3,
            entities=["Hacker News", author],
        )

    def _story_url(self, story: dict[str, Any]) -> Optional[str]:
        # 外链优先；没有外链的Ask/Show HN故事使用HN讨论页作为证据链接。
        url = story.get("url") or story.get("story_url")
        if isinstance(url, str) and url.startswith("http"):
            return url
        object_id = story.get("objectID")
        if object_id:
            return f"https://news.ycombinator.com/item?id={object_id}"
        return None

    def _parse_hn_date(self, value: Any) -> Optional[datetime]:
        # HN Algolia返回UTC ISO时间，入库前先换算为北京时间。
        if not isinstance(value, str):
            return None
        try:
            return to_beijing_naive(datetime.fromisoformat(value.replace("Z", "+00:00")))
        except ValueError:
            return None