"""RSS feed service: fetch, parse with feedparser, and cache items to DB."""

import asyncio
import logging
from datetime import datetime, timezone

import feedparser
from sqlalchemy import select, text

from fabledassistant.models import async_session
from fabledassistant.models.rss_feed import RssFeed, RssItem

logger = logging.getLogger(__name__)

CONTENT_MAX_CHARS = 2000
# Keep only items from the last N days to avoid unbounded growth
ITEM_MAX_AGE_DAYS = 90


def extract_item(entry) -> dict:
    """Extract a clean item dict from a feedparser entry object."""
    # Prefer full content over summary (feedparser uses a list of Content objects)
    content = ""
    raw_content = getattr(entry, "content", None)
    if isinstance(raw_content, list) and raw_content:
        content = raw_content[0].value
    else:
        content = entry.get("summary", "")
    content = content[:CONTENT_MAX_CHARS]

    pub = None
    if entry.published_parsed:
        try:
            pub = datetime(*entry.published_parsed[:6], tzinfo=timezone.utc)
        except Exception:
            pass

    return {
        "guid": entry.get("id", entry.get("link", "")),
        "title": entry.get("title", ""),
        "url": entry.get("link", ""),
        "content": content,
        "published_at": pub,
    }


async def _parse_feed(url: str) -> feedparser.FeedParserDict:
    """Run feedparser in a thread executor so we don't block the event loop."""
    loop = asyncio.get_event_loop()
    return await loop.run_in_executor(None, feedparser.parse, url)


async def fetch_and_cache_feed(feed_id: int, url: str) -> int:
    """
    Fetch a feed URL, parse it, and upsert new items into rss_items.
    Returns the number of new items stored.
    """
    scheme = url.split("://")[0].lower() if "://" in url else ""
    if scheme not in ("http", "https"):
        logger.warning("Blocked RSS fetch with non-http(s) scheme: %s", url[:80])
        return 0
    try:
        parsed = await _parse_feed(url)
    except Exception:
        logger.warning("Failed to fetch RSS feed %s", url, exc_info=True)
        return 0

    if parsed.bozo and not parsed.entries:
        logger.warning("Malformed RSS feed %s: %s", url, parsed.bozo_exception)
        return 0

    new_count = 0
    feed_user_id: int | None = None

    async with async_session() as session:
        for entry in parsed.entries:
            item_data = extract_item(entry)
            if not item_data["guid"]:
                continue
            # Check if already stored
            existing = await session.execute(
                select(RssItem).where(
                    RssItem.feed_id == feed_id,
                    RssItem.guid == item_data["guid"],
                )
            )
            if existing.scalars().first() is not None:
                continue
            item = RssItem(
                feed_id=feed_id,
                **item_data,
            )
            session.add(item)
            new_count += 1

        # Update last_fetched_at on the feed
        feed_row = await session.get(RssFeed, feed_id)
        if feed_row:
            feed_row.last_fetched_at = datetime.now(timezone.utc)
            feed_user_id = feed_row.user_id
            # Auto-populate title from feed metadata if blank
            if not feed_row.title and parsed.feed.get("title"):
                feed_row.title = parsed.feed.title[:200]

        await session.commit()

        # Collect IDs of unclassified items after commit.
        # We query classified_at IS NULL (not just the items inserted above) because
        # classification is best-effort and may have failed on previous fetches.
        # Re-queuing all unclassified items for this feed on each fetch is intentional:
        # it provides automatic retry without a separate retry loop. The classifier
        # only writes to items it successfully classifies, so already-classified items
        # are not re-processed (they have classified_at set).
        unclassified_ids: list[int] = []
        if new_count > 0:
            result = await session.execute(
                select(RssItem.id).where(
                    RssItem.feed_id == feed_id,
                    RssItem.classified_at.is_(None),
                )
            )
            unclassified_ids = list(result.scalars().all())

    # Prune old items to keep DB tidy
    await _prune_old_items(feed_id)

    # Fire-and-forget classification for unclassified items
    if unclassified_ids and feed_user_id is not None:
        from fabledassistant.services.rss_classifier import classify_and_store
        asyncio.create_task(classify_and_store(unclassified_ids, feed_user_id))

    return new_count


async def _prune_old_items(feed_id: int) -> None:
    """Delete items older than ITEM_MAX_AGE_DAYS from a feed."""
    async with async_session() as session:
        await session.execute(
            text("""
                DELETE FROM rss_items
                WHERE feed_id = :feed_id
                  AND published_at < NOW() - INTERVAL '90 days'
            """).bindparams(feed_id=feed_id)
        )
        await session.commit()


async def get_recent_items(user_id: int, limit: int = 20) -> list[dict]:
    """Return the most recent RSS items across all of a user's feeds."""
    async with async_session() as session:
        result = await session.execute(
            select(RssItem, RssFeed.title.label("feed_title"))
            .join(RssFeed, RssItem.feed_id == RssFeed.id)
            .where(RssFeed.user_id == user_id)
            .order_by(RssItem.published_at.desc().nullslast())
            .limit(limit)
        )
        rows = result.all()

    return [
        {**item.to_dict(), "feed_title": feed_title}
        for item, feed_title in rows
    ]


async def refresh_all_feeds(user_id: int) -> dict[int, int]:
    """Fetch all feeds for a user. Returns {feed_id: new_items_count}."""
    async with async_session() as session:
        result = await session.execute(
            select(RssFeed).where(RssFeed.user_id == user_id)
        )
        feeds = list(result.scalars().all())

    results = {}
    for feed in feeds:
        count = await fetch_and_cache_feed(feed.id, feed.url)
        results[feed.id] = count
    return results