"""Feed fetching worker — RQ tasks and scheduling loop."""

import logging
import re
import time
from datetime import datetime, timezone

import feedparser
import httpx
from dateutil import parser as dateparser
from redis import Redis
from rq import Queue
from sqlalchemy import create_engine, select
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.orm import Session, sessionmaker

from app.config import DATABASE_URL_SYNC, FEED_FETCH_INTERVAL, REDIS_URL
from app.models import Category, Entry, Feed

log = logging.getLogger(__name__)

# ── Sync DB engine (for RQ worker) ──
_engine = create_engine(DATABASE_URL_SYNC, echo=False, pool_size=5, max_overflow=3)
SyncSession = sessionmaker(_engine, class_=Session, expire_on_commit=False)

# ── RQ queue ──
_redis = Redis.from_url(REDIS_URL)
queue = Queue("reader", connection=_redis)

# HTML tag stripper
_html_re = re.compile(r"<[^>]+>")


def _strip_html(text: str) -> str:
    """Remove HTML tags for word counting."""
    if not text:
        return ""
    return _html_re.sub("", text)


def _calc_reading_time(html_content: str) -> int:
    """Estimate reading time in minutes from HTML content."""
    plain = _strip_html(html_content)
    word_count = len(plain.split())
    return max(1, word_count // 200)


def _parse_date(entry: dict) -> datetime | None:
    """Parse published date from a feedparser entry."""
    for field in ("published", "updated", "created"):
        val = entry.get(field)
        if val:
            try:
                return dateparser.parse(val)
            except (ValueError, TypeError):
                continue
    # Try struct_time fields
    for field in ("published_parsed", "updated_parsed", "created_parsed"):
        val = entry.get(field)
        if val:
            try:
                return datetime(*val[:6], tzinfo=timezone.utc)
            except (ValueError, TypeError):
                continue
    return None


def _get_entry_content(entry: dict) -> str:
    """Extract the best content from a feedparser entry."""
    # Prefer content field (often full HTML)
    if entry.get("content"):
        return entry["content"][0].get("value", "")
    # Fall back to summary
    if entry.get("summary"):
        return entry["summary"]
    # Fall back to description
    if entry.get("description"):
        return entry["description"]
    return ""


def _get_entry_author(entry: dict) -> str | None:
    """Extract author from a feedparser entry."""
    if entry.get("author"):
        return entry["author"]
    if entry.get("author_detail", {}).get("name"):
        return entry["author_detail"]["name"]
    return None


def _ensure_uncategorized(db: Session, user_id: str) -> int:
    """Ensure an 'Uncategorized' category exists for the user, return its ID."""
    row = db.execute(
        select(Category).where(
            Category.user_id == user_id,
            Category.title == "Uncategorized",
        )
    ).scalar_one_or_none()
    if row:
        return row.id
    cat = Category(user_id=user_id, title="Uncategorized")
    db.add(cat)
    db.flush()
    return cat.id


def fetch_single_feed(feed_id: int):
    """Fetch and parse a single feed, inserting new entries."""
    with SyncSession() as db:
        feed = db.execute(select(Feed).where(Feed.id == feed_id)).scalar_one_or_none()
        if not feed:
            log.warning("Feed %d not found, skipping", feed_id)
            return

        log.info("Fetching feed %d: %s", feed.id, feed.feed_url)

        headers = {"User-Agent": "Reader/1.0"}
        if feed.etag:
            headers["If-None-Match"] = feed.etag
        if feed.last_modified:
            headers["If-Modified-Since"] = feed.last_modified

        try:
            resp = httpx.get(feed.feed_url, headers=headers, timeout=30, follow_redirects=True)
        except httpx.HTTPError as e:
            log.error("HTTP error fetching feed %d: %s", feed.id, e)
            return

        # 304 Not Modified
        if resp.status_code == 304:
            log.debug("Feed %d not modified", feed.id)
            feed.last_fetched_at = datetime.utcnow()
            db.commit()
            return

        if resp.status_code != 200:
            log.warning("Feed %d returned status %d", feed.id, resp.status_code)
            return

        # Update etag/last-modified
        feed.etag = resp.headers.get("ETag")
        feed.last_modified = resp.headers.get("Last-Modified")
        feed.last_fetched_at = datetime.utcnow()

        parsed = feedparser.parse(resp.text)
        if not parsed.entries:
            log.debug("Feed %d has no entries", feed.id)
            db.commit()
            return

        new_count = 0
        new_entry_ids = []
        for fe in parsed.entries:
            url = fe.get("link")
            if not url:
                continue

            content = _get_entry_content(fe)
            pub_date = _parse_date(fe)

            stmt = pg_insert(Entry).values(
                feed_id=feed.id,
                user_id=feed.user_id,
                title=fe.get("title", "")[:1000] if fe.get("title") else None,
                url=url,
                content=content,
                author=_get_entry_author(fe),
                published_at=pub_date,
                status="unread",
                starred=False,
                reading_time=_calc_reading_time(content),
            ).on_conflict_do_nothing(
                constraint="uq_reader_entries_feed_url"
            ).returning(Entry.id)
            result = db.execute(stmt)
            row = result.fetchone()
            if row:
                new_entry_ids.append(row[0])
                new_count += 1

        db.commit()
        log.info("Feed %d: %d new entries from %d total", feed.id, new_count, len(parsed.entries))

        # Fetch full content for new entries
        if new_entry_ids:
            _fetch_full_content_for_entries(db, new_entry_ids)


def _fetch_full_content_for_entries(db, entry_ids: list[int]):
    """Fetch full article content for specific entries."""
    from app.config import CRAWLER_URL

    entries = db.execute(
        select(Entry).where(Entry.id.in_(entry_ids))
    ).scalars().all()

    log.info("Fetching full content for %d new entries", len(entries))
    for entry in entries:
        if not entry.url:
            continue
        try:
            resp = httpx.post(
                f"{CRAWLER_URL}/crawl",
                json={"url": entry.url},
                timeout=45,
            )
            if resp.status_code == 200:
                data = resp.json()
                readable = data.get("readable_html", "")
                full_text = data.get("text", "")
                if readable:
                    entry.full_content = readable
                    if full_text:
                        entry.reading_time = max(1, len(full_text.split()) // 200)
                elif full_text and len(full_text) > len(_strip_html(entry.content or "")):
                    paragraphs = [p.strip() for p in full_text.split("\n\n") if p.strip()]
                    if not paragraphs:
                        paragraphs = [p.strip() for p in full_text.split("\n") if p.strip()]
                    entry.full_content = "\n".join(f"<p>{p}</p>" for p in paragraphs)
                    entry.reading_time = max(1, len(full_text.split()) // 200)
                else:
                    entry.full_content = entry.content or ""
            else:
                entry.full_content = entry.content or ""
        except Exception as e:
            log.warning("Full content fetch failed for entry %d: %s", entry.id, e)
            entry.full_content = entry.content or ""

    db.commit()
    log.info("Full content done for %d entries", len(entries))


def fetch_full_content_batch():
    """Fetch full article content for entries that only have RSS summaries."""
    from app.config import CRAWLER_URL

    with SyncSession() as db:
        # Find entries with short content and no full_content (limit batch size)
        entries = db.execute(
            select(Entry).where(
                Entry.full_content.is_(None),
                Entry.url.isnot(None),
                Entry.status == "unread",
            ).order_by(Entry.published_at.desc()).limit(20)
        ).scalars().all()

        if not entries:
            return

        log.info("Fetching full content for %d entries", len(entries))
        for entry in entries:
            try:
                resp = httpx.post(
                    f"{CRAWLER_URL}/crawl",
                    json={"url": entry.url},
                    timeout=45,
                )
                if resp.status_code == 200:
                    data = resp.json()
                    readable = data.get("readable_html", "")
                    full_text = data.get("text", "")
                    if readable:
                        entry.full_content = readable
                        if full_text:
                            entry.reading_time = max(1, len(full_text.split()) // 200)
                    elif full_text and len(full_text) > len(_strip_html(entry.content or "")):
                        paragraphs = [p.strip() for p in full_text.split("\n\n") if p.strip()]
                        if not paragraphs:
                            paragraphs = [p.strip() for p in full_text.split("\n") if p.strip()]
                        entry.full_content = "\n".join(f"<p>{p}</p>" for p in paragraphs)
                        entry.reading_time = max(1, len(full_text.split()) // 200)
                    else:
                        entry.full_content = entry.content or ""
                else:
                    entry.full_content = entry.content or ""
            except Exception as e:
                log.warning("Full content fetch failed for entry %d: %s", entry.id, e)
                entry.full_content = entry.content or ""

        db.commit()
        log.info("Full content fetched for %d entries", len(entries))


def fetch_all_feeds():
    """Fetch all feeds — called on schedule."""
    with SyncSession() as db:
        feeds = db.execute(select(Feed)).scalars().all()

    log.info("Scheduling fetch for %d feeds", len(feeds))
    for feed in feeds:
        try:
            fetch_single_feed(feed.id)
        except Exception:
            log.exception("Error fetching feed %d", feed.id)

    # Full content is now fetched inline for each new entry


def cleanup_old_entries():
    """Delete old entries: read > 30 days, unread > 60 days."""
    from sqlalchemy import delete as sa_delete

    with SyncSession() as db:
        now = datetime.utcnow()
        thirty_days = now - __import__('datetime').timedelta(days=30)
        sixty_days = now - __import__('datetime').timedelta(days=60)

        # Read entries older than 30 days
        result1 = db.execute(
            sa_delete(Entry).where(
                Entry.status == "read",
                Entry.created_at < thirty_days,
            )
        )

        # Unread entries older than 60 days
        result2 = db.execute(
            sa_delete(Entry).where(
                Entry.status == "unread",
                Entry.created_at < sixty_days,
            )
        )

        db.commit()
        total = (result1.rowcount or 0) + (result2.rowcount or 0)
        if total > 0:
            log.info("Cleanup: deleted %d old entries (%d read, %d unread)",
                     total, result1.rowcount or 0, result2.rowcount or 0)


def run_scheduler():
    """Simple loop that runs fetch_all_feeds every FEED_FETCH_INTERVAL seconds."""
    log.info("Reader scheduler started — interval: %ds", FEED_FETCH_INTERVAL)

    # Create tables on first run (for the sync engine)
    from app.database import Base
    from app.models import Category, Feed, Entry  # noqa: register models
    Base.metadata.create_all(_engine)

    cycles = 0
    while True:
        try:
            fetch_all_feeds()
        except Exception:
            log.exception("Scheduler error in fetch_all_feeds")

        # Run cleanup once per day (every ~144 cycles at 10min interval)
        cycles += 1
        if cycles % 144 == 0:
            try:
                cleanup_old_entries()
            except Exception:
                log.exception("Scheduler error in cleanup")

        time.sleep(FEED_FETCH_INTERVAL)


if __name__ == "__main__":
    logging.basicConfig(
        level=logging.INFO,
        format="%(asctime)s %(levelname)s %(name)s: %(message)s",
    )
    run_scheduler()