from __future__ import annotations

import asyncio
import hashlib
import logging
import sys
from collections import defaultdict
from datetime import datetime, timezone, timedelta
from typing import Any, Dict

from news_mcp.config import (
    DEFAULT_LOOKBACK_HOURS,
    DEFAULT_TOPICS,
    DB_PATH,
    ENRICH_OTHER_TOPICS_ONLY,
    ENRICHMENT_MAX_PER_REFRESH,
    NEWS_EXTRACT_PROVIDER,
    NEWS_FEED_URL,
    NEWS_FEED_URLS,
    NEWS_PRUNE_INTERVAL_HOURS,
    NEWS_PRUNING_ENABLED,
    NEWS_RETENTION_DAYS,
    NEWS_CLUSTER_MAX_AGE_HOURS,
    llm_concurrency,
)
from news_mcp.dedup.cluster import dedup_and_cluster_articles
from news_mcp.enrichment.enrich import enrich_cluster
from news_mcp.enrichment.llm_enrich import classify_cluster_llm
from news_mcp.sources.news_feeds import fetch_news_articles
from news_mcp.storage.sqlite_store import SQLiteClusterStore
from news_mcp.trends_resolution import resolve_entity_via_trends


def _load_feed_urls() -> list[str]:
    """Return the configured feed URLs from environment (unsorted)."""
    urls = [u.strip() for u in NEWS_FEED_URLS.split(",") if u.strip()]
    if not urls:
        urls = [NEWS_FEED_URL]
    return urls


MAX_ENRICHMENT_RETRIES = 3  # per-cluster retries before giving up for this cycle

async def _enrich_single_cluster(
    c: dict,
    topic: str,
    llm_enabled: bool,
    semaphore: asyncio.Semaphore,
    store: SQLiteClusterStore,
    logger: logging.Logger,
) -> dict:
    """Enrich one cluster: heuristic + optional LLM extraction, concurrency-limited.

    On LLM failure the cluster is retried up to MAX_ENRICHMENT_RETRIES times
    with exponential backoff.  If all retries are exhausted the cluster is
    marked with enrichment_failed_at and enrichment_retry_count so the next
    polling cycle can re-attempt it.
    """
    c2 = enrich_cluster(c)
    c2.setdefault("topic", topic)

    cluster_id = c2.get("cluster_id")
    if llm_enabled and cluster_id:
        # Cache: if we already have entities/sentiment for this cluster, skip LLM call.
        existing = store.get_cluster_by_id(cluster_id)
        if existing and existing.get("entities"):
            c2 = dict(c2)
            c2["entities"] = existing.get("entities", [])

            existing_resolutions = existing.get("entityResolutions", None)
            if isinstance(existing_resolutions, list) and existing_resolutions:
                c2["entityResolutions"] = existing_resolutions
            else:
                c2["entityResolutions"] = [resolve_entity_via_trends(e) for e in c2["entities"]]

            if existing.get("sentiment"):
                c2["sentiment"] = existing.get("sentiment")
            if existing.get("sentimentScore") is not None:
                c2["sentimentScore"] = existing.get("sentimentScore")
            if existing.get("keywords"):
                c2["keywords"] = existing.get("keywords")
            if existing.get("topic"):
                c2["topic"] = existing.get("topic")
        else:
            # Retry loop with exponential backoff | semaphore held per-attempt
            last_err = ""
            for attempt in range(1 + MAX_ENRICHMENT_RETRIES):
                if attempt > 0:
                    backoff = 2 ** attempt
                    logger.info(
                        "retry cluster=%s topic=%s attempt=%d/%d backoff=%.0fs",
                        cluster_id, topic, attempt, MAX_ENRICHMENT_RETRIES, backoff,
                    )
                    await asyncio.sleep(backoff)
                try:
                    async with semaphore:
                        c2 = await classify_cluster_llm(dict(c2))
                    break  # success
                except Exception:
                    last_err = str(sys.exc_info()[1])[:200] if sys.exc_info()[1] else "unknown"
                    logger.warning(
                        "LLM enrichment failed cluster=%s topic=%s attempt=%d/%d err=%s",
                        cluster_id, topic, attempt, MAX_ENRICHMENT_RETRIES, last_err,
                    )
            else:
                # Loop completed without break = all retries exhausted
                prev_count = c2.get("enrichment_retry_count", 0)
                c2["enrichment_failed_at"] = datetime.now(timezone.utc).isoformat()
                c2["enrichment_retry_count"] = prev_count + 1
                logger.error(
                    "LLM enrichment exhausted cluster=%s topic=%s after %d retries",
                    cluster_id, topic, MAX_ENRICHMENT_RETRIES,
                )

    return c2


async def _enrich_topic_clusters(
    clusters: list[dict],
    topic: str,
    semaphore: asyncio.Semaphore,
    store: SQLiteClusterStore,
    logger: logging.Logger,
    enrich_limit: int,
) -> list[dict]:
    """Enrich all clusters for a single topic concurrently."""
    llm_enabled = (not ENRICH_OTHER_TOPICS_ONLY) or (topic == "other")

    # Persist the raw clusters first so a slow enrichment pass does not
    # leave the first bootstrap run with nothing stored.
    store.upsert_clusters(clusters, topic=topic)
    logger.info("refresh stored raw topic=%s clusters=%s", topic, len(clusters))

    targets = clusters[:enrich_limit]
    tasks = [
        _enrich_single_cluster(c, topic, llm_enabled, semaphore, store, logger)
        for c in targets
    ]
    enriched = await asyncio.gather(*tasks, return_exceptions=False)

    # Any clusters beyond enrich_limit still need importance enrichment
    for c in clusters[enrich_limit:]:
        c2 = enrich_cluster(c)
        c2.setdefault("topic", topic)
        enriched.append(c2)

    logger.info("refresh enriched topic=%s clusters=%s", topic, len(enriched))
    return enriched


def _cluster_age_ok(cluster: dict, max_age_hours: float) -> bool:
    """Check whether a cluster's last_updated is within the merge window."""
    if max_age_hours <= 0:
        return True
    ts_str = cluster.get("last_updated") or cluster.get("timestamp") or ""
    if not ts_str:
        return True
    try:
        s = str(ts_str).replace("Z", "+00:00")
        dt = datetime.fromisoformat(s)
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=timezone.utc)
        dt = dt.astimezone(timezone.utc)
    except Exception:
        try:
            from email.utils import parsedate_to_datetime
            dt = parsedate_to_datetime(str(ts_str))
            if dt.tzinfo is None:
                dt = dt.replace(tzinfo=timezone.utc)
            dt = dt.astimezone(timezone.utc)
        except Exception:
            return True
    cutoff = datetime.now(timezone.utc) - timedelta(hours=max_age_hours)
    return dt >= cutoff


async def refresh_clusters(topic: str | None = None, limit: int = 80) -> None:
    logger = logging.getLogger("news_mcp.refresh")
    store = SQLiteClusterStore(DB_PATH)

    logger.info("refresh start topic=%s limit=%s", topic, limit)

    # Get enabled feed URLs from store (seeds new ones as enabled by default).
    configured_urls = _load_feed_urls()
    enabled_urls = store.get_enabled_feed_urls(configured_urls)
    logger.info("refresh enabled feeds=%d / configured=%d", len(enabled_urls), len(configured_urls))

    # fetch_news_articles is now fully async (concurrent RSS fetching)
    articles = await fetch_news_articles(limit, url_list=enabled_urls)
    logger.info("refresh fetched articles=%s", len(articles))

    # Drop legacy aggregate feed-state rows so the dashboard only reflects
    # real per-feed poll status from this point forward.
    with store._conn() as conn:
        conn.execute("DELETE FROM feed_state WHERE feed_key LIKE 'newsfeeds:%'")

    # Track feed freshness per RSS URL so unchanged feeds can be skipped.
    per_feed: dict[str, list[dict[str, Any]]] = defaultdict(list)
    for article in articles:
        feed_url = str(article.get("feed_url") or NEWS_FEED_URL).strip() or NEWS_FEED_URL
        per_feed[feed_url].append(article)

    changed_articles: list[dict[str, Any]] = []
    changed_feed_urls: list[str] = []
    for feed_url, feed_articles in per_feed.items():
        logger.info("refresh feed batch start feed_url=%s count=%s", feed_url, len(feed_articles))
        material = "\n".join(
            f"{a.get('title','')}|{a.get('url','')}|{a.get('timestamp','')}"
            for a in feed_articles
        )
        last_hash = hashlib.sha1(material.encode("utf-8")).hexdigest()
        feed_key = feed_url
        prev_hash = store.get_feed_hash(feed_key)
        if prev_hash == last_hash:
            logger.info("refresh unchanged feed_url=%s count=%s topic=%s", feed_url, len(feed_articles), topic)
        else:
            logger.info("refresh changed feed_url=%s count=%s topic=%s", feed_url, len(feed_articles), topic)
            changed_feed_urls.append(feed_url)
            changed_articles.extend(feed_articles)
        logger.info("refresh feed batch complete feed_url=%s changed_total=%s", feed_url, len(changed_articles))

    if not changed_articles:
        logger.info("refresh unchanged all feeds topic=%s", topic)
        store.set_meta("last_refresh_at", datetime.now(timezone.utc).isoformat())
        prune_result = store.prune_if_due(
            pruning_enabled=NEWS_PRUNING_ENABLED,
            retention_days=NEWS_RETENTION_DAYS,
            interval_hours=NEWS_PRUNE_INTERVAL_HOURS,
        )
        logger.info("refresh prune_result=%s", prune_result)
        return

    articles = changed_articles
    logger.info("refresh clustering start articles=%s topic=%s", len(articles), topic)

    # Pre-seed with recent clusters from the DB so new articles can merge
    # into existing clusters across polling cycles.
    max_age = NEWS_CLUSTER_MAX_AGE_HOURS
    recent_clusters: list[dict] = []
    if max_age != 0:
        lookback = max_age if max_age > 0 else 72
        all_recent = store.get_latest_clusters_all_topics(
            ttl_hours=lookback,
            limit=500,
        )
        recent_clusters = [c for c in all_recent if _cluster_age_ok(c, max_age)]
        logger.info(
            "refresh pre-seeded existing_clusters=%s max_age_h=%s",
            len(recent_clusters), max_age,
        )

    # Clustering is sync but may do concurrent embedding fetches internally.
    # Run off-thread so the event loop stays responsive for MCP tool calls.
    clustered_by_topic = await asyncio.to_thread(
        dedup_and_cluster_articles,
        articles,
        None,  # use default similarity_threshold
        existing_clusters=recent_clusters if recent_clusters else None,
        max_age_hours=max_age,
    )
    logger.info("refresh clustered topics=%s", list(clustered_by_topic.keys()))

    # Build LLM concurrency semaphore from the extract provider's config.
    max_llm_concurrent = llm_concurrency(NEWS_EXTRACT_PROVIDER)
    llm_semaphore = asyncio.Semaphore(max_llm_concurrent)
    logger.info("refresh llm semaphore limit=%s provider=%s", max_llm_concurrent, NEWS_EXTRACT_PROVIDER)

    # Enrich each topic's clusters concurrently.
    topic_tasks = []
    for t, clusters in clustered_by_topic.items():
        if topic and t != topic:
            continue

        # Determine how many clusters to LLM-enrich.
        # ENRICHMENT_MAX_PER_REFRESH=0 means enrich every cluster (no cap).
        enrich_limit = ENRICHMENT_MAX_PER_REFRESH or len(clusters)

        topic_tasks.append(
            _enrich_topic_clusters(
                clusters=clusters,
                topic=t,
                semaphore=llm_semaphore,
                store=store,
                logger=logger,
                enrich_limit=enrich_limit,
            )
        )

    # Run all topic enrichment phases concurrently
    topic_results = await asyncio.gather(*topic_tasks, return_exceptions=False)

    # Persist enriched clusters grouped by their final topic
    for enriched in topic_results:
        by_final_topic: Dict[str, list] = {}
        for c2 in enriched:
            final_topic = str(c2.get("topic") or "other").strip().lower()
            if final_topic not in {x.lower() for x in DEFAULT_TOPICS}:
                final_topic = "other"
            by_final_topic.setdefault(final_topic, []).append(c2)
        for final_topic, group in by_final_topic.items():
            store.upsert_clusters(group, topic=final_topic)
            logger.info("refresh stored topic=%s clusters=%s", final_topic, len(group))

    # Retry previously failed enrichments
    failed_clusters = store.get_failed_enrichment_clusters(max_retries=3)
    if failed_clusters:
        logger.info("retry enrich failed clusters count=%d", len(failed_clusters))
        retry_tasks = [
            _enrich_single_cluster(
                c, str(c.get("topic") or "other"), True, llm_semaphore, store, logger
            )
            for c in failed_clusters
        ]
        retry_results = await asyncio.gather(*retry_tasks, return_exceptions=False)
        # Persist retried results
        by_topic_retry: Dict[str, list] = {}
        for c2 in retry_results:
            # Clear stale failure marker on success
            if not c2.get("enrichment_failed_at") or c2.get("entities"):
                c2.pop("enrichment_failed_at", None)
                c2.pop("enrichment_retry_count", None)
            t = str(c2.get("topic") or "other").strip().lower()
            if t not in {x.lower() for x in DEFAULT_TOPICS}:
                t = "other"
            by_topic_retry.setdefault(t, []).append(c2)
        for t, group in by_topic_retry.items():
            store.upsert_clusters(group, topic=t)
            logger.info("retry stored topic=%s clusters=%s", t, len(group))

    prune_result = store.prune_if_due(
        pruning_enabled=NEWS_PRUNING_ENABLED,
        retention_days=NEWS_RETENTION_DAYS,
        interval_hours=NEWS_PRUNE_INTERVAL_HOURS,
    )
    for feed_url in changed_feed_urls:
        feed_articles = per_feed[feed_url]
        material = "\n".join(
            f"{a.get('title','')}|{a.get('url','')}|{a.get('timestamp','')}"
            for a in feed_articles
        )
        last_hash = hashlib.sha1(material.encode("utf-8")).hexdigest()
        store.set_feed_state(feed_url, last_hash, len(feed_articles))
    store.set_meta("last_refresh_at", datetime.now(timezone.utc).isoformat())
    logger.info("refresh prune_result=%s", prune_result)