from __future__ import annotations

import asyncio
import logging
from collections import Counter
from datetime import datetime, timezone
from email.utils import parsedate_to_datetime

from fastapi import FastAPI
from mcp.server.fastmcp import FastMCP
from mcp.server.transport_security import TransportSecuritySettings

from news_mcp.config import DEFAULT_LOOKBACK_HOURS, DEFAULT_TOPICS, DB_PATH
from news_mcp.config import (
    NEWS_PRUNE_INTERVAL_HOURS,
    NEWS_PRUNING_ENABLED,
    NEWS_REFRESH_INTERVAL_SECONDS,
    NEWS_BACKGROUND_REFRESH_ENABLED,
    NEWS_BACKGROUND_REFRESH_ON_START,
    NEWS_RETENTION_DAYS,
)
from news_mcp.jobs.poller import refresh_clusters
from news_mcp.storage.sqlite_store import SQLiteClusterStore
from news_mcp.enrichment.llm_enrich import summarize_cluster_llm
from news_mcp.trends_resolution import resolve_entity_via_trends
from news_mcp.llm import active_llm_config
from news_mcp.entity_normalize import normalize_query


mcp = FastMCP(
    "news-mcp",
    transport_security=TransportSecuritySettings(enable_dns_rebinding_protection=False),
)


def _cluster_entity_haystack(cluster: dict) -> list[str]:
    """Collect the normalized entity clues attached to a cluster."""
    values: list[str] = []
    for ent in cluster.get("entities", []) or []:
        values.append(str(ent).strip().lower())
    for res in cluster.get("entityResolutions", []) or []:
        if not isinstance(res, dict):
            continue
        for key in ("normalized", "canonical_label", "mid"):
            val = res.get(key)
            if val:
                values.append(str(val).strip().lower())
    return [v for v in values if v]


def _parse_cluster_timestamp(value) -> datetime:
    if not value:
        return datetime.min.replace(tzinfo=timezone.utc)
    text = str(value).strip()
    if not text:
        return datetime.min.replace(tzinfo=timezone.utc)
    try:
        dt = datetime.fromisoformat(text.replace("Z", "+00:00"))
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=timezone.utc)
        return dt.astimezone(timezone.utc)
    except Exception:
        pass
    try:
        dt = parsedate_to_datetime(text)
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=timezone.utc)
        return dt.astimezone(timezone.utc)
    except Exception:
        return datetime.min.replace(tzinfo=timezone.utc)


def _sort_clusters_by_recency(clusters: list[dict]) -> list[dict]:
    return sorted(
        clusters,
        key=lambda c: (
            _parse_cluster_timestamp(c.get("timestamp")),
            float(c.get("importance", 0.0) or 0.0),
        ),
        reverse=True,
    )


@mcp.tool(description="Investigate a topic and return the newest deduplicated news clusters, sorted by recency.")
async def get_latest_events(topic: str = "crypto", limit: int = 5, include_articles: bool = False):
    limit = max(1, min(int(limit), 20))
    # If the caller passes an entity-like value, resolve it and use the canonical
    # entity as the query lens. Otherwise keep the original topic path.
    topic_norm = normalize_query(topic).lower()
    resolved = resolve_entity_via_trends(topic_norm)
    allowed = {t.lower() for t in DEFAULT_TOPICS}
    is_topic = topic_norm in allowed
    query_terms = {
        topic_norm,
        str(resolved.get("normalized") or "").strip().lower(),
        str(resolved.get("canonical_label") or "").strip().lower(),
        str(resolved.get("mid") or "").strip().lower(),
    }
    query_terms = {q for q in query_terms if q}

    store = SQLiteClusterStore(DB_PATH)

    if is_topic:
        # Cache-first: only refresh if we currently have no fresh clusters for this topic.
        clusters = store.get_latest_clusters(topic=topic_norm, ttl_hours=DEFAULT_LOOKBACK_HOURS, limit=limit)
        if not clusters:
            await refresh_clusters(topic=topic_norm, limit=200)
            clusters = store.get_latest_clusters(topic=topic_norm, ttl_hours=DEFAULT_LOOKBACK_HOURS, limit=limit)
    else:
        # Entity-aware mode: search recent clusters across all topics and match by
        # raw entity, canonical label, or MID.
        clusters = store.get_latest_clusters_all_topics(ttl_hours=DEFAULT_LOOKBACK_HOURS, limit=limit * 8)
        filtered = []
        for c in clusters:
            haystack = _cluster_entity_haystack(c)
            if any(any(term in item for item in haystack) for term in query_terms):
                filtered.append(c)
            if len(filtered) >= limit:
                break
        clusters = filtered

    out = []
    for c in _sort_clusters_by_recency(clusters):
        item = {
            "cluster_id": c.get("cluster_id"),
            "headline": c.get("headline"),
            "summary": c.get("summary"),
            "entities": c.get("entities", []),
            "sentiment": c.get("sentiment", "neutral"),
            "importance": c.get("importance", 0.0),
            "sources": c.get("sources", []),
            "timestamp": c.get("timestamp"),
        }
        if include_articles:
            # Return minimal article fields to keep responses compact.
            arts = c.get("articles", []) or []
            item["articles"] = [
                {
                    "title": a.get("title"),
                    "url": a.get("url"),
                    "source": a.get("source"),
                    "timestamp": a.get("timestamp"),
                }
                for a in arts
                if isinstance(a, dict)
            ]
        out.append(item)

    return out


@mcp.tool(description="Investigate a person, company, place, or theme by matching extracted entities within a time window.")
async def get_events_for_entity(entity: str, limit: int = 10, timeframe: str = "24h", include_articles: bool = False):
    limit = max(1, min(int(limit), 30))
    query = normalize_query(entity).strip().lower()
    if not query:
        return []

    resolved = resolve_entity_via_trends(query)
    query_terms = {
        query,
        str(resolved.get("normalized") or "").strip().lower(),
        str(resolved.get("canonical_label") or "").strip().lower(),
        str(resolved.get("mid") or "").strip().lower(),
    }
    query_terms = {q for q in query_terms if q}

    store = SQLiteClusterStore(DB_PATH)

    def _match_clusters(clusters: list[dict]) -> list[dict]:
        hits: list[dict] = []
        for c in _sort_clusters_by_recency(clusters):
            haystack = _cluster_entity_haystack(c)
            if any(any(term in item for item in haystack) for term in query_terms):
                hits.append(c)
            if len(hits) >= limit:
                break
        return hits

    hours = _parse_timeframe_to_hours(timeframe)
    clusters = store.get_latest_clusters_all_topics(ttl_hours=hours, limit=max(200, limit * 10))
    hits = _match_clusters(clusters)

    out = []
    for c in hits:
        item = {
            "cluster_id": c.get("cluster_id"),
            "headline": c.get("headline"),
            "summary": c.get("summary"),
            "entities": c.get("entities", []),
            "sentiment": c.get("sentiment", "neutral"),
            "importance": c.get("importance", 0.0),
            "sources": c.get("sources", []),
            "timestamp": c.get("timestamp"),
        }
        if include_articles:
            arts = c.get("articles", []) or []
            item["articles"] = [
                {
                    "title": a.get("title"),
                    "url": a.get("url"),
                    "source": a.get("source"),
                    "timestamp": a.get("timestamp"),
                }
                for a in arts
                if isinstance(a, dict)
            ]
        out.append(item)
    return out


@mcp.tool(description="Investigate one cluster in depth and return a concise LLM-written explanation plus key facts.")
async def get_event_summary(event_id: str, include_articles: bool = False):
    store = SQLiteClusterStore(DB_PATH)

    # Summary cache: reuse if present within TTL.
    cached_summary = store.get_cluster_summary(
        cluster_id=event_id,
        ttl_hours=DEFAULT_LOOKBACK_HOURS,
    )
    if cached_summary:
        out = {
            "event_id": event_id,
            "headline": cached_summary.get("headline"),
            "mergedSummary": cached_summary.get("mergedSummary"),
            "keyFacts": cached_summary.get("keyFacts", []),
            "sources": cached_summary.get("sources", []),
        }

        if include_articles:
            cluster = store.get_cluster_by_id(event_id)
            arts = (cluster or {}).get("articles", []) or []
            out["articles"] = [
                {
                    "title": a.get("title"),
                    "url": a.get("url"),
                    "source": a.get("source"),
                    "timestamp": a.get("timestamp"),
                }
                for a in arts
                if isinstance(a, dict)
            ]
        return out

    cluster = store.get_cluster_by_id(event_id)
    if not cluster:
        return {
            "event_id": event_id,
            "error": "NOT_FOUND",
        }

    articles_out = None
    if include_articles:
        arts = cluster.get("articles", []) or []
        articles_out = [
            {
                "title": a.get("title"),
                "url": a.get("url"),
                "source": a.get("source"),
                "timestamp": a.get("timestamp"),
            }
            for a in arts
            if isinstance(a, dict)
        ]

    summary = await summarize_cluster_llm(cluster)

    store.upsert_cluster_summary(event_id, summary)
    out = {
        "event_id": event_id,
        "headline": summary.get("headline"),
        "mergedSummary": summary.get("mergedSummary"),
        "keyFacts": summary.get("keyFacts", []),
        "sources": summary.get("sources", []),
    }

    if include_articles:
        out["articles"] = articles_out or []
    return out


@mcp.tool(description="Explore what is starting to matter: surface emerging entities and phrases from recent clusters.")
async def detect_emerging_topics(limit: int = 10):
    limit = max(1, min(int(limit), 20))
    store = SQLiteClusterStore(DB_PATH)
    clusters = store.get_latest_clusters_all_topics(ttl_hours=DEFAULT_LOOKBACK_HOURS, limit=200)

    import re

    entity_counts = Counter()
    entity_importance_sum = Counter()
    # co-occurrence: ent -> other_ent -> count
    entity_cooccur = {}
    phrase_counts = Counter()
    topic_counts = Counter()

    # Very light heuristics to reduce “meta entities” dominating emerging topics.
    # Keep it conservative: only skip obvious boilerplate.
    def _is_generic_entity(ent: str) -> bool:
        e = str(ent).strip().lower()
        if not e:
            return True
        if len(e) < 4:
            return True
        # common outlet-ish / meta-ish tokens
        if e in {"news", "latest", "breaking"}:
            return True
        return False

    for c in clusters:
        topic_counts[c.get("topic", "other")] += 1
        ents_in_cluster = [e for e in (c.get("entities", []) or []) if not _is_generic_entity(e)]
        ents_in_cluster_norm = [str(e).strip().lower() for e in ents_in_cluster if str(e).strip()]
        for ent in ents_in_cluster_norm:
            if _is_generic_entity(ent):
                continue
            entity_counts[ent] += 1
            try:
                entity_importance_sum[ent] += float(c.get("importance", 0.0) or 0.0)
            except Exception:
                pass

        # update co-occurrence counts
        for i in range(len(ents_in_cluster_norm)):
            a = ents_in_cluster_norm[i]
            if not a:
                continue
            entity_cooccur.setdefault(a, Counter())
            for j in range(len(ents_in_cluster_norm)):
                if i == j:
                    continue
                b = ents_in_cluster_norm[j]
                if not b:
                    continue
                entity_cooccur[a][b] += 1

        text = f"{c.get('headline','')} {c.get('summary','')}"
        words = [w for w in re.findall(r"[A-Za-z][A-Za-z0-9\-]{2,}", text.lower())]
        for i in range(len(words) - 1):
            phrase = f"{words[i]} {words[i+1]}"
            if len(phrase) > 6:
                phrase_counts[phrase] += 1

    emerging = []
    # Combine frequency with average importance so “big signal” rises over pure repetition.
    for ent, count in entity_counts.most_common(limit):
        avg_imp = entity_importance_sum[ent] / max(1, count)
        # avg_imp is typically 0..~1; keep score bounded.
        trend_score = 0.25 + 0.40 * min(1.0, avg_imp) + 0.08 * min(6.0, float(count))
        related = []
        for other, _cnt in (entity_cooccur.get(ent) or Counter()).most_common(3):
            # avoid returning the entity itself (shouldn't happen, but be safe)
            if other != ent:
                related.append(other)

        emerging.append({
            "topic": ent,
            "trend_score": min(0.99, round(trend_score, 2)),
            "related_entities": related if related else [ent],
            "signal_type": "entity",
            "count": count,
            "avg_importance": round(avg_imp, 3),
        })

    for phrase, count in phrase_counts.most_common(limit * 2):
        if any(item["topic"] == phrase for item in emerging):
            continue
        emerging.append({
            "topic": phrase.title(),
            "trend_score": min(0.99, round(0.20 + 0.10 * count, 2)),
            "related_entities": [],
            "signal_type": "phrase",
            "count": count,
        })
        if len(emerging) >= limit:
            break

    return emerging[:limit]


@mcp.tool(description="Investigate whether sentiment around an entity is positive, negative, or neutral over a chosen lookback window.")
async def get_news_sentiment(entity: str, timeframe: str = "24h"):
    store = SQLiteClusterStore(DB_PATH)

    ent = normalize_query(entity).strip().lower()
    resolved = resolve_entity_via_trends(ent)
    query_terms = {
        ent,
        str(resolved.get("normalized") or "").strip().lower(),
        str(resolved.get("canonical_label") or "").strip().lower(),
        str(resolved.get("mid") or "").strip().lower(),
    }
    query_terms = {q for q in query_terms if q}
    if not ent:
        return {
            "entity": entity,
            "sentiment": "neutral",
            "score": 0.0,
            "cluster_count": 0,
        }

    # timeframe: accept '24h' or '24'
    tf = str(timeframe).strip().lower()
    try:
        hours = int(tf[:-1]) if tf.endswith("h") else int(tf)
    except Exception:
        hours = 24
    hours = max(1, min(int(hours), 168))

    clusters = store.get_latest_clusters_all_topics(ttl_hours=hours, limit=500)
    matched = []
    for c in clusters:
        haystack = _cluster_entity_haystack(c)
        if any(any(term in item for item in haystack) for term in query_terms):
            matched.append(c)

    if not matched:
        return {
            "entity": entity,
            "sentiment": "neutral",
            "score": 0.0,
            "cluster_count": 0,
        }

    scores = []
    for c in matched:
        s = c.get("sentimentScore")
        if s is not None:
            try:
                scores.append(float(s))
            except Exception:
                pass

    avg_score = sum(scores) / len(scores) if scores else 0.0

    # Keep the label aligned with the numeric score.
    # Small magnitudes are treated as neutral to avoid noisy label flips.
    if avg_score >= 0.15:
        sentiment = "positive"
    elif avg_score <= -0.15:
        sentiment = "negative"
    else:
        sentiment = "neutral"

    return {
        "entity": entity,
        "sentiment": sentiment,
        "score": round(avg_score, 3),
        "cluster_count": len(matched),
    }


def _parse_timeframe_to_hours(timeframe: str) -> int:
    tf = str(timeframe).strip().lower()
    try:
        if tf.endswith("d"):
            days = int(tf[:-1])
            return max(1, days * 24)
        if tf.endswith("h"):
            return max(1, int(tf[:-1]))
        return max(1, int(tf))
    except Exception:
        return 24


@mcp.tool(
    description="Investigate which entities tend to appear alongside a subject entity in recent clusters, based on co-occurrence."
)
async def get_related_entities(subject: str, timeframe: str = "24h", limit: int = 10):
    store = SQLiteClusterStore(DB_PATH)
    limit = max(1, min(int(limit), 30))

    subj = normalize_query(subject).strip().lower()
    if not subj:
        return []

    resolved = resolve_entity_via_trends(subj)
    query_terms = {
        subj,
        str(resolved.get("normalized") or "").strip().lower(),
        str(resolved.get("canonical_label") or "").strip().lower(),
        str(resolved.get("mid") or "").strip().lower(),
    }
    query_terms = {q for q in query_terms if q}

    hours = _parse_timeframe_to_hours(timeframe)
    clusters = store.get_latest_clusters_all_topics(ttl_hours=hours, limit=500)

    # Aggregate related metrics per entity.
    rel_count = Counter()
    rel_imp_sum = Counter()
    rel_sent_sum = Counter()
    rel_sent_n = Counter()

    for c in clusters:
        haystack = _cluster_entity_haystack(c)
        if not any(term in item for item in haystack for term in query_terms):
            continue

        ents = [str(e).strip().lower() for e in (c.get("entities", []) or []) if str(e).strip()]
        # remove generic/meta-ish short tokens conservatively
        ents = [e for e in ents if len(e) >= 4]
        for e in ents:
            if e in query_terms:
                continue
            rel_count[e] += 1
            try:
                rel_imp_sum[e] += float(c.get("importance", 0.0) or 0.0)
            except Exception:
                pass

            # sentiment aggregation based on sentimentScore if available.
            s = c.get("sentimentScore")
            if s is not None:
                try:
                    rel_sent_sum[e] += float(s)
                    rel_sent_n[e] += 1
                except Exception:
                    pass

    # Sort by count, then avg importance.
    items = []
    for ent, cnt in rel_count.most_common():
        avg_imp = rel_imp_sum[ent] / max(1, cnt)
        avg_score = rel_sent_sum[ent] / max(1, rel_sent_n[ent]) if rel_sent_n[ent] else 0.0
        if avg_score >= 0.15:
            sentiment = "positive"
        elif avg_score <= -0.15:
            sentiment = "negative"
        else:
            sentiment = "neutral"

        items.append(
            {
                "entity": ent,
                "count": cnt,
                "avg_importance": round(avg_imp, 3),
                "sentiment": sentiment,
                "score": round(avg_score, 3),
            }
        )
        if len(items) >= limit:
            break

    return items


app = FastAPI(title="News MCP Server")

logger = logging.getLogger("news_mcp.startup")

app.mount("/mcp", mcp.sse_app())


_background_task_started = False


@app.on_event("startup")
async def _start_background_refresh():
    global _background_task_started
    if _background_task_started:
        return
    if not NEWS_BACKGROUND_REFRESH_ENABLED:
        return
    _background_task_started = True
    logger.info("news-mcp llm config: %s", active_llm_config())

    store = SQLiteClusterStore(DB_PATH)
    prune_result = store.prune_if_due(
        pruning_enabled=NEWS_PRUNING_ENABLED,
        retention_days=NEWS_RETENTION_DAYS,
        interval_hours=NEWS_PRUNE_INTERVAL_HOURS,
    )
    logger.info("startup prune_result=%s", prune_result)

    async def _loop():
        if not NEWS_BACKGROUND_REFRESH_ON_START:
            await asyncio.sleep(float(NEWS_REFRESH_INTERVAL_SECONDS))
        while True:
            try:
                # Refresh all topics by passing topic=None
                await refresh_clusters(topic=None, limit=200)
            except Exception:
                # Avoid crashing the server on network errors.
                pass
            await asyncio.sleep(float(NEWS_REFRESH_INTERVAL_SECONDS))

    asyncio.create_task(_loop())


@app.get("/")
def root():
    return {
        "status": "ok",
        "transport": "fastmcp+sse",
        "mount": "/mcp",
        "tools": ["get_latest_events", "get_events_for_entity", "get_event_summary", "detect_emerging_topics"],
        "refresh": {
            "enabled": NEWS_BACKGROUND_REFRESH_ENABLED,
            "interval_seconds": NEWS_REFRESH_INTERVAL_SECONDS,
        },
        "retention": {
            "lookback_hours": DEFAULT_LOOKBACK_HOURS,
            "retention_days": NEWS_RETENTION_DAYS,
        },
        "pruning": {
            "enabled": NEWS_PRUNING_ENABLED,
            "interval_hours": NEWS_PRUNE_INTERVAL_HOURS,
        },
    }


@app.get("/health")
def health():
    store = SQLiteClusterStore(DB_PATH)
    return {
        "status": "ok",
        "lookback_hours": DEFAULT_LOOKBACK_HOURS,
        "db": str(DB_PATH),
        "refresh": store.get_feed_state("breakingthenews"),
        "pruning": store.get_prune_state(
            pruning_enabled=NEWS_PRUNING_ENABLED,
            retention_days=NEWS_RETENTION_DAYS,
            interval_hours=NEWS_PRUNE_INTERVAL_HOURS,
        ),
    }