from __future__ import annotations

import json
import sqlite3
from dataclasses import dataclass
from datetime import datetime, timezone, timedelta
from pathlib import Path
from typing import Any
from urllib.parse import urlparse

from news_mcp.entity_normalize import normalize_entities
from news_mcp.trends_resolution import resolve_entity_via_trends


@dataclass
class ClusterRow:
    cluster_id: str
    topic: str
    payload: dict
    updated_at: datetime


def _article_key(article: dict[str, Any]) -> str:
    url = str(article.get("url") or "").strip()
    if not url:
        return str(article.get("title") or "")
    try:
        parsed = urlparse(url)
        parts = [p for p in parsed.path.split("/") if p]
        if parts:
            return parts[-1]
    except Exception:
        pass
    return url


def _dedup_articles(articles: list[dict[str, Any]]) -> list[dict[str, Any]]:
    seen: set[str] = set()
    out: list[dict[str, Any]] = []
    for article in articles:
        key = _article_key(article)
        if key in seen:
            continue
        seen.add(key)
        out.append(article)
    return out


def _has_valid_entity_resolutions(resolutions: Any, entities: list[str]) -> bool:
    if not isinstance(resolutions, list):
        return False
    if len(resolutions) != len(entities):
        return False
    for res in resolutions:
        if not isinstance(res, dict):
            return False
        if not res.get("normalized") or not res.get("canonical_label"):
            return False
    return True


def sanitize_cluster_payload(cluster: dict[str, Any], *, include_resolutions: bool = True) -> dict[str, Any]:
    """Normalize cluster payload so every stored payload is internally consistent."""
    out = dict(cluster)

    raw_articles = out.get("articles", []) or []
    articles = [a for a in raw_articles if isinstance(a, dict)]
    out["articles"] = _dedup_articles(articles)

    raw_entities = out.get("entities", []) or []
    entities = normalize_entities(raw_entities)
    out["entities"] = entities

    if not include_resolutions:
        return out

    resolutions = out.get("entityResolutions", None)
    if entities:
        if not _has_valid_entity_resolutions(resolutions, entities):
            out["entityResolutions"] = [resolve_entity_via_trends(e) for e in entities]
    else:
        # Keep the empty case explicit and stable.
        out["entityResolutions"] = []

    return out


class SQLiteClusterStore:
    def __init__(self, db_path: str | Path):
        self.db_path = str(db_path)
        self._init_db()

    def _conn(self) -> sqlite3.Connection:
        return sqlite3.connect(self.db_path)

    def _init_db(self) -> None:
        Path(self.db_path).parent.mkdir(parents=True, exist_ok=True)
        with self._conn() as conn:
            conn.execute(
                """
                CREATE TABLE IF NOT EXISTS clusters (
                  cluster_id TEXT PRIMARY KEY,
                  topic TEXT NOT NULL,
                  payload TEXT NOT NULL,
                  updated_at TEXT NOT NULL,
                  summary_payload TEXT,
                  summary_updated_at TEXT
                )
                """
            )

            # If the table already exists without the summary columns,
            # add them (SQLite-friendly incremental migrations).
            for col_def in [
                "summary_payload TEXT",
                "summary_updated_at TEXT",
            ]:
                col = col_def.split()[0]
                try:
                    conn.execute(f"ALTER TABLE clusters ADD COLUMN {col_def}")
                except sqlite3.OperationalError:
                    pass
            conn.execute(
                "CREATE INDEX IF NOT EXISTS idx_clusters_topic ON clusters(topic)"
            )

            conn.execute(
                """
                CREATE TABLE IF NOT EXISTS feed_state (
                  feed_key TEXT PRIMARY KEY,
                  last_hash TEXT NOT NULL,
                  updated_at TEXT NOT NULL
                )
                """
            )

    def upsert_clusters(self, clusters: list[dict], topic: str) -> None:
        now = datetime.now(timezone.utc)
        with self._conn() as conn:
            for c in clusters:
                c = sanitize_cluster_payload(c)
                cluster_id = c["cluster_id"]
                payload = json.dumps(c, ensure_ascii=False)
                conn.execute(
                    "INSERT INTO clusters(cluster_id, topic, payload, updated_at) VALUES(?,?,?,?) "
                    "ON CONFLICT(cluster_id) DO UPDATE SET topic=excluded.topic, payload=excluded.payload, updated_at=excluded.updated_at",
                    (cluster_id, topic, payload, now.isoformat()),
                )

    def upsert_cluster_summary(
        self,
        cluster_id: str,
        summary_payload: dict,
    ) -> None:
        now = datetime.now(timezone.utc).isoformat()
        with self._conn() as conn:
            conn.execute(
                "INSERT INTO clusters(cluster_id, topic, payload, updated_at, summary_payload, summary_updated_at) "
                "VALUES(?,?,?,?,?,?) "
                "ON CONFLICT(cluster_id) DO UPDATE SET "
                "summary_payload=excluded.summary_payload, summary_updated_at=excluded.summary_updated_at",
                (
                    cluster_id,
                    "",  # topic not used for update
                    json.dumps({}, ensure_ascii=False),
                    now,
                    json.dumps(summary_payload, ensure_ascii=False),
                    now,
                ),
            )

    def get_cluster_summary(self, cluster_id: str, ttl_hours: float) -> dict | None:
        cutoff = datetime.now(timezone.utc) - timedelta(hours=ttl_hours)
        cutoff_iso = cutoff.isoformat()
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT summary_payload, summary_updated_at FROM clusters "
                "WHERE cluster_id=? AND summary_updated_at >= ?",
                (cluster_id, cutoff_iso),
            )
            row = cur.fetchone()
            if not row or not row[0]:
                return None
            return json.loads(row[0])

    def get_latest_clusters(self, topic: str, ttl_hours: float, limit: int) -> list[dict]:
        cutoff = datetime.now(timezone.utc) - timedelta(hours=ttl_hours)
        cutoff_iso = cutoff.isoformat()
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT payload FROM clusters WHERE topic=? AND updated_at >= ? ORDER BY updated_at DESC LIMIT ?",
                (topic, cutoff_iso, int(limit)),
            )
            rows = [json.loads(r[0]) for r in cur.fetchall()]
        return rows

    def get_latest_clusters_all_topics(self, ttl_hours: float, limit: int) -> list[dict]:
        cutoff = datetime.now(timezone.utc) - timedelta(hours=ttl_hours)
        cutoff_iso = cutoff.isoformat()
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT payload FROM clusters WHERE updated_at >= ? ORDER BY updated_at DESC LIMIT ?",
                (cutoff_iso, int(limit)),
            )
            return [json.loads(r[0]) for r in cur.fetchall()]

    def get_cluster_by_id(self, cluster_id: str) -> dict | None:
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT payload FROM clusters WHERE cluster_id=?",
                (cluster_id,),
            )
            row = cur.fetchone()
            return json.loads(row[0]) if row else None

    def get_feed_hash(self, feed_key: str) -> str | None:
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT last_hash FROM feed_state WHERE feed_key=?",
                (feed_key,),
            )
            row = cur.fetchone()
            return row[0] if row else None

    def set_feed_hash(self, feed_key: str, last_hash: str) -> None:
        now = datetime.now(timezone.utc).isoformat()
        with self._conn() as conn:
            conn.execute(
                "INSERT INTO feed_state(feed_key, last_hash, updated_at) VALUES(?,?,?) "
                "ON CONFLICT(feed_key) DO UPDATE SET last_hash=excluded.last_hash, updated_at=excluded.updated_at",
                (feed_key, last_hash, now),
            )

    def get_feed_state(self, feed_key: str) -> dict | None:
        with self._conn() as conn:
            cur = conn.execute(
                "SELECT last_hash, updated_at FROM feed_state WHERE feed_key=?",
                (feed_key,),
            )
            row = cur.fetchone()
            if not row:
                return None
            return {"last_hash": row[0], "updated_at": row[1]}