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


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


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:
                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]}