from __future__ import annotations

import logging
from datetime import datetime, timezone
from pathlib import Path
from typing import Optional

import psycopg2
from psycopg2.pool import ThreadedConnectionPool

from app.db.models import MarketComp, ScammerEntry, Seller

log = logging.getLogger(__name__)

_MIN_CONN = 2
_MAX_CONN = 20


class SnipeSharedDB:
    """Thread-safe Postgres connection pool for Snipe shared tables."""

    def __init__(self, dsn: str) -> None:
        self._pool = ThreadedConnectionPool(_MIN_CONN, _MAX_CONN, dsn=dsn)

    def getconn(self):
        return self._pool.getconn()

    def putconn(self, conn) -> None:
        self._pool.putconn(conn)

    def close(self) -> None:
        self._pool.closeall()

    def run_migrations(self) -> None:
        """Apply pg_migrations/*.sql in filename order. Idempotent."""
        migrations_dir = Path(__file__).parent / "pg_migrations"
        files = sorted(migrations_dir.glob("*.sql"), key=lambda p: p.name)

        conn = self.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute("""
                    CREATE TABLE IF NOT EXISTS _snipe_shared_migrations (
                        filename   TEXT PRIMARY KEY,
                        applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
                    )
                """)
                conn.commit()
                for f in files:
                    cur.execute(
                        "SELECT 1 FROM _snipe_shared_migrations WHERE filename = %s",
                        (f.name,),
                    )
                    if cur.fetchone():
                        continue
                    log.info("Applying migration: %s", f.name)
                    cur.execute(f.read_text())
                    cur.execute(
                        "INSERT INTO _snipe_shared_migrations (filename) VALUES (%s)",
                        (f.name,),
                    )
                    conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self.putconn(conn)


class SnipeSharedStore:
    """Postgres-backed store for sellers, market_comps, and reported_sellers.

    Satisfies SharedTableProtocol. clone() returns self — ThreadedConnectionPool
    is already thread-safe, so no new instance is needed per thread.
    """

    def __init__(self, db: SnipeSharedDB) -> None:
        self._db = db

    def clone(self) -> "SnipeSharedStore":
        return self

    # Sellers

    def save_seller(self, seller: Seller) -> None:
        self.save_sellers([seller])

    def save_sellers(self, sellers: list[Seller]) -> None:
        if not sellers:
            return
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.executemany(
                    """
                    INSERT INTO sellers
                        (platform, platform_seller_id, username, account_age_days,
                         feedback_count, feedback_ratio, category_history_json)
                    VALUES (%s, %s, %s, %s, %s, %s, %s)
                    ON CONFLICT (platform, platform_seller_id) DO UPDATE SET
                        username              = EXCLUDED.username,
                        feedback_count        = EXCLUDED.feedback_count,
                        feedback_ratio        = EXCLUDED.feedback_ratio,
                        account_age_days      = COALESCE(
                            EXCLUDED.account_age_days,
                            sellers.account_age_days
                        ),
                        category_history_json = COALESCE(
                            NULLIF(NULLIF(EXCLUDED.category_history_json, '{}'), ''),
                            NULLIF(NULLIF(sellers.category_history_json, '{}'), ''),
                            '{}'
                        ),
                        fetched_at = NOW()
                    """,
                    [
                        (s.platform, s.platform_seller_id, s.username, s.account_age_days,
                         s.feedback_count, s.feedback_ratio, s.category_history_json or "{}")
                        for s in sellers
                    ],
                )
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    def get_seller(self, platform: str, platform_seller_id: str) -> Optional[Seller]:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    SELECT platform, platform_seller_id, username, account_age_days,
                           feedback_count, feedback_ratio, category_history_json,
                           id, fetched_at
                    FROM sellers
                    WHERE platform = %s AND platform_seller_id = %s
                    """,
                    (platform, platform_seller_id),
                )
                row = cur.fetchone()
            if not row:
                return None
            return Seller(*row[:7], id=row[7], fetched_at=str(row[8]))
        finally:
            self._db.putconn(conn)

    def delete_seller_data(self, platform: str, platform_seller_id: str) -> None:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    "DELETE FROM sellers WHERE platform = %s AND platform_seller_id = %s",
                    (platform, platform_seller_id),
                )
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    # MarketComps

    def save_market_comp(self, comp: MarketComp) -> None:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    INSERT INTO market_comps
                        (platform, query_hash, median_price, sample_count, expires_at)
                    VALUES (%s, %s, %s, %s, %s::TIMESTAMPTZ)
                    ON CONFLICT (platform, query_hash) DO UPDATE SET
                        median_price = EXCLUDED.median_price,
                        sample_count = EXCLUDED.sample_count,
                        expires_at   = EXCLUDED.expires_at,
                        fetched_at   = NOW()
                    """,
                    (comp.platform, comp.query_hash, comp.median_price,
                     comp.sample_count, comp.expires_at),
                )
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    def get_market_comp(self, platform: str, query_hash: str) -> Optional[MarketComp]:
        now = datetime.now(timezone.utc).isoformat()
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    SELECT platform, query_hash, median_price, sample_count,
                           expires_at, id, fetched_at
                    FROM market_comps
                    WHERE platform = %s AND query_hash = %s AND expires_at > %s::TIMESTAMPTZ
                    """,
                    (platform, query_hash, now),
                )
                row = cur.fetchone()
            if not row:
                return None
            return MarketComp(*row[:5], id=row[5], fetched_at=str(row[6]))
        finally:
            self._db.putconn(conn)

    # Reported Sellers

    def mark_reported(
        self,
        platform: str,
        platform_seller_id: str,
        username: Optional[str] = None,
        reported_by: str = "user",
    ) -> None:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    INSERT INTO reported_sellers
                        (platform, platform_seller_id, username, reported_by)
                    VALUES (%s, %s, %s, %s)
                    ON CONFLICT (platform, platform_seller_id) DO NOTHING
                    """,
                    (platform, platform_seller_id, username, reported_by),
                )
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    def list_reported(self, platform: str = "ebay") -> list[str]:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    "SELECT platform_seller_id FROM reported_sellers WHERE platform = %s",
                    (platform,),
                )
                return [row[0] for row in cur.fetchall()]
        finally:
            self._db.putconn(conn)

    # Seller Category Refresh

    def refresh_seller_categories(
        self,
        platform: str,
        seller_ids: list[str],
        listing_store=None,  # always a SQLite Store in practice
    ) -> int:
        """Derive category_history_json from listing data and update sellers in Postgres.

        listing_store must be provided (it's always the per-user SQLite Store).
        Returns count of sellers updated.
        """
        from app.platforms.ebay.scraper import _classify_category_label  # lazy to avoid circular
        import json

        if not seller_ids or listing_store is None:
            return 0

        updated = 0
        for sid in seller_ids:
            seller = self.get_seller(platform, sid)
            if not seller or seller.category_history_json not in ("{}", "", None):
                continue
            # listing_store is always a SQLite Store; access _conn directly for the query.
            rows = listing_store._conn.execute(
                "SELECT category_name, COUNT(*) FROM listings "
                "WHERE platform=? AND seller_platform_id=? AND category_name IS NOT NULL "
                "GROUP BY category_name",
                (platform, sid),
            ).fetchall()
            if not rows:
                continue
            counts: dict[str, int] = {}
            for cat_name, cnt in rows:
                key = _classify_category_label(cat_name)
                if key:
                    counts[key] = counts.get(key, 0) + cnt
            if counts:
                from dataclasses import replace
                self.save_sellers([replace(seller, category_history_json=json.dumps(counts))])
                updated += 1
        return updated

    # Scammer Blocklist

    def is_blocklisted(self, platform: str, platform_seller_id: str) -> bool:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    "SELECT 1 FROM scammer_blocklist "
                    "WHERE platform = %s AND platform_seller_id = %s LIMIT 1",
                    (platform, platform_seller_id),
                )
                return cur.fetchone() is not None
        finally:
            self._db.putconn(conn)

    def add_to_blocklist(self, entry: ScammerEntry) -> ScammerEntry:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    INSERT INTO scammer_blocklist
                        (platform, platform_seller_id, username, reason, source)
                    VALUES (%s, %s, %s, %s, %s)
                    ON CONFLICT (platform, platform_seller_id) DO UPDATE SET
                        username = EXCLUDED.username,
                        reason   = COALESCE(EXCLUDED.reason, scammer_blocklist.reason),
                        source   = EXCLUDED.source
                    """,
                    (entry.platform, entry.platform_seller_id, entry.username,
                     entry.reason, entry.source),
                )
                conn.commit()
                cur.execute(
                    "SELECT id, created_at FROM scammer_blocklist "
                    "WHERE platform = %s AND platform_seller_id = %s",
                    (entry.platform, entry.platform_seller_id),
                )
                row = cur.fetchone()
            from dataclasses import replace
            return replace(entry, id=row[0], created_at=str(row[1]))
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    def remove_from_blocklist(self, platform: str, platform_seller_id: str) -> None:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    "DELETE FROM scammer_blocklist "
                    "WHERE platform = %s AND platform_seller_id = %s",
                    (platform, platform_seller_id),
                )
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            self._db.putconn(conn)

    def list_blocklist(self, platform: str = "ebay") -> list[ScammerEntry]:
        conn = self._db.getconn()
        try:
            with conn.cursor() as cur:
                cur.execute(
                    """
                    SELECT platform, platform_seller_id, username, reason, source, id, created_at
                    FROM scammer_blocklist
                    WHERE platform = %s
                    ORDER BY created_at DESC
                    """,
                    (platform,),
                )
                return [
                    ScammerEntry(
                        platform=r[0], platform_seller_id=r[1], username=r[2],
                        reason=r[3], source=r[4], id=r[5], created_at=str(r[6]),
                    )
                    for r in cur.fetchall()
                ]
        finally:
            self._db.putconn(conn)