from datetime import datetime
from typing import Optional

from sqlalchemy import create_engine, func, select, text, update
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import Session

import config
from db.models import Base, Filing, PriceCache, Signal


def _engine():
    url = f"sqlite:///{config.DB_PATH}"
    return create_engine(url, connect_args={"check_same_thread": False})


_ENGINE = None


def _get_engine():
    global _ENGINE
    if _ENGINE is None:
        _ENGINE = _engine()
    return _ENGINE


def init_db():
    engine = _get_engine()
    with engine.connect() as conn:
        conn.execute(text("PRAGMA journal_mode=WAL"))
        conn.execute(text("PRAGMA foreign_keys=ON"))
    Base.metadata.create_all(engine)


def _session() -> Session:
    return Session(_get_engine())


def insert_filing(filing: dict) -> bool:
    with _session() as session:
        exists = session.scalar(
            select(Filing.id).where(Filing.accession_number == filing["accession_number"])
        )
        if exists is not None:
            return False

        row = Filing(
            accession_number=filing["accession_number"],
            ticker=filing.get("ticker"),
            cik=filing.get("cik"),
            insider_name=filing.get("insider_name"),
            role=filing.get("role"),
            transaction_date=filing.get("transaction_date"),
            filed_date=filing.get("filed_date"),
            shares=filing.get("shares"),
            price=filing.get("price"),
            total_value=filing.get("total_value"),
            flag=filing.get("flag"),
            is_10b51=bool(filing.get("is_10b51", False)),
            post_tx_shares=filing.get("post_tx_shares"),
        )
        session.add(row)
        try:
            session.commit()
            return True
        except IntegrityError:
            session.rollback()
            return False


def accession_exists(accession_number: str) -> bool:
    with _session() as session:
        return session.scalar(
            select(Filing.id).where(Filing.accession_number == accession_number)
        ) is not None


def mark_accession_seen(accession_number: str) -> None:
    """Store a placeholder row so derivative-only/empty filings aren't re-fetched."""
    with _session() as session:
        exists = session.scalar(
            select(Filing.id).where(Filing.accession_number == accession_number)
        )
        if exists is not None:
            return
        session.add(Filing(accession_number=accession_number))
        try:
            session.commit()
        except IntegrityError:
            session.rollback()


def filter_new_accessions(accessions: list[str]) -> set[str]:
    """Return the subset of accessions not already in the DB."""
    if not accessions:
        return set()
    existing: set[str] = set()
    chunk_size = 900  # SQLite SQLITE_MAX_VARIABLE_NUMBER limit
    with _session() as session:
        for i in range(0, len(accessions), chunk_size):
            chunk = accessions[i:i + chunk_size]
            existing.update(
                session.execute(
                    select(Filing.accession_number).where(
                        Filing.accession_number.in_(chunk)
                    )
                ).scalars().all()
            )
    return set(accessions) - existing


def get_latest_filed_date() -> Optional[str]:
    with _session() as session:
        return session.scalar(select(func.max(Filing.filed_date)))


def insert_signal(signal: dict) -> int:
    with _session() as session:
        row = Signal(
            ticker=signal["ticker"],
            trigger_date=signal["trigger_date"],
            cluster_size=signal["cluster_size"],
            total_cluster_value=signal.get("total_cluster_value", 0.0),
            score=signal["score"],
        )
        session.add(row)
        session.commit()
        return row.id


def mark_signal_alerted(signal_id: int):
    with _session() as session:
        session.execute(
            update(Signal).where(Signal.id == signal_id).values(alerted=True)
        )
        session.commit()


def mark_signal_executed(signal_id: int):
    with _session() as session:
        session.execute(
            update(Signal)
            .where(Signal.id == signal_id)
            .values(executed=True, executed_at=datetime.utcnow())
        )
        session.commit()


def mark_signal_closed(signal_id: int):
    with _session() as session:
        session.execute(
            update(Signal).where(Signal.id == signal_id).values(closed=True)
        )
        session.commit()


def get_unalerted_signals() -> list[dict]:
    with _session() as session:
        rows = session.scalars(
            select(Signal).where(Signal.alerted == False).order_by(Signal.created_at)
        ).all()
        return [_signal_to_dict(r) for r in rows]


def get_executed_unclosed_signals() -> list[dict]:
    with _session() as session:
        rows = session.scalars(
            select(Signal).where(
                Signal.executed == True,
                Signal.closed == False,
                Signal.executed_at.is_not(None),
            )
        ).all()
        return [_signal_to_dict(r) for r in rows]


def get_recent_buys_for_ticker(
    ticker: str, window_days: int, as_of_date: Optional[str] = None
) -> list[dict]:
    from datetime import timedelta

    ref = datetime.strptime(as_of_date, "%Y-%m-%d") if as_of_date else datetime.utcnow()
    cutoff = (ref - timedelta(days=window_days)).strftime("%Y-%m-%d")
    ref_str = ref.strftime("%Y-%m-%d")
    with _session() as session:
        rows = session.scalars(
            select(Filing)
            .where(
                Filing.ticker == ticker,
                Filing.flag == "A",
                Filing.is_10b51 == False,
                Filing.transaction_date >= cutoff,
                Filing.transaction_date <= ref_str,
            )
            .order_by(Filing.transaction_date.desc())
        ).all()
        return [_filing_to_dict(r) for r in rows]


def get_all_buys_for_reprocess() -> list[dict]:
    """Return all buy filings for signal reprocessing (used after bulk ingest)."""
    with _session() as session:
        rows = session.scalars(
            select(Filing)
            .where(Filing.flag == "A")
            .order_by(Filing.transaction_date)
        ).all()
        return [_filing_to_dict(r) for r in rows]


def get_signals_for_backtest(min_score: float, min_cluster_size: int) -> list[dict]:
    with _session() as session:
        rows = session.scalars(
            select(Signal).where(
                Signal.score >= min_score,
                Signal.cluster_size >= min_cluster_size,
            )
        ).all()
        return [_signal_to_dict(r) for r in rows]


def get_cached_prices(ticker: str, start_date: str, end_date: str) -> dict[str, float]:
    with _session() as session:
        rows = session.scalars(
            select(PriceCache).where(
                PriceCache.ticker == ticker,
                PriceCache.date >= start_date,
                PriceCache.date <= end_date,
            )
        ).all()
        return {r.date: r.close for r in rows}


def upsert_prices(ticker: str, prices: dict[str, float]):
    with _session() as session:
        for date_str, close in prices.items():
            existing = session.scalar(
                select(PriceCache).where(
                    PriceCache.ticker == ticker,
                    PriceCache.date == date_str,
                )
            )
            if existing is None:
                session.add(PriceCache(ticker=ticker, date=date_str, close=close))
        session.commit()


def _filing_to_dict(row: Filing) -> dict:
    return {
        "id": row.id,
        "accession_number": row.accession_number,
        "ticker": row.ticker,
        "cik": row.cik,
        "insider_name": row.insider_name,
        "role": row.role,
        "transaction_date": row.transaction_date,
        "filed_date": row.filed_date,
        "shares": row.shares,
        "price": row.price,
        "total_value": row.total_value,
        "flag": row.flag,
        "is_10b51": row.is_10b51,
        "post_tx_shares": row.post_tx_shares,
        "created_at": row.created_at.isoformat() if row.created_at else None,
    }


def _signal_to_dict(row: Signal) -> dict:
    return {
        "id": row.id,
        "ticker": row.ticker,
        "trigger_date": row.trigger_date,
        "cluster_size": row.cluster_size,
        "total_cluster_value": row.total_cluster_value,
        "score": row.score,
        "alerted": row.alerted,
        "executed": row.executed,
        "executed_at": row.executed_at.strftime("%Y-%m-%dT%H:%M:%SZ") if row.executed_at else None,
        "closed": row.closed,
        "created_at": row.created_at.isoformat() if row.created_at else None,
    }