import logging
from datetime import datetime, timezone, date as dt_date

from sqlalchemy.orm import Session

from ..models import OHLCCandle
from .btc import get_btc_ohlc_eur, aggregate_to_daily

logger = logging.getLogger(__name__)


def seed_candles(db: Session) -> None:
    """Fetch 30 days of daily OHLC candles from CoinGecko and store them.
    Free tier gives 4-hour bars for days<=30, which aggregate cleanly to daily candles.
    days>30 drops to 4-day granularity (unusable for a daily chart).
    """
    raw = get_btc_ohlc_eur(days=30)
    if not raw:
        logger.warning("Candle seed: CoinGecko returned no data — will retry on next startup.")
        return

    daily = aggregate_to_daily(raw)
    rows = [
        OHLCCandle(date=date, open=v["open"], high=v["high"], low=v["low"], close=v["close"])
        for date, v in sorted(daily.items())
    ]
    for row in rows:
        db.merge(row)
    db.commit()
    logger.info("Candle seed: stored %d daily candles (%s → %s).", len(rows), min(daily.keys()), max(daily.keys()))


def refresh_latest_candles(db: Session) -> None:
    """Add any missing candles up to today. Seeds the DB if empty.
    Also detects and replaces coarse (>2-day gap) legacy data from a previous days=365 seed.
    """
    # Sparse-data detection: if existing candles have >2-day gaps, wipe and re-seed
    first_two = db.query(OHLCCandle).order_by(OHLCCandle.date.asc()).limit(2).all()
    if len(first_two) == 2:
        d1 = dt_date.fromisoformat(first_two[0].date)
        d2 = dt_date.fromisoformat(first_two[1].date)
        if (d2 - d1).days > 2:
            logger.warning("Candle refresh: detected coarse candle data (gap=%d days). Wiping and re-seeding with daily candles.", (d2 - d1).days)
            db.query(OHLCCandle).delete()
            db.commit()
            seed_candles(db)
            return

    latest = db.query(OHLCCandle).order_by(OHLCCandle.date.desc()).first()

    if latest is None:
        seed_candles(db)
        return

    today = datetime.now(tz=timezone.utc).strftime("%Y-%m-%d")
    if latest.date >= today:
        return  # Already up to date

    raw = get_btc_ohlc_eur(days=7)
    if not raw:
        logger.warning("Candle refresh: CoinGecko returned no data.")
        return

    daily = aggregate_to_daily(raw)
    new_dates = [d for d in daily if d > latest.date]
    if not new_dates:
        return

    for date in new_dates:
        v = daily[date]
        db.merge(OHLCCandle(date=date, open=v["open"], high=v["high"], low=v["low"], close=v["close"]))
    db.commit()
    logger.info("Candle refresh: upserted %d candle(s) up to %s.", len(new_dates), max(new_dates))