from datetime import date, datetime

from sqlalchemy import func

from .extensions import db
from .models import OrlenPrice
from .services import fetch_orlen_range


def _year_bounds(year, today=None):
    today = today or date.today()
    start = date(year, 1, 1)
    end = min(date(year, 12, 31), today)
    if end < start:
        raise ValueError("Nie można synchronizować danych dla przyszłego roku")
    return start, end


def _latest_date(fuel, start, end, region=""):
    query = db.session.query(func.max(OrlenPrice.effective_date)).filter(
        OrlenPrice.fuel_type == fuel,
        OrlenPrice.effective_date.between(start, end),
    )
    if fuel == "LPG":
        query = query.filter(OrlenPrice.region == region)
    else:
        query = query.filter(OrlenPrice.region == "")
    return query.scalar()


def _sync_start(fuel, start, end, regions, full_refresh):
    if full_refresh:
        return start

    if fuel != "LPG":
        return _latest_date(fuel, start, end) or start

    latest_dates = [_latest_date("LPG", start, end, region) for region in regions]
    return min((value or start) for value in latest_dates)


def sync_orlen_prices(fuels, year, regions, default_region, full_refresh=False, today=None):
    start, end = _year_bounds(year, today=today)
    target_regions = [str(region).strip().lower() for region in regions if str(region).strip()]
    if not target_regions:
        target_regions = [str(default_region).strip().lower()]

    result = {}
    total = 0

    for fuel in fuels:
        fuel_regions = target_regions if fuel == "LPG" else []
        date_from = _sync_start(fuel, start, end, fuel_regions, full_refresh)
        added = 0
        updated = 0

        rows = fetch_orlen_range(
            fuel,
            date_from,
            end,
            "all" if fuel == "LPG" else default_region,
        )
        for row in rows:
            if fuel == "LPG" and row.get("region") not in fuel_regions:
                continue

            existing = OrlenPrice.query.filter_by(
                fuel_type=row["fuel_type"],
                effective_date=row["effective_date"],
                region=row["region"],
            ).first()
            if existing:
                for key, value in row.items():
                    setattr(existing, key, value)
                existing.fetched_at = datetime.utcnow()
                updated += 1
            else:
                db.session.add(OrlenPrice(**row))
                added += 1

        processed = added + updated
        result[fuel] = {
            "added": added,
            "updated": updated,
            "from": date_from.isoformat(),
            "to": end.isoformat(),
            "full_refresh": bool(full_refresh),
        }
        total += processed

    return result, total