"""
Occupancy report sync — populates newbook_occupancy_report_data so the
Bookability matrix can show availability alongside rates.

Uses snapshot model (mirrors newbook_current_rates): only inserts a new row
when occupied/available/maintenance figures change; otherwise bumps
last_verified_at on the existing row.  This lets the history popup show
how pick-up evolved over time for a given stay date.
"""
import logging
from datetime import date, timedelta

from sqlalchemy import text

logger = logging.getLogger(__name__)


async def _save_occupancy_snapshot(db, category_id, category_name, report_date,
                                    occupied, available, maintenance, allotted,
                                    revenue_gross, revenue_net, occupancy_pct):
    """
    Insert a new occupancy snapshot only when figures have changed;
    otherwise update last_verified_at on the latest row.
    Returns 'inserted' or 'verified'.
    """
    existing = (await db.execute(
        text("""
            SELECT id, occupied, available, maintenance
            FROM newbook_occupancy_report_data
            WHERE date = :date AND category_id = :category_id
            ORDER BY valid_from DESC
            LIMIT 1
        """),
        {"date": report_date, "category_id": category_id}
    )).fetchone()

    changed = (
        existing is None
        or int(existing.occupied   or 0) != occupied
        or int(existing.available  or 0) != available
        or int(existing.maintenance or 0) != maintenance
    )

    if changed:
        await db.execute(
            text("""
                INSERT INTO newbook_occupancy_report_data (
                    date, category_id, category_name,
                    available, occupied, maintenance, allotted,
                    revenue_gross, revenue_net, occupancy_pct,
                    valid_from, last_verified_at, fetched_at
                ) VALUES (
                    :date, :category_id, :category_name,
                    :available, :occupied, :maintenance, :allotted,
                    :revenue_gross, :revenue_net, :occupancy_pct,
                    NOW(), NOW(), NOW()
                )
            """),
            {
                "date": report_date,
                "category_id": category_id,
                "category_name": category_name,
                "available": available,
                "occupied": occupied,
                "maintenance": maintenance,
                "allotted": allotted,
                "revenue_gross": round(revenue_gross, 2),
                "revenue_net": round(revenue_net, 2),
                "occupancy_pct": round(occupancy_pct, 2),
            }
        )
        return 'inserted'
    else:
        await db.execute(
            text("""
                UPDATE newbook_occupancy_report_data
                SET last_verified_at = NOW(), fetched_at = NOW()
                WHERE id = :id
            """),
            {"id": existing.id}
        )
        return 'verified'


async def run_sync_occupancy(days_ahead: int = 365):
    """
    Fetch the Newbook occupancy report from today forward and snapshot
    per-category, per-date availability into newbook_occupancy_report_data.
    """
    from database import AsyncSessionLocal
    from services.newbook_rates_client import NewbookRatesClient

    from_date = date.today()
    to_date = from_date + timedelta(days=days_ahead)

    async with AsyncSessionLocal() as db:
        client = await NewbookRatesClient.from_db(db)
        async with client:
            report = await client.get_occupancy_report(from_date, to_date)

        logger.info(f"Occupancy report: {len(report)} categories, {from_date} to {to_date}")
        vat = float(client.vat_rate or 0)
        inserted = 0
        verified = 0

        for category in report:
            category_id = str(category.get("category_id") or "")
            category_name = category.get("category_name") or ""
            if not category_id:
                continue

            for date_str, day in (category.get("occupancy") or {}).items():
                try:
                    report_date  = date.fromisoformat(date_str) if isinstance(date_str, str) else date_str
                    available    = int(day.get("available",    0) or 0)
                    occupied     = int(day.get("occupied",     0) or 0)
                    maintenance  = int(day.get("maintenance",  0) or 0)
                    allotted     = int(day.get("allotted",     0) or 0)
                    revenue_gross = float(day.get("revenue_gross", 0) or 0)
                    revenue_net   = day.get("revenue_net")
                    if revenue_net is None:
                        revenue_net = revenue_gross / (1 + vat) if vat else revenue_gross
                    occupancy_pct = (occupied / available * 100) if available > 0 else 0

                    result = await _save_occupancy_snapshot(
                        db, category_id, category_name, report_date,
                        occupied, available, maintenance, allotted,
                        revenue_gross, revenue_net, occupancy_pct
                    )
                    if result == 'inserted':
                        inserted += 1
                    else:
                        verified += 1

                except Exception as e:
                    logger.warning(f"Skipping occupancy row {category_id}/{date_str}: {e}")
                    await db.rollback()

        await db.commit()
        logger.info(f"Occupancy sync complete: {inserted} new snapshots, {verified} unchanged")
        return inserted + verified