"""Booking service — async layer between handlers and DB."""
from app.db.postgres import PostgresDB
from app.db.memory import (
    create_booking as json_create_booking,
    get_busy_times as json_get_busy_times,
    get_user_bookings as json_get_user_bookings,
    cancel_booking as json_cancel_booking,
    update_booking as json_update_booking,
    load_bookings as json_load_bookings,
    save_bookings as json_save_bookings,
    USE_POSTGRES,
)
from app.logger import logger


async def create_booking(user_id, service, master, date, time, user_name=""):
    if USE_POSTGRES:
        booking = await PostgresDB.create_booking(user_id, service, master, date, time, user_name)
        return {"id": booking["id"], "user_id": booking["user_id"], "service": booking["service"],
                "master": booking["master"], "date": booking["date"], "time": booking["time"],
                "status": booking["status"]}
    return json_create_booking(user_id, service, master, date, time, user_name)


async def get_busy_times(master, date):
    if USE_POSTGRES:
        return await PostgresDB.get_busy_times(master, date)
    return json_get_busy_times(master, date)


async def get_user_bookings(user_id):
    if USE_POSTGRES:
        bookings = await PostgresDB.get_user_bookings(user_id)
        return [{"id": b["id"], "user_id": b["user_id"], "service": b["service"],
                  "master": b["master"], "date": b["date"], "time": b["time"],
                  "status": b["status"]} for b in bookings]
    return json_get_user_bookings(user_id)


async def cancel_booking(booking_id):
    if USE_POSTGRES:
        return await PostgresDB.cancel_booking(booking_id)
    return json_cancel_booking(booking_id)


async def update_booking(booking_id, service, master, date, time):
    if USE_POSTGRES:
        result = await PostgresDB.update_booking(booking_id, service, master, date, time)
        if result:
            return {"id": result["id"], "service": result["service"], "master": result["master"],
                    "date": result["date"], "time": result["time"]}
        return None
    return json_update_booking(booking_id, service, master, date, time)


async def is_slot_busy(master, date, time):
    busy = await get_busy_times(master, date)
    return time in busy


async def cleanup_cancelled():
    """Remove cancelled bookings older than the head (keep only last 5 cancelled per user)."""
    if USE_POSTGRES:
        # Postgres handles this with status column, no cleanup needed
        pass
    else:
        bookings = json_load_bookings()
        active = [b for b in bookings if b["status"] == "active"]
        cancelled = [b for b in bookings if b["status"] == "cancelled"]
        from collections import defaultdict
        by_user = defaultdict(list)
        for b in cancelled:
            by_user[b["user_id"]].append(b)
        keep_ids = set()
        for uid, user_cancel in by_user.items():
            user_cancel.sort(key=lambda x: x.get("id", 0), reverse=True)
            for b in user_cancel[:5]:
                keep_ids.add(b["id"])
        bookings = active + [b for b in cancelled if b["id"] in keep_ids]
        json_save_bookings(bookings)
        removed = len(cancelled) - len(keep_ids)
        if removed > 0:
            logger.info("Cleaned up {n} old cancelled bookings", n=removed)