import logging
import os
from datetime import datetime, timezone

from apscheduler.schedulers.background import BackgroundScheduler
from tinydb import Query

from events.types.child_chore_confirmation import ChildChoreConfirmation
from events.types.child_reward_request import ChildRewardRequest
from events.types.event import Event
from events.types.event_types import EventType
from events.sse import send_event_to_user

logger = logging.getLogger(__name__)


def _get_today_start_timestamp(tz_str: str | None) -> float:
    """Return a Unix timestamp for the start of today (midnight) in the user's timezone."""
    try:
        if tz_str:
            from zoneinfo import ZoneInfo
            now_local = datetime.now(ZoneInfo(tz_str))
            today_local = now_local.replace(hour=0, minute=0, second=0, microsecond=0)
            return today_local.timestamp()
    except Exception:
        pass
    now_utc = datetime.now(timezone.utc)
    today_utc = now_utc.replace(hour=0, minute=0, second=0, microsecond=0)
    return today_utc.timestamp()


def expire_stale_pending_for_user(user_id: str, tz_str: str | None) -> int:
    """Delete stale pending confirmations for a user and fire SSE events.

    A record is stale if status='pending' and created_at is before the start of
    today in the user's timezone. Returns the number of records expired.
    Must be called within a Flask app context.
    """
    from db.db import pending_confirmations_db

    today_start = _get_today_start_timestamp(tz_str)
    PendingQ = Query()

    stale_items = pending_confirmations_db.search(
        (PendingQ.user_id == user_id) &
        (PendingQ.status == 'pending') &
        (PendingQ.created_at < today_start)
    )

    if not stale_items:
        return 0

    for item in stale_items:
        item_id = item.get('id')
        child_id = item.get('child_id')
        entity_id = item.get('entity_id')
        entity_type = item.get('entity_type')

        pending_confirmations_db.remove(PendingQ.id == item_id)

        if entity_type == 'chore':
            event = Event(
                EventType.CHILD_CHORE_CONFIRMATION.value,
                ChildChoreConfirmation(
                    child_id=child_id,
                    task_id=entity_id,
                    operation=ChildChoreConfirmation.OPERATION_RESET,
                )
            )
        else:
            event = Event(
                EventType.CHILD_REWARD_REQUEST.value,
                ChildRewardRequest(
                    child_id=child_id,
                    reward_id=entity_id,
                    operation=ChildRewardRequest.REQUEST_CANCELLED,
                )
            )

        send_event_to_user(user_id, event)
        logger.info(
            f'State expiry: expired {entity_type} {entity_id} for child {child_id} (user {user_id})'
        )

    return len(stale_items)


def run_state_expiry_check(app) -> None:
    """Check all verified users and expire stale pending records."""
    if os.environ.get('DB_ENV') == 'e2e':
        return

    with app.app_context():
        try:
            from db.db import users_db

            UserQ = Query()
            users = users_db.search(UserQ.verified == True)

            for user_dict in users:
                user_id = user_dict.get('id')
                tz_str = user_dict.get('timezone')
                try:
                    expired = expire_stale_pending_for_user(user_id, tz_str)
                    if expired:
                        logger.info(f'State expiry: expired {expired} record(s) for user {user_id}')
                except Exception as e:
                    logger.error(f'State expiry: failed for user {user_id}: {e}')

        except Exception as e:
            logger.error(f'Error in run_state_expiry_check: {e}')


def start_state_expiry_scheduler(app) -> BackgroundScheduler:
    """Start the hourly state expiry scheduler. Returns the scheduler instance."""
    scheduler = BackgroundScheduler()
    scheduler.add_job(
        run_state_expiry_check,
        'cron',
        minute=0,
        args=[app],
        id='state_expiry_scheduler',
        replace_existing=True,
    )
    scheduler.start()
    logger.info('State expiry scheduler started (hourly)')

    # Run immediately on startup to handle any records that expired while server was down
    run_state_expiry_check(app)

    return scheduler