import logging
from datetime import datetime, timezone

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.chat.notice_inbox import post_notice_to_latest_chat
from app.db.models import Reminder
from app.reminders.notify import bump_notify_seq
from app.reminders.service import RECURRENCE_NONE, _advance_due, _format_local

logger = logging.getLogger(__name__)


def _utcnow() -> datetime:
    return datetime.now(timezone.utc)


def check_due_reminders(db: Session) -> int:
    now = _utcnow()
    stmt = (
        select(Reminder)
        .where(
            Reminder.enabled.is_(True),
            Reminder.completed_at.is_(None),
            Reminder.due_at <= now,
        )
        .order_by(Reminder.due_at.asc())
    )
    rows = list(db.scalars(stmt).all())
    fired = 0

    for row in rows:
        if row.last_fired_at and row.last_fired_at >= row.due_at:
            continue

        local_when = _format_local(row.due_at, row.timezone, all_day=row.all_day)
        notice = f"📅 **Напоминание** · {row.title}\n\n_{local_when}_"
        if row.notes:
            notice += f"\n{row.notes}"

        post_notice_to_latest_chat(notice)
        row.last_fired_at = now

        if row.recurrence == RECURRENCE_NONE:
            row.completed_at = now
            row.enabled = False
        else:
            row.due_at = _advance_due(row.due_at, row.recurrence)
            row.last_fired_at = None

        row.updated_at = now
        fired += 1

    if fired:
        db.commit()
        bump_notify_seq(db)
        logger.info("Reminders fired: %d", fired)

    return fired