from __future__ import annotations

import logging
from datetime import datetime, timezone

import pytz
from telegram import Bot

from bot.models.database import Session
from bot.models.reminder import Reminder, ReminderLog
from bot.utils.holiday import is_holiday
from bot.utils.keyboards import reminder_action_keyboard

logger = logging.getLogger(__name__)


async def execute_reminder(reminder_id: int, bot: Bot) -> None:
    """Send a reminder message. Called by APScheduler."""
    session = Session()
    try:
        reminder = session.get(Reminder, reminder_id)
        if reminder is None or not reminder.is_active:
            return

        now_utc = datetime.now(timezone.utc)
        tz = pytz.timezone("Asia/Shanghai")
        now_local = now_utc.astimezone(tz)

        # Skip on holidays if requested
        if reminder.skip_holidays and is_holiday(now_local.date()):
            logger.info("Skipping reminder %d on holiday", reminder_id)
            return

        # Send the reminder
        await _send_reminder_message(reminder, bot, session, now_utc, now_local)

    except Exception:
        logger.exception("Error executing reminder %d", reminder_id)
        session.rollback()
    finally:
        Session.remove()


async def _send_reminder_message(
    reminder: Reminder, bot: Bot, session, now_utc: datetime, now_local: datetime
) -> None:
    """Send a single reminder message."""
    # Build message
    text = _build_message(reminder)
    keyboard = reminder_action_keyboard(reminder.id)

    # Fetch the telegram_id from users table
    from bot.models.user import User  # avoid circular import at module level
    user_obj = session.get(User, reminder.user_id)
    if user_obj is None:
        return

    await bot.send_message(
        chat_id=user_obj.telegram_id,
        text=text,
        parse_mode="Markdown",
        reply_markup=keyboard,
    )

    # Update reminder timestamps
    reminder.last_sent_at = now_utc
    log = ReminderLog(reminder_id=reminder.id, sent_at=now_utc, status="sent")
    session.add(log)

    # Deactivate one-time reminders after firing
    if reminder.reminder_type == "once":
        reminder.is_active = False

    session.commit()
    logger.info("Sent reminder %d to user %d", reminder.id, user_obj.telegram_id)


def _build_message(reminder: Reminder) -> str:
    lines = [f"⏰ *{_escape(reminder.title)}*"]
    if reminder.description:
        lines.append(f"\n{_escape(reminder.description)}")
    lines.append(f"\n_类型：{reminder.type_display()}  |  {reminder.schedule_summary()}_")
    return "\n".join(lines)


def _escape(text: str) -> str:
    """Escape Markdown v1 special chars."""
    for ch in ["_", "*", "`", "["]:
        text = text.replace(ch, f"\\{ch}")
    return text