"""
daemon.py - Background polling loop for scheduled tasks

Override poll_callback() with your domain-specific logic.
"""

import os
import time
import logging
from datetime import datetime, timezone, timedelta

import core.postgres as postgres
import core.notifications as notifications

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

POLL_INTERVAL = int(os.environ.get("POLL_INTERVAL", 60))


def _user_now_for(user_uuid):
    """Get current datetime in a user's timezone using their stored offset."""
    prefs = postgres.select_one("user_preferences", {"user_uuid": user_uuid})
    offset_minutes = 0
    if prefs and prefs.get("timezone_offset") is not None:
        offset_minutes = prefs["timezone_offset"]
    # JS getTimezoneOffset: positive = behind UTC, so negate
    tz_obj = timezone(timedelta(minutes=-offset_minutes))
    return datetime.now(tz_obj)


def check_medication_reminders():
    """Check for medications due now and send notifications."""
    try:
        from datetime import date as date_type

        meds = postgres.select("medications", where={"active": True})

        # Group by user so we only look up timezone once per user
        user_meds = {}
        for med in meds:
            uid = med.get("user_uuid")
            if uid not in user_meds:
                user_meds[uid] = []
            user_meds[uid].append(med)

        for user_uuid, user_med_list in user_meds.items():
            now = _user_now_for(user_uuid)
            current_time = now.strftime("%H:%M")
            current_day = now.strftime("%a").lower()
            today = now.date()
            today_str = today.isoformat()

            for med in user_med_list:
                freq = med.get("frequency", "daily")

                # Skip as_needed -- no scheduled reminders for PRN
                if freq == "as_needed":
                    continue

                # Day-of-week check for specific_days
                if freq == "specific_days":
                    med_days = med.get("days_of_week", [])
                    if current_day not in med_days:
                        continue

                # Interval check for every_n_days
                if freq == "every_n_days":
                    start = med.get("start_date")
                    interval = med.get("interval_days")
                    if start and interval:
                        start_d = (
                            start
                            if isinstance(start, date_type)
                            else datetime.strptime(str(start), "%Y-%m-%d").date()
                        )
                        if (today - start_d).days < 0 or (
                            today - start_d
                        ).days % interval != 0:
                            continue
                    else:
                        continue

                # Time check
                times = med.get("times", [])
                if current_time not in times:
                    continue

                # Already taken today? Check by created_at date
                logs = postgres.select(
                    "med_logs", where={"medication_id": med["id"], "action": "taken"}
                )
                already_taken = any(
                    log.get("scheduled_time") == current_time
                    and str(log.get("created_at", ""))[:10] == today_str
                    for log in logs
                )
                if already_taken:
                    continue

                user_settings = notifications.getNotificationSettings(user_uuid)
                if user_settings:
                    msg = f"Time to take {med['name']} ({med['dosage']} {med['unit']}) · {current_time}"
                    notifications._sendToEnabledChannels(
                        user_settings, msg, user_uuid=user_uuid
                    )
    except Exception as e:
        logger.error(f"Error checking medication reminders: {e}")


def check_routine_reminders():
    """Check for scheduled routines due now and send notifications."""
    try:
        schedules = postgres.select("routine_schedules", where={"remind": True})

        for schedule in schedules:
            routine = postgres.select_one("routines", {"id": schedule["routine_id"]})
            if not routine:
                continue

            now = _user_now_for(routine["user_uuid"])
            current_time = now.strftime("%H:%M")
            current_day = now.strftime("%a").lower()

            if current_time != schedule.get("time"):
                continue
            days = schedule.get("days", [])
            if current_day not in days:
                continue

            user_settings = notifications.getNotificationSettings(routine["user_uuid"])
            if user_settings:
                msg = f"Time to start your routine: {routine['name']}"
                notifications._sendToEnabledChannels(
                    user_settings, msg, user_uuid=routine["user_uuid"]
                )
    except Exception as e:
        logger.error(f"Error checking routine reminders: {e}")


def check_refills():
    """Check for medications running low on refills."""
    try:
        meds = postgres.select("medications")
        for med in meds:
            qty = med.get("quantity_remaining")
            if qty is not None and qty <= 7:
                user_settings = notifications.getNotificationSettings(med["user_uuid"])
                if user_settings:
                    msg = f"Low on {med['name']}: only {qty} doses remaining. Time to refill!"
                    notifications._sendToEnabledChannels(
                        user_settings, msg, user_uuid=med["user_uuid"]
                    )
    except Exception as e:
        logger.error(f"Error checking refills: {e}")


def poll_callback():
    """Called every POLL_INTERVAL seconds."""
    check_medication_reminders()
    check_routine_reminders()
    check_refills()


def daemon_loop():
    logger.info("Scheduler daemon starting")
    while True:
        try:
            poll_callback()
        except Exception as e:
            logger.error(f"Poll callback error: {e}")
        time.sleep(POLL_INTERVAL)


if __name__ == "__main__":
    daemon_loop()
