"""Синхронизация Google Calendar → локальные Event. Запускается таймером."""
import fcntl
import os
from datetime import datetime, timezone, timedelta

from google.oauth2 import service_account
from googleapiclient.discovery import build
from sqlmodel import Session, select

from . import config
from .db import engine
from .models import Event

SCOPES = ['https://www.googleapis.com/auth/calendar.readonly']

_LOCK_PATH = "/tmp/morozovka-google-sync.lock"


def _try_lock():
    """Не даём двум копиям sync работать одновременно (таймер + ручной запуск)."""
    f = open(_LOCK_PATH, "w")
    try:
        fcntl.flock(f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
    except BlockingIOError:
        f.close()
        return None
    return f


def sync_google_calendar():
    lock = _try_lock()
    if lock is None:
        print("[Google Sync] Уже выполняется другой процесс, выходим.", flush=True)
        return

    try:
        _sync_locked()
    finally:
        try:
            fcntl.flock(lock.fileno(), fcntl.LOCK_UN)
            lock.close()
        except Exception:
            pass


def _sync_locked():
    print("[Google Sync] Начинаем синхронизацию...", flush=True)

    if not os.path.isfile(config.GOOGLE_CREDENTIALS_FILE):
        print(f"[Google Sync] Нет файла credentials: {config.GOOGLE_CREDENTIALS_FILE}", flush=True)
        return

    creds = service_account.Credentials.from_service_account_file(
        config.GOOGLE_CREDENTIALS_FILE, scopes=SCOPES)
    service = build('calendar', 'v3', credentials=creds)

    time_min = (datetime.now(timezone.utc) - timedelta(days=30)).isoformat()
    calendar_id = config.GOOGLE_CALENDAR_ID

    print(f"[Google Sync] Запрашиваем календарь: {calendar_id}", flush=True)
    events_result = service.events().list(
        calendarId=calendar_id,
        timeMin=time_min,
        maxResults=100,
        singleEvents=True,
        orderBy='startTime',
    ).execute()

    google_events = events_result.get('items', [])
    print(f"[Google Sync] Найдено событий в Google API: {len(google_events)}", flush=True)

    count = 0
    with Session(engine) as session:
        for g_event in google_events:
            g_id = g_event['id']

            start = g_event['start'].get('dateTime', g_event['start'].get('date'))
            end = g_event['end'].get('dateTime', g_event['end'].get('date'))
            if 'T' not in start:
                continue

            start_dt = datetime.fromisoformat(start.replace('Z', '+00:00'))
            end_dt = datetime.fromisoformat(end.replace('Z', '+00:00'))

            existing = session.exec(
                select(Event).where(Event.google_event_id == g_id)
            ).first()

            if existing:
                if getattr(existing, 'manually_edited', False):
                    continue
                existing.title = g_event.get('summary', 'Без названия')
                existing.start_time = start_dt
                existing.end_time = end_dt
                existing.location = g_event.get('location')
                existing.description = g_event.get('description')
                session.add(existing)
            else:
                session.add(Event(
                    google_event_id=g_id,
                    title=g_event.get('summary', 'Без названия'),
                    event_type='lecture',
                    start_time=start_dt,
                    end_time=end_dt,
                    location=g_event.get('location'),
                    description=g_event.get('description'),
                    is_public=True,
                ))
                count += 1

        session.commit()

    print(f"[Google Sync] Новых событий: {count}", flush=True)