"""
Бизнес-логика отправки уведомлений для django-scheduler.

Функции:
- get_event_recipients - определение получателей уведомлений
- notify_event_created - уведомление о новом событии
- notify_event_changed - уведомление об изменении события
- notify_event_cancelled - уведомление об отмене события
"""

import logging

from django.contrib.auth import get_user_model
from django.contrib.contenttypes.models import ContentType

logger = logging.getLogger(__name__)

Employee = get_user_model()


def get_event_recipients(event) -> list:
    """
    Возвращает список получателей уведомлений для события django-scheduler.

    Args:
        event: Объект schedule.Event

    Returns:
        list: Список пользователей (Employee) с доступом к календарю события
    """
    from schedule.models import CalendarRelation

    if not event.calendar:
        return []

    # Получаем всех пользователей с доступом к календарю
    user_ct = ContentType.objects.get_for_model(Employee)
    relations = CalendarRelation.objects.filter(
        calendar=event.calendar, content_type=user_ct, object_id__isnull=False
    )

    # Собираем активных пользователей
    user_ids = relations.values_list("object_id", flat=True)
    recipients = list(Employee.objects.filter(id__in=user_ids, is_active=True))

    return recipients


def notify_event_created(event, creator=None):
    """
    Отправляет уведомления о новом событии всем участникам календаря.

    Args:
        event: Объект schedule.Event
        creator: Пользователь, создавший событие (исключается из получателей)
    """
    from scheduling.services import calendar_notification_enabled

    if not calendar_notification_enabled(event.calendar, "notify_event_created"):
        return

    try:
        from notifications.signals import notify

        from .config import (
            ActionURLs,
            MessageTemplates,
            NotificationVerbs,
            format_date,
        )

        recipients = get_event_recipients(event)

        # Исключаем создателя события
        if creator:
            recipients = [r for r in recipients if r.id != creator.id]

        if not recipients:
            return

        # Формируем сообщение
        event_date = format_date(event.start)
        calendar_name = event.calendar.name if event.calendar else None
        description = MessageTemplates.event_created(
            event.title, event_date, calendar_name
        )

        # Отправляем уведомления
        for recipient in recipients:
            notify.send(
                sender=creator,
                recipient=recipient,
                verb=NotificationVerbs.EVENT_CREATED,
                action_object=event,
                description=description,
                action_url=ActionURLs.CALENDAR,
                data={
                    "title": MessageTemplates.event_created_title(),
                    "event_id": event.id,
                    "event_title": event.title,
                    "event_start": (event.start.isoformat() if event.start else None),
                    "calendar_id": (event.calendar.id if event.calendar else None),
                    "calendar_name": calendar_name,
                    "creator_id": creator.id if creator else None,
                },
            )

        logger.info(
            "Schedule event creation notifications sent",
            extra={
                "event": "schedule.event.created_notifications_sent",
                "schedule_event_id": event.id,
                "recipient_count": len(recipients),
            },
        )

    except Exception as e:
        logger.exception(
            "Schedule event creation notifications failed",
            extra={
                "event": "schedule.event.created_notifications_failed",
                "schedule_event_id": getattr(event, "id", None),
                "error_type": type(e).__name__,
            },
        )


def notify_event_changed(event, changed_fields: list[str] = None, modifier=None):
    """
    Отправляет уведомления об изменении события.

    Args:
        event: Объект schedule.Event
        changed_fields: Список изменённых полей
        modifier: Пользователь, изменивший событие
    """
    from scheduling.services import calendar_notification_enabled

    if not calendar_notification_enabled(event.calendar, "notify_event_changed"):
        return

    try:
        from notifications.signals import notify

        from .config import (
            ActionURLs,
            MessageTemplates,
            NotificationVerbs,
            format_changes,
        )

        recipients = get_event_recipients(event)

        # Исключаем модификатора
        if modifier:
            recipients = [r for r in recipients if r.id != modifier.id]

        if not recipients:
            return

        # Формируем сообщение об изменениях
        changes_text = format_changes(changed_fields) if changed_fields else None
        description = MessageTemplates.event_changed(event.title, changes_text)

        # Отправляем уведомления
        for recipient in recipients:
            notify.send(
                sender=modifier,
                recipient=recipient,
                verb=NotificationVerbs.EVENT_CHANGED,
                action_object=event,
                description=description,
                action_url=ActionURLs.CALENDAR,
                data={
                    "title": MessageTemplates.event_changed_title(),
                    "event_id": event.id,
                    "event_title": event.title,
                    "changed_fields": changed_fields,
                    "event_start": event.start.isoformat() if event.start else None,
                    "calendar_id": event.calendar.id if event.calendar else None,
                    "modifier_id": modifier.id if modifier else None,
                },
            )

        logger.info(
            "Schedule event update notifications sent",
            extra={
                "event": "schedule.event.updated_notifications_sent",
                "schedule_event_id": event.id,
                "recipient_count": len(recipients),
                "changed_field_count": len(changed_fields or []),
            },
        )

    except Exception as e:
        logger.exception(
            "Schedule event update notifications failed",
            extra={
                "event": "schedule.event.updated_notifications_failed",
                "schedule_event_id": getattr(event, "id", None),
                "error_type": type(e).__name__,
            },
        )


def notify_event_cancelled(event, canceller=None):
    """
    Отправляет уведомления об отмене (удалении) события.

    Args:
        event: Объект schedule.Event
        canceller: Пользователь, отменивший событие
    """
    from scheduling.services import calendar_notification_enabled

    if not calendar_notification_enabled(event.calendar, "notify_event_cancelled"):
        return

    try:
        from notifications.signals import notify

        from .config import (
            ActionURLs,
            MessageTemplates,
            NotificationVerbs,
            format_date,
        )

        recipients = get_event_recipients(event)

        # Исключаем отменившего
        if canceller:
            recipients = [r for r in recipients if r.id != canceller.id]

        if not recipients:
            return

        # Формируем сообщение
        event_date = format_date(event.start)
        description = MessageTemplates.event_cancelled(event.title, event_date)

        # Отправляем уведомления
        for recipient in recipients:
            notify.send(
                sender=canceller,
                recipient=recipient,
                verb=NotificationVerbs.EVENT_CANCELLED,
                description=description,
                action_url=ActionURLs.CALENDAR,
                data={
                    "title": MessageTemplates.event_cancelled_title(),
                    "event_id": event.id,
                    "event_title": event.title,
                    "event_start": event.start.isoformat() if event.start else None,
                    "calendar_id": event.calendar.id if event.calendar else None,
                    "canceller_id": canceller.id if canceller else None,
                },
            )

        logger.info(
            "Schedule event cancellation notifications sent",
            extra={
                "event": "schedule.event.cancelled_notifications_sent",
                "schedule_event_id": event.id,
                "recipient_count": len(recipients),
            },
        )

    except Exception as e:
        logger.exception(
            "Schedule event cancellation notifications failed",
            extra={
                "event": "schedule.event.cancelled_notifications_failed",
                "schedule_event_id": getattr(event, "id", None),
                "error_type": type(e).__name__,
            },
        )