# backend/modules/task_management/services.py

from .models import Task
from rest_framework.exceptions import ValidationError
from django.core.exceptions import ValidationError as DjangoValidationError
import logging

logger = logging.getLogger(__name__)

class TaskService:
    @staticmethod
    def create_task_entry(data: dict, user=None) -> Task:
        """
        Univerzalna metoda: prihvaća podatke i opcionalnog korisnika.
        """
        # Poslovna pravila
        if data.get('status') == 'DONE' and (user and not user.is_staff):
            raise ValidationError({"status": "Samo admini mogu odmah označiti zadatak kao gotov."})

        payload = dict(data)
        if user and 'assigned_to' not in payload:
            payload['assigned_to'] = user

        entry = Task(**payload)
        try:
            entry.full_clean()
        except DjangoValidationError as exc:
            logger.error(f"Neuspješna validacija zadatka: {exc}")
            raise ValidationError(exc.message_dict if hasattr(exc, 'message_dict') else exc.messages)
        entry.save()
        logger.info(f"Zadatak uspješno kreiran: {entry.id}")
        return entry

    @staticmethod
    def update_task_entry(instance, data, user):
        # Validacija za update (npr. samo vlasnik ili admin smije ažurirati)
        if not user.is_staff and instance.assigned_to != user:
            raise ValidationError("Nemate dozvolu za izmjenu ovog zadatka.")
        
        # Spremanje
        for attr, value in data.items():
            setattr(instance, attr, value)
        try:
            instance.full_clean()
        except DjangoValidationError as exc:
            raise ValidationError(exc.message_dict if hasattr(exc, 'message_dict') else exc.messages)
        instance.save()
        return instance