# backend/modules/invoicing/views.py

import logging
from rest_framework import viewsets, permissions, status
from rest_framework.response import Response
from rest_framework.exceptions import ValidationError

from .models import InvoiceTransaction, Invoice
from .serializers import InvoiceSerializer, InvoiceTransactionSerializer
from .services import InvoiceService

# Postavljanje loggera za modul
logger = logging.getLogger(__name__)

class InvoiceViewSet(viewsets.ModelViewSet):
    queryset = Invoice.objects.all().select_related('client', 'creator')
    serializer_class = InvoiceSerializer
    permission_classes = [permissions.IsAuthenticated]

    def perform_create(self, serializer):
        validated_data = serializer.validated_data
    
        # 2. Delegiraj SVE servisu
        from .services import InvoiceService
        invoice_instance = InvoiceService.create_full_invoice(
            user=self.request.user, 
            **validated_data
        )

        serializer.instance = invoice_instance
    
    def get_queryset(self):
        """
        Filtriraj samo aktivne zapise
        """
        # Korisnik vidi samo fakture koje je on kreirao 
        # (ili koje su povezane s njegovim profilom, ako si klijent)
        if self.request.user.is_staff:
            return Invoice.objects.all()
        return Invoice.objects.filter(creator=self.request.user, is_active=True)

class InvoiceTransactionEntryViewSet(viewsets.ModelViewSet):
    """
    ViewSet za upravljanje financijskim zapisima.
    Korištenjem InvoiceService-a, ViewSet ostaje lagan i fokusiran samo na HTTP sloj.
    """
    queryset = InvoiceTransaction.objects.filter(is_active=True).select_related('invoice', 'work_order').order_by('-created_at')
    serializer_class = InvoiceTransactionSerializer
    permission_classes = [permissions.IsAuthenticated]

    def perform_create(self, serializer):
        """
        Presrećemo proces kreiranja kako bismo koristili InvoiceService.
        """
        try:
            # Proslijeđujemo validirane podatke i korisnika u servis
            InvoiceService.create_invoice_entry(
                data=serializer.validated_data, 
                user=self.request.user
            )
        except ValidationError as e:
            # Ponovno podižemo iznimku kako bi DRF ispravno vratio 400 Bad Request
            logger.warning(f"Validacijska greška pri kreiranju računa od strane {self.request.user}: {e}")
            raise e
        except Exception as e:
            logger.error(f"Kritična greška pri kreiranju financijskog zapisa: {str(e)}", exc_info=True)
            raise ValidationError({"error": "Došlo je do greške prilikom spremanja zapisa."})

    def perform_destroy(self, instance):
        """
        Umjesto fizičkog brisanja, radimo soft-delete ako je potrebno.
        """
        instance.is_active = False
        instance.save()
        logger.info(f"Financijski zapis {instance.id} je deaktiviran od strane {self.request.user}")