import pytest
from django.core.exceptions import ValidationError
from modules.fleet.models import Vehicle 
from django.contrib.auth import get_user_model

@pytest.mark.django_db
def test_vehicle_servicer_one_to_one_constraint(test_user):
    
    # Prvo vozilo prolazi
    Vehicle.objects.create(registration_number="ZG-111-AA", assigned_servicer=test_user)
    
    # Drugo vozilo za istog servisera mora baciti IntegrityError
    with pytest.raises(Exception): # Django IntegrityError
        Vehicle.objects.create(registration_number="ZG-222-BB", assigned_servicer=test_user)

@pytest.mark.django_db
def test_vehicle_next_service_logic():
    # current=12000, interval=15000 -> next_service_at = 15000
    vehicle = Vehicle.objects.create(
        registration_number="ZG-001", 
        current_mileage=12000, 
        service_interval_km=15000
    )
    assert vehicle.next_service_at() == 15000
    
    # current=16000, interval=15000 -> next_service_at = 30000
    vehicle.current_mileage = 16000
    assert vehicle.next_service_at() == 30000