from django.test import TestCase
from datetime import date
from decimal import Decimal

from django.contrib.auth import get_user_model
from modules.invoicing.models import Invoice
from modules.invoicing.utils import generate_invoice_number
from modules.crm.models import Client


class UtilsTests(TestCase):
    def setUp(self):
        User = get_user_model()
        self.user = User.objects.create_user(username="creator", email="c@example.com", password="pass")
        self.client = Client.objects.create(name="Client Utils")

    def test_generate_invoice_number_increments(self):
        year = date.today().year
        Invoice.objects.create(
            invoice_number=f"INV-{year}-0001",
            creator=self.user,
            client=self.client,
            amount=Decimal("1.00"),
            due_date=date.today()
        )
        next_num = generate_invoice_number()
        # očekujemo INV-<year>-0002
        self.assertTrue(next_num.endswith("-0002"))