from django.test import TestCase
from django.contrib.auth import get_user_model
from datetime import date
from decimal import Decimal

from modules.crm.models import Client
from modules.invoicing.models import Invoice, InvoiceItem
from modules.invoicing.services import InvoiceService


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

    def test_create_full_invoice_creates_invoice_and_items(self):
        items = [
            {"description": "Item A", "quantity": Decimal("2.00"), "unit_price": Decimal("10.00")},
            {"description": "Item B", "quantity": Decimal("1.00"), "unit_price": Decimal("5.50")},
        ]
        validated_data = {
            "client": self.client,
            "due_date": date.today(),
            "items": items,
        }

        invoice = InvoiceService.create_full_invoice(user=self.creator, **validated_data)

        # Basic assertions
        self.assertIsInstance(invoice, Invoice)
        self.assertEqual(invoice.creator, self.creator)
        self.assertEqual(invoice.client, self.client)
        self.assertEqual(invoice.items.count(), 2)

        # Total should be 2*10 + 1*5.5 = 25.5
        self.assertEqual(invoice.amount, Decimal("25.50"))
        item_descriptions = [i.description for i in invoice.items.all()]
        self.assertIn("Item A", item_descriptions)
        self.assertIn("Item B", item_descriptions)