import datetime
import pytz

from decimal import Decimal
from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.test import TestCase
from django.utils import timezone

from registrasion import models as rego
from registrasion.controllers.cart import CartController
from registrasion.controllers.invoice import InvoiceController

from test_cart import RegistrationCartTestCase

UTC = pytz.timezone('UTC')


class InvoiceTestCase(RegistrationCartTestCase):

    def test_create_invoice(self):
        current_cart = CartController.for_user(self.USER_1)

        # Should be able to create an invoice after the product is added
        current_cart.add_to_cart(self.PROD_1, 1)
        invoice_1 = InvoiceController.for_cart(current_cart.cart)
        # That invoice should have a single line item
        line_items = rego.LineItem.objects.filter(invoice=invoice_1.invoice)
        self.assertEqual(1, len(line_items))
        # That invoice should have a value equal to cost of PROD_1
        self.assertEqual(self.PROD_1.price, invoice_1.invoice.value)

        # Adding item to cart should void all active invoices and produce
        # a new invoice
        current_cart.add_to_cart(self.PROD_2, 1)
        invoice_2 = InvoiceController.for_cart(current_cart.cart)
        self.assertNotEqual(invoice_1.invoice, invoice_2.invoice)
        # Invoice should have two line items
        line_items = rego.LineItem.objects.filter(invoice=invoice_2.invoice)
        self.assertEqual(2, len(line_items))
        # Invoice should have a value equal to cost of PROD_1 and PROD_2
        self.assertEqual(
            self.PROD_1.price + self.PROD_2.price,
            invoice_2.invoice.value)

    def test_create_invoice_fails_if_cart_invalid(self):
        self.make_ceiling("Limit ceiling", limit=1)
        self.set_time(datetime.datetime(2015, 01, 01, tzinfo=UTC))
        current_cart = CartController.for_user(self.USER_1)
        current_cart.add_to_cart(self.PROD_1, 1)

        self.add_timedelta(self.RESERVATION * 2)
        cart_2 = CartController.for_user(self.USER_2)
        cart_2.add_to_cart(self.PROD_1, 1)

        # Now try to invoice the first user
        with self.assertRaises(ValidationError):
            InvoiceController.for_cart(current_cart.cart)

    def test_paying_invoice_makes_new_cart(self):
        current_cart = CartController.for_user(self.USER_1)
        current_cart.add_to_cart(self.PROD_1, 1)

        invoice = InvoiceController.for_cart(current_cart.cart)
        invoice.pay("A payment!", invoice.invoice.value)

        # This payment is for the correct amount invoice should be paid.
        self.assertTrue(invoice.invoice.paid)

        # Cart should not be active
        self.assertFalse(invoice.invoice.cart.active)

        # Asking for a cart should generate a new one
        new_cart = CartController.for_user(self.USER_1)
        self.assertNotEqual(current_cart.cart, new_cart.cart)


    def test_invoice_includes_discounts(self):
        voucher = rego.Voucher.objects.create(
            recipient="Voucher recipient",
            code="VOUCHER",
            limit=1
        )
        voucher.save()
        discount = rego.VoucherDiscount.objects.create(
            description="VOUCHER RECIPIENT",
            voucher=voucher,
        )
        discount.save()
        rego.DiscountForProduct.objects.create(
            discount=discount,
            product=self.PROD_1,
            percentage=Decimal(50),
            quantity=1
        ).save()

        current_cart = CartController.for_user(self.USER_1)
        current_cart.apply_voucher(voucher)

        # Should be able to create an invoice after the product is added
        current_cart.add_to_cart(self.PROD_1, 1)
        invoice_1 = InvoiceController.for_cart(current_cart.cart)

        # That invoice should have two line items
        line_items = rego.LineItem.objects.filter(invoice=invoice_1.invoice)
        self.assertEqual(2, len(line_items))
        # That invoice should have a value equal to 50% of the cost of PROD_1
        self.assertEqual(self.PROD_1.price * Decimal("0.5"), invoice_1.invoice.value)