import datetime
import pytz

from decimal import Decimal
from django.core.exceptions import ValidationError
from django.db import IntegrityError

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 VoucherTestCases(RegistrationCartTestCase):

    @classmethod
    def new_voucher(self, code="VOUCHER", limit=1):
        voucher = rego.Voucher.objects.create(
            recipient="Voucher recipient",
            code=code,
            limit=limit,
        )
        voucher.save()
        return voucher

    def test_apply_voucher(self):
        voucher = self.new_voucher()

        self.set_time(datetime.datetime(2015, 01, 01, tzinfo=UTC))

        cart_1 = CartController.for_user(self.USER_1)
        cart_1.apply_voucher(voucher.code)
        self.assertIn(voucher, cart_1.cart.vouchers.all())

        # Second user should not be able to apply this voucher (it's exhausted)
        cart_2 = CartController.for_user(self.USER_2)
        with self.assertRaises(ValidationError):
            cart_2.apply_voucher(voucher.code)

        # After the reservation duration
        # user 2 should be able to apply voucher
        self.add_timedelta(rego.Voucher.RESERVATION_DURATION * 2)
        cart_2.apply_voucher(voucher.code)
        cart_2.cart.active = False
        cart_2.cart.save()

        # After the reservation duration, user 1 should not be able to apply
        # voucher, as user 2 has paid for their cart.
        self.add_timedelta(rego.Voucher.RESERVATION_DURATION * 2)
        with self.assertRaises(ValidationError):
            cart_1.apply_voucher(voucher.code)

    def test_voucher_enables_item(self):
        voucher = self.new_voucher()

        enabling_condition = rego.VoucherEnablingCondition.objects.create(
            description="Voucher condition",
            voucher=voucher,
            mandatory=False,
        )
        enabling_condition.save()
        enabling_condition.products.add(self.PROD_1)
        enabling_condition.save()

        # Adding the product without a voucher will not work
        current_cart = CartController.for_user(self.USER_1)
        with self.assertRaises(ValidationError):
            current_cart.add_to_cart(self.PROD_1, 1)

        # Apply the voucher
        current_cart.apply_voucher(voucher.code)
        current_cart.add_to_cart(self.PROD_1, 1)

    def test_voucher_enables_discount(self):
        voucher = self.new_voucher()

        discount = rego.VoucherDiscount.objects.create(
            description="VOUCHER RECIPIENT",
            voucher=voucher,
        )
        discount.save()
        rego.DiscountForProduct.objects.create(
            discount=discount,
            product=self.PROD_1,
            percentage=Decimal(100),
            quantity=1
        ).save()

        # Having PROD_1 in place should add a discount
        current_cart = CartController.for_user(self.USER_1)
        current_cart.apply_voucher(voucher.code)
        current_cart.add_to_cart(self.PROD_1, 1)
        self.assertEqual(1, len(current_cart.cart.discountitem_set.all()))

    def test_voucher_codes_unique(self):
        self.new_voucher(code="VOUCHER")
        with self.assertRaises(IntegrityError):
            self.new_voucher(code="VOUCHER")

    def test_multiple_vouchers_work(self):
        self.new_voucher(code="VOUCHER1")
        self.new_voucher(code="VOUCHER2")

    def test_vouchers_case_insensitive(self):
        voucher = self.new_voucher(code="VOUCHeR")
        current_cart = CartController.for_user(self.USER_1)
        current_cart.apply_voucher(voucher.code.lower())

    def test_voucher_can_only_be_applied_once(self):
        voucher = self.new_voucher(limit=2)
        current_cart = CartController.for_user(self.USER_1)
        current_cart.apply_voucher(voucher.code)
        with self.assertRaises(ValidationError):
            current_cart.apply_voucher(voucher.code)

    def test_voucher_can_only_be_applied_once_across_multiple_carts(self):
        voucher = self.new_voucher(limit=2)
        current_cart = CartController.for_user(self.USER_1)
        current_cart.apply_voucher(voucher.code)

        inv = InvoiceController.for_cart(current_cart.cart)
        inv.pay("Hello!", inv.invoice.value)

        with self.assertRaises(ValidationError):
            current_cart.apply_voucher(voucher.code)