"""PostgreSQL-only regression for simultaneous notice deletion/receipt submission."""
from concurrent.futures import ThreadPoolExecutor
from threading import Barrier

import pytest
from django.core.exceptions import ValidationError
from django.db import close_old_connections, connection

from apps.payments import services
from apps.payments.forms import ReceiptForm
from apps.payments.models import PaymentReceipt
from tests.test_payments import case, data, upload

pytestmark = [pytest.mark.django_db(transaction=True),
    pytest.mark.skipif(connection.vendor != 'postgresql', reason='Requires PostgreSQL row locks')]


def test_simultaneous_delete_and_receipt_allow_exactly_one_operation(case):
    form = ReceiptForm(data(case), {'receipt_image': upload()}, customer=case['customer'])
    assert form.is_valid(), form.errors
    barrier = Barrier(2)

    def operate(operation):
        close_old_connections()
        try:
            barrier.wait(timeout=10)
            try:
                if operation == 'delete':
                    services.delete_notice(case['creator'], case['notice'])
                else:
                    services.submit_receipt(case['customer'], case['customer'], form.cleaned_data)
                return operation
            except ValidationError:
                return 'blocked'
        finally:
            connection.close()

    with ThreadPoolExecutor(max_workers=2) as pool:
        outcomes = list(pool.map(operate, ['delete', 'receipt']))
    case['notice'].refresh_from_db()
    assert outcomes.count('blocked') == 1
    if case['notice'].deleted_at:
        assert not PaymentReceipt.objects.filter(notice=case['notice']).exists()
        assert 'delete' in outcomes
    else:
        assert PaymentReceipt.objects.filter(notice=case['notice']).count() == 1
        assert 'receipt' in outcomes