// ==========================================================================
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex UG (haftungsbeschraenkt)
//  All rights reserved. Licensed under the MIT license.
// ==========================================================================

using FakeItEasy;
using Xunit;

namespace Squidex.Infrastructure.EventSourcing
{
    public class RetrySubscriptionTests
    {
        private readonly IEventStore eventStore = A.Fake<IEventStore>();
        private readonly IEventSubscriber<StoredEvent> eventSubscriber = A.Fake<IEventSubscriber<StoredEvent>>();
        private readonly IEventSubscription eventSubscription = A.Fake<IEventSubscription>();
        private readonly IEventSubscriber<StoredEvent> sutSubscriber;
        private readonly RetrySubscription<StoredEvent> sut;

        public RetrySubscriptionTests()
        {
            A.CallTo(() => eventStore.CreateSubscription(A<IEventSubscriber<StoredEvent>>._, A<string>._, A<string>._))
                .Returns(eventSubscription);

            sut = new RetrySubscription<StoredEvent>(eventSubscriber, s => eventStore.CreateSubscription(s)) { ReconnectWaitMs = 50 };
            sutSubscriber = sut;
        }

        [Fact]
        public void Should_subscribe_after_constructor()
        {
            sut.Dispose();

            A.CallTo(() => eventStore.CreateSubscription(sut, A<string>._, A<string>._))
                .MustHaveHappened();
        }

        [Fact]
        public async Task Should_reopen_subscription_once_if_exception_is_retrieved()
        {
            var ex = new InvalidOperationException();

            await OnErrorAsync(eventSubscription, ex, times: 1);

            await Task.Delay(1000);

            sut.Dispose();

            A.CallTo(() => eventSubscription.Dispose())
                .MustHaveHappened(2, Times.Exactly);

            A.CallTo(() => eventStore.CreateSubscription(A<IEventSubscriber<StoredEvent>>._, A<string>._, A<string>._))
                .MustHaveHappened(2, Times.Exactly);

            A.CallTo(() => eventSubscriber.OnErrorAsync(eventSubscription, A<Exception>._))
                .MustNotHaveHappened();
        }

        [Fact]
        public async Task Should_forward_error_from_inner_subscription_if_failed_often()
        {
            var ex = new InvalidOperationException();

            await OnErrorAsync(eventSubscription, ex, times: 6);

            sut.Dispose();

            A.CallTo(() => eventSubscriber.OnErrorAsync(sut, ex))
                .MustHaveHappened();
        }

        [Fact]
        public async Task Should_ignore_operation_cancelled_error_from_inner_subscription_if_failed_often()
        {
            var ex = new OperationCanceledException();

            await OnErrorAsync(eventSubscription, ex, times: 6);

            sut.Dispose();

            A.CallTo(() => eventSubscriber.OnErrorAsync(sut, ex))
                .MustNotHaveHappened();
        }

        [Fact]
        public async Task Should_not_forward_error_if_exception_is_raised_after_unsubscribe()
        {
            var ex = new InvalidOperationException();

            await OnErrorAsync(eventSubscription, ex, times: 1);

            sut.Dispose();

            A.CallTo(() => eventSubscriber.OnErrorAsync(eventSubscription, A<Exception>._))
                .MustNotHaveHappened();
        }

        [Fact]
        public async Task Should_forward_event_from_inner_subscription()
        {
            var @event = new StoredEvent("Stream", "1", 2, new EventData("Type", new EnvelopeHeaders(), "Payload"));

            await OnNextAsync(eventSubscription, @event);

            sut.Dispose();

            A.CallTo(() => eventSubscriber.OnNextAsync(sut, @event))
                .MustHaveHappened();
        }

        [Fact]
        public async Task Should_not_forward_event_if_message_is_from_another_subscription()
        {
            var @event = new StoredEvent("Stream", "1", 2, new EventData("Type", new EnvelopeHeaders(), "Payload"));

            await OnNextAsync(A.Fake<IEventSubscription>(), @event);

            sut.Dispose();

            A.CallTo(() => eventSubscriber.OnNextAsync(A<IEventSubscription>._, A<StoredEvent>._))
                .MustNotHaveHappened();
        }

        [Fact]
        public async Task Should_be_able_to_unsubscribe_within_exception_handler()
        {
            var ex = new InvalidOperationException();

            A.CallTo(() => eventSubscriber.OnErrorAsync(A<IEventSubscription>._, A<Exception>._))
                .Invokes(() => sut.Dispose());

            await OnErrorAsync(eventSubscription, ex, times: 6);

            Assert.False(sut.IsSubscribed);
        }

        [Fact]
        public async Task Should_be_able_to_unsubscribe_within_event_handler()
        {
            var @event = new StoredEvent("Stream", "1", 2, new EventData("Type", new EnvelopeHeaders(), "Payload"));

            A.CallTo(() => eventSubscriber.OnNextAsync(A<IEventSubscription>._, A<StoredEvent>._))
                .Invokes(() => sut.Dispose());

            await OnNextAsync(eventSubscription, @event);

            Assert.False(sut.IsSubscribed);
        }

        private async ValueTask OnErrorAsync(IEventSubscription subscriber, Exception ex, int times)
        {
            for (var i = 0; i < times; i++)
            {
                await sutSubscriber.OnErrorAsync(subscriber, ex);
            }
        }

        private ValueTask OnNextAsync(IEventSubscription subscriber, StoredEvent ev)
        {
            return sutSubscriber.OnNextAsync(subscriber, ev);
        }
    }
}