// ==========================================================================
//  EventReceiverTests.cs
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex Group
//  All rights reserved.
// ==========================================================================

using System;
using System.Collections.Generic;
using System.Reactive.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using Moq;
using Squidex.Infrastructure.Tasks;
using Xunit;

// ReSharper disable UnusedAutoPropertyAccessor.Local

namespace Squidex.Infrastructure.CQRS.Events
{
    public class EventReceiverTests : IDisposable
    {
        public sealed class MyEvent : IEvent
        {
        }

        private sealed class MyEventConsumerInfo : IEventConsumerInfo
        {
            public long LastHandledEventNumber { get; set; }

            public bool IsStopped { get; set; }

            public bool IsResetting { get; set; }

            public string Name { get; set; }

            public string Error { get; set; }
        }

        private sealed class MyLogger : ILogger<EventReceiver>
        {
            public Dictionary<LogLevel, int> LogCount { get; } = new Dictionary<LogLevel, int>();

            public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatterr)
            {
                var count = LogCount.GetOrDefault(logLevel);

                LogCount[logLevel] = count + 1;
            }

            public bool IsEnabled(LogLevel logLevel)
            {
                return false;
            }

            public IDisposable BeginScope<TState>(TState state)
            {
                return null;
            }
        }

        private readonly Mock<IEventConsumerInfoRepository> eventConsumerInfoRepository = new Mock<IEventConsumerInfoRepository>();
        private readonly Mock<IEventConsumer> eventConsumer = new Mock<IEventConsumer>();
        private readonly Mock<IEventNotifier> eventNotifier = new Mock<IEventNotifier>();
        private readonly Mock<IEventStore> eventStore = new Mock<IEventStore>();
        private readonly Mock<EventDataFormatter> formatter = new Mock<EventDataFormatter>(new TypeNameRegistry(), null);
        private readonly EventData eventData1 = new EventData();
        private readonly EventData eventData2 = new EventData();
        private readonly EventData eventData3 = new EventData();
        private readonly Envelope<IEvent> envelope1 = new Envelope<IEvent>(new MyEvent());
        private readonly Envelope<IEvent> envelope2 = new Envelope<IEvent>(new MyEvent());
        private readonly Envelope<IEvent> envelope3 = new Envelope<IEvent>(new MyEvent());
        private readonly EventReceiver sut;
        private readonly MyLogger logger = new MyLogger();
        private readonly StoredEvent[] events;
        private readonly MyEventConsumerInfo consumerInfo = new MyEventConsumerInfo();
        private readonly string consumerName;

        public EventReceiverTests()
        {
            events = new[]
            {
                new StoredEvent(3, 3, eventData1),
                new StoredEvent(4, 4, eventData2),
                new StoredEvent(4, 4, eventData3)
            };

            consumerName = eventConsumer.Object.GetType().Name;

            eventStore.Setup(x => x.GetEventsAsync(2)).Returns(events.ToObservable());

            eventConsumerInfoRepository.Setup(x => x.FindAsync(consumerName)).Returns(Task.FromResult<IEventConsumerInfo>(consumerInfo));

            formatter.Setup(x => x.Parse(eventData1)).Returns(envelope1);
            formatter.Setup(x => x.Parse(eventData2)).Returns(envelope2);
            formatter.Setup(x => x.Parse(eventData3)).Returns(envelope3);

            sut = new EventReceiver(formatter.Object, eventStore.Object, eventNotifier.Object, eventConsumerInfoRepository.Object, logger);
        }

        public void Dispose()
        {
            sut.Dispose();
        }

        [Fact]
        public void Should_only_connect_once()
        {
            sut.Subscribe(eventConsumer.Object);
            sut.Subscribe(eventConsumer.Object);

            eventConsumerInfoRepository.Verify(x => x.CreateAsync(consumerName), Times.Once());
        }

        [Fact]
        public async Task Should_subscribe_to_consumer_and_handle_events()
        {
            consumerInfo.LastHandledEventNumber = 2L;
            
            sut.Subscribe(eventConsumer.Object);

            await Task.Delay(20);

            Assert.Equal(1, logger.LogCount.Count);
            Assert.Equal(6, logger.LogCount[LogLevel.Debug]);

            eventConsumer.Verify(x => x.On(envelope1), Times.Once());
            eventConsumer.Verify(x => x.On(envelope2), Times.Once());
            eventConsumer.Verify(x => x.On(envelope3), Times.Once());
        }

        [Fact]
        public async Task Should_abort_if_handling_failed()
        {
            consumerInfo.LastHandledEventNumber = 2L;

            eventConsumer.Setup(x => x.On(envelope1)).Returns(TaskHelper.True);
            eventConsumer.Setup(x => x.On(envelope2)).Throws(new InvalidOperationException());

            sut.Subscribe(eventConsumer.Object);

            await Task.Delay(20);

            Assert.Equal(2, logger.LogCount.Count);
            Assert.Equal(2, logger.LogCount[LogLevel.Error]);
            Assert.Equal(3, logger.LogCount[LogLevel.Debug]);

            eventConsumer.Verify(x => x.On(envelope1), Times.Once());
            eventConsumer.Verify(x => x.On(envelope2), Times.Once());
            eventConsumer.Verify(x => x.On(envelope3), Times.Never());

            eventConsumerInfoRepository.Verify(x => x.StopAsync(consumerName, It.IsAny<string>()), Times.Once());
        }

        [Fact]
        public async Task Should_abort_if_serialization_failed()
        {
            consumerInfo.LastHandledEventNumber = 2L;

            formatter.Setup(x => x.Parse(eventData2)).Throws(new InvalidOperationException());

            sut.Subscribe(eventConsumer.Object);

            await Task.Delay(20);

            Assert.Equal(2, logger.LogCount.Count);
            Assert.Equal(2, logger.LogCount[LogLevel.Error]);
            Assert.Equal(2, logger.LogCount[LogLevel.Debug]);

            eventConsumer.Verify(x => x.On(envelope1), Times.Once());
            eventConsumer.Verify(x => x.On(envelope2), Times.Never());
            eventConsumer.Verify(x => x.On(envelope3), Times.Never());

            eventConsumerInfoRepository.Verify(x => x.StopAsync(consumerName, It.IsAny<string>()), Times.Once());
        }

        [Fact]
        public async Task Should_reset_if_requested()
        {
            consumerInfo.IsResetting = true;
            consumerInfo.LastHandledEventNumber = 2L;
            
            eventStore.Setup(x => x.GetEventsAsync(-1)).Returns(events.ToObservable());

            sut.Subscribe(eventConsumer.Object);

            await Task.Delay(20);

            Assert.Equal(1, logger.LogCount.Count);
            Assert.Equal(8, logger.LogCount[LogLevel.Debug]);

            eventConsumer.Verify(x => x.On(envelope1), Times.Once());
            eventConsumer.Verify(x => x.On(envelope2), Times.Once());
            eventConsumer.Verify(x => x.On(envelope3), Times.Once());

            eventConsumer.Verify(x => x.ClearAsync(), Times.Once());
        }
    }
}