using AsbCloudInfrastructure.Background;
using Microsoft.Extensions.DependencyInjection;
using NSubstitute;
using System;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using Xunit;

namespace AsbCloudWebApi.Tests.Services;

public class BackgroundWorkerTest
{
    private IServiceProvider provider;
    private BackgroundWorker service;

    public BackgroundWorkerTest()
    {
        provider = Substitute.For<IServiceProvider, ISupportRequiredService>();
        var serviceScope = Substitute.For<IServiceScope>();
        var serviceScopeFactory = Substitute.For<IServiceScopeFactory>();
        serviceScopeFactory.CreateScope().Returns(serviceScope);
        ((ISupportRequiredService)provider).GetRequiredService(typeof(IServiceScopeFactory)).Returns(serviceScopeFactory);

        service = new BackgroundWorker(provider);        
        typeof(BackgroundWorker)
            .GetField("minDelay", BindingFlags.NonPublic | BindingFlags.Instance)
            .SetValue(service, TimeSpan.FromMilliseconds(1));
    }

    [Fact]
    public async Task Enqueue_n_works()
    {
        var workCount = 10;
        var result = 0;
        Task workAction(string id, IServiceProvider services, Action<string, double?> callback, CancellationToken token)
        {
            result++;
            return Task.Delay(1);
        }

        //act
        for (int i = 0; i < workCount; i++)
        {
            var work = Work.CreateByDelegate(i.ToString(), workAction);
            service.Enqueue(work);
        }

        await service.ExecuteTask;

        //assert
        Assert.Equal(workCount, result);
    }

    [Fact]
    public async Task Enqueue_continues_after_exceptions()
    {
        var expectadResult = 42;
        var result = 0;

        Task workAction(string id, IServiceProvider services, Action<string, double?> callback, CancellationToken token)
        {
            result = expectadResult;
            return Task.CompletedTask;
        }
        var goodWork = Work.CreateByDelegate("", workAction);

        Task failAction(string id, IServiceProvider services, Action<string, double?> callback, CancellationToken token)
            => throw new Exception();

        var badWork = Work.CreateByDelegate("", failAction);
        badWork.OnErrorAsync = (id, exception, token) => throw new Exception();

        //act
        service.Enqueue(badWork);
        service.Enqueue(goodWork);
        
        await service.ExecuteTask;

        //assert
        Assert.Equal(expectadResult, result);
        Assert.Equal(1, service.Felled.Count);
        Assert.Equal(1, service.Done.Count);
    }

    [Fact]
    public async Task TryRemove()
    {
        var workCount = 5;
        var result = 0;
        Task workAction(string id, IServiceProvider services, Action<string, double?> callback, CancellationToken token)
        {
            result++;
            return Task.Delay(10);
        }

        //act
        for (int i = 0; i < workCount; i++)
        {
            var work = Work.CreateByDelegate(i.ToString(), workAction);
            service.Enqueue(work);
        }

        var removed = service.TryRemoveFromQueue((workCount - 1).ToString());

        await service.ExecuteTask;

        //assert
        Assert.True(removed);
        Assert.Equal(workCount - 1, result);
        Assert.Equal(workCount - 1, service.Done.Count);
    }
}