using Grpc.Core;
using Grpc.Net.Client;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.TestHost;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System.Diagnostics;
using Xunit.Abstractions;

namespace TestGrpc.Test;

public class UnitTest1 : IntegrationTestBase
{
    public UnitTest1(GrpcTestFixture<Startup> fixture, ITestOutputHelper outputHelper)
        : base(fixture, outputHelper)
    {
    }

    [Fact]
    public async Task Test1()
    {
        // Arrange
        var client = new Greeter.GreeterClient(Channel);

        // Act
        using var response = client.DownloadFile(new FileRequest { FilePath = "Files/test.txt" });
        using var memoryStream = new MemoryStream();

        var receivedFileName = string.Empty;
        await foreach (var chunk in response.ResponseStream.ReadAllAsync())
        {
            if (!string.IsNullOrEmpty(chunk.FileName))
            {
                receivedFileName = chunk.FileName;
            }

            memoryStream.Write(chunk.Chunk.Span);
        }

        memoryStream.Seek(0, SeekOrigin.Begin);
        using var reader = new StreamReader(memoryStream);
        while (!reader.EndOfStream)
        {
            var line = await reader.ReadLineAsync();
            Console.WriteLine(line);
        }

        // Assert
        Assert.Equal("test.txt", receivedFileName);
    }
}

internal class ForwardingLoggerProvider : ILoggerProvider
{
    private readonly LogMessage _logAction;

    public ForwardingLoggerProvider(LogMessage logAction)
    {
        _logAction = logAction;
    }

    public ILogger CreateLogger(string categoryName)
    {
        return new ForwardingLogger(categoryName, _logAction);
    }

    public void Dispose()
    {
    }

    internal class ForwardingLogger : ILogger
    {
        private readonly string _categoryName;
        private readonly LogMessage _logAction;

        public ForwardingLogger(string categoryName, LogMessage logAction)
        {
            _categoryName = categoryName;
            _logAction = logAction;
        }

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

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

        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
        {
            _logAction(logLevel, _categoryName, eventId, formatter(state, exception), exception);
        }
    }
}

internal class GrpcTestContext<TStartup> : IDisposable where TStartup : class
{
    private readonly Stopwatch _stopwatch;
    private readonly GrpcTestFixture<TStartup> _fixture;
    private readonly ITestOutputHelper _outputHelper;

    public GrpcTestContext(GrpcTestFixture<TStartup> fixture, ITestOutputHelper outputHelper)
    {
        _stopwatch = Stopwatch.StartNew();
        _fixture = fixture;
        _outputHelper = outputHelper;
        _fixture.LoggedMessage += WriteMessage;
    }

    private void WriteMessage(LogLevel logLevel, string category, EventId eventId, string message, Exception? exception)
    {
        var log = $"{_stopwatch.Elapsed.TotalSeconds:N3}s {category} - {logLevel}: {message}";
        if (exception != null)
        {
            log += Environment.NewLine + exception.ToString();
        }
        _outputHelper.WriteLine(log);
    }

    public void Dispose()
    {
        _fixture.LoggedMessage -= WriteMessage;
    }
}

public delegate void LogMessage(LogLevel logLevel, string categoryName, EventId eventId, string message, Exception? exception);

public class GrpcTestFixture<TStartup> : IDisposable where TStartup : class
{
    private TestServer? _server;
    private IHost? _host;
    private HttpMessageHandler? _handler;
    private Action<IWebHostBuilder>? _configureWebHost;

    public event LogMessage? LoggedMessage;

    public GrpcTestFixture()
    {
        LoggerFactory = new LoggerFactory();
        LoggerFactory.AddProvider(new ForwardingLoggerProvider((logLevel, category, eventId, message, exception) =>
        {
            LoggedMessage?.Invoke(logLevel, category, eventId, message, exception);
        }));
    }

    public void ConfigureWebHost(Action<IWebHostBuilder> configure)
    {
        _configureWebHost = configure;
    }

    private void EnsureServer()
    {
        if (_host == null)
        {
            var builder = new HostBuilder()
                .ConfigureServices(services =>
                {
                    services.AddSingleton<ILoggerFactory>(LoggerFactory);
                })
                .ConfigureWebHostDefaults(webHost =>
                {
                    webHost
                        .UseTestServer()
                        .UseStartup<TStartup>();

                    _configureWebHost?.Invoke(webHost);
                });
            _host = builder.Start();
            _server = _host.GetTestServer();
            _handler = _server.CreateHandler();
        }
    }

    public LoggerFactory LoggerFactory { get; }

    public HttpMessageHandler Handler
    {
        get
        {
            EnsureServer();
            return _handler!;
        }
    }

    public void Dispose()
    {
        _handler?.Dispose();
        _host?.Dispose();
        _server?.Dispose();
    }

    public IDisposable GetTestContext(ITestOutputHelper outputHelper)
    {
        return new GrpcTestContext<TStartup>(this, outputHelper);
    }
}

public class IntegrationTestBase : IClassFixture<GrpcTestFixture<Startup>>, IDisposable
{
    private GrpcChannel? _channel;
    private IDisposable? _testContext;

    protected GrpcTestFixture<Startup> Fixture { get; set; }

    protected ILoggerFactory LoggerFactory => Fixture.LoggerFactory;

    protected GrpcChannel Channel => _channel ??= CreateChannel();

    protected GrpcChannel CreateChannel()
    {
        return GrpcChannel.ForAddress("http://localhost", new GrpcChannelOptions
        {
            LoggerFactory = LoggerFactory,
            HttpHandler = Fixture.Handler
        });
    }

    public IntegrationTestBase(GrpcTestFixture<Startup> fixture, ITestOutputHelper outputHelper)
    {
        Fixture = fixture;
        _testContext = Fixture.GetTestContext(outputHelper);
    }

    public void Dispose()
    {
        _testContext?.Dispose();
        _channel = null;
    }
}