using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Emby.Server.Implementations;
using Emby.Server.Implementations.QuickConnect;
using Jellyfin.Server.Extensions;
using Jellyfin.Server.Helpers;
using Jellyfin.Server.Migrations.Stages;
using Jellyfin.Server.ServerSetupApp;
using Jellyfin.Server.Tests.HighAvailability;
using MediaBrowser.Common.Configuration;
using MediaBrowser.Common.Extensions;
using MediaBrowser.Controller.Net;
using MediaBrowser.Controller.QuickConnect;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using StackExchange.Redis;
using Xunit;

namespace Jellyfin.Server.Tests.QuickConnect;

/// <summary>
/// Brings the server up the way <c>Program</c> does - the real host over <see cref="Startup"/>, the
/// startup and core migrations, then <see cref="ApplicationHost.InitializeServices"/> - to pin down what
/// a pod does when the quick connect store it is configured against cannot be reached.
/// </summary>
[Trait("Category", "RequiresDocker")]
[Collection("JellyfinSectionConfiguration")]
public sealed class QuickConnectStartupTests : IAsyncLifetime
{
    private const string RedisConnectionStringVariable = "Jellyfin__TranscodeStore__RedisConnectionString";

    private RedisTestServer _redis = null!;

    /// <inheritdoc/>
    public async ValueTask InitializeAsync()
    {
        _redis = await RedisTestServer.StartAsync().ConfigureAwait(false);
    }

    /// <inheritdoc/>
    public async ValueTask DisposeAsync()
    {
        Environment.SetEnvironmentVariable(RedisConnectionStringVariable, null);
        await _redis.DisposeAsync().ConfigureAwait(false);
    }

    /// <summary>
    /// A configured but unreachable store stops the server coming up, so the outage is visible where the
    /// server is started instead of arriving later as a failure on every request that needs the store. The
    /// connection string carries the <c>abortConnect=false</c> a deployment uses, so the multiplexer
    /// connects lazily and only a real read settles whether the store can be served.
    /// </summary>
    [Fact]
    public void UnreachableStore_StopsStartup()
    {
        Environment.SetEnvironmentVariable(
            RedisConnectionStringVariable,
            "127.0.0.1:1,abortConnect=false,connectTimeout=250,connectRetry=0,syncTimeout=250");

        using var server = new StartupHarness();

        Assert.ThrowsAny<ServiceUnavailableException>(() => server.Services);
        Assert.Contains(
            server.CriticalEntries,
            entry => entry.Contains("Quick connect", StringComparison.Ordinal)
                && entry.Contains("UNREACHABLE", StringComparison.Ordinal)
                && entry.Contains("valkey", StringComparison.Ordinal));
    }

    /// <summary>
    /// A reachable store lets the server come up, and the quick connect it comes up with holds its
    /// requests in the shared store every instance reads.
    /// </summary>
    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
    [Fact]
    public async Task ReachableStore_StartsAndServesQuickConnect()
    {
        Environment.SetEnvironmentVariable(RedisConnectionStringVariable, _redis.ConnectionString);

        using var server = new StartupHarness();

        Assert.IsType<RedisQuickConnectStore>(server.Services.GetRequiredService<IQuickConnectStore>());

        var quickConnect = server.Services.GetRequiredService<IQuickConnect>();
        var request = await quickConnect.TryConnect(NewAuthorizationInfo());

        Assert.Equal(request.Code, (await quickConnect.CheckRequestStatus(request.Secret)).Code);

        await using var redis = await _redis.ConnectAsync();
        Assert.True(await redis.GetDatabase().KeyExistsAsync("jellyfin:quickconnect:request:" + request.Secret));
    }

    /// <summary>
    /// Without a connection string the deployment is single-instance, and it starts on the process-local
    /// store upstream uses.
    /// </summary>
    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
    [Fact]
    public async Task NoConnectionString_StartsOnTheProcessLocalStore()
    {
        Environment.SetEnvironmentVariable(RedisConnectionStringVariable, null);

        using var server = new StartupHarness();

        Assert.IsType<InMemoryQuickConnectStore>(server.Services.GetRequiredService<IQuickConnectStore>());

        var quickConnect = server.Services.GetRequiredService<IQuickConnect>();
        var request = await quickConnect.TryConnect(NewAuthorizationInfo());

        Assert.Equal(request.Code, (await quickConnect.CheckRequestStatus(request.Secret)).Code);
    }

    private static AuthorizationInfo NewAuthorizationInfo() => new AuthorizationInfo
    {
        DeviceId = Guid.NewGuid().ToString("N"),
        Device = "Living Room TV",
        Client = "Jellyfin Web",
        Version = "1.0.0"
    };

    private sealed class StartupHarness : WebApplicationFactory<Startup>
    {
        private readonly ConcurrentBag<IDisposable> _disposables = new();
        private readonly ConcurrentQueue<string> _criticalEntries = new();
        private readonly string _root = Path.Combine(
            Path.GetTempPath(),
            "jellyfin-quickconnect-startup",
            Path.GetRandomFileName());

        static StartupHarness()
        {
            StartupHelpers.PerformStaticInitialization();
        }

        public IReadOnlyCollection<string> CriticalEntries => _criticalEntries.ToArray();

        protected override IHostBuilder CreateHostBuilder() => new HostBuilder();

        protected override void ConfigureWebHost(IWebHostBuilder builder)
        {
            Environment.SetEnvironmentVariable("JELLYFIN_FFMPEG__NOVALIDATION", "true");

            var commandLineOpts = new StartupOptions();
            Directory.CreateDirectory(Path.Combine(_root, "logs"));
            Directory.CreateDirectory(Path.Combine(_root, "config"));
            Directory.CreateDirectory(Path.Combine(_root, "cache"));
            Directory.CreateDirectory(Path.Combine(_root, "jellyfin-web"));
            var appPaths = new ServerApplicationPaths(
                _root,
                Path.Combine(_root, "logs"),
                Path.Combine(_root, "config"),
                Path.Combine(_root, "cache"),
                Path.Combine(_root, "jellyfin-web"));

            StartupHelpers.InitLoggingConfigFile(appPaths).GetAwaiter().GetResult();

            var startupConfig = Program.CreateAppConfiguration(commandLineOpts, appPaths);

            ILoggerFactory loggerFactory = LoggerFactory.Create(logging => logging
                .SetMinimumLevel(LogLevel.Critical)
                .AddProvider(new CriticalEntryProvider(_criticalEntries)));
            _disposables.Add(loggerFactory);

            var appHost = new CoreAppHost(appPaths, loggerFactory, commandLineOpts, startupConfig);
            _disposables.Add(appHost);

            builder.ConfigureServices(services => appHost.Init(services))
                .ConfigureWebHostBuilder(appHost, startupConfig, appPaths, NullLogger.Instance)
                .ConfigureAppConfiguration((context, configuration) => configuration
                    .SetBasePath(appPaths.ConfigurationDirectoryPath)
                    .AddInMemoryCollection(Emby.Server.Implementations.ConfigurationOptions.DefaultConfiguration)
                    .AddEnvironmentVariables("JELLYFIN_")
                    .AddInMemoryCollection(commandLineOpts.ConvertToConfig()))
                .ConfigureServices(services => services.RegisterStartupLogger());
        }

        protected override IHost CreateHost(IHostBuilder builder)
        {
            var host = builder.Build();
            var appHost = (CoreAppHost)host.Services.GetRequiredService<MediaBrowser.Common.IApplicationHost>();
            appHost.ServiceProvider = host.Services;
            var appPaths = (ServerApplicationPaths)host.Services.GetRequiredService<IApplicationPaths>();
            var configuration = host.Services.GetRequiredService<IConfiguration>();

            Program.ApplyStartupMigrationAsync(appPaths, configuration, new StartupOptions()).GetAwaiter().GetResult();
            Program.ApplyCoreMigrationsAsync(host.Services, JellyfinMigrationStageTypes.CoreInitialisation).GetAwaiter().GetResult();
            appHost.InitializeServices(configuration).GetAwaiter().GetResult();
            Program.ApplyCoreMigrationsAsync(host.Services, JellyfinMigrationStageTypes.AppInitialisation).GetAwaiter().GetResult();
            host.Start();

            return host;
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);

            foreach (var disposable in _disposables)
            {
                disposable.Dispose();
            }

            _disposables.Clear();

            try
            {
                Directory.Delete(_root, true);
            }
            catch (IOException)
            {
                // A temporary directory left behind is not worth failing a test over.
            }
        }

        private sealed class CriticalEntryProvider : ILoggerProvider
        {
            private readonly ConcurrentQueue<string> _entries;

            public CriticalEntryProvider(ConcurrentQueue<string> entries)
            {
                _entries = entries;
            }

            public ILogger CreateLogger(string categoryName) => new CriticalEntryLogger(_entries);

            public void Dispose()
            {
            }

            private sealed class CriticalEntryLogger : ILogger
            {
                private readonly ConcurrentQueue<string> _entries;

                public CriticalEntryLogger(ConcurrentQueue<string> entries)
                {
                    _entries = entries;
                }

                public IDisposable? BeginScope<TState>(TState state)
                    where TState : notnull
                    => null;

                public bool IsEnabled(LogLevel logLevel) => logLevel == LogLevel.Critical;

                public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
                {
                    if (logLevel == LogLevel.Critical)
                    {
                        _entries.Enqueue(formatter!(state, exception));
                    }
                }
            }
        }
    }
}