using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using DryIoc;
using DryIoc.Microsoft.DependencyInjection;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Hosting.WindowsServices;
using NLog;
using NzbDrone.Common.Composition.Extensions;
using NzbDrone.Common.Disk;
using NzbDrone.Common.EnvironmentInfo;
using NzbDrone.Common.Exceptions;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Instrumentation;
using NzbDrone.Common.Instrumentation.Extensions;
using NzbDrone.Core.Configuration;
using NzbDrone.Core.Datastore.Extensions;
using NzbDrone.Core.Lifecycle;
using NzbDrone.Core.Messaging.Events;

namespace NzbDrone.Host
{
    public static class Bootstrap
    {
        private static readonly Logger Logger = NzbDroneLogger.GetLogger(typeof(Bootstrap));

        public static readonly List<string> ASSEMBLIES = new List<string>
        {
            "Readarr.Host",
            "Readarr.Core",
            "Readarr.SignalR",
            "Readarr.Api.V1",
            "Readarr.Http"
        };

        public static void Start(string[] args, Action<IHostBuilder> trayCallback = null)
        {
            try
            {
                Logger.Info("Starting Readarr - {0} - Version {1}", Assembly.GetCallingAssembly().Location, Assembly.GetExecutingAssembly().GetName().Version);

                var startupContext = new StartupContext(args);

                LongPathSupport.Enable();
                Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

                var appMode = GetApplicationMode(startupContext);

                switch (appMode)
                {
                    case ApplicationModes.Service:
                    {
                        Logger.Debug("Service selected");

                        CreateConsoleHostBuilder(args, startupContext).UseWindowsService().Build().Run();
                        break;
                    }

                    case ApplicationModes.Interactive:
                    {
                        Logger.Debug(trayCallback != null ? "Tray selected" : "Console selected");
                        var builder = CreateConsoleHostBuilder(args, startupContext);

                        if (trayCallback != null)
                        {
                            trayCallback(builder);
                        }

                        builder.Build().Run();
                        break;
                    }

                    // Utility mode
                    default:
                    {
                        new Container(rules => rules.WithNzbDroneRules())
                            .AutoAddServices(ASSEMBLIES)
                            .AddNzbDroneLogger()
                            .AddStartupContext(startupContext)
                            .Resolve<UtilityModeRouter>()
                            .Route(appMode);
                        break;
                    }
                }
            }
            catch (InvalidConfigFileException ex)
            {
                throw new ReadarrStartupException(ex);
            }
            catch (AccessDeniedConfigFileException ex)
            {
                throw new ReadarrStartupException(ex);
            }
            catch (TerminateApplicationException ex)
            {
                Logger.Info(ex.Message);
                LogManager.Configuration = null;
            }
        }

        public static IHostBuilder CreateConsoleHostBuilder(string[] args, StartupContext context)
        {
            var config = GetConfiguration(context);

            var bindAddress = config.GetValue(nameof(ConfigFileProvider.BindAddress), "*");
            var port = config.GetValue(nameof(ConfigFileProvider.Port), 8787);
            var sslPort = config.GetValue(nameof(ConfigFileProvider.SslPort), 6868);
            var enableSsl = config.GetValue(nameof(ConfigFileProvider.EnableSsl), false);
            var sslCertPath = config.GetValue<string>(nameof(ConfigFileProvider.SslCertPath));
            var sslCertPassword = config.GetValue<string>(nameof(ConfigFileProvider.SslCertPassword));

            var urls = new List<string> { BuildUrl("http", bindAddress, port) };

            if (enableSsl && sslCertPath.IsNotNullOrWhiteSpace())
            {
                urls.Add(BuildUrl("https", bindAddress, sslPort));
            }

            return new HostBuilder()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseServiceProviderFactory(new DryIocServiceProviderFactory(new Container(rules => rules.WithNzbDroneRules())))
                .ConfigureContainer<IContainer>(c =>
                {
                    c.AutoAddServices(Bootstrap.ASSEMBLIES)
                        .AddNzbDroneLogger()
                        .AddDatabase()
                        .Resolve<IEventAggregator>().PublishEvent(new ApplicationStartingEvent());

                    c.AddStartupContext(context);
                })
                .ConfigureWebHost(builder =>
                {
                    builder.UseUrls(urls.ToArray());
                    builder.UseKestrel(options =>
                    {
                        if (enableSsl && sslCertPath.IsNotNullOrWhiteSpace())
                        {
                            options.ConfigureHttpsDefaults(configureOptions =>
                            {
                                configureOptions.ServerCertificate = ValidateSslCertificate(sslCertPath, sslCertPassword);
                            });
                        }
                    });
                    builder.ConfigureKestrel(serverOptions =>
                    {
                        serverOptions.AllowSynchronousIO = true;
                        serverOptions.Limits.MaxRequestBodySize = null;
                    });
                    builder.UseStartup<Startup>();
                });
        }

        public static ApplicationModes GetApplicationMode(IStartupContext startupContext)
        {
            if (startupContext.Help)
            {
                return ApplicationModes.Help;
            }

            if (OsInfo.IsWindows && startupContext.RegisterUrl)
            {
                return ApplicationModes.RegisterUrl;
            }

            if (OsInfo.IsWindows && startupContext.InstallService)
            {
                return ApplicationModes.InstallService;
            }

            if (OsInfo.IsWindows && startupContext.UninstallService)
            {
                return ApplicationModes.UninstallService;
            }

            if (OsInfo.IsWindows && WindowsServiceHelpers.IsWindowsService())
            {
                return ApplicationModes.Service;
            }

            return ApplicationModes.Interactive;
        }

        private static IConfiguration GetConfiguration(StartupContext context)
        {
            var appFolder = new AppFolderInfo(context);
            return new ConfigurationBuilder()
                .AddXmlFile(appFolder.GetConfigPath(), optional: true, reloadOnChange: false)
                .Build();
        }

        private static string BuildUrl(string scheme, string bindAddress, int port)
        {
            return $"{scheme}://{bindAddress}:{port}";
        }

        private static X509Certificate2 ValidateSslCertificate(string cert, string password)
        {
            X509Certificate2 certificate;

            try
            {
                certificate = new X509Certificate2(cert, password, X509KeyStorageFlags.DefaultKeySet);
            }
            catch (CryptographicException ex)
            {
                if (ex.HResult == 0x2 || ex.HResult == 0x2006D080)
                {
                    throw new ReadarrStartupException(ex,
                        $"The SSL certificate file {cert} does not exist");
                }

                throw new ReadarrStartupException(ex);
            }

            return certificate;
        }
    }
}