using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Localization;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using Microsoft.Net.Http.Headers;
using Sarand.Net.Standard.Base.App;
using Sarand.Net.Standard.Base.Core;
using Saxonite.Net.Core.Web.Base.Middleware;
using Saxonite.Net.Standard.Base.App;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Net.Http;
using System.Text;

namespace Saxonite.Net.Core.Web.Base.App
{
	//=======================================================================
	public class SaxStartup
	{
		//-------------------------------------------------------------------
		// Data members.
		// Localisation.
		private static RequestCulture defaultRequestCulture = new RequestCulture("en-GB", "en-GB");
		private static List<CultureInfo> supportedCultures = new List<CultureInfo>
		{
			new CultureInfo("en-GB"),
			new CultureInfo("en-US"),
			new CultureInfo("en"),
			new CultureInfo("fr-FR"),
			new CultureInfo("fr"),
		};

		//-------------------------------------------------------------------
		// Protected construction.
		protected SaxStartup(IConfiguration configuration)
		{
			Configuration = configuration;
		}

		//-------------------------------------------------------------------
		// Properties.
		public IConfiguration Configuration { get; }
		public static RequestCulture DefaultRequestCulture { get { return defaultRequestCulture; } }
		public static List<CultureInfo> SupportedCultures { get { return new List<CultureInfo>(supportedCultures); } }

		//-------------------------------------------------------------------
		// This method gets called by the runtime. Use this method to add services to the container.
		protected class ConfigureServicesConfig
		{
			public IServiceCollection services;
			public String sessionCookieName;
			public bool sessionCookieHttpOnly;
			public TimeSpan sessionIdleTimeout;
		}
		protected void ConfigureServices(ConfigureServicesConfig config)
		{
			// Authentication service.
			// Required to handle 'Forbidden' responses etc.
			config.services
				.AddAuthentication(options => {
					options.DefaultAuthenticateScheme = "forbidScheme";
					options.DefaultForbidScheme = "forbidScheme";
					options.AddScheme<SaxAuthenticationHandler>("forbidScheme", "Handle Forbidden");
				});         
			
			// Added to support memory caching of sessions.
			config.services.AddMemoryCache();
			//config.services.AddDistributedMemoryCache(); - for multiple web servers.
			// Online web application cookie definition.
			config.services.AddSession
				(options =>
				{
					options.Cookie.Name = config.sessionCookieName;
					options.Cookie.HttpOnly = config.sessionCookieHttpOnly;
					options.IdleTimeout = config.sessionIdleTimeout;
					// Override cookie policy for session cookie. Ref. config.app.UseCookiePolicy()
					options.Cookie.IsEssential = true;
				}
				);

			// Localisation properties folder.
			String resourcesPath = "Localisation";
			config.services.AddLocalization(opts => { opts.ResourcesPath = resourcesPath; });

			// Modify pages during debug.
#if DEBUG
			if (SaxSystem.DebugMode)
				// If the following line throws an error such as:
				//   'imvcbuilder' does not contain a definition for 'addrazorruntimecompilation'
				// Revert the NuGet Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package
				// to a previous version and then reinstal the latest version.
				config.services.AddRazorPages().AddRazorRuntimeCompilation();
#endif

			config.services.AddMvc
				(options =>
				{
					// Model binding - intercepting form values being bound to models.
					options.ModelBinderProviders.Insert(0, new SaxModelBinderProvider());
					// Blank form values to be populated to model as empty strings rather than null values.
					options.ModelMetadataDetailsProviders.Add(new SaxMetadataProvider());
				}
				)
				// View and data annotation localisations.
				.AddViewLocalization(
					LanguageViewLocationExpanderFormat.Suffix,
					opts => { opts.ResourcesPath = resourcesPath; })
				.AddDataAnnotationsLocalization()
				// Ignore null values during object serisliation.
				.AddJsonOptions(options => { options.JsonSerializerOptions.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull; });

			// Configure localisation middleware.
			config.services.Configure<RequestLocalizationOptions>
			(opts =>
			{
				// Default culture to use for requests.
				opts.DefaultRequestCulture = DefaultRequestCulture;
				// Cultures supported by the application. Formatting numbers, dates, etc.
				opts.SupportedCultures = SupportedCultures;
				// UI cultures supported by the application. UI strings that have been localized.
				opts.SupportedUICultures = SupportedCultures;
			}
			);

			// Allows access to the HttpContext inside a service.
			config.services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
		}

		//-------------------------------------------------------------------
		// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
		protected class ConfigureConfig
		{
			public IApplicationBuilder app;
			public IHostApplicationLifetime hostApplicationLifetime;
			public IWebHostEnvironment env;
		}
		protected void Configure(ConfigureConfig config)
		{
			if (config.env.IsDevelopment())
			{
				config.app.UseDeveloperExceptionPage();
			}
			else
			{
				config.app.UseExceptionHandler("/Home/Error");
				// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
				config.app.UseHsts();
			}

			config.app.UseHttpsRedirection();
			config.app.UseStaticFiles();
			config.app.UseCookiePolicy();
			config.app.UseSession();
			config.app.UseRouting();
			//config.app.UseAuthorization();
			config.app.UseAntiforgeryTokens();

			// Localisation.
			IOptions<RequestLocalizationOptions> localizationOptions = config.app.ApplicationServices.GetService<IOptions<RequestLocalizationOptions>>();
			config.app.UseRequestLocalization(localizationOptions.Value);

			config.app.UseEndpoints(endpoints =>
			{
				endpoints.MapControllerRoute(
					name: "default",
					pattern: "{controller=Home}/{action=Index}/{id?}");
			});

			// Application events.
			// NB The shutdown events only fire if he application stops 'gracefully'.
			config.hostApplicationLifetime.ApplicationStarted.Register(OnApplicationStarted);
			config.hostApplicationLifetime.ApplicationStopping.Register(OnApplicationStopping);
			config.hostApplicationLifetime.ApplicationStopped.Register(OnApplicationStopped);

			config.app.Use(async (context, next) =>
			{
				if (context.Request.Method.Equals(HttpMethod.Get.Method))
				{
					context.Response.GetTypedHeaders().CacheControl = new CacheControlHeaderValue()
					{
						Public = true,
						MaxAge = TimeSpan.FromSeconds(10)
					};
					//context.Response.Headers[HeaderNames.Vary] = new string[] { "Accept-Encoding" };
				}
				await next();
			});
		}

		//-------------------------------------------------------------------
		// Application events.
		private readonly static String ApplicationEventLogPrefix = "### ";
		private void OnApplicationStarted()
		{
			SaLogger.Info(ApplicationEventLogPrefix + "Application started");
		}
		private void OnApplicationStopping()
		{
			SaLogger.Info(ApplicationEventLogPrefix + "Application stopping");
		}
		private void OnApplicationStopped()
		{
			SaLogger.Info(ApplicationEventLogPrefix + "Application stopped");
		}

		//-------------------------------------------------------------------
	}
	//=======================================================================
}