Refactor BotBuilder and add authorization features

Removed IBotBuilder interface and updated BotBuilder class.
Extended BotControllerBase with Void() method.
Added UseAuthorizationHandler<THandler> to ServiceCollectionExtensions.
Introduced IBotAuthorizationHandler interface.
Added EmptyResult class implementing IActionResult.
Added AuthorizeAttribute for class/method authorization.

Author: bvdcode

Sources/TelegramBot/Abstractions/IBotAuthorizationHandler.cs

@@ -0,0 +1,25 @@
+using Telegram.Bot.Types;
+using TelegramBot.ActionResults;
+
+namespace TelegramBot.Abstractions
+{
+    /// <summary>
+    /// Defines the bot authorization handler.
+    /// </summary>
+    public interface IBotAuthorizationHandler
+    {
+        /// <summary>
+        /// Authorize the user.
+        /// </summary>
+        /// <param name="authorizingUser">The user who is trying to perform the action.</param>
+        /// <returns>True if the user is authorized, otherwise false.</returns>
+        bool Authorize(User authorizingUser);
+
+        /// <summary>
+        /// Handle the unauthorized user.
+        /// </summary>
+        /// <param name="authorizingUser">The user who is trying to perform the action.</param>
+        /// <returns>Result of the <see cref="IActionResult"/> action, ex. <see cref="TextResult"/> or <see cref="EmptyResult"/>.</returns>
+        IActionResult HandleUnauthorized(User authorizingUser);
+    }
+}

Sources/TelegramBot/ActionResults/EmptyResult.cs

@@ -0,0 +1,21 @@
+using System.Threading.Tasks;
+using TelegramBot.Abstractions;
+
+namespace TelegramBot.ActionResults
+{
+    /// <summary>
+    /// Defines an empty result.
+    /// </summary>
+    public class EmptyResult : IActionResult
+    {
+        /// <summary>
+        /// Does nothing.
+        /// </summary>
+        /// <param name="context">The context.</param>
+        /// <returns>Task representing the result of the action.</returns>
+        public Task ExecuteResultAsync(ActionContext context)
+        {
+            return Task.CompletedTask;
+        }
+    }
+}

Sources/TelegramBot/Attributes/AuthorizeAttribute.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace TelegramBot.Attributes
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
+    public class AuthorizeAttribute : Attribute
+    {
+
+    }
+}

Sources/TelegramBot/Builders/BotBuilder.cs

@@ -1,21 +1,24 @@
 using System;
 using System.Linq;
 using Telegram.Bot;
+using System.Threading;
+using Telegram.Bot.Types;
 using TelegramBot.Services;
 using TelegramBot.Providers;
+using TelegramBot.Attributes;
 using TelegramBot.Abstractions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
-using System.Threading;
+using TelegramBot.Controllers;
 
 namespace TelegramBot.Builders
 {
     /// <summary>
     /// A builder for bot application and services.
     /// </summary>
-    public class BotBuilder : IBotBuilder
+    public class BotBuilder
     {
         /// <summary>
         /// A collection of services for the application to compose. This is useful for adding user provided or framework provided services.
@@ -60,7 +63,7 @@ public BotBuilder(params string[] args)
         /// Use the Telegram server with the specified base URL.
         /// </summary>
         /// <param name="configure">The configuration for the Telegram server.</param>
-        /// <returns>This instance of <see cref="IBotBuilder"/>.</returns>
+        /// <returns>This instance of <see cref="BotBuilder"/>.</returns>
         /// <exception cref="ArgumentException">Thrown when the base URL is not a valid URI.</exception>
         public BotBuilder UseTelegramServer(Action<TelegramServerBuilder> configure)
         {
@@ -87,7 +90,7 @@ public BotBuilder UseTelegramServer(Action<TelegramServerBuilder> configure)
         /// Use the API key for the Telegram bot.
         /// </summary>
         /// <param name="value">The configuration for the Telegram API key.</param>
-        /// <returns>This instance of <see cref="IBotBuilder"/>.</returns>
+        /// <returns>This instance of <see cref="BotBuilder"/>.</returns>
         /// <exception cref="ArgumentNullException">Thrown when the Telegram bot token is not set in the configuration.</exception>
         public BotBuilder UseApiKey(Action<TelegramApiKeyBuilder> value)
         {
@@ -109,7 +112,7 @@ public BotBuilder UseApiKey(Action<TelegramApiKeyBuilder> value)
         /// Use custom services for the bot additionally to the built-in services.
         /// </summary>
         /// <param name="services">The services to use.</param>
-        /// <returns>This instance of <see cref="IBotBuilder"/>.</returns>
+        /// <returns>This instance of <see cref="BotBuilder"/>.</returns>
         public BotBuilder UseServices(IServiceCollection services)
         {
             foreach (var service in services)

Sources/TelegramBot/Builders/IBotBuilder.cs

@@ -80,6 +80,15 @@ public IActionResult Inline(string prompt, InlineKeyboardMarkup keyboard, bool u
             return new InlineResult(prompt, keyboard, useMarkdown);
         }
 
+        /// <summary>
+        /// Do nothing.
+        /// </summary>
+        /// <returns>Result of the <see cref="IActionResult"/> action.</returns>
+        public IActionResult Void()
+        {
+            return new EmptyResult();
+        }
+
         /// <summary>
         /// Sets the value of the key in the key-value provider.
         /// </summary>

Sources/TelegramBot/Controllers/BotControllerBase.cs

@@ -1,4 +1,5 @@
 using System;
+using TelegramBot.Attributes;
 using TelegramBot.Abstractions;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -9,6 +10,17 @@ namespace TelegramBot.Extensions
     /// </summary>
     public static class ServiceCollectionExtensions
     {
+        /// <summary>
+        /// Use the authorization predicate for methods and controllers with <see cref="AuthorizeAttribute"/>
+        /// </summary>
+        /// <typeparam name="THandler">The type of the authorization handler.</typeparam>
+        /// <param name="services">The service collection.</param>
+        /// <returns>The modified service collection.</returns>
+        public static IServiceCollection UseAuthorizationHandler<THandler>(this IServiceCollection services) where THandler : class, IBotAuthorizationHandler
+        {
+            return services.AddSingleton<IBotAuthorizationHandler, THandler>();
+        }
+
         /// <summary>
         /// Registers the specified <see cref="IKeyValueProvider"/> instance as a singleton service in the service collection.
         /// </summary>
@@ -17,8 +29,7 @@ public static class ServiceCollectionExtensions
         /// <returns>The modified service collection.</returns>
         public static IServiceCollection UseKeyValueProvider(this IServiceCollection services, IKeyValueProvider provider)
         {
-            services.AddSingleton(provider);
-            return services;
+            return services.AddSingleton(provider);
         }
 
         /// <summary>
@@ -41,8 +52,7 @@ public static IServiceCollection UseKeyValueProvider(this IServiceCollection ser
         /// <returns>The modified service collection.</returns>
         public static IServiceCollection UseKeyValueProvider<TImplementation>(this IServiceCollection services) where TImplementation : class, IKeyValueProvider
         {
-            services.AddSingleton<IKeyValueProvider, TImplementation>();
-            return services;
+            return services.AddSingleton<IKeyValueProvider, TImplementation>();
         }
     }
 }