Adds distribution OAuth2 flow

Samples/HelloWorld/Program.cs

@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using Slackbot.Net.Endpoints.Hosting;
 using Slackbot.Net.Endpoints.Authentication;
 using Slackbot.Net.Endpoints.Abstractions;
@@ -38,4 +39,5 @@ class TokenStore : ITokenStore
     public Task<IEnumerable<string>> GetTokens() => Task.FromResult(new [] { SlackToken }.AsEnumerable());
     public Task<string> GetTokenByTeamId(string teamId) => Task.FromResult(SlackToken);
     public Task Delete(string token) => throw new NotImplementedException("Single workspace app");
+    public Task Insert(Workspace slackTeam) => throw new NotImplementedException("Single workspace app");
 }

source/src/Slackbot.Net.Endpoints/Configurations/ITokenStore.cs

@@ -11,5 +11,8 @@ public interface ITokenStore
         Task<IEnumerable<string>> GetTokens();
         Task<string> GetTokenByTeamId(string teamId);
         Task Delete(string token);
+        Task Insert(Workspace slackTeam);
     }
-}   
+
+    public record Workspace(string TeamId, string TeamName, string Scope, string Token);
+}

source/src/Slackbot.Net.Endpoints/Hosting/IAppBuilderExtensions.cs

@@ -20,6 +20,19 @@ public static IApplicationBuilder UseSlackbot(this IApplicationBuilder app, bool
 
             return app;
         }
+
+        /// <summary>
+        /// NB! The path you run this middleware must:
+        /// - match redirect_uri in your 1st redirect to Slack
+        /// - be a valid redirect_uri in your Slack app configuration
+        /// </summary>
+        /// <param name="app"></param>
+        /// <returns></returns>
+        public static IApplicationBuilder UseSlackbotDistribution(this IApplicationBuilder app)
+        {
+            app.UseMiddleware<SlackbotCodeTokenExchangeMiddleware>();
+            return app;
+        }
     }
 }
 

source/src/Slackbot.Net.Endpoints/Hosting/ServiceCollectionExtensions.cs

@@ -1,6 +1,9 @@
+using System;
+using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Slackbot.Net.Abstractions.Hosting;
 using Slackbot.Net.Endpoints.Abstractions;
+using Slackbot.Net.Endpoints.OAuth;
 
 namespace Slackbot.Net.Endpoints.Hosting
 {
@@ -12,5 +15,28 @@ public static ISlackbotHandlersBuilder AddSlackBotEvents<T>(this IServiceCollect
             services.AddSingleton<ISelectAppMentionEventHandlers, AppMentionEventHandlerSelector>();
             return new SlackBotHandlersBuilder(services);
         }
+
+        public static IServiceCollection AddSlackbotDistribution(this IServiceCollection services, Action<OAuthOptions> action)
+        {
+            services.Configure<OAuthOptions>(action);
+            services.AddHttpClient<OAuthClient>((s, c) =>
+            {
+                c.BaseAddress = new Uri("https://slack.com/api/");
+                c.Timeout = TimeSpan.FromSeconds(15);
+            });
+            return services;
+        }
+    }
+
+    public class OAuthOptions
+    {
+        public OAuthOptions()
+        {
+            OnSuccess = (_,_,_) => Task.CompletedTask;
+        }
+        public string CLIENT_ID { get; set; }
+        public string CLIENT_SECRET { get; set; }
+        public string SuccessRedirectUri { get; set; } = "/success?default=1";
+        public Func<string, string, IServiceProvider, Task> OnSuccess { get; set; }
     }
-}
+}

source/src/Slackbot.Net.Endpoints/Middlewares/SlackbotCodeTokenExchangeMiddleware.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using Slackbot.Net.Abstractions.Hosting;
+using Slackbot.Net.Endpoints.Hosting;
+using Slackbot.Net.Endpoints.OAuth;
+
+namespace Slackbot.Net.Endpoints.Middlewares
+{
+    internal class SlackbotCodeTokenExchangeMiddleware
+    {
+        private readonly RequestDelegate _next;
+
+        public SlackbotCodeTokenExchangeMiddleware(RequestDelegate next)
+        {
+            _next = next;
+        }
+
+        public async Task Invoke(HttpContext ctx, OAuthClient oAuthAccessClient, IServiceProvider provider, IOptions<OAuthOptions> options, ITokenStore slackTeamRepository, ILogger<SlackbotCodeTokenExchangeMiddleware> logger)
+        {
+            logger.LogInformation("Installing!");
+            var redirect_uri = new Uri($"{ctx.Request.Scheme}://{ctx.Request.Host.Value.ToString()}{ctx.Request.PathBase.Value}");
+            var code = ctx.Request.Query["code"].FirstOrDefault();
+
+            if(code == null)
+                await _next(ctx);
+
+            var response = await oAuthAccessClient.OAuthAccessV2(new OAuthClient.OauthAccessV2Request(
+                code,
+                options.Value.CLIENT_ID,
+                options.Value.CLIENT_SECRET,
+                redirect_uri.ToString()
+            ));
+
+            if (response.Ok)
+            {
+                logger.LogInformation($"Oauth response! ok:{response.Ok}");
+                await slackTeamRepository.Insert(new Workspace
+                (
+                    response.Team.Id,
+                    response.Team.Name,
+                    response.Scope,
+                    response.Access_Token
+                ));
+                await options.Value.OnSuccess(response.Team.Id, response.Team.Name, provider);
+
+                ctx.Response.Redirect(options.Value.SuccessRedirectUri);
+            }
+            else
+            {
+                logger.LogError($"Bad Oauth response! {response}");
+                ctx.Response.StatusCode = StatusCodes.Status500InternalServerError;
+                await ctx.Response.WriteAsync(response.Error);
+            }
+        }
+    }
+}

source/src/Slackbot.Net.Endpoints/OAuth/OAuthClient.cs

@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+
+namespace Slackbot.Net.Endpoints.OAuth
+{
+    internal record Response(bool Ok, string Error);
+
+    internal class OAuthClient
+    {
+        private readonly HttpClient _client;
+        private readonly ILogger<OAuthClient> _logger;
+
+        internal record OauthAccessV2Request(string Code, string ClientId, string ClientSecret, string RedirectUri);
+
+        internal record OAuthAccessV2Response(string Access_Token, string Scope, Team Team, string App_Id, OAuthUser Authed_User, bool Ok, string Error) : Response(Ok, Error);
+        internal record Team(string Id, string Name);
+        internal record OAuthUser(string User_Id, string App_Home);
+
+
+        public OAuthClient(HttpClient client, ILogger<OAuthClient> logger)
+        {
+            _client = client;
+            _logger = logger;
+        }
+
+        public async Task<OAuthAccessV2Response> OAuthAccessV2(OauthAccessV2Request oauthAccessRequest)
+        {
+            var parameters = new List<KeyValuePair<string, string>>
+            {
+                new("code", oauthAccessRequest.Code)
+            };
+
+            if (!string.IsNullOrEmpty(oauthAccessRequest.RedirectUri))
+            {
+                parameters.Add(new KeyValuePair<string, string>("redirect_uri", oauthAccessRequest.RedirectUri));
+            }
+
+            if (!string.IsNullOrEmpty(oauthAccessRequest.ClientId))
+            {
+                parameters.Add(new KeyValuePair<string, string>("client_id", oauthAccessRequest.ClientId));
+            }
+
+            if (!string.IsNullOrEmpty(oauthAccessRequest.ClientSecret))
+            {
+                parameters.Add(new KeyValuePair<string, string>("client_secret", oauthAccessRequest.ClientSecret));
+            }
+
+            return await _client.PostParametersAsForm<OAuthAccessV2Response>(parameters,"oauth.v2.access", s => _logger.LogInformation(s));
+        }
+    }
+
+    internal static class HttpClientExtensions
+    {
+        internal static async Task<T> PostParametersAsForm<T>(this HttpClient httpClient, IEnumerable<KeyValuePair<string, string>> parameters, string api, Action<string> logger = null) where T: Response
+        {
+            var request = new HttpRequestMessage(HttpMethod.Post, api);
+
+            if (parameters != null && parameters.Any())
+            {
+                var formUrlEncodedContent = new FormUrlEncodedContent(parameters);
+                var requestContent = await formUrlEncodedContent.ReadAsStringAsync();
+                var httpContent = new StringContent(requestContent, Encoding.UTF8, "application/x-www-form-urlencoded");
+                httpContent.Headers.ContentType.CharSet = string.Empty;
+                request.Content = httpContent;
+            }
+
+            var response =  await httpClient.SendAsync(request);
+            var responseContent = await response.Content.ReadAsStringAsync();
+
+            if (!response.IsSuccessStatusCode)
+            {
+                logger?.Invoke($"{response.StatusCode} \n {responseContent}");
+            }
+
+            response.EnsureSuccessStatusCode();
+
+            var resObj = JsonSerializer.Deserialize<T>(responseContent, new JsonSerializerOptions(JsonSerializerDefaults.Web));
+
+            if(!resObj.Ok)
+                throw new SlackApiException(error: $"{resObj.Error}", responseContent:responseContent);
+
+            return resObj;
+        }
+    }
+
+    internal class SlackApiException : Exception
+    {
+        public string Error { get; }
+        public string ResponseContent { get; }
+
+        public SlackApiException(string error, string responseContent): base(responseContent)
+        {
+            Error = error;
+            ResponseContent = responseContent;
+        }
+    }
+
+
+}

source/src/Slackbot.Net.Endpoints/Slackbot.Net.Endpoints.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netcoreapp3.1;net5.0;net6.0</TargetFrameworks>
+        <TargetFrameworks>net5.0;net6.0</TargetFrameworks>
         <RootNamespace>Slackbot.Net.Endpoints</RootNamespace>
         <PackageId>Slackbot.Net.Endpoints</PackageId>
         <Authors>John Korsnes</Authors>

source/src/Slackbot.Net.Shared/Slackbot.Net.Shared.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netcoreapp3.1;net5.0</TargetFrameworks>
+        <TargetFrameworks>net5.0;net6.0</TargetFrameworks>
     </PropertyGroup>
 
 </Project>

source/src/Slackbot.Net.SlackClients.Http/Slackbot.Net.SlackClients.Http.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netcoreapp3.1;net5.0;net6.0</TargetFrameworks>
+        <TargetFrameworks>net5.0;net6.0</TargetFrameworks>
         <RootNamespace>Slackbot.Net.SlackClients.Http</RootNamespace>
         <PackageId>Slackbot.Net.SlackClients.Http</PackageId>
         <Authors>John Korsnes</Authors>