Merge pull request #138 from NicolasConstant/develop

0.20.0 PR

VARIABLES.md

@@ -49,6 +49,8 @@ If both whitelisting and blacklisting are set, only the whitelisting will be act
 * `Instance:UnlistedTwitterAccounts` (default: null) to enable unlisted publication for selected twitter accounts, separated by `;` (please limit this to brands and other public profiles). 
 * `Instance:SensitiveTwitterAccounts` (default: null) mark all media from given accounts as sensitive by default, separated by `;`. 
 * `Instance:FailingTwitterUserCleanUpThreshold` (default: 700) set the max allowed errors (due to a banned/deleted/private account) from a Twitter Account retrieval before auto-removal. (by default an account is called every 15 mins)
+* `Instance:FailingFollowerCleanUpThreshold` (default: 30000) set the max allowed errors from a Follower (Fediverse) Account before auto-removal. (often due to account suppression, instance issues, etc)
+* `Instance:UserCacheCapacity` (default: 10000) set the caching limit of the Twitter User retrieval. Must be higher than the number of synchronized accounts on the instance.
 
 # Docker Compose full example
 

src/BirdsiteLive.ActivityPub/ApDeserializer.cs

@@ -1,4 +1,5 @@
 using System;
+using BirdsiteLive.ActivityPub.Models;
 using Newtonsoft.Json;
 
 namespace BirdsiteLive.ActivityPub
@@ -19,6 +20,8 @@ namespace BirdsiteLive.ActivityPub
                         if(a.apObject.type == "Follow")
                             return JsonConvert.DeserializeObject<ActivityUndoFollow>(json);
                         break;
+                    case "Delete":
+                        return JsonConvert.DeserializeObject<ActivityDelete>(json);
                     case "Accept":
                         var accept = JsonConvert.DeserializeObject<ActivityAccept>(json);
                         //var acceptType = JsonConvert.DeserializeObject<Activity>(accept.apObject);

src/BirdsiteLive.ActivityPub/Models/ActivityDelete.cs

@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace BirdsiteLive.ActivityPub.Models
+{
+    public class ActivityDelete : Activity
+    {
+        [JsonProperty("object")]
+        public object apObject { get; set; }
+    }
+}

src/BirdsiteLive.Common/Settings/InstanceSettings.cs

@@ -13,5 +13,8 @@
         public string SensitiveTwitterAccounts { get; set; }
 
         public int FailingTwitterUserCleanUpThreshold { get; set; }
+        public int FailingFollowerCleanUpThreshold { get; set; } = -1;
+
+        public int UserCacheCapacity { get; set; }
     }
 }

src/BirdsiteLive.Domain/ActivityPubService.cs

@@ -11,7 +11,6 @@ using BirdsiteLive.ActivityPub.Models;
 using BirdsiteLive.Common.Settings;
 using Microsoft.Extensions.Logging;
 using Newtonsoft.Json;
-using Org.BouncyCastle.Bcpg;
 
 namespace BirdsiteLive.Domain
 {
@@ -45,6 +44,12 @@ namespace BirdsiteLive.Domain
             var httpClient = _httpClientFactory.CreateClient();
             httpClient.DefaultRequestHeaders.Add("Accept", "application/activity+json");
             var result = await httpClient.GetAsync(objectId);
+
+            if (result.StatusCode == HttpStatusCode.Gone)
+                throw new FollowerIsGoneException();
+
+            result.EnsureSuccessStatusCode();
+
             var content = await result.Content.ReadAsStringAsync();
 
             var actor = JsonConvert.DeserializeObject<Actor>(content);

src/BirdsiteLive.Domain/BusinessUseCases/ProcessDeleteUser.cs

@@ -0,0 +1,51 @@
+using System.Linq;
+using System.Threading.Tasks;
+using BirdsiteLive.DAL.Contracts;
+using BirdsiteLive.DAL.Models;
+
+namespace BirdsiteLive.Domain.BusinessUseCases
+{
+    public interface IProcessDeleteUser
+    {
+        Task ExecuteAsync(Follower follower);
+        Task ExecuteAsync(string followerUsername, string followerDomain);
+    }
+    
+    public class ProcessDeleteUser : IProcessDeleteUser
+    {
+        private readonly IFollowersDal _followersDal;
+        private readonly ITwitterUserDal _twitterUserDal;
+
+        #region Ctor
+        public ProcessDeleteUser(IFollowersDal followersDal, ITwitterUserDal twitterUserDal)
+        {
+            _followersDal = followersDal;
+            _twitterUserDal = twitterUserDal;
+        }
+        #endregion
+        
+        public async Task ExecuteAsync(string followerUsername, string followerDomain)
+        {
+            // Get Follower and Twitter Users
+            var follower = await _followersDal.GetFollowerAsync(followerUsername, followerDomain);
+            if (follower == null) return;
+
+            await ExecuteAsync(follower);
+        }
+
+        public async Task ExecuteAsync(Follower follower)
+        {
+            // Remove twitter users if no more followers
+            var followings = follower.Followings;
+            foreach (var following in followings)
+            {
+                var followers = await _followersDal.GetFollowersAsync(following);
+                if (followers.Length == 1 && followers.First().Id == follower.Id)
+                    await _twitterUserDal.DeleteTwitterUserAsync(following);
+            }
+
+            // Remove follower from DB
+            await _followersDal.DeleteFollowerAsync(follower.Id);
+        }
+    }
+}

src/BirdsiteLive.Domain/Exceptions/FollowerIsGoneException.cs

@@ -0,0 +1,8 @@
+using System;
+
+namespace BirdsiteLive.Domain
+{
+    public class FollowerIsGoneException : Exception
+    {
+    }
+}

src/BirdsiteLive.Domain/Tools/SigValidationResultExtractor.cs

@@ -0,0 +1,22 @@
+using System.Linq;
+
+namespace BirdsiteLive.Domain.Tools
+{
+    public class SigValidationResultExtractor
+    {
+        public static string GetUserName(SignatureValidationResult result)
+        {
+            return result.User.preferredUsername.ToLowerInvariant().Trim();
+        }
+
+        public static string GetHost(SignatureValidationResult result)
+        {
+            return result.User.url.Replace("https://", string.Empty).Split('/').First();
+        }
+
+        public static string GetSharedInbox(SignatureValidationResult result)
+        {
+            return result.User?.endpoints?.sharedInbox;
+        }
+    }
+}

src/BirdsiteLive.Domain/UserService.cs

@@ -7,6 +7,7 @@ using System.Text;
 using System.Threading.Tasks;
 using BirdsiteLive.ActivityPub;
 using BirdsiteLive.ActivityPub.Converters;
+using BirdsiteLive.ActivityPub.Models;
 using BirdsiteLive.Common.Regexes;
 using BirdsiteLive.Common.Settings;
 using BirdsiteLive.Cryptography;
@@ -28,10 +29,12 @@ namespace BirdsiteLive.Domain
         Task<bool> UndoFollowRequestedAsync(string signature, string method, string path, string queryString, Dictionary<string, string> requestHeaders, ActivityUndoFollow activity, string body);
 
         Task<bool> SendRejectFollowAsync(ActivityFollow activity, string followerHost);
+        Task<bool> DeleteRequestedAsync(string signature, string method, string path, string queryString, Dictionary<string, string> requestHeaders, ActivityDelete activity, string body);
     }
 
     public class UserService : IUserService
     {
+        private readonly IProcessDeleteUser _processDeleteUser;
         private readonly IProcessFollowUser _processFollowUser;
         private readonly IProcessUndoFollowUser _processUndoFollowUser;
 
@@ -46,7 +49,7 @@ namespace BirdsiteLive.Domain
         private readonly IModerationRepository _moderationRepository;
 
         #region Ctor
-        public UserService(InstanceSettings instanceSettings, ICryptoService cryptoService, IActivityPubService activityPubService, IProcessFollowUser processFollowUser, IProcessUndoFollowUser processUndoFollowUser, IStatusExtractor statusExtractor, IExtractionStatisticsHandler statisticsHandler, ITwitterUserService twitterUserService, IModerationRepository moderationRepository)
+        public UserService(InstanceSettings instanceSettings, ICryptoService cryptoService, IActivityPubService activityPubService, IProcessFollowUser processFollowUser, IProcessUndoFollowUser processUndoFollowUser, IStatusExtractor statusExtractor, IExtractionStatisticsHandler statisticsHandler, ITwitterUserService twitterUserService, IModerationRepository moderationRepository, IProcessDeleteUser processDeleteUser)
         {
             _instanceSettings = instanceSettings;
             _cryptoService = cryptoService;
@@ -57,6 +60,7 @@ namespace BirdsiteLive.Domain
             _statisticsHandler = statisticsHandler;
             _twitterUserService = twitterUserService;
             _moderationRepository = moderationRepository;
+            _processDeleteUser = processDeleteUser;
         }
         #endregion
 
@@ -126,10 +130,10 @@ namespace BirdsiteLive.Domain
             if (!sigValidation.SignatureIsValidated) return false;
 
             // Prepare data
-            var followerUserName = sigValidation.User.preferredUsername.ToLowerInvariant().Trim();
-            var followerHost = sigValidation.User.url.Replace("https://", string.Empty).Split('/').First();
+            var followerUserName = SigValidationResultExtractor.GetUserName(sigValidation);
+            var followerHost = SigValidationResultExtractor.GetHost(sigValidation);
             var followerInbox = sigValidation.User.inbox;
-            var followerSharedInbox = sigValidation.User?.endpoints?.sharedInbox;
+            var followerSharedInbox = SigValidationResultExtractor.GetSharedInbox(sigValidation);
             var twitterUser = activity.apObject.Split('/').Last().Replace("@", string.Empty).ToLowerInvariant().Trim();
 
             // Make sure to only keep routes
@@ -213,7 +217,7 @@ namespace BirdsiteLive.Domain
             return result == HttpStatusCode.Accepted ||
                    result == HttpStatusCode.OK; //TODO: revamp this for better error handling
         }
-
+        
         private string OnlyKeepRoute(string inbox, string host)
         {
             if (string.IsNullOrWhiteSpace(inbox)) 
@@ -258,6 +262,22 @@ namespace BirdsiteLive.Domain
             return result == HttpStatusCode.Accepted || result == HttpStatusCode.OK; //TODO: revamp this for better error handling
         }
 
+        public async Task<bool> DeleteRequestedAsync(string signature, string method, string path, string queryString, Dictionary<string, string> requestHeaders,
+            ActivityDelete activity, string body)
+        {
+            // Validate
+            var sigValidation = await ValidateSignature(activity.actor, signature, method, path, queryString, requestHeaders, body);
+            if (!sigValidation.SignatureIsValidated) return false;
+
+            // Remove user and followings
+            var followerUserName = SigValidationResultExtractor.GetUserName(sigValidation);
+            var followerHost = SigValidationResultExtractor.GetHost(sigValidation);
+
+            await _processDeleteUser.ExecuteAsync(followerUserName, followerHost);
+
+            return true;
+        }
+
         private async Task<SignatureValidationResult> ValidateSignature(string actor, string rawSig, string method, string path, string queryString, Dictionary<string, string> requestHeaders, string body)
         {
             //Check Date Validity

src/BirdsiteLive.Moderation/Actions/RemoveFollowerAction.cs

@@ -1,12 +1,6 @@
-using System;
-using System.Linq;
-using System.Threading.Tasks;
-using BirdsiteLive.ActivityPub;
-using BirdsiteLive.ActivityPub.Converters;
-using BirdsiteLive.Common.Settings;
-using BirdsiteLive.DAL.Contracts;
+using System.Threading.Tasks;
 using BirdsiteLive.DAL.Models;
-using BirdsiteLive.Domain;
+using BirdsiteLive.Domain.BusinessUseCases;
 
 namespace BirdsiteLive.Moderation.Actions
 {
@@ -17,16 +11,14 @@ namespace BirdsiteLive.Moderation.Actions
 
     public class RemoveFollowerAction : IRemoveFollowerAction
     {
-        private readonly IFollowersDal _followersDal;
-        private readonly ITwitterUserDal _twitterUserDal;
         private readonly IRejectAllFollowingsAction _rejectAllFollowingsAction;
+        private readonly IProcessDeleteUser _processDeleteUser;
 
         #region Ctor
-        public RemoveFollowerAction(IFollowersDal followersDal, ITwitterUserDal twitterUserDal, IRejectAllFollowingsAction rejectAllFollowingsAction)
+        public RemoveFollowerAction(IRejectAllFollowingsAction rejectAllFollowingsAction, IProcessDeleteUser processDeleteUser)
         {
-            _followersDal = followersDal;
-            _twitterUserDal = twitterUserDal;
             _rejectAllFollowingsAction = rejectAllFollowingsAction;
+            _processDeleteUser = processDeleteUser;
         }
         #endregion
 
@@ -36,16 +28,7 @@ namespace BirdsiteLive.Moderation.Actions
             await _rejectAllFollowingsAction.ProcessAsync(follower);
 
             // Remove twitter users if no more followers
-            var followings = follower.Followings;
-            foreach (var following in followings)
-            {
-                var followers = await _followersDal.GetFollowersAsync(following);
-                if (followers.Length == 1 && followers.First().Id == follower.Id)
-                    await _twitterUserDal.DeleteTwitterUserAsync(following);
-            }
-
-            // Remove follower from DB
-            await _followersDal.DeleteFollowerAsync(follower.Id);
+            await _processDeleteUser.ExecuteAsync(follower);
         }
     }
 }

src/BirdsiteLive.Pipeline/Processors/RefreshTwitterUserStatusProcessor.cs

@@ -9,6 +9,7 @@ using BirdsiteLive.Moderation.Actions;
 using BirdsiteLive.Pipeline.Contracts;
 using BirdsiteLive.Pipeline.Models;
 using BirdsiteLive.Twitter;
+using BirdsiteLive.Twitter.Models;
 
 namespace BirdsiteLive.Pipeline.Processors
 {
@@ -35,26 +36,61 @@ namespace BirdsiteLive.Pipeline.Processors
 
             foreach (var user in syncTwitterUsers)
             {
-                var userView = _twitterUserService.GetUser(user.Acct);
-                if (userView == null)
-                {
-                    await AnalyseFailingUserAsync(user);
-                }
-                else if (!userView.Protected)
-                {
-                    user.FetchingErrorCount = 0;
-                    var userWtData = new UserWithDataToSync
-                    {
-                        User = user
-                    };
-                    usersWtData.Add(userWtData);
-                }
-            }
+                TwitterUser userView = null;
 
+                try
+                {
+                    userView = _twitterUserService.GetUser(user.Acct);
+                }
+                catch (UserNotFoundException)
+                {
+                    await ProcessNotFoundUserAsync(user);
+                    continue;
+                }
+                catch (UserHasBeenSuspendedException)
+                {
+                    await ProcessNotFoundUserAsync(user);
+                    continue;
+                }
+                catch (RateLimitExceededException)
+                {
+                    await ProcessRateLimitExceededAsync(user);
+                    continue;
+                }
+                catch (Exception)
+                {
+                    // ignored
+                }
+
+                if (userView == null || userView.Protected)
+                {
+                    await ProcessFailingUserAsync(user);
+                    continue;
+                }
+
+                user.FetchingErrorCount = 0;
+                var userWtData = new UserWithDataToSync
+                {
+                    User = user
+                };
+                usersWtData.Add(userWtData);
+            }
             return usersWtData.ToArray();
         }
 
-        private async Task AnalyseFailingUserAsync(SyncTwitterUser user)
+        private async Task ProcessRateLimitExceededAsync(SyncTwitterUser user)
+        {
+            var dbUser = await _twitterUserDal.GetTwitterUserAsync(user.Acct);
+            dbUser.LastSync = DateTime.UtcNow;
+            await _twitterUserDal.UpdateTwitterUserAsync(dbUser);
+        }
+
+        private async Task ProcessNotFoundUserAsync(SyncTwitterUser user)
+        {
+            await _removeTwitterAccountAction.ProcessAsync(user);
+        }
+
+        private async Task ProcessFailingUserAsync(SyncTwitterUser user)
         {
             var dbUser = await _twitterUserDal.GetTwitterUserAsync(user.Acct);
             dbUser.FetchingErrorCount++;
@@ -68,9 +104,6 @@ namespace BirdsiteLive.Pipeline.Processors
             {
                 await _twitterUserDal.UpdateTwitterUserAsync(dbUser);
             }
-
-            // Purge
-            _twitterUserService.PurgeUser(user.Acct);
         }
     }
 }

src/BirdsiteLive.Pipeline/Processors/SendTweetsToFollowersProcessor.cs

@@ -5,9 +5,11 @@ using System.Net;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Xml;
+using BirdsiteLive.Common.Settings;
 using BirdsiteLive.DAL.Contracts;
 using BirdsiteLive.DAL.Models;
 using BirdsiteLive.Domain;
+using BirdsiteLive.Moderation.Actions;
 using BirdsiteLive.Pipeline.Contracts;
 using BirdsiteLive.Pipeline.Models;
 using BirdsiteLive.Pipeline.Processors.SubTasks;
@@ -23,14 +25,18 @@ namespace BirdsiteLive.Pipeline.Processors
         private readonly ISendTweetsToInboxTask _sendTweetsToInboxTask;
         private readonly ISendTweetsToSharedInboxTask _sendTweetsToSharedInbox;
         private readonly IFollowersDal _followersDal;
+        private readonly InstanceSettings _instanceSettings;
         private readonly ILogger<SendTweetsToFollowersProcessor> _logger;
+        private readonly IRemoveFollowerAction _removeFollowerAction;
 
         #region Ctor
-        public SendTweetsToFollowersProcessor(ISendTweetsToInboxTask sendTweetsToInboxTask, ISendTweetsToSharedInboxTask sendTweetsToSharedInbox, IFollowersDal followersDal, ILogger<SendTweetsToFollowersProcessor> logger)
+        public SendTweetsToFollowersProcessor(ISendTweetsToInboxTask sendTweetsToInboxTask, ISendTweetsToSharedInboxTask sendTweetsToSharedInbox, IFollowersDal followersDal, ILogger<SendTweetsToFollowersProcessor> logger, InstanceSettings instanceSettings, IRemoveFollowerAction removeFollowerAction)
         {
             _sendTweetsToInboxTask = sendTweetsToInboxTask;
             _sendTweetsToSharedInbox = sendTweetsToSharedInbox;
             _logger = logger;
+            _instanceSettings = instanceSettings;
+            _removeFollowerAction = removeFollowerAction;
             _followersDal = followersDal;
         }
         #endregion
@@ -107,7 +113,17 @@ namespace BirdsiteLive.Pipeline.Processors
         private async Task ProcessFailingUserAsync(Follower follower)
         {
             follower.PostingErrorCount++;
-            await _followersDal.UpdateFollowerAsync(follower);
+
+            if (follower.PostingErrorCount > _instanceSettings.FailingFollowerCleanUpThreshold 
+                && _instanceSettings.FailingFollowerCleanUpThreshold > 0
+                || follower.PostingErrorCount > 2147483600)
+            {
+                await _removeFollowerAction.ProcessAsync(follower);
+            }
+            else
+            {
+                await _followersDal.UpdateFollowerAsync(follower);
+            }
         }
     }
 }

src/BirdsiteLive.Twitter/CachedTwitterService.cs

@@ -1,4 +1,5 @@
 using System;
+using BirdsiteLive.Common.Settings;
 using BirdsiteLive.Twitter.Models;
 using Microsoft.Extensions.Caching.Memory;
 
@@ -13,11 +14,8 @@ namespace BirdsiteLive.Twitter
     {
         private readonly ITwitterUserService _twitterService;
 
-        private MemoryCache _userCache = new MemoryCache(new MemoryCacheOptions()
-        {
-            SizeLimit = 5000
-        });
-        private MemoryCacheEntryOptions _cacheEntryOptions = new MemoryCacheEntryOptions()
+        private readonly MemoryCache _userCache;
+        private readonly MemoryCacheEntryOptions _cacheEntryOptions = new MemoryCacheEntryOptions()
             .SetSize(1)//Size amount
             //Priority on removing when reaching size limit (memory pressure)
             .SetPriority(CacheItemPriority.High)
@@ -27,9 +25,14 @@ namespace BirdsiteLive.Twitter
             .SetAbsoluteExpiration(TimeSpan.FromDays(7));
 
         #region Ctor
-        public CachedTwitterUserService(ITwitterUserService twitterService)
+        public CachedTwitterUserService(ITwitterUserService twitterService, InstanceSettings settings)
         {
             _twitterService = twitterService;
+
+            _userCache = new MemoryCache(new MemoryCacheOptions()
+            {
+                SizeLimit = settings.UserCacheCapacity
+            });
         }
         #endregion
 
@@ -44,6 +47,11 @@ namespace BirdsiteLive.Twitter
             return user;
         }
 
+        public bool IsUserApiRateLimited()
+        {
+            return _twitterService.IsUserApiRateLimited();
+        }
+
         public void PurgeUser(string username)
         {
             _userCache.Remove(username);

src/BirdsiteLive.Twitter/Exceptions/RateLimitExceededException.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace BirdsiteLive.Twitter
+{
+    public class RateLimitExceededException : Exception
+    {
+
+    }
+}

src/BirdsiteLive.Twitter/Exceptions/UserHasBeenSuspendedException.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace BirdsiteLive.Twitter
+{
+    public class UserHasBeenSuspendedException : Exception
+    {
+
+    }
+}

src/BirdsiteLive.Twitter/Exceptions/UserNotFoundException.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace BirdsiteLive.Twitter
+{
+    public class UserNotFoundException : Exception
+    {
+
+    }
+}

src/BirdsiteLive.Twitter/Statistics/TwitterStatisticsHandler.cs

@@ -13,6 +13,8 @@ namespace BirdsiteLive.Statistics.Domain
         void CalledTweetApi();
         void CalledTimelineApi();
         ApiStatistics GetStatistics();
+
+        int GetCurrentUserCalls();
     }
 
     //Rate limits: https://developer.twitter.com/en/docs/twitter-api/v1/rate-limits
@@ -60,7 +62,12 @@ namespace BirdsiteLive.Statistics.Domain
             foreach (var old in oldSnapshots) _snapshots.TryRemove(old, out var data);
         }
 
-        public void CalledUserApi()  //GET users/show - 900/15mins
+        public int GetCurrentUserCalls()
+        {
+            return _userCalls;
+        }
+
+        public void CalledUserApi()  //GET users/show - 300/15mins
         {
             Interlocked.Increment(ref _userCalls);
         }

src/BirdsiteLive.Twitter/TwitterUserService.cs

@@ -6,6 +6,7 @@ using BirdsiteLive.Twitter.Models;
 using BirdsiteLive.Twitter.Tools;
 using Microsoft.Extensions.Logging;
 using Tweetinvi;
+using Tweetinvi.Exceptions;
 using Tweetinvi.Models;
 
 namespace BirdsiteLive.Twitter
@@ -13,6 +14,7 @@ namespace BirdsiteLive.Twitter
     public interface ITwitterUserService
     {
         TwitterUser GetUser(string username);
+        bool IsUserApiRateLimited();
     }
 
     public class TwitterUserService : ITwitterUserService
@@ -32,27 +34,46 @@ namespace BirdsiteLive.Twitter
 
         public TwitterUser GetUser(string username)
         {
+            //Check if API is saturated 
+            if (IsUserApiRateLimited()) throw new RateLimitExceededException();
+
+            //Proceed to account retrieval
             _twitterAuthenticationInitializer.EnsureAuthenticationIsInitialized();
             ExceptionHandler.SwallowWebExceptions = false;
+            RateLimit.RateLimitTrackerMode = RateLimitTrackerMode.TrackOnly;
 
             IUser user;
             try
             {
                 user = User.GetUserFromScreenName(username);
-                _statisticsHandler.CalledUserApi();
-                if (user == null)
+            }
+            catch (TwitterException e)
+            {
+                if (e.TwitterExceptionInfos.Any(x => x.Message.ToLowerInvariant().Contains("User has been suspended".ToLowerInvariant())))
                 {
-                    _logger.LogWarning("User {username} not found", username);
-                    return null;
+                    throw new UserHasBeenSuspendedException();
+                }
+                else if (e.TwitterExceptionInfos.Any(x => x.Message.ToLowerInvariant().Contains("User not found".ToLowerInvariant())))
+                {
+                    throw new UserNotFoundException();
+                }
+                else if (e.TwitterExceptionInfos.Any(x => x.Message.ToLowerInvariant().Contains("Rate limit exceeded".ToLowerInvariant())))
+                {
+                    throw new RateLimitExceededException();
+                }
+                else
+                {
+                    throw;
                 }
             }
             catch (Exception e)
             {
                 _logger.LogError(e, "Error retrieving user {Username}", username);
-
-                // TODO keep track of error, see where to remove user if too much errors
-
-                return null;
+                throw;
+            }
+            finally
+            {
+                _statisticsHandler.CalledUserApi();
             }
 
             // Expand URLs
@@ -73,5 +94,32 @@ namespace BirdsiteLive.Twitter
                 Protected = user.Protected
             };
         }
+
+        public bool IsUserApiRateLimited()
+        {
+            // Retrieve limit from tooling
+            _twitterAuthenticationInitializer.EnsureAuthenticationIsInitialized();
+            ExceptionHandler.SwallowWebExceptions = false;
+            RateLimit.RateLimitTrackerMode = RateLimitTrackerMode.TrackOnly;
+
+            try
+            {
+                var queryRateLimits = RateLimit.GetQueryRateLimit("https://api.twitter.com/1.1/users/show.json?screen_name=mastodon");
+
+                if (queryRateLimits != null)
+                {
+                    return queryRateLimits.Remaining <= 0;
+                }
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Error retrieving rate limits");
+            }
+
+            // Fallback
+            var currentCalls = _statisticsHandler.GetCurrentUserCalls();
+            var maxCalls = _statisticsHandler.GetStatistics().UserCallsMax;
+            return currentCalls >= maxCalls;
+        }
     }
 }

src/BirdsiteLive/BirdsiteLive.csproj

@@ -4,7 +4,7 @@
     <TargetFramework>netcoreapp3.1</TargetFramework>
     <UserSecretsId>d21486de-a812-47eb-a419-05682bb68856</UserSecretsId>
     <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
-    <Version>0.19.1</Version>
+    <Version>0.20.0</Version>
   </PropertyGroup>
 
   <ItemGroup>

src/BirdsiteLive/Controllers/DebugingController.cs

@@ -14,6 +14,7 @@ using Newtonsoft.Json;
 
 namespace BirdsiteLive.Controllers
 {
+    #if DEBUG
     public class DebugingController : Controller
     {
         private readonly InstanceSettings _instanceSettings;
@@ -67,7 +68,7 @@ namespace BirdsiteLive.Controllers
             var noteGuid = Guid.NewGuid();
             var noteId = $"https://{_instanceSettings.Domain}/users/{username}/statuses/{noteGuid}";
             var noteUrl = $"https://{_instanceSettings.Domain}/@{username}/{noteGuid}";
-            
+
             var to = $"{actor}/followers";
 
             var now = DateTime.UtcNow;
@@ -80,12 +81,12 @@ namespace BirdsiteLive.Controllers
                 type = "Create",
                 actor = actor,
                 published = nowString,
-                to = new []{ to },
+                to = new[] { to },
                 //cc = new [] { "https://www.w3.org/ns/activitystreams#Public" },
                 apObject = new Note()
                 {
                     id = noteId,
-                    summary = null, 
+                    summary = null,
                     inReplyTo = null,
                     published = nowString,
                     url = noteUrl,
@@ -93,7 +94,7 @@ namespace BirdsiteLive.Controllers
 
                     // Unlisted
                     to = new[] { to },
-                    cc = new [] { "https://www.w3.org/ns/activitystreams#Public" },
+                    cc = new[] { "https://www.w3.org/ns/activitystreams#Public" },
 
                     //// Public
                     //to = new[] { "https://www.w3.org/ns/activitystreams#Public" },
@@ -125,6 +126,7 @@ namespace BirdsiteLive.Controllers
             return View("Index");
         }
     }
+    #endif
 
     public static class HtmlHelperExtensions
     {

src/BirdsiteLive/Controllers/InboxController.cs

@@ -3,6 +3,10 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
+using BirdsiteLive.ActivityPub;
+using BirdsiteLive.ActivityPub.Models;
+using BirdsiteLive.Domain;
+using BirdsiteLive.Tools;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Logging;
@@ -13,11 +17,13 @@ namespace BirdsiteLive.Controllers
     public class InboxController : ControllerBase
     {
         private readonly ILogger<InboxController> _logger;
+        private readonly IUserService _userService;
 
         #region Ctor
-        public InboxController(ILogger<InboxController> logger)
+        public InboxController(ILogger<InboxController> logger, IUserService userService)
         {
             _logger = logger;
+            _userService = userService;
         }
         #endregion
 
@@ -25,15 +31,32 @@ namespace BirdsiteLive.Controllers
         [HttpPost]
         public async Task<IActionResult> Inbox()
         {
-            var r = Request;
-            using (var reader = new StreamReader(Request.Body))
+            try
             {
-                var body = await reader.ReadToEndAsync();
+                var r = Request;
+                using (var reader = new StreamReader(Request.Body))
+                {
+                    var body = await reader.ReadToEndAsync();
 
-                _logger.LogTrace("Inbox: {Body}", body);
-                //System.IO.File.WriteAllText($@"C:\apdebug\inbox\{Guid.NewGuid()}.json", body);
+                    _logger.LogTrace("Inbox: {Body}", body);
+                    //System.IO.File.WriteAllText($@"C:\apdebug\inbox\{Guid.NewGuid()}.json", body);
 
+                    var activity = ApDeserializer.ProcessActivity(body);
+                    var signature = r.Headers["Signature"].First();
+
+                    switch (activity?.type)
+                    {
+                        case "Delete":
+                        {
+                            var succeeded = await _userService.DeleteRequestedAsync(signature, r.Method, r.Path,
+                                r.QueryString.ToString(), HeaderHandler.RequestHeaders(r.Headers), activity as ActivityDelete, body);
+                            if (succeeded) return Accepted();
+                            else return Unauthorized();
+                        }
+                    }
+                }
             }
+            catch (FollowerIsGoneException) { } //TODO: check if user in DB
 
             return Accepted();
         }

src/BirdsiteLive/Controllers/UsersController.cs

@@ -13,6 +13,7 @@ using BirdsiteLive.Common.Regexes;
 using BirdsiteLive.Common.Settings;
 using BirdsiteLive.Domain;
 using BirdsiteLive.Models;
+using BirdsiteLive.Tools;
 using BirdsiteLive.Twitter;
 using BirdsiteLive.Twitter.Models;
 using Microsoft.AspNetCore.Http;
@@ -65,11 +66,42 @@ namespace BirdsiteLive.Controllers
 
             id = id.Trim(new[] { ' ', '@' }).ToLowerInvariant();
 
+            TwitterUser user = null;
+            var isSaturated = false;
+            var notFound = false;
+
             // Ensure valid username 
             // https://help.twitter.com/en/managing-your-account/twitter-username-rules
-            TwitterUser user = null;
             if (!string.IsNullOrWhiteSpace(id) && UserRegexes.TwitterAccount.IsMatch(id) && id.Length <= 15)
-                user = _twitterUserService.GetUser(id);
+            {
+                try
+                {
+                    user = _twitterUserService.GetUser(id);
+                }
+                catch (UserNotFoundException)
+                {
+                    notFound = true;
+                }
+                catch (UserHasBeenSuspendedException)
+                {
+                    notFound = true;
+                }
+                catch (RateLimitExceededException)
+                {
+                    isSaturated = true;
+                }
+                catch (Exception e)
+                {
+                    _logger.LogError(e, "Exception getting {Id}", id);
+                    throw;
+                }
+            }
+            else
+            {
+                notFound = true;
+            }
+
+            //var isSaturated = _twitterUserService.IsUserApiRateLimited();
 
             var acceptHeaders = Request.Headers["Accept"];
             if (acceptHeaders.Any())
@@ -77,14 +109,16 @@ namespace BirdsiteLive.Controllers
                 var r = acceptHeaders.First();
                 if (r.Contains("application/activity+json"))
                 {
-                    if (user == null) return NotFound();
+                    if (isSaturated) return new ObjectResult("Too Many Requests") { StatusCode = 429 };
+                    if (notFound) return NotFound();
                     var apUser = _userService.GetUser(user);
                     var jsonApUser = JsonConvert.SerializeObject(apUser);
                     return Content(jsonApUser, "application/activity+json; charset=utf-8");
                 }
             }
 
-            if (user == null) return View("UserNotFound");
+            if (isSaturated) return View("ApiSaturated");
+            if (notFound) return View("UserNotFound");
 
             var displayableUser = new DisplayTwitterUser
             {
@@ -133,40 +167,69 @@ namespace BirdsiteLive.Controllers
         [HttpPost]
         public async Task<IActionResult> Inbox()
         {
-            var r = Request;
-            using (var reader = new StreamReader(Request.Body))
+            try
             {
-                var body = await reader.ReadToEndAsync();
-
-                _logger.LogTrace("User Inbox: {Body}", body);
-                //System.IO.File.WriteAllText($@"C:\apdebug\{Guid.NewGuid()}.json", body);
-
-                var activity = ApDeserializer.ProcessActivity(body);
-                // Do something
-                var signature = r.Headers["Signature"].First();
-                
-                switch (activity?.type)
+                var r = Request;
+                using (var reader = new StreamReader(Request.Body))
                 {
-                    case "Follow":
+                    var body = await reader.ReadToEndAsync();
+
+                    _logger.LogTrace("User Inbox: {Body}", body);
+                    //System.IO.File.WriteAllText($@"C:\apdebug\{Guid.NewGuid()}.json", body);
+
+                    var activity = ApDeserializer.ProcessActivity(body);
+                    var signature = r.Headers["Signature"].First();
+
+                    switch (activity?.type)
+                    {
+                        case "Follow":
                         {
                             var succeeded = await _userService.FollowRequestedAsync(signature, r.Method, r.Path,
-                                r.QueryString.ToString(), RequestHeaders(r.Headers), activity as ActivityFollow, body);
+                                r.QueryString.ToString(), HeaderHandler.RequestHeaders(r.Headers),
+                                activity as ActivityFollow, body);
                             if (succeeded) return Accepted();
                             else return Unauthorized();
                         }
-                    case "Undo":
-                        if (activity is ActivityUndoFollow)
+                        case "Undo":
+                            if (activity is ActivityUndoFollow)
+                            {
+                                var succeeded = await _userService.UndoFollowRequestedAsync(signature, r.Method, r.Path,
+                                    r.QueryString.ToString(), HeaderHandler.RequestHeaders(r.Headers),
+                                    activity as ActivityUndoFollow, body);
+                                if (succeeded) return Accepted();
+                                else return Unauthorized();
+                            }
+
+                            return Accepted();
+                        case "Delete":
                         {
-                            var succeeded = await _userService.UndoFollowRequestedAsync(signature, r.Method, r.Path,
-                                r.QueryString.ToString(), RequestHeaders(r.Headers), activity as ActivityUndoFollow, body);
+                            var succeeded = await _userService.DeleteRequestedAsync(signature, r.Method, r.Path,
+                                r.QueryString.ToString(), HeaderHandler.RequestHeaders(r.Headers),
+                                activity as ActivityDelete, body);
                             if (succeeded) return Accepted();
                             else return Unauthorized();
                         }
-                        return Accepted();
-                    default:
-                        return Accepted();
+                        default:
+                            return Accepted();
+                    }
                 }
             }
+            catch (FollowerIsGoneException)  //TODO: check if user in DB
+            {
+                return Accepted();
+            }
+            catch (UserNotFoundException)
+            {
+                return NotFound();
+            }
+            catch (UserHasBeenSuspendedException)
+            {
+                return NotFound();
+            }
+            catch (RateLimitExceededException)
+            {
+                return new ObjectResult("Too Many Requests") { StatusCode = 429 };
+            }
         }
 
         [Route("/users/{id}/followers")]
@@ -183,10 +246,5 @@ namespace BirdsiteLive.Controllers
             var jsonApUser = JsonConvert.SerializeObject(followers);
             return Content(jsonApUser, "application/activity+json; charset=utf-8");
         }
-
-        private Dictionary<string, string> RequestHeaders(IHeaderDictionary header)
-        {
-            return header.ToDictionary<KeyValuePair<string, StringValues>, string, string>(h => h.Key.ToLowerInvariant(), h => h.Value);
-        }
     }
 }

src/BirdsiteLive/Controllers/WellKnownController.cs

@@ -12,6 +12,7 @@ using BirdsiteLive.Models;
 using BirdsiteLive.Models.WellKnownModels;
 using BirdsiteLive.Twitter;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
 namespace BirdsiteLive.Controllers
@@ -23,13 +24,15 @@ namespace BirdsiteLive.Controllers
         private readonly ITwitterUserService _twitterUserService;
         private readonly ITwitterUserDal _twitterUserDal;
         private readonly InstanceSettings _settings;
-
+        private readonly ILogger<WellKnownController> _logger;
+        
         #region Ctor
-        public WellKnownController(InstanceSettings settings, ITwitterUserService twitterUserService, ITwitterUserDal twitterUserDal, IModerationRepository moderationRepository)
+        public WellKnownController(InstanceSettings settings, ITwitterUserService twitterUserService, ITwitterUserDal twitterUserDal, IModerationRepository moderationRepository, ILogger<WellKnownController> logger)
         {
             _twitterUserService = twitterUserService;
             _twitterUserDal = twitterUserDal;
             _moderationRepository = moderationRepository;
+            _logger = logger;
             _settings = settings;
         }
         #endregion
@@ -141,30 +144,54 @@ namespace BirdsiteLive.Controllers
         [Route("/.well-known/webfinger")]
         public IActionResult Webfinger(string resource = null)
         {
-            var acct = resource.Split("acct:")[1].Trim();
+            if (string.IsNullOrWhiteSpace(resource)) 
+                return BadRequest();
 
             string name = null;
             string domain = null;
 
-            var splitAcct = acct.Split('@', StringSplitOptions.RemoveEmptyEntries);
+            if (resource.StartsWith("acct:"))
+            {
+                var acct = resource.Split("acct:")[1].Trim();
+                var splitAcct = acct.Split('@', StringSplitOptions.RemoveEmptyEntries);
 
-            var atCount = acct.Count(x => x == '@');
-            if (atCount == 1 && acct.StartsWith('@'))
-            {
-                name = splitAcct[1];
+                var atCount = acct.Count(x => x == '@');
+                if (atCount == 1 && acct.StartsWith('@'))
+                {
+                    name = splitAcct[1];
+                }
+                else if (atCount == 1 || atCount == 2)
+                {
+                    name = splitAcct[0];
+                    domain = splitAcct[1];
+                }
+                else
+                {
+                    return BadRequest();
+                }
             }
-            else if (atCount == 1 || atCount == 2)
+            else if (resource.StartsWith("https://"))
             {
-                name = splitAcct[0];
-                domain = splitAcct[1];
+                try
+                {
+                    name = resource.Split('/').Last().Trim();
+                    domain = resource.Split("https://", StringSplitOptions.RemoveEmptyEntries)[0].Split('/')[0].Trim();
+                }
+                catch (Exception e)
+                {
+                    _logger.LogError(e, "Error parsing {Resource}", resource);
+                    throw new NotImplementedException();
+                }
             }
             else
             {
-                return BadRequest();
+                _logger.LogError("Error parsing {Resource}", resource);
+                throw new NotImplementedException();
             }
 
             // Ensure lowercase
             name = name.ToLowerInvariant();
+            domain = domain?.ToLowerInvariant();
 
             // Ensure valid username 
             // https://help.twitter.com/en/managing-your-account/twitter-username-rules
@@ -174,9 +201,27 @@ namespace BirdsiteLive.Controllers
             if (!string.IsNullOrWhiteSpace(domain) && domain != _settings.Domain)
                 return NotFound();
 
-            var user = _twitterUserService.GetUser(name);
-            if (user == null)
+            try
+            {
+                _twitterUserService.GetUser(name);
+            }
+            catch (UserNotFoundException)
+            {
                 return NotFound();
+            }
+            catch (UserHasBeenSuspendedException)
+            {
+                return NotFound();
+            }
+            catch (RateLimitExceededException)
+            {
+                return new ObjectResult("Too Many Requests") { StatusCode = 429 };
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Exception getting {Name}", name);
+                throw;
+            }
 
             var actorUrl = UrlFactory.GetActorUrl(_settings.Domain, name);
 

src/BirdsiteLive/Tools/HeaderHandler.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+
+namespace BirdsiteLive.Tools
+{
+    public class HeaderHandler
+    {
+        public static Dictionary<string, string> RequestHeaders(IHeaderDictionary header)
+        {
+            return header.ToDictionary<KeyValuePair<string, StringValues>, string, string>(h => h.Key.ToLowerInvariant(), h => h.Value);
+        }
+    }
+}

src/BirdsiteLive/Views/Users/ApiSaturated.cshtml

@@ -0,0 +1,13 @@
+@using BirdsiteLive.Controllers;
+@{
+    ViewData["Title"] = "Api Saturated";
+}
+
+<div class="text-center">
+    <h1 class="display-4">429 Too Many Requests</h1>
+    <p>
+        <br />
+        The API is saturated.<br/>
+        Please consider using another instance.
+    </p>
+</div>

src/BirdsiteLive/appsettings.json

@@ -23,7 +23,9 @@
     "MaxUsersCapacity": 1000,
     "UnlistedTwitterAccounts": null,
     "SensitiveTwitterAccounts": null,
-    "FailingTwitterUserCleanUpThreshold": 700
+    "FailingTwitterUserCleanUpThreshold": 700,
+    "FailingFollowerCleanUpThreshold": 30000,
+    "UserCacheCapacity": 10000 
   },
   "Db": {
     "Type": "postgres",

src/DataAccessLayers/BirdsiteLive.DAL.Postgres/DataAccessLayers/DbInitializerPostgresDal.cs

@@ -23,7 +23,7 @@ namespace BirdsiteLive.DAL.Postgres.DataAccessLayers
     public class DbInitializerPostgresDal : PostgresBase, IDbInitializerDal
     {
         private readonly PostgresTools _tools;
-        private readonly Version _currentVersion = new Version(2, 3);
+        private readonly Version _currentVersion = new Version(2, 4);
         private const string DbVersionType = "db-version";
 
         #region Ctor
@@ -134,7 +134,8 @@ namespace BirdsiteLive.DAL.Postgres.DataAccessLayers
                 new Tuple<Version, Version>(new Version(1,0), new Version(2,0)),
                 new Tuple<Version, Version>(new Version(2,0), new Version(2,1)),
                 new Tuple<Version, Version>(new Version(2,1), new Version(2,2)),
-                new Tuple<Version, Version>(new Version(2,2), new Version(2,3))
+                new Tuple<Version, Version>(new Version(2,2), new Version(2,3)),
+                new Tuple<Version, Version>(new Version(2,3), new Version(2,4))
             };
         }
 
@@ -163,6 +164,14 @@ namespace BirdsiteLive.DAL.Postgres.DataAccessLayers
                 var addPostingError = $@"ALTER TABLE {_settings.FollowersTableName} ADD postingErrorCount SMALLINT";
                 await _tools.ExecuteRequestAsync(addPostingError);
             }
+            else if (from == new Version(2, 3) && to == new Version(2, 4))
+            {
+                var alterLastSync = $@"ALTER TABLE {_settings.TwitterUserTableName} ALTER COLUMN fetchingErrorCount TYPE INTEGER";
+                await _tools.ExecuteRequestAsync(alterLastSync);
+
+                var alterPostingError = $@"ALTER TABLE {_settings.FollowersTableName} ALTER COLUMN postingErrorCount TYPE INTEGER";
+                await _tools.ExecuteRequestAsync(alterPostingError);
+            }
             else
             {
                 throw new NotImplementedException();

src/Tests/BirdsiteLive.ActivityPub.Tests/ApDeserializerTests.cs

@@ -1,4 +1,5 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using BirdsiteLive.ActivityPub.Models;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Newtonsoft.Json;
 
 namespace BirdsiteLive.ActivityPub.Tests
@@ -48,6 +49,20 @@ namespace BirdsiteLive.ActivityPub.Tests
             Assert.AreEqual("https://mamot.fr/users/testtest", data.apObject.apObject);
         }
 
+        [TestMethod]
+        public void DeleteDeserializationTest()
+        {
+            var json =
+                "{\"@context\": \"https://www.w3.org/ns/activitystreams\", \"id\": \"https://mastodon.technology/users/deleteduser#delete\", \"type\": \"Delete\", \"actor\": \"https://mastodon.technology/users/deleteduser\", \"to\": [\"https://www.w3.org/ns/activitystreams#Public\"],\"object\": \"https://mastodon.technology/users/deleteduser\",\"signature\": {\"type\": \"RsaSignature2017\",\"creator\": \"https://mastodon.technology/users/deleteduser#main-key\",\"created\": \"2020-11-19T22:43:01Z\",\"signatureValue\": \"peksQao4v5N+sMZgHXZ6xZnGaZrd0s+LqZimu63cnp7O5NBJM6gY9AAu/vKUgrh4C50r66f9OQdHg5yChQhc4ViE+yLR/3/e59YQimelmXJPpcC99Nt0YLU/iTRLsBehY3cDdC6+ogJKgpkToQvB6tG2KrPdrkreYh4Il4eXLKMfiQhgdKluOvenLnl2erPWfE02hIu/jpuljyxSuvJunMdU4yQVSZHTtk/I8q3jjzIzhgyb7ICWU5Hkx0H/47Q24ztsvOgiTWNgO+v6l9vA7qIhztENiRPhzGP5RCCzUKRAe6bcSu1Wfa3NKWqB9BeJ7s+2y2bD7ubPbiEE1MQV7Q==\"}}";
+
+            var data = ApDeserializer.ProcessActivity(json) as ActivityDelete;
+
+            Assert.AreEqual("https://mastodon.technology/users/deleteduser#delete", data.id);
+            Assert.AreEqual("Delete", data.type);
+            Assert.AreEqual("https://mastodon.technology/users/deleteduser", data.actor);
+            Assert.AreEqual("https://mastodon.technology/users/deleteduser", data.apObject);
+        }
+
         //[TestMethod]
         //public void NoteDeserializationTest()
         //{

src/Tests/BirdsiteLive.DAL.Postgres.Tests/DataAccessLayers/FollowersPostgresDalTests.cs

@@ -340,6 +340,48 @@ namespace BirdsiteLive.DAL.Postgres.Tests.DataAccessLayers
             Assert.AreEqual(10, result.PostingErrorCount);
         }
 
+        [TestMethod]
+        public async Task CreateUpdateAndGetFollower_Integer()
+        {
+            var acct = "myhandle";
+            var host = "domain.ext";
+            var following = new[] { 12, 19, 23 };
+            var followingSync = new Dictionary<int, long>()
+            {
+                {12, 165L},
+                {19, 166L},
+                {23, 167L}
+            };
+            var inboxRoute = "/myhandle/inbox";
+            var sharedInboxRoute = "/inbox";
+            var actorId = $"https://{host}/{acct}";
+
+            var dal = new FollowersPostgresDal(_settings);
+            await dal.CreateFollowerAsync(acct, host, inboxRoute, sharedInboxRoute, actorId, following, followingSync);
+            var result = await dal.GetFollowerAsync(acct, host);
+
+            var updatedFollowing = new List<int> { 12, 19, 23, 24 };
+            var updatedFollowingSync = new Dictionary<int, long>(){
+                {12, 170L},
+                {19, 171L},
+                {23, 172L},
+                {24, 173L}
+            };
+            result.Followings = updatedFollowing.ToList();
+            result.FollowingsSyncStatus = updatedFollowingSync;
+            result.PostingErrorCount = 32768;
+
+            await dal.UpdateFollowerAsync(result);
+            result = await dal.GetFollowerAsync(acct, host);
+
+            Assert.AreEqual(updatedFollowing.Count, result.Followings.Count);
+            Assert.AreEqual(updatedFollowing[0], result.Followings[0]);
+            Assert.AreEqual(updatedFollowingSync.Count, result.FollowingsSyncStatus.Count);
+            Assert.AreEqual(updatedFollowingSync.First().Key, result.FollowingsSyncStatus.First().Key);
+            Assert.AreEqual(updatedFollowingSync.First().Value, result.FollowingsSyncStatus.First().Value);
+            Assert.AreEqual(32768, result.PostingErrorCount);
+        }
+
         [TestMethod]
         public async Task CreateUpdateAndGetFollower_Remove()
         {

src/Tests/BirdsiteLive.DAL.Postgres.Tests/DataAccessLayers/TwitterUserPostgresDalTests.cs

@@ -130,6 +130,38 @@ namespace BirdsiteLive.DAL.Postgres.Tests.DataAccessLayers
             Assert.IsTrue(Math.Abs((now.ToUniversalTime() - result.LastSync).Milliseconds) < 100);
         }
 
+        [TestMethod]
+        public async Task CreateUpdate3AndGetUser()
+        {
+            var acct = "myid";
+            var lastTweetId = 1548L;
+
+            var dal = new TwitterUserPostgresDal(_settings);
+
+            await dal.CreateTwitterUserAsync(acct, lastTweetId);
+            var result = await dal.GetTwitterUserAsync(acct);
+
+
+            var updatedLastTweetId = 1600L;
+            var updatedLastSyncId = 1550L;
+            var now = DateTime.Now;
+            var errors = 32768;
+
+            result.LastTweetPostedId = updatedLastTweetId;
+            result.LastTweetSynchronizedForAllFollowersId = updatedLastSyncId;
+            result.FetchingErrorCount = errors;
+            result.LastSync = now;
+            await dal.UpdateTwitterUserAsync(result);
+
+            result = await dal.GetTwitterUserAsync(acct);
+
+            Assert.AreEqual(acct, result.Acct);
+            Assert.AreEqual(updatedLastTweetId, result.LastTweetPostedId);
+            Assert.AreEqual(updatedLastSyncId, result.LastTweetSynchronizedForAllFollowersId);
+            Assert.AreEqual(errors, result.FetchingErrorCount);
+            Assert.IsTrue(Math.Abs((now.ToUniversalTime() - result.LastSync).Milliseconds) < 100);
+        }
+
         [TestMethod]
         [ExpectedException(typeof(ArgumentException))]
         public async Task Update_NoId()

src/Tests/BirdsiteLive.Domain.Tests/BusinessUseCases/ProcessDeleteUserTests.cs

@@ -0,0 +1,97 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using BirdsiteLive.DAL.Contracts;
+using BirdsiteLive.DAL.Models;
+using BirdsiteLive.Domain.BusinessUseCases;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq;
+
+namespace BirdsiteLive.Domain.Tests.BusinessUseCases
+{
+    [TestClass]
+    public class ProcessDeleteUserTests
+    {
+        [TestMethod]
+        public async Task ExecuteAsync_NoMoreFollowings()
+        {
+            #region Stubs
+            var follower = new Follower
+            {
+                Id = 12,
+                Followings = new List<int> { 1 }
+            };
+            #endregion
+
+            #region Mocks
+            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
+            followersDalMock
+                .Setup(x => x.GetFollowersAsync(
+                    It.Is<int>(y => y == 1)))
+                .ReturnsAsync(new[] { follower });
+
+            followersDalMock
+                .Setup(x => x.DeleteFollowerAsync(
+                    It.Is<int>(y => y == 12)))
+                .Returns(Task.CompletedTask);
+
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            twitterUserDalMock
+                .Setup(x => x.DeleteTwitterUserAsync(
+                    It.Is<int>(y => y == 1)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var action = new ProcessDeleteUser(followersDalMock.Object, twitterUserDalMock.Object);
+            await action.ExecuteAsync(follower);
+
+            #region Validations
+            followersDalMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ExecuteAsync_HaveFollowings()
+        {
+            #region Stubs
+            var follower = new Follower
+            {
+                Id = 12,
+                Followings = new List<int> { 1 }
+            };
+
+            var followers = new List<Follower>
+            {
+                follower,
+                new Follower
+                {
+                    Id = 11
+                }
+            };
+            #endregion
+
+            #region Mocks
+            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
+            followersDalMock
+                .Setup(x => x.GetFollowersAsync(
+                    It.Is<int>(y => y == 1)))
+                .ReturnsAsync(followers.ToArray());
+
+            followersDalMock
+                .Setup(x => x.DeleteFollowerAsync(
+                    It.Is<int>(y => y == 12)))
+                .Returns(Task.CompletedTask);
+
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            #endregion
+
+            var action = new ProcessDeleteUser(followersDalMock.Object, twitterUserDalMock.Object);
+            await action.ExecuteAsync(follower);
+
+            #region Validations
+            followersDalMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            #endregion
+        }
+    }
+}

src/Tests/BirdsiteLive.Moderation.Tests/Actions/RemoveFollowerActionTests.cs

@@ -2,6 +2,7 @@
 using System.Threading.Tasks;
 using BirdsiteLive.DAL.Contracts;
 using BirdsiteLive.DAL.Models;
+using BirdsiteLive.Domain.BusinessUseCases;
 using BirdsiteLive.Moderation.Actions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
@@ -29,31 +30,19 @@ namespace BirdsiteLive.Moderation.Tests.Actions
                     It.Is<Follower>(y => y.Id == follower.Id)))
                 .Returns(Task.CompletedTask);
 
-            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
-            followersDalMock
-                .Setup(x => x.GetFollowersAsync(
-                    It.Is<int>(y => y == 1)))
-                .ReturnsAsync(new[] {follower});
-
-            followersDalMock
-                .Setup(x => x.DeleteFollowerAsync(
-                    It.Is<int>(y => y == 12)))
-                .Returns(Task.CompletedTask);
-
-            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
-            twitterUserDalMock
-                .Setup(x => x.DeleteTwitterUserAsync(
-                    It.Is<int>(y => y == 1)))
+            var processDeleteUserMock = new Mock<IProcessDeleteUser>(MockBehavior.Strict);
+            processDeleteUserMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<Follower>(y => y.Id == follower.Id)))
                 .Returns(Task.CompletedTask);
             #endregion
 
-            var action = new RemoveFollowerAction(followersDalMock.Object, twitterUserDalMock.Object, rejectAllFollowingsActionMock.Object);
+            var action = new RemoveFollowerAction(rejectAllFollowingsActionMock.Object, processDeleteUserMock.Object);
             await action.ProcessAsync(follower);
 
             #region Validations
-            followersDalMock.VerifyAll();
-            twitterUserDalMock.VerifyAll();
             rejectAllFollowingsActionMock.VerifyAll();
+            processDeleteUserMock.VerifyAll();
             #endregion
         }
 
@@ -66,15 +55,6 @@ namespace BirdsiteLive.Moderation.Tests.Actions
                 Id = 12,
                 Followings = new List<int> { 1 }
             };
-
-            var followers = new List<Follower>
-            {
-                follower,
-                new Follower
-                {
-                    Id = 11
-                }
-            };
             #endregion
 
             #region Mocks
@@ -84,27 +64,19 @@ namespace BirdsiteLive.Moderation.Tests.Actions
                     It.Is<Follower>(y => y.Id == follower.Id)))
                 .Returns(Task.CompletedTask);
 
-            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
-            followersDalMock
-                .Setup(x => x.GetFollowersAsync(
-                    It.Is<int>(y => y == 1)))
-                .ReturnsAsync(followers.ToArray());
-
-            followersDalMock
-                .Setup(x => x.DeleteFollowerAsync(
-                    It.Is<int>(y => y == 12)))
+            var processDeleteUserMock = new Mock<IProcessDeleteUser>(MockBehavior.Strict);
+            processDeleteUserMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<Follower>(y => y.Id == follower.Id)))
                 .Returns(Task.CompletedTask);
-
-            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
             #endregion
 
-            var action = new RemoveFollowerAction(followersDalMock.Object, twitterUserDalMock.Object, rejectAllFollowingsActionMock.Object);
+            var action = new RemoveFollowerAction(rejectAllFollowingsActionMock.Object, processDeleteUserMock.Object);
             await action.ProcessAsync(follower);
 
             #region Validations
-            followersDalMock.VerifyAll();
-            twitterUserDalMock.VerifyAll();
             rejectAllFollowingsActionMock.VerifyAll();
+            processDeleteUserMock.VerifyAll();
             #endregion
         }
     }

src/Tests/BirdsiteLive.Pipeline.Tests/Processors/RefreshTwitterUserStatusProcessorTests.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -159,11 +160,136 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
 
             twitterUserServiceMock
                 .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
-                .Returns((TwitterUser) null);
+                .Throws(new UserNotFoundException());
+
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+
+            var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
+            removeTwitterAccountActionMock
+                .Setup(x => x.ProcessAsync(It.Is<SyncTwitterUser>(y => y.Acct == acct2)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var processor = new RefreshTwitterUserStatusProcessor(twitterUserServiceMock.Object, twitterUserDalMock.Object, removeTwitterAccountActionMock.Object, settings);
+            var result = await processor.ProcessAsync(users.ToArray(), CancellationToken.None);
+
+            #region Validations
+            Assert.AreEqual(1, result.Length);
+            Assert.IsTrue(result.Any(x => x.User.Id == userId1));
+
+            twitterUserServiceMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            removeTwitterAccountActionMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ProcessAsync_Suspended_Test()
+        {
+            #region Stubs
+            var userId1 = 1;
+            var acct1 = "user1";
+
+            var userId2 = 2;
+            var acct2 = "user2";
+
+            var users = new List<SyncTwitterUser>
+            {
+                new SyncTwitterUser
+                {
+                    Id = userId1,
+                    Acct = acct1
+                },
+                new SyncTwitterUser
+                {
+                    Id = userId2,
+                    Acct = acct2
+                }
+            };
+
+            var settings = new InstanceSettings
+            {
+                FailingTwitterUserCleanUpThreshold = 300
+            };
+            #endregion
+
+            #region Mocks
+            var twitterUserServiceMock = new Mock<ICachedTwitterUserService>(MockBehavior.Strict);
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
+                .Returns(new TwitterUser
+                {
+                    Protected = false
+                });
 
             twitterUserServiceMock
-                .Setup(x => x.PurgeUser(It.Is<string>(y => y == acct2)));
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
+                .Throws(new UserHasBeenSuspendedException());
 
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+
+            var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
+            removeTwitterAccountActionMock
+                .Setup(x => x.ProcessAsync(It.Is<SyncTwitterUser>(y => y.Acct == acct2)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var processor = new RefreshTwitterUserStatusProcessor(twitterUserServiceMock.Object, twitterUserDalMock.Object, removeTwitterAccountActionMock.Object, settings);
+            var result = await processor.ProcessAsync(users.ToArray(), CancellationToken.None);
+
+            #region Validations
+            Assert.AreEqual(1, result.Length);
+            Assert.IsTrue(result.Any(x => x.User.Id == userId1));
+
+            twitterUserServiceMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            removeTwitterAccountActionMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ProcessAsync_Exception_Test()
+        {
+            #region Stubs
+            var userId1 = 1;
+            var acct1 = "user1";
+
+            var userId2 = 2;
+            var acct2 = "user2";
+
+            var users = new List<SyncTwitterUser>
+            {
+                new SyncTwitterUser
+                {
+                    Id = userId1,
+                    Acct = acct1
+                },
+                new SyncTwitterUser
+                {
+                    Id = userId2,
+                    Acct = acct2
+                }
+            };
+
+            var settings = new InstanceSettings
+            {
+                FailingTwitterUserCleanUpThreshold = 300
+            };
+            #endregion
+
+            #region Mocks
+            var twitterUserServiceMock = new Mock<ICachedTwitterUserService>(MockBehavior.Strict);
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
+                .Returns(new TwitterUser
+                {
+                    Protected = false
+                });
+
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
+                .Throws(new Exception());
+            
             var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
             twitterUserDalMock
                 .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
@@ -194,7 +320,7 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
         }
 
         [TestMethod]
-        public async Task ProcessAsync_Unfound_OverThreshold_Test()
+        public async Task ProcessAsync_Error_Test()
         {
             #region Stubs
             var userId1 = 1;
@@ -235,10 +361,79 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
             twitterUserServiceMock
                 .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
                 .Returns((TwitterUser)null);
+            
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            twitterUserDalMock
+                .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
+                .ReturnsAsync(new SyncTwitterUser
+                {
+                    Id = userId2,
+                    FetchingErrorCount = 0
+                });
+
+            twitterUserDalMock
+                .Setup(x => x.UpdateTwitterUserAsync(It.Is<SyncTwitterUser>(y => y.Id == userId2 && y.FetchingErrorCount == 1)))
+                .Returns(Task.CompletedTask);
+
+            var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
+            #endregion
+
+            var processor = new RefreshTwitterUserStatusProcessor(twitterUserServiceMock.Object, twitterUserDalMock.Object, removeTwitterAccountActionMock.Object, settings);
+            var result = await processor.ProcessAsync(users.ToArray(), CancellationToken.None);
+
+            #region Validations
+            Assert.AreEqual(1, result.Length);
+            Assert.IsTrue(result.Any(x => x.User.Id == userId1));
+
+            twitterUserServiceMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            removeTwitterAccountActionMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ProcessAsync_Error_OverThreshold_Test()
+        {
+            #region Stubs
+            var userId1 = 1;
+            var acct1 = "user1";
+
+            var userId2 = 2;
+            var acct2 = "user2";
+
+            var users = new List<SyncTwitterUser>
+            {
+                new SyncTwitterUser
+                {
+                    Id = userId1,
+                    Acct = acct1
+                },
+                new SyncTwitterUser
+                {
+                    Id = userId2,
+                    Acct = acct2
+                }
+            };
+
+            var settings = new InstanceSettings
+            {
+                FailingTwitterUserCleanUpThreshold = 300
+            };
+            #endregion
+
+            #region Mocks
+            var twitterUserServiceMock = new Mock<ICachedTwitterUserService>(MockBehavior.Strict);
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
+                .Returns(new TwitterUser
+                {
+                    Protected = false
+                });
 
             twitterUserServiceMock
-                .Setup(x => x.PurgeUser(It.Is<string>(y => y == acct2)));
-
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
+                .Returns((TwitterUser)null);
+            
             var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
             twitterUserDalMock
                 .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
@@ -312,8 +507,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 {
                     Protected = true
                 });
-
+            
             var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            twitterUserDalMock
+                .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
+                .ReturnsAsync(new SyncTwitterUser
+                {
+                    Id = userId2,
+                    FetchingErrorCount = 0
+                });
+
+            twitterUserDalMock
+                .Setup(x => x.UpdateTwitterUserAsync(It.Is<SyncTwitterUser>(y => y.Id == userId2 && y.FetchingErrorCount == 1)))
+                .Returns(Task.CompletedTask);
+
             var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
             #endregion
 
@@ -331,7 +538,81 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
         }
 
         [TestMethod]
-        public async Task ProcessAsync_Unfound_NotInit_Test()
+        public async Task ProcessAsync_Protected_OverThreshold_Test()
+        {
+            #region Stubs
+            var userId1 = 1;
+            var acct1 = "user1";
+
+            var userId2 = 2;
+            var acct2 = "user2";
+
+            var users = new List<SyncTwitterUser>
+            {
+                new SyncTwitterUser
+                {
+                    Id = userId1,
+                    Acct = acct1
+                },
+                new SyncTwitterUser
+                {
+                    Id = userId2,
+                    Acct = acct2
+                }
+            };
+
+            var settings = new InstanceSettings
+            {
+                FailingTwitterUserCleanUpThreshold = 300
+            };
+            #endregion
+
+            #region Mocks
+            var twitterUserServiceMock = new Mock<ICachedTwitterUserService>(MockBehavior.Strict);
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
+                .Returns(new TwitterUser
+                {
+                    Protected = false
+                });
+
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
+                .Returns(new TwitterUser
+                {
+                    Protected = true
+                });
+            
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            twitterUserDalMock
+                .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
+                .ReturnsAsync(new SyncTwitterUser
+                {
+                    Id = userId2,
+                    FetchingErrorCount = 500
+                });
+
+            var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
+            removeTwitterAccountActionMock
+                .Setup(x => x.ProcessAsync(It.Is<SyncTwitterUser>(y => y.Id == userId2)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var processor = new RefreshTwitterUserStatusProcessor(twitterUserServiceMock.Object, twitterUserDalMock.Object, removeTwitterAccountActionMock.Object, settings);
+            var result = await processor.ProcessAsync(users.ToArray(), CancellationToken.None);
+
+            #region Validations
+            Assert.AreEqual(1, result.Length);
+            Assert.IsTrue(result.Any(x => x.User.Id == userId1));
+
+            twitterUserServiceMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            removeTwitterAccountActionMock.VerifyAll();
+            #endregion
+        }
+        
+        [TestMethod]
+        public async Task ProcessAsync_Error_NotInit_Test()
         {
             #region Stubs
             var userId1 = 1;
@@ -361,9 +642,6 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
                 .Returns((TwitterUser)null);
             
-            twitterUserServiceMock
-                .Setup(x => x.PurgeUser(It.Is<string>(y => y == acct1)));
-
             var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
             twitterUserDalMock
                 .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct1)))
@@ -388,5 +666,77 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
             removeTwitterAccountActionMock.VerifyAll();
             #endregion
         }
+
+        [TestMethod]
+        public async Task ProcessAsync_RateLimited_Test()
+        {
+            #region Stubs
+            var userId1 = 1;
+            var acct1 = "user1";
+
+            var userId2 = 2;
+            var acct2 = "user2";
+
+            var users = new List<SyncTwitterUser>
+            {
+                new SyncTwitterUser
+                {
+                    Id = userId1,
+                    Acct = acct1
+                },
+                new SyncTwitterUser
+                {
+                    Id = userId2,
+                    Acct = acct2
+                }
+            };
+
+            var settings = new InstanceSettings
+            {
+                FailingTwitterUserCleanUpThreshold = 300
+            };
+            #endregion
+
+            #region Mocks
+            var twitterUserServiceMock = new Mock<ICachedTwitterUserService>(MockBehavior.Strict);
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct1)))
+                .Returns(new TwitterUser
+                {
+                    Protected = false,
+                });
+
+            twitterUserServiceMock
+                .Setup(x => x.GetUser(It.Is<string>(y => y == acct2)))
+                .Throws(new RateLimitExceededException());
+            
+            var twitterUserDalMock = new Mock<ITwitterUserDal>(MockBehavior.Strict);
+            twitterUserDalMock
+                .Setup(x => x.GetTwitterUserAsync(It.Is<string>(y => y == acct2)))
+                .ReturnsAsync(new SyncTwitterUser
+                {
+                    Id = userId2,
+                    FetchingErrorCount = 20
+                });
+
+            twitterUserDalMock
+                .Setup(x => x.UpdateTwitterUserAsync(It.Is<SyncTwitterUser>(y => y.Id == userId2 && y.FetchingErrorCount == 20)))
+                .Returns(Task.CompletedTask);
+
+            var removeTwitterAccountActionMock = new Mock<IRemoveTwitterAccountAction>(MockBehavior.Strict);
+            #endregion
+
+            var processor = new RefreshTwitterUserStatusProcessor(twitterUserServiceMock.Object, twitterUserDalMock.Object, removeTwitterAccountActionMock.Object, settings);
+            var result = await processor.ProcessAsync(users.ToArray(), CancellationToken.None);
+
+            #region Validations
+            Assert.AreEqual(1, result.Length);
+            Assert.IsTrue(result.Any(x => x.User.Id == userId1));
+
+            twitterUserServiceMock.VerifyAll();
+            twitterUserDalMock.VerifyAll();
+            removeTwitterAccountActionMock.VerifyAll();
+            #endregion
+        }
     }
 }

src/Tests/BirdsiteLive.Pipeline.Tests/Processors/SendTweetsToFollowersProcessorTests.cs

@@ -2,8 +2,10 @@
 using System.Threading;
 using System.Threading.Tasks;
 using System.Xml;
+using BirdsiteLive.Common.Settings;
 using BirdsiteLive.DAL.Contracts;
 using BirdsiteLive.DAL.Models;
+using BirdsiteLive.Moderation.Actions;
 using BirdsiteLive.Pipeline.Models;
 using BirdsiteLive.Pipeline.Processors;
 using BirdsiteLive.Pipeline.Processors.SubTasks;
@@ -72,17 +74,22 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
-
+            
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -147,15 +154,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
             var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
             
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -229,15 +241,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -312,15 +329,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -400,15 +422,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -471,15 +498,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
             var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -543,15 +575,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
             var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -623,15 +660,196 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ProcessAsync_MultiInstances_Inbox_OneTweet_Error_SettingsThreshold_Test()
+        {
+            #region Stubs
+            var tweetId = 1;
+            var host1 = "domain1.ext";
+            var host2 = "domain2.ext";
+            var inbox = "/user/inbox";
+            var userId1 = 2;
+            var userId2 = 3;
+            var userAcct = "user";
+
+            var userWithTweets = new UserWithDataToSync()
+            {
+                Tweets = new[]
+                {
+                    new ExtractedTweet
+                    {
+                        Id = tweetId
+                    }
+                },
+                User = new SyncTwitterUser
+                {
+                    Acct = userAcct
+                },
+                Followers = new[]
+                {
+                    new Follower
+                    {
+                        Id = userId1,
+                        Host = host1,
+                        InboxRoute = inbox
+                    },
+                    new Follower
+                    {
+                        Id = userId2,
+                        Host = host2,
+                        InboxRoute = inbox,
+                        PostingErrorCount = 42
+                    },
+                }
+            };
+            #endregion
+
+            #region Mocks
+            var sendTweetsToInboxTaskMock = new Mock<ISendTweetsToInboxTask>(MockBehavior.Strict);
+            sendTweetsToInboxTaskMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<ExtractedTweet[]>(y => y.Length == 1),
+                    It.Is<Follower>(y => y.Id == userId1),
+                    It.Is<SyncTwitterUser>(y => y.Acct == userAcct)))
+                .Returns(Task.CompletedTask);
+
+            sendTweetsToInboxTaskMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<ExtractedTweet[]>(y => y.Length == 1),
+                    It.Is<Follower>(y => y.Id == userId2),
+                    It.Is<SyncTwitterUser>(y => y.Acct == userAcct)))
+                .Throws(new Exception());
+
+            var sendTweetsToSharedInboxTaskMock = new Mock<ISendTweetsToSharedInboxTask>(MockBehavior.Strict);
+
+            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
+
+            var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings
+            {
+                FailingFollowerCleanUpThreshold = 10
+            };
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
+            removeFollowerMock
+                .Setup(x => x.ProcessAsync(It.Is<Follower>(y => y.Id == userId2)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
+            var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
+
+            #region Validations
+            sendTweetsToInboxTaskMock.VerifyAll();
+            sendTweetsToSharedInboxTaskMock.VerifyAll();
+            followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
+            #endregion
+        }
+
+        [TestMethod]
+        public async Task ProcessAsync_MultiInstances_Inbox_OneTweet_Error_MaxThreshold_Test()
+        {
+            #region Stubs
+            var tweetId = 1;
+            var host1 = "domain1.ext";
+            var host2 = "domain2.ext";
+            var inbox = "/user/inbox";
+            var userId1 = 2;
+            var userId2 = 3;
+            var userAcct = "user";
+
+            var userWithTweets = new UserWithDataToSync()
+            {
+                Tweets = new[]
+                {
+                    new ExtractedTweet
+                    {
+                        Id = tweetId
+                    }
+                },
+                User = new SyncTwitterUser
+                {
+                    Acct = userAcct
+                },
+                Followers = new[]
+                {
+                    new Follower
+                    {
+                        Id = userId1,
+                        Host = host1,
+                        InboxRoute = inbox
+                    },
+                    new Follower
+                    {
+                        Id = userId2,
+                        Host = host2,
+                        InboxRoute = inbox,
+                        PostingErrorCount = 2147483600
+                    },
+                }
+            };
+            #endregion
+
+            #region Mocks
+            var sendTweetsToInboxTaskMock = new Mock<ISendTweetsToInboxTask>(MockBehavior.Strict);
+            sendTweetsToInboxTaskMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<ExtractedTweet[]>(y => y.Length == 1),
+                    It.Is<Follower>(y => y.Id == userId1),
+                    It.Is<SyncTwitterUser>(y => y.Acct == userAcct)))
+                .Returns(Task.CompletedTask);
+
+            sendTweetsToInboxTaskMock
+                .Setup(x => x.ExecuteAsync(
+                    It.Is<ExtractedTweet[]>(y => y.Length == 1),
+                    It.Is<Follower>(y => y.Id == userId2),
+                    It.Is<SyncTwitterUser>(y => y.Acct == userAcct)))
+                .Throws(new Exception());
+
+            var sendTweetsToSharedInboxTaskMock = new Mock<ISendTweetsToSharedInboxTask>(MockBehavior.Strict);
+
+            var followersDalMock = new Mock<IFollowersDal>(MockBehavior.Strict);
+
+            var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings
+            {
+                FailingFollowerCleanUpThreshold = 0
+            };
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
+            removeFollowerMock
+                .Setup(x => x.ProcessAsync(It.Is<Follower>(y => y.Id == userId2)))
+                .Returns(Task.CompletedTask);
+            #endregion
+
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
+            var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
+
+            #region Validations
+            sendTweetsToInboxTaskMock.VerifyAll();
+            sendTweetsToSharedInboxTaskMock.VerifyAll();
+            followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -704,15 +922,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
 
@@ -790,15 +1013,20 @@ namespace BirdsiteLive.Pipeline.Tests.Processors
                 .Returns(Task.CompletedTask);
 
             var loggerMock = new Mock<ILogger<SendTweetsToFollowersProcessor>>();
+
+            var settings = new InstanceSettings();
+
+            var removeFollowerMock = new Mock<IRemoveFollowerAction>(MockBehavior.Strict);
             #endregion
 
-            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object);
+            var processor = new SendTweetsToFollowersProcessor(sendTweetsToInboxTaskMock.Object, sendTweetsToSharedInboxTaskMock.Object, followersDalMock.Object, loggerMock.Object, settings, removeFollowerMock.Object);
             var result = await processor.ProcessAsync(userWithTweets, CancellationToken.None);
 
             #region Validations
             sendTweetsToInboxTaskMock.VerifyAll();
             sendTweetsToSharedInboxTaskMock.VerifyAll();
             followersDalMock.VerifyAll();
+            removeFollowerMock.VerifyAll();
             #endregion
         }
     }