(GH-198) Remove existing pending packages

If any packages are in a pending state, it means the install did not
complete successfully, so those packages should not actually be
considered "installed". Those pending packages should be removed with a
warning.

src/chocolatey/chocolatey.csproj

@@ -99,6 +99,7 @@
     <Compile Include="infrastructure.app\events\HandlePackageResultCompletedMessage.cs" />
     <Compile Include="infrastructure.app\services\FileTypeDetectorService.cs" />
     <Compile Include="infrastructure.app\services\IFileTypeDetectorService.cs" />
+    <Compile Include="infrastructure.app\tasks\RemovePendingPackagesTask.cs" />
     <Compile Include="infrastructure.app\templates\ChocolateyBeforeModifyTemplate.cs" />
     <Compile Include="infrastructure.app\templates\ChocolateyLicenseFileTemplate.cs" />
     <Compile Include="infrastructure.app\templates\ChocolateyVerificationFileTemplate.cs" />

src/chocolatey/infrastructure.app/registration/ContainerBinding.cs

@@ -17,6 +17,7 @@ namespace chocolatey.infrastructure.app.registration
 {
     using System.Collections.Generic;
     using infrastructure.events;
+    using infrastructure.tasks;
     using NuGet;
     using SimpleInjector;
     using adapters;
@@ -28,6 +29,7 @@ namespace chocolatey.infrastructure.app.registration
     using infrastructure.services;
     using nuget;
     using services;
+    using tasks;
     using CryptoHashProvider = cryptography.CryptoHashProvider;
     using IFileSystem = filesystem.IFileSystem;
     using IHashProvider = cryptography.IHashProvider;
@@ -111,6 +113,18 @@ public void RegisterComponents(Container container)
             container.Register<IEventSubscriptionManagerService, EventSubscriptionManagerService>(Lifestyle.Singleton);
             EventManager.initialize_with(container.GetInstance<IEventSubscriptionManagerService>);
 
+            container.Register<IEnumerable<ITask>>(
+              () =>
+              {
+                  var list = new List<ITask>
+                    {
+                        new RemovePendingPackagesTask(container.GetInstance<IFileSystem>())
+                    };
+
+                  return list.AsReadOnly();
+              },
+              Lifestyle.Singleton);
+
             container.Register<IDateTimeService, SystemDateTimeUtcService>(Lifestyle.Singleton);
         }
     }

src/chocolatey/infrastructure.app/tasks/RemovePendingPackagesTask.cs

@@ -0,0 +1,63 @@
+// Copyright © 2011 - Present RealDimensions Software, LLC
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// 
+// You may obtain a copy of the License at
+// 
+// 	http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace chocolatey.infrastructure.app.tasks
+{
+    using System;
+    using System.IO;
+    using System.Linq;
+    using events;
+    using filesystem;
+    using infrastructure.events;
+    using infrastructure.tasks;
+    using logging;
+    using tolerance;
+
+    public class RemovePendingPackagesTask : ITask
+    {
+        private readonly IFileSystem _fileSystem;
+        private IDisposable _subscription;
+
+        public RemovePendingPackagesTask(IFileSystem fileSystem)
+        {
+            _fileSystem = fileSystem;
+        }
+
+        public void initialize()
+        {
+            _subscription = EventManager.subscribe<PreRunMessage>(handle_message, null, null);
+            this.Log().Debug(ChocolateyLoggers.Verbose, () => "{0} is now ready and waiting for {1}.".format_with(GetType().Name, typeof(PreRunMessage).Name));
+        }
+
+        public void shutdown()
+        {
+            if (_subscription != null) _subscription.Dispose();
+        }
+
+        private void handle_message(PreRunMessage message)
+        {
+            this.Log().Debug(ChocolateyLoggers.Verbose, "[Pending] Removing all pending packages that should not be considered installed...");
+
+            var pendingFiles = _fileSystem.get_files(ApplicationParameters.PackagesLocation, ApplicationParameters.PackagePendingFileName, SearchOption.AllDirectories).ToList();
+            foreach (var pendingFile in pendingFiles.or_empty_list_if_null())
+            {
+                var packageFolder = _fileSystem.get_directory_name(pendingFile);
+                this.Log().Warn("[Pending] Removing incomplete install for '{0}'".format_with(_fileSystem.get_directory_info_for(packageFolder).Name));
+
+                FaultTolerance.retry(2, () => _fileSystem.delete_directory_if_exists(packageFolder, recursive: true, overrideAttributes: true, isSilent: true), 500, isSilent: true);
+            }
+        }
+    }
+}