Adding functionality to revert a commit in HistoryView

src/GitHub.Api/Git/GitClient.cs

@@ -32,6 +32,9 @@ ITask<string> Pull(string remote, string branch,
         ITask<string> Push(string remote, string branch,
             IOutputProcessor<string> processor = null);
 
+        ITask<string> Revert(string changeset,
+            IOutputProcessor<string> processor = null);
+
         ITask<string> Fetch(string remote,
             IOutputProcessor<string> processor = null);
 
@@ -198,6 +201,12 @@ public ITask<string> Push(string remote, string branch,
                 .Configure(processManager);
         }
 
+        public ITask<string> Revert(string changeset, IOutputProcessor<string> processor = null)
+        {
+            return new GitRevertTask(changeset, cancellationToken, processor)
+                .Configure(processManager);
+        }
+
         public ITask<string> Fetch(string remote,
             IOutputProcessor<string> processor = null)
         {

src/GitHub.Api/Git/IRepository.cs

@@ -12,6 +12,7 @@ interface IRepository : IEquatable<IRepository>
         ITask SetupRemote(string remoteName, string remoteUrl);
         ITask Pull();
         ITask Push();
+        ITask Revert(string changeset);
         ITask ListLocks();
         ITask RequestLock(string file);
         ITask ReleaseLock(string file, bool force);

src/GitHub.Api/Git/Repository.cs

@@ -88,6 +88,11 @@ public ITask Push()
             return repositoryManager.Push(CurrentRemote.Value.Name, CurrentBranch);
         }
 
+        public ITask Revert(string changeset)
+        {
+            return repositoryManager.Revert(changeset);
+        }
+
         public ITask ListLocks()
         {
             return repositoryManager.ListLocks(false);

src/GitHub.Api/Git/RepositoryManager.cs

@@ -34,6 +34,7 @@ interface IRepositoryManager : IDisposable
         ITask Fetch(string remote);
         ITask Pull(string remote, string branch);
         ITask Push(string remote, string branch);
+        ITask Revert(string changeset);
         ITask RemoteAdd(string remote, string url);
         ITask RemoteRemove(string remote);
         ITask RemoteChange(string remote, string url);
@@ -234,6 +235,12 @@ public ITask Push(string remote, string branch)
             return HookupHandlers(task);
         }
 
+        public ITask Revert(string changeset)
+        {
+            var task = GitClient.Revert(changeset);
+            return HookupHandlers(task);
+        }
+
         public ITask RemoteAdd(string remote, string url)
         {
             var task = GitClient.RemoteAdd(remote, url);

src/GitHub.Api/Git/Tasks/GitRevertTask.cs

@@ -0,0 +1,22 @@
+using System.Threading;
+
+namespace GitHub.Unity
+{
+    class GitRevertTask : ProcessTask<string>
+    {
+        private readonly string arguments;
+
+        public GitRevertTask(string changeset,
+            CancellationToken token, IOutputProcessor<string> processor = null)
+            : base(token, processor ?? new SimpleOutputProcessor())
+        {
+            Guard.ArgumentNotNull(changeset, "changeset");
+
+            arguments = $"revert --no-edit {changeset}";
+        }
+
+        public override string Name { get { return "git revert"; } }
+        public override string ProcessArguments { get { return arguments; } }
+        public override TaskAffinity Affinity { get { return TaskAffinity.Exclusive; } }
+    }
+}

src/GitHub.Api/GitHub.Api.csproj

@@ -115,6 +115,7 @@
     <Compile Include="Git\GitObjectFactory.cs" />
     <Compile Include="Git\GitStatusEntry.cs" />
     <Compile Include="Git\IGitObjectFactory.cs" />
+    <Compile Include="Git\Tasks\GitRevertTask.cs" />
     <Compile Include="IO\FileSystemHelpers.cs" />
     <Compile Include="Application\IApplicationManager.cs" />
     <Compile Include="NewTaskSystem\ActionTask.cs" />

src/UnityExtension/Assets/Editor/GitHub.Unity/UI/HistoryView.cs

@@ -557,6 +557,28 @@ private void CullHistory()
                                 EntryHeight + 1, 0, history.Count);
         }
 
+        private void RevertCommit()
+        {
+            var selection = history[selectionIndex];
+
+            var dialogTitle = "Revert commit";
+            var dialogBody = string.Format(@"Are you sure you want to revert the following commit:""{0}""", selection.Summary);
+
+            if (EditorUtility.DisplayDialog(dialogTitle, dialogBody, "Revert", "Cancel"))
+            {
+                Repository
+                    .Revert(selection.CommitID)
+                    .FinallyInUI((success, e) => {
+                        if (!success)
+                        {
+                            EditorUtility.DisplayDialog(dialogTitle,
+                                "Error reverting commit: " + e.Message, Localization.Cancel);
+                        }
+                    })
+                    .Start();
+            }
+        }
+
         private bool HistoryEntry(GitLogEntry entry, LogEntryState state, bool selected)
         {
             var entryRect = GUILayoutUtility.GetRect(Styles.HistoryEntryHeight, Styles.HistoryEntryHeight);
@@ -620,6 +642,14 @@ private bool HistoryEntry(GitLogEntry entry, LogEntryState state, bool selected)
                     GUI.DrawTexture(normalIndicatorRect, Styles.DotIcon);
                 }
             }
+            else if (Event.current.type == EventType.ContextClick && entryRect.Contains(Event.current.mousePosition))
+            {
+                GenericMenu menu = new GenericMenu();
+                menu.AddItem(new GUIContent("Revert"), false, RevertCommit);
+                menu.ShowAsContext();
+
+                Event.current.Use();
+            }
             else if (Event.current.type == EventType.MouseDown && entryRect.Contains(Event.current.mousePosition))
             {
                 Event.current.Use();