feature<TextDiffView>: supports line staging/unstaging in working copy diff view

src/Commands/Apply.cs

@@ -1,11 +1,12 @@
 namespace SourceGit.Commands {
     public class Apply : Command {
-        public Apply(string repo, string file, bool ignoreWhitespace, string whitespaceMode) {
+        public Apply(string repo, string file, bool ignoreWhitespace, string whitespaceMode, string extra) {
             WorkingDirectory = repo;
             Context = repo;
             Args = "apply ";
             if (ignoreWhitespace) Args += "--ignore-whitespace ";
             else Args += $"--whitespace={whitespaceMode} ";
+            if (!string.IsNullOrEmpty(extra)) Args += $"{extra} ";
             Args += $"\"{file}\"";
         }
     }

src/Commands/Diff.cs

@@ -65,11 +65,11 @@ namespace SourceGit.Commands {
 
                 _oldLine = int.Parse(match.Groups[1].Value);
                 _newLine = int.Parse(match.Groups[2].Value);
-                _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Indicator, line, "", ""));
+                _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Indicator, line, 0, 0));
             } else {
                 if (line.Length == 0) {
                     ProcessInlineHighlights();
-                    _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Normal, "", $"{_oldLine}", $"{_newLine}"));
+                    _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Normal, "", _oldLine, _newLine));
                     _oldLine++;
                     _newLine++;
                     return;
@@ -77,10 +77,10 @@ namespace SourceGit.Commands {
 
                 var ch = line[0];
                 if (ch == '-') {
-                    _deleted.Add(new Models.TextDiffLine(Models.TextDiffLineType.Deleted, line.Substring(1), $"{_oldLine}", ""));
+                    _deleted.Add(new Models.TextDiffLine(Models.TextDiffLineType.Deleted, line.Substring(1), _oldLine, 0));
                     _oldLine++;
                 } else if (ch == '+') {
-                    _added.Add(new Models.TextDiffLine(Models.TextDiffLineType.Added, line.Substring(1), "", $"{_newLine}"));
+                    _added.Add(new Models.TextDiffLine(Models.TextDiffLineType.Added, line.Substring(1), 0, _newLine));
                     _newLine++;
                 } else if (ch != '\\') {
                     ProcessInlineHighlights();
@@ -88,7 +88,7 @@ namespace SourceGit.Commands {
                     if (match.Success) {
                         _oldLine = int.Parse(match.Groups[1].Value);
                         _newLine = int.Parse(match.Groups[2].Value);
-                        _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Indicator, line, "", ""));
+                        _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Indicator, line, 0, 0));
                     } else {
                         if (line.StartsWith(PREFIX_LFS)) {
                             _result.IsLFS = true;
@@ -96,7 +96,7 @@ namespace SourceGit.Commands {
                             return;
                         }
 
-                        _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Normal, line.Substring(1), $"{_oldLine}", $"{_newLine}"));
+                        _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Normal, line.Substring(1), _oldLine, _newLine));
                         _oldLine++;
                         _newLine++;
                     }

src/Commands/QueryStagedFileBlobGuid.cs

@@ -0,0 +1,23 @@
+using System.Text.RegularExpressions;
+
+namespace SourceGit.Commands {
+    public class QueryStagedFileBlobGuid : Command {
+        private static readonly Regex REG_FORMAT = new Regex(@"^\d+\s+([0-9a-f]+)\s+.*$");
+
+        public QueryStagedFileBlobGuid(string repo, string file) {
+            WorkingDirectory = repo;
+            Context = repo;
+            Args = $"ls-files -s -- \"{file}\"";
+        }
+
+        public string Result() {
+            var rs = ReadToEnd();
+            var match = REG_FORMAT.Match(rs.StdOut.Trim());
+            if (match.Success) {
+                return match.Groups[1].Value;
+            }
+
+            return string.Empty;
+        }
+    }
+}

src/Models/DiffOption.cs

@@ -3,6 +3,8 @@ using System.Text;
 
 namespace SourceGit.Models {
     public class DiffOption {
+        public Change WorkingCopyChange => _workingCopyChange;
+        public bool IsUnstaged => _isUnstaged;
         public List<string> Revisions => _revisions;
         public string Path => _path;
         public string OrgPath => _orgPath;
@@ -13,6 +15,9 @@ namespace SourceGit.Models {
         /// <param name="change"></param>
         /// <param name="isUnstaged"></param>
         public DiffOption(Change change, bool isUnstaged) {
+            _workingCopyChange = change;
+            _isUnstaged = isUnstaged;
+
             if (isUnstaged) {
                 switch (change.WorkTree) {
                 case ChangeState.Added:
@@ -47,7 +52,7 @@ namespace SourceGit.Models {
         }
 
         /// <summary>
-        ///     Diff with filepath.
+        ///     Diff with filepath. Used by FileHistories
         /// </summary>
         /// <param name="commit"></param>
         /// <param name="file"></param>
@@ -87,6 +92,8 @@ namespace SourceGit.Models {
             return builder.ToString();
         }
 
+        private Change _workingCopyChange = null;
+        private bool _isUnstaged = false;
         private string _orgPath = string.Empty;
         private string _path = string.Empty;
         private string _extra = string.Empty;

src/Models/DiffResult.cs

@@ -18,16 +18,19 @@ namespace SourceGit.Models {
     public class TextDiffLine {
         public TextDiffLineType Type { get; set; } = TextDiffLineType.None;
         public string Content { get; set; } = "";
-        public string OldLine { get; set; } = "";
-        public string NewLine { get; set; } = "";
+        public int OldLineNumber { get; set; } = 0;
+        public int NewLineNumber { get; set; } = 0;
         public List<TextInlineRange> Highlights { get; set; } = new List<TextInlineRange>();
 
+        public string OldLine => OldLineNumber == 0 ? string.Empty : OldLineNumber.ToString();
+        public string NewLine => NewLineNumber == 0 ? string.Empty : NewLineNumber.ToString();
+
         public TextDiffLine() { }
-        public TextDiffLine(TextDiffLineType type, string content, string oldLine, string newLine) {
+        public TextDiffLine(TextDiffLineType type, string content, int oldLine, int newLine) {
             Type = type;
             Content = content;
-            OldLine = oldLine;
-            NewLine = newLine;
+            OldLineNumber = oldLine;
+            NewLineNumber = newLine;
         }
     }
 

src/Resources/Locales/en_US.axaml

@@ -228,6 +228,9 @@
   <sys:String x:Key="Text.FileCM.StashMulti">Stash {0} files...</sys:String>
   <sys:String x:Key="Text.FileCM.SaveAsPatch">Save As Patch...</sys:String>
   <sys:String x:Key="Text.FileCM.AssumeUnchanged">Assume unchaged</sys:String>
+  <sys:String x:Key="Text.FileCM.StageSelectedLines">Stage Changes in Selected Line(s)</sys:String>
+  <sys:String x:Key="Text.FileCM.DiscardSelectedLines">Discard Changes in Selected Line(s)</sys:String>
+  <sys:String x:Key="Text.FileCM.UnstageSelectedLines">Unstage Changes in Selected Line(s)</sys:String>
 
   <sys:String x:Key="Text.DeleteBranch">Delete Branch</sys:String>
   <sys:String x:Key="Text.DeleteBranch.Branch">Branch :</sys:String>

src/Resources/Locales/zh_CN.axaml

@@ -227,6 +227,9 @@
   <sys:String x:Key="Text.FileCM.StashMulti">贮藏选中的 {0} 个文件...</sys:String>
   <sys:String x:Key="Text.FileCM.SaveAsPatch">另存为补丁...</sys:String>
   <sys:String x:Key="Text.FileCM.AssumeUnchanged">不跟踪此文件的更改</sys:String>
+  <sys:String x:Key="Text.FileCM.StageSelectedLines">暂存选中的更改</sys:String>
+  <sys:String x:Key="Text.FileCM.DiscardSelectedLines">放弃选中的更改</sys:String>
+  <sys:String x:Key="Text.FileCM.UnstageSelectedLines">从暂存中移除选中的更改</sys:String>
 
   <sys:String x:Key="Text.DeleteBranch">确定要删除此分支吗？</sys:String>
   <sys:String x:Key="Text.DeleteBranch.Branch">分支名 ：</sys:String>

src/ViewModels/Apply.cs

@@ -54,7 +54,7 @@ namespace SourceGit.ViewModels {
             ProgressDescription = "Apply patch...";
 
             return Task.Run(() => {
-                var succ = new Commands.Apply(_repo.FullPath, _patchFile, _ignoreWhiteSpace, SelectedWhiteSpaceMode.Arg).Exec();
+                var succ = new Commands.Apply(_repo.FullPath, _patchFile, _ignoreWhiteSpace, SelectedWhiteSpaceMode.Arg, null).Exec();
                 CallUIThread(() => _repo.SetWatcherEnabled(true));
                 return succ;
             });

src/ViewModels/DiffContext.cs

@@ -5,6 +5,18 @@ using System.Threading.Tasks;
 
 namespace SourceGit.ViewModels {
     public class DiffContext : ObservableObject {
+        public string RepositoryPath {
+            get => _repo;
+        }
+
+        public Models.Change WorkingCopyChange {
+            get => _option.WorkingCopyChange;
+        }
+
+        public bool IsUnstaged {
+            get => _option.IsUnstaged;
+        }
+
         public string FilePath {
             get => _option.Path;
         }

src/Views/TextDiffView.axaml.cs

@@ -4,6 +4,7 @@ using Avalonia.Controls.Primitives;
 using Avalonia.Interactivity;
 using Avalonia.Media;
 using Avalonia.Styling;
+using Avalonia.VisualTree;
 using AvaloniaEdit;
 using AvaloniaEdit.Document;
 using AvaloniaEdit.Editing;
@@ -11,12 +12,27 @@ using AvaloniaEdit.Rendering;
 using AvaloniaEdit.TextMate;
 using AvaloniaEdit.Utils;
 using System;
+using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Text;
+using System.Text.RegularExpressions;
 using TextMateSharp.Grammars;
 
 namespace SourceGit.Views {
+    public class TextDiffUnifiedSelection {
+        public int StartLine { get; set; } = 0;
+        public int EndLine { get; set; } = 0;
+        public bool HasChanges { get; set; } = false;
+        public bool HasLeftChanges { get; set; } = false;
+        public int IgnoredAdds { get; set; } = 0;
+        public int IgnoredDeletes { get; set; } = 0;
+
+        public bool IsInRange(int idx) {
+            return idx >= StartLine - 1 && idx < EndLine;
+        }
+    }
+
     public class CombinedTextDiffPresenter : TextEditor {
         public class LineNumberMargin : AbstractMargin {
             public LineNumberMargin(CombinedTextDiffPresenter editor, bool isOldLine) {
@@ -231,24 +247,23 @@ namespace SourceGit.Views {
         }
 
         private void OnTextViewContextRequested(object sender, ContextRequestedEventArgs e) {
-            var selected = SelectedText;
-            if (string.IsNullOrEmpty(selected)) return;
+            var selection = TextArea.Selection;
+            if (selection.IsEmpty) return;
 
-            var icon = new Avalonia.Controls.Shapes.Path();
-            icon.Width = 10;
-            icon.Height = 10;
-            icon.Stretch = Stretch.Uniform;
-            icon.Data = App.Current?.FindResource("Icons.Copy") as StreamGeometry;
+            var menu = new ContextMenu();
+            var parentView = this.FindAncestorOfType<TextDiffView>();
+            if (parentView != null) {
+                parentView.FillContextMenuForWorkingCopyChange(menu, selection.StartPosition.Line, selection.EndPosition.Line, false);
+            }
 
             var copy = new MenuItem();
             copy.Header = App.Text("Copy");
-            copy.Icon = icon;
+            copy.Icon = App.CreateMenuIcon("Icons.Copy");
             copy.Click += (o, ev) => {
-                App.CopyText(selected);
+                App.CopyText(SelectedText);
                 ev.Handled = true;
             };
 
-            var menu = new ContextMenu();
             menu.Items.Add(copy);
             menu.Open(TextArea.TextView);
             e.Handled = true;
@@ -527,24 +542,23 @@ namespace SourceGit.Views {
         }
 
         private void OnTextViewContextRequested(object sender, ContextRequestedEventArgs e) {
-            var selected = SelectedText;
-            if (string.IsNullOrEmpty(selected)) return;
+            var selection = TextArea.Selection;
+            if (selection.IsEmpty) return;
 
-            var icon = new Avalonia.Controls.Shapes.Path();
-            icon.Width = 10;
-            icon.Height = 10;
-            icon.Stretch = Stretch.Uniform;
-            icon.Data = App.Current?.FindResource("Icons.Copy") as StreamGeometry;
+            var menu = new ContextMenu();
+            var parentView = this.FindAncestorOfType<TextDiffView>();
+            if (parentView != null) {
+                parentView.FillContextMenuForWorkingCopyChange(menu, selection.StartPosition.Line, selection.EndPosition.Line, IsOld);
+            }
 
             var copy = new MenuItem();
             copy.Header = App.Text("Copy");
-            copy.Icon = icon;
+            copy.Icon = App.CreateMenuIcon("Icons.Copy");
             copy.Click += (o, ev) => {
-                App.CopyText(selected);
+                App.CopyText(SelectedText);
                 ev.Handled = true;
             };
 
-            var menu = new ContextMenu();
             menu.Items.Add(copy);
             menu.Open(TextArea.TextView);
             e.Handled = true;
@@ -617,18 +631,150 @@ namespace SourceGit.Views {
             set => SetValue(UseCombinedProperty, value);
         }
 
-        public static readonly StyledProperty<Vector> SyncScrollOffsetProperty =
-            AvaloniaProperty.Register<TextDiffView, Vector>(nameof(SyncScrollOffset), Vector.Zero);
-
-        public Vector SyncScrollOffset {
-            get => GetValue(SyncScrollOffsetProperty);
-            set => SetValue(SyncScrollOffsetProperty, value);
-        }
-
         public TextDiffView() {
             InitializeComponent();
         }
 
+        public void FillContextMenuForWorkingCopyChange(ContextMenu menu, int startLine, int endLine, bool isOldSide) {
+            var parentView = this.FindAncestorOfType<DiffView>();
+            if (parentView == null) return;
+
+            var ctx = parentView.DataContext as ViewModels.DiffContext;
+            if (ctx == null) return;
+
+            var change = ctx.WorkingCopyChange;
+            if (change == null) return;
+
+            if (startLine > endLine) {
+                var tmp = startLine;
+                startLine = endLine;
+                endLine = tmp;
+            }
+
+            var selection = GetUnifiedSelection(startLine, endLine, isOldSide);
+            if (!selection.HasChanges) return;
+
+            // If all changes has been selected the use method provided by ViewModels.WorkingCopy.
+            // Otherwise, use `git apply`
+            if (!selection.HasLeftChanges) {
+                var workcopyView = this.FindAncestorOfType<WorkingCopy>();
+                if (workcopyView == null) return;
+
+                if (ctx.IsUnstaged) {
+                    var stage = new MenuItem();
+                    stage.Header = App.Text("FileCM.StageSelectedLines");
+                    stage.Icon = App.CreateMenuIcon("Icons.File.Add");
+                    stage.Click += (_, e) => {
+                        var workcopy = workcopyView.DataContext as ViewModels.WorkingCopy;
+                        workcopy.StageChanges(new List<Models.Change> { change });
+                        e.Handled = true;
+                    };
+
+                    var discard = new MenuItem();
+                    discard.Header = App.Text("FileCM.DiscardSelectedLines");
+                    discard.Icon = App.CreateMenuIcon("Icons.Undo");
+                    discard.Click += (_, e) => {
+                        var workcopy = workcopyView.DataContext as ViewModels.WorkingCopy;
+                        workcopy.Discard(new List<Models.Change> { change });
+                        e.Handled = true;
+                    };
+
+                    menu.Items.Add(stage);
+                    menu.Items.Add(discard);
+                } else {
+                    var unstage = new MenuItem();
+                    unstage.Header = App.Text("FileCM.UnstageSelectedLines");
+                    unstage.Icon = App.CreateMenuIcon("Icons.File.Remove");
+                    unstage.Click += (_, e) => {
+                        var workcopy = workcopyView.DataContext as ViewModels.WorkingCopy;
+                        workcopy.UnstageChanges(new List<Models.Change> { change });
+                        e.Handled = true;
+                    };
+                    menu.Items.Add(unstage);
+                }
+            } else {
+                var repoView = this.FindAncestorOfType<Repository>();
+                if (repoView == null) return;
+
+                if (ctx.IsUnstaged) {
+                    var stage = new MenuItem();
+                    stage.Header = App.Text("FileCM.StageSelectedLines");
+                    stage.Icon = App.CreateMenuIcon("Icons.File.Add");
+                    stage.Click += (_, e) => {
+                        var repo = repoView.DataContext as ViewModels.Repository;
+                        repo.SetWatcherEnabled(false);
+
+                        var tmpFile = Path.GetTempFileName();
+                        if (change.WorkTree == Models.ChangeState.Untracked) {
+                            GenerateNewPatchFromSelection(change, null, selection, false, tmpFile);
+                        } else if (UseCombined) {
+                            var treeGuid = new Commands.QueryStagedFileBlobGuid(ctx.RepositoryPath, change.Path).Result();
+                            GenerateCombinedPatchFromSelection(change, treeGuid, selection, false, tmpFile);
+                        }
+
+                        new Commands.Apply(ctx.RepositoryPath, tmpFile, true, "nowarn", "--cache --index").Exec();
+                        File.Delete(tmpFile);
+
+                        repo.RefreshWorkingCopyChanges();
+                        repo.SetWatcherEnabled(true);
+                        e.Handled = true;
+                    };
+
+                    var discard = new MenuItem();
+                    discard.Header = App.Text("FileCM.DiscardSelectedLines");
+                    discard.Icon = App.CreateMenuIcon("Icons.Undo");
+                    discard.Click += (_, e) => {
+                        var repo = repoView.DataContext as ViewModels.Repository;
+                        repo.SetWatcherEnabled(false);
+
+                        var tmpFile = Path.GetTempFileName();
+                        if (change.WorkTree == Models.ChangeState.Untracked) {
+                            GenerateNewPatchFromSelection(change, null, selection, true, tmpFile);
+                        } else if (UseCombined) {
+                            var treeGuid = new Commands.QueryStagedFileBlobGuid(ctx.RepositoryPath, change.Path).Result();
+                            GenerateCombinedPatchFromSelection(change, treeGuid, selection, true, tmpFile);
+                        }
+
+                        new Commands.Apply(ctx.RepositoryPath, tmpFile, true, "nowarn", "--reverse").Exec();
+                        File.Delete(tmpFile);
+
+                        repo.RefreshWorkingCopyChanges();
+                        repo.SetWatcherEnabled(true);
+                        e.Handled = true;
+                    };
+
+                    menu.Items.Add(stage);
+                    menu.Items.Add(discard);
+                } else {
+                    var unstage = new MenuItem();
+                    unstage.Header = App.Text("FileCM.UnstageSelectedLines");
+                    unstage.Icon = App.CreateMenuIcon("Icons.File.Remove");
+                    unstage.Click += (_, e) => {
+                        var repo = repoView.DataContext as ViewModels.Repository;
+                        repo.SetWatcherEnabled(false);
+
+                        var treeGuid = new Commands.QueryStagedFileBlobGuid(ctx.RepositoryPath, change.Path).Result();
+                        var tmpFile = Path.GetTempFileName();
+                        if (change.Index == Models.ChangeState.Added) {
+                            GenerateNewPatchFromSelection(change, treeGuid, selection, true, tmpFile);
+                        } else if (UseCombined) {
+                            GenerateCombinedPatchFromSelection(change, treeGuid, selection, true, tmpFile);
+                        }
+
+                        new Commands.Apply(ctx.RepositoryPath, tmpFile, true, "nowarn", "--cache --index --reverse").Exec();
+                        File.Delete(tmpFile);
+
+                        repo.RefreshWorkingCopyChanges();
+                        repo.SetWatcherEnabled(true);
+                        e.Handled = true;
+                    };
+                    menu.Items.Add(unstage);
+                }
+            }
+
+            menu.Items.Add(new MenuItem() { Header = "-" });
+        }
+
         protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change) {
             base.OnPropertyChanged(change);
 
@@ -636,11 +782,210 @@ namespace SourceGit.Views {
                 if (TextDiff == null) {
                     Content = null;
                 } else if (UseCombined) {
-                    Content = new ViewModels.TwoSideTextDiff(TextDiff);
-                } else {
                     Content = TextDiff;
+                } else {
+                    Content = new ViewModels.TwoSideTextDiff(TextDiff);
+                }
+            }
+        }
+
+        private TextDiffUnifiedSelection GetUnifiedSelection(int startLine, int endLine, bool isOldSide) {
+            var rs = new TextDiffUnifiedSelection();
+            if (Content is Models.TextDiff combined) {
+                rs.StartLine = startLine;
+                rs.EndLine = endLine;
+
+                for (int i = 0; i < startLine - 1; i++) {
+                    var line = combined.Lines[i];
+                    if (line.Type == Models.TextDiffLineType.Added) {
+                        rs.HasLeftChanges = true;
+                        rs.IgnoredAdds++;
+                    } else if (line.Type == Models.TextDiffLineType.Deleted) {
+                        rs.HasLeftChanges = true;
+                        rs.IgnoredDeletes++;
+                    }
+                }
+
+                for (int i = startLine - 1; i < endLine; i++) {
+                    var line = combined.Lines[i];
+                    if (line.Type == Models.TextDiffLineType.Added || line.Type == Models.TextDiffLineType.Deleted) {
+                        rs.HasChanges = true;
+                        break;
+                    }
+                }
+
+                if (!rs.HasLeftChanges) {
+                    for (int i = endLine; i < combined.Lines.Count; i++) {
+                        var line = combined.Lines[i];
+                        if (line.Type == Models.TextDiffLineType.Added || line.Type == Models.TextDiffLineType.Deleted) {
+                            rs.HasLeftChanges = true;
+                            break;
+                        }
+                    }
+                }
+            } else if (Content is ViewModels.TwoSideTextDiff twoSides) {
+
+            }
+
+            return rs;
+        }
+
+        private void GenerateNewPatchFromSelection(Models.Change change, string fileBlobGuid, TextDiffUnifiedSelection selection, bool revert, string output) {
+            var isTracked = !string.IsNullOrEmpty(fileBlobGuid);
+            var fileGuid = isTracked ? fileBlobGuid.Substring(0, 8) : "00000000";
+
+            var builder = new StringBuilder();
+            builder.Append("diff --git a/").Append(change.Path).Append(" b/").Append(change.Path).Append('\n');
+            if (!revert && !isTracked) builder.Append("new file mode 100644\n");
+            builder.Append("index 00000000...").Append(fileGuid).Append('\n');
+            builder.Append("--- ").Append((revert || isTracked) ? $"a/{change.Path}\n" : "/dev/null\n");
+            builder.Append("+++ b/").Append(change.Path).Append('\n');
+
+            var additions = selection.EndLine - selection.StartLine;
+            if (selection.StartLine != 1) additions++;
+
+            if (revert) {
+                var totalLines = TextDiff.Lines.Count - 1;
+                builder.Append($"@@ -0,").Append(totalLines - additions).Append(" +0,").Append(totalLines).Append(" @@");
+                for (int i = 1; i <= totalLines; i++) {
+                    var line = TextDiff.Lines[i];
+                    if (line.Type != Models.TextDiffLineType.Added) continue;
+                    builder.Append(selection.IsInRange(i) ? "\n+" : "\n ").Append(line.Content);
+                }
+            } else {
+                builder.Append("@@ -0,0 +0,").Append(additions).Append(" @@");
+                for (int i = selection.StartLine - 1; i < selection.EndLine; i++) {
+                    var line = TextDiff.Lines[i];
+                    if (line.Type != Models.TextDiffLineType.Added) continue;
+                    builder.Append("\n+").Append(line.Content);
+                }
+            }
+
+            builder.Append("\n\\ No newline at end of file\n");
+            File.WriteAllText(output, builder.ToString());
+        }
+
+        private void GenerateCombinedPatchFromSelection(Models.Change change, string fileTreeGuid, TextDiffUnifiedSelection selection, bool revert, string output) {
+            var orgFile = !string.IsNullOrEmpty(change.OriginalPath) ? change.OriginalPath : change.Path;
+            var indicatorRegex = new Regex(@"^@@ \-(\d+),?\d* \+(\d+),?\d* @@");
+            var diff = TextDiff;
+
+            var builder = new StringBuilder();
+            builder.Append("diff --git a/").Append(change.Path).Append(" b/").Append(change.Path).Append('\n');
+            builder.Append("index 00000000...").Append(fileTreeGuid).Append(" 100644\n");
+            builder.Append("--- a/").Append(orgFile).Append('\n');
+            builder.Append("+++ b/").Append(change.Path).Append('\n');
+
+            // If last line of selection is a change. Find one more line.
+            var tail = null as string;
+            if (selection.EndLine < diff.Lines.Count) {
+                var lastLine = diff.Lines[selection.EndLine - 1];
+                if (lastLine.Type == Models.TextDiffLineType.Added || lastLine.Type == Models.TextDiffLineType.Deleted) {
+                    for (int i = selection.EndLine; i < diff.Lines.Count; i++) {
+                        var line = diff.Lines[i];
+                        if (line.Type == Models.TextDiffLineType.Indicator) break;
+                        if (line.Type == Models.TextDiffLineType.Normal || line.Type == Models.TextDiffLineType.Deleted) {
+                            tail = line.Content;
+                            break;
                         }
                     }
                 }
             }
+
+            // If the first line is not indicator.
+            if (diff.Lines[selection.StartLine - 1].Type != Models.TextDiffLineType.Indicator) {
+                var indicator = selection.StartLine - 1;
+                for (int i = selection.StartLine - 2; i >= 0; i--) {
+                    var line = diff.Lines[i];
+                    if (line.Type == Models.TextDiffLineType.Indicator) {
+                        indicator = i;
+                        break;
+                    }
+                }
+
+                var ignoreAdds = 0;
+                var ignoreRemoves = 0;
+                for (int i = 0; i < indicator; i++) {
+                    var line = diff.Lines[i];
+                    if (line.Type == Models.TextDiffLineType.Added) {
+                        ignoreAdds++;
+                    } else if (line.Type == Models.TextDiffLineType.Deleted) {
+                        ignoreRemoves++;
+                    }
+                }
+
+                for (int i = indicator; i < selection.StartLine - 1; i++) {
+                    var line = diff.Lines[i];
+                    if (line.Type == Models.TextDiffLineType.Indicator) {
+                        ProcessIndicatorForPatch(builder, line, i, selection.StartLine, selection.EndLine, ignoreRemoves, ignoreAdds, tail != null);
+                    } else if (line.Type == Models.TextDiffLineType.Added) {
+                        // Ignores
+                    } else if (line.Type == Models.TextDiffLineType.Deleted || line.Type == Models.TextDiffLineType.Normal) {
+                        // Traits ignored deleted as normal.
+                        builder.Append("\n ").Append(line.Content);
+                    }
+                }
+            }
+
+            // Outputs the selected lines.
+            for (int i = selection.StartLine - 1; i < selection.EndLine; i++) {
+                var line = diff.Lines[i];
+                if (line.Type == Models.TextDiffLineType.Indicator) {
+                    if (!ProcessIndicatorForPatch(builder, line, i, selection.StartLine, selection.EndLine, selection.IgnoredDeletes, selection.IgnoredAdds, tail != null)) {
+                        break;
+                    }
+                } else if (line.Type == Models.TextDiffLineType.Normal) {
+                    builder.Append("\n ").Append(line.Content);
+                } else if (line.Type == Models.TextDiffLineType.Added) {
+                    builder.Append("\n+").Append(line.Content);
+                } else if (line.Type == Models.TextDiffLineType.Deleted) {
+                    builder.Append("\n-").Append(line.Content);
+                }
+            }
+
+            builder.Append("\n ").Append(tail);
+            builder.Append("\n");
+            File.WriteAllText(output, builder.ToString());
+        }
+
+        private bool ProcessIndicatorForPatch(StringBuilder builder, Models.TextDiffLine indicator, int idx, int start, int end, int ignoreRemoves, int ignoreAdds, bool tailed) {
+            var indicatorRegex = new Regex(@"^@@ \-(\d+),?\d* \+(\d+),?\d* @@");
+            var diff = TextDiff;
+
+            var match = indicatorRegex.Match(indicator.Content);
+            var oldStart = int.Parse(match.Groups[1].Value);
+            var newStart = int.Parse(match.Groups[2].Value) + ignoreRemoves - ignoreAdds;
+            var oldCount = 0;
+            var newCount = 0;
+            for (int i = idx + 1; i < end; i++) {
+                var test = diff.Lines[i];
+                if (test.Type == Models.TextDiffLineType.Indicator) break;
+
+                if (test.Type == Models.TextDiffLineType.Normal) {
+                    oldCount++;
+                    newCount++;
+                } else if (test.Type == Models.TextDiffLineType.Added) {
+                    if (i >= start - 1) newCount++;
+
+                    if (i == end - 1 && tailed) {
+                        newCount++;
+                        oldCount++;
+                    }
+                } else if (test.Type == Models.TextDiffLineType.Deleted) {
+                    if (i < start - 1) newCount++;
+                    oldCount++;
+
+                    if (i == end - 1 && tailed) {
+                        newCount++;
+                        oldCount++;
+                    }
+                }
+            }
+
+            if (oldCount == 0 && newCount == 0) return false;
+
+            builder.Append($"@@ -{oldStart},{oldCount} +{newStart},{newCount} @@");
+            return true;
+        }
+    }
 }