fix: no changes were displayed when try to amend a commit without parent (branch first commit) (#1231)

Signed-off-by: leo <[email protected]>

Author: love-linger

src/Commands/QueryStagedChangesWithAmend.cs

@@ -11,11 +11,11 @@ public partial class QueryStagedChangesWithAmend : Command
         [GeneratedRegex(@"^:[\d]{6} ([\d]{6}) ([0-9a-f]{40}) [0-9a-f]{40} R\d{0,6}\t(.*\t.*)$")]
         private static partial Regex REG_FORMAT2();
 
-        public QueryStagedChangesWithAmend(string repo)
+        public QueryStagedChangesWithAmend(string repo, string parent)
         {
             WorkingDirectory = repo;
             Context = repo;
-            Args = "diff-index --cached -M HEAD^";
+            Args = $"diff-index --cached -M {parent}";
         }
 
         public List<Models.Change> Result()

src/ViewModels/WorkingCopy.cs

@@ -1524,7 +1524,10 @@ public ContextMenu CreateContextForOpenAI()
         private List<Models.Change> GetStagedChanges()
         {
             if (_useAmend)
-                return new Commands.QueryStagedChangesWithAmend(_repo.FullPath).Result();
+            {
+                var head = new Commands.QuerySingleCommit(_repo.FullPath, "HEAD").Result();
+                return new Commands.QueryStagedChangesWithAmend(_repo.FullPath, head.Parents.Count == 0 ? "4b825dc642cb6eb9a060e54bf8d69288fbee4904" : "HEAD^").Result();
+            }                
 
             var rs = new List<Models.Change>();
             foreach (var c in _cached)