private Task Diff(string filePath)
{
// TODO: throw? warn?
if (string.IsNullOrEmpty(diffTool.Cmd))
{
return(Task.CompletedTask);
}
var changes = repository.Diff.Compare <TreeChanges>().Modified.First(x => x.Path == filePath);
var old = repository.Lookup <Blob>(changes.OldOid);
// We can't show diff in this case
if (changes.Mode != Mode.NonExecutableFile || !changes.Exists || old == null || old.IsBinary)
{
return(Task.CompletedTask);
}
// Write the old content to a temp file for comparison.
var baseFile = Path.Combine(Path.GetTempPath(), Path.ChangeExtension(Path.GetFileName(filePath), ".BASE" + Path.GetExtension(filePath)));
File.WriteAllText(baseFile, old.GetContentText());
#pragma warning disable CS8602 // Dereference of a possibly null reference.
var indexOfDolar = diffTool.Cmd.IndexOf("$");
if (indexOfDolar == -1)
{
// TODO: There were no replacements, so we can't diff anything. Report warning/error?
return(Task.CompletedTask);
}
var indexOfArgs = diffTool.Cmd.Substring(0, indexOfDolar).LastIndexOf(' ');
var toolFilePath = diffTool.Cmd.Substring(0, indexOfArgs).Trim();
var fullFilePath = repository.GetFullPath(filePath);
// Replace arguments as documented in https://git-scm.com/docs/git-difftool#_options
var arguments = diffTool.Cmd.Substring(indexOfArgs)
// "$LOCAL is set to the name of the temporary file containing the contents of the diff pre-image"
.Replace("$LOCAL", baseFile)
// "$REMOTE is set to the name of the temporary file containing the contents of the diff post-image"
// We want the current file to be the one including the "changes post-image".
.Replace("$REMOTE", fullFilePath)
// Yes, it's confusing even in the docs that $BASE == $MERGED.
// "$MERGED is the name of the file which is being compared.
.Replace("$MERGED", fullFilePath)
// "$BASE is provided for compatibility with custom merge tool commands and has the same value as $MERGED."
.Replace("$BASE", fullFilePath);
#pragma warning restore CS8602 // Dereference of a possibly null reference.
RunTool(toolFilePath, arguments);
return(Task.CompletedTask);
}