convert to Code Cell respecting IndentingNewLine

[kubaPod]

It is quite annoying when an Input cell converted to Code looses all automatic indentation.

[kubaPod]

Prototype

inputToCodeCell[cell_CellObject]:=NotebookWrite[
  cell,
  NotebookRead[cell]//ReplacePart[2->"Code"]//MapAt[toRealIndents,1]
]

Module[{$inside=False},
toRealIndents[arg_]/;TrueQ[!$inside]:= Block[{$inside=True,$level=0, $indent = "  "}, toRealIndents[arg]]
];

$opening="["|"("|"{";
$closing="]"|")"|"}";

toRealIndents[BoxData[box_]]:= BoxData @ RowBox @ Block[{RowBox=Flatten}, toRealIndents@box];
toRealIndents[BoxData[box:{(_RowBox|_String)..}]]:= BoxData[ RowBox /@ Flatten /@ List /@ Block[{RowBox=Flatten}, toRealIndents/@box] ]
toRealIndents[row_List]:= BlockMap[Apply@toRealIndents, Append["$END$"]@row, 2,1];

toRealIndents[previous_,next___]:=previous;
toRealIndents[o:$opening, next___]:=($level++;o);
toRealIndents[c:$closing, next___]:= ($level--;c);
toRealIndents[FromCharacterCode@{62371}, c:$closing]:= Sequence @@ Characters["\n"<>StringRepeat[$indent,$level-1]]
toRealIndents[FromCharacterCode@{62371}, next_]:= Sequence @@ Characters["\n"<>StringRepeat[$indent,$level]]