Hooking an environment inside `document` environment

Question

I am making a beamer-document that is basically a one-page frame. Since don't want to explicitly call the frame inside the environment, I how \begin{frame}[t] at the beginning of the document and \end{frame} at the end (plus two \vfill commands). This is the code:

\documentclass{beamer}

\AtBeginDocument{\begin{frame}[t]\vfill}
\AtEndDocument{\vfill\end{frame}}

\begin{document}

Cogito ergo sum.

\end{document}

Which returns the following error message:

File ended while scanning use of \beamer@collect@@body.

And here is the log file.

This, I suppose, means that I cannot hook environments to the document environment in this way. What would be the right way to do it? Is there a general way to do so for any environment? (That is, not only for frame.)

Thanks in advance for the help.

---

UPDATE:

Thanks to @koleygr I could use the following code:

\documentclass{beamer}

\let\olddocument\document
\let\oldenddocument\enddocument

\renewenvironment{document}{\olddocument\begin{frame}[t]\vfill}
  {\vfill\end{frame}\oldenddocument}

\begin{document}

Cogito ergo sum.

\end{document}

However, it doesn't work very well when I add another environment as follows:

\newcommand{\spacer}{\begin{column}{.02\textwidth}\end{column}}

\let\olddocument\document
\let\oldenddocument\enddocument

\renewenvironment{document}%
  {\olddocument\begin{frame}[t]\vfill%
    \begin{columns}[t]\spacer}
  {\spacer\end{columns}%
    \vfill\end{frame}\oldenddocument}

\begin{document}

Cogito ergo sum.

\end{document}

This returns the following error message:

File ended while scanning use of \frame.

And here is the log file.

How should I deal with this? Should I define some commands \oldolddocument and \oldoldenddocument for storing the recently redefined document environment or is there a more straightforward solution?

Answer 1

Edit after OPs edit:

This should work in this case:

\documentclass{beamer}

\newcommand{\Lspacer}{\columns[t]\column{.02\textwidth}\column{0.96\textwidth}}
\newcommand{\Rspacer}{\column{.02\textwidth}\endcolumns}

\let\olddocument\document
\let\oldenddocument\enddocument

\renewenvironment{document}%
  {\olddocument\begin{frame}[t]\vfill\par%
    \Lspacer%
    }
  {\Rspacer%
    \vfill\end{frame}\oldenddocument
    }

\begin{document}

Cogito ergo sum.

\end{document}

Old answer:

You could try this way in this case:

\documentclass{beamer}
\let\olddocument\document
\let\oldenddocument\enddocument
\renewenvironment{document}{\olddocument\begin{frame}[t]\vfill}
{\vfill\end{frame}\oldenddocument}

\begin{document}

Cogito ergo sum.

\end{document}

Your problem is possibly that there are more commands using the \AtEndDocument inside beamer class and thus they the order of the frame environment \begin and \end commands is not the expected.