Pass parrameter of custom enviroment as parameter of theorem

Question

I want to create basically a shortcut for
begin{sometheorem}[optional parameter]
    leavevmode vspace{-baselineskip}vspace{-baselineskip}vspace{3pt} %some space adjustments
    begin{leftbar}
        some text
    end{leftbar}
end{sometheorem}

so i tried:
newenvironment{defi}[1]
{
begin{definition}[#1]
leavevmode vspace{-baselineskip}vspace{-baselineskip}vspace{3pt}
begin{leftbar}noindent
}
{
end{leftbar}
end{definition}
}

But this gives me

Theorem (])
Optional parameter] some text

What can i do, to properly pass the parameter along?
Edit: I am using the framed package for leftbar and amsthm for the theorems.

egreg · Accepted Answer

You need to branch on whether the optional argument is given or not.
documentclass{article}
usepackage{framed}

newtheorem{innertheorem}{Theorem}
newenvironment{theorem}[1][]
 {ifrelaxdetokenize{#1}relax
    begin{innertheorem}%
  else
    begin{innertheorem}[#1]%
  fi
  mbox{}parnobreak
  vspace{-baselineskip}vspace{3pt}%
  begin{leftbar}noindentignorespaces}
 {end{leftbar}end{innertheorem}}

begin{document}

begin{theorem}
Some statement Some statement Some statement
Some statement Some statement Some statement
Some statement Some statement
end{theorem}

begin{theorem}[Something]
Some statement Some statement Some statement
Some statement Some statement Some statement
Some statement Some statement
end{theorem}

end{document}

Pass parrameter of custom enviroment as parameter of theorem

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