\documentclass{article}

\usepackage{amsmath}
\usepackage{mdframed}
\usepackage{amsthm}
\usepackage{thmtools}
\usepackage{mkessler-hypersetup}
\usepackage{verbatim}

\usepackage{mkessler-refproof}


\def\cname#1{\texttt{$\backslash$#1}}



\NewDocumentEnvironment{remark}{!s o}


\newcounter{all}

\declaretheorem[sibling = all]{definition}

\declaretheorem[sibling = all, name = Theorem ]{intntheorem}
\declaretheorem[sibling = all, name = Theorem*]{intstheorem}
\declaretheorem[sibling = all, name = Theorem$^{\dagger}$]{intdtheorem}

\declaretheorem[sibling = all, parent = section ]{testthm}
\declaretheorem[sibling = all, parent = section ]{lemma}

\NewDocumentEnvironment{theorem}{ !s !t+ }
{
  \IfBooleanTF{#1}
  {
    \begin{intstheorem}
  }
  {
    \IfBooleanTF{#2}
    {
      \begin{intdtheorem}
    }
    {
      \begin{intntheorem}
    }
  }
}
{
  \IfBooleanTF{#1}
  {
    \end{intstheorem}
  }
  {
    \IfBooleanTF{#2}
    {
      \end{intdtheorem}
    }
    {
      \end{intntheorem}
    }
  }
}

\addtotheorempreheadhook{test}
\addtotheorempostheadhook{test}

\begin{document}

\section{What we need}
\subsection{Groups / classes of theorems}
These share some properties and are controlled via options.

Things an environment should change dynamically:
\begin{itemize}
  \item parent, sibling
  \item title: variants with * or $^{\dagger}$
\end{itemize}

\subsection{Greater Syntax for theorems}
Expand the \cname{NewDocumentEnvironment}-like syntax to theorems as well.

\subsection{Example Code}

\begin{verbatim}
  \NewTheoremGroup { all }
  [
  ]

  \NewTheoremGroup { big }
  [
    thmtools = { sibling = insection }
  ]

  \NewTheoremGroup { dagger }
  [
    postname = { $\dagger$ },
    thmtools = { sibling = insubsection }
  ]

  \NewTheoremGroup { small }
  [
    thmtools = { sibling = insubsection }
  ]

  \NewTheoremGroup { star }
  [
    thmtools = { sibling = insubsection },
    postname = { * }
  ]

  \NewTheoremGroup { starred }
  [
    thmtools = { numbered = no }
  ]

  \DeclareTheoremVariants { theorem } { !s !t+ o}
  {
    \AddTheoremToGroup { big }
    \IfBooleanT {#1} { \AddTheoremToGroup{star}     }
    \IfBooleanT {#2} { \AddTheoremToGroup{daggered} }
  }
\end{verbatim}

\subsection{Syntax}

\begin{verbatim}
  \NewTheoremGroup {<name>}
  [
    thmtools = {<options passed to thmtools>},
    prename  = <inserted before name>,
    postname = <inserted after name>,
    mapname  = <applied to name as function>,
  ]

  \NewGroupedTheorem
  [
    thmtools = {<options passed to thmtools>},
    group    = {<comma separated list of groups}
  ]
  {<name>}

  \NewDocumentTheorem{<name>}{<signature>}
  {
    any legal xparse code that issues the commands
    \AddTheoremToGroup{<groupname>}
    and
    \PassToThmtools{<comma separated list>}
    \PassAsOptionalArgument{<token list>}
  }

\end{verbatim}
Last case: For the powerset of the mentioned theorems, generate internal theorem variants,
that are part of the corresponding groups, where in the document, the signature will be 
calling the corresponding theorem variant automatically.


A typical declaration would thus be:
\begin{verbatim}
  \NewDocumentTheorem{theorem}{ !s !t+ o}
  {
    \IfBooleanT{#1}{ \AddTheoremToGroup{star}   }
    \IfBooleanT{#2}{ \AddTheoremToGroup{dagger} }
    \PassAsOptionalArgument{#3}
  }
\end{verbatim}


\section{Testing}
\begin{theorem}\label{normal}
 test 
\end{theorem}

\begin{theorem}*\label{star}

\end{theorem}

\begin{theorem}+[comment]\label{dagger}
  test
\end{theorem}

\def\foo#1.#2ab#3.\end{foo: #1 #2 #3}

\foo 1.2ab3.\end

\section{test}\label{sec}

\section*{test}
\phantomsection\label{sec2}

\autoref{sec}

\autoref{sec2}

\begin{theorem}
\end{theorem}

\autoref{test}

\begin{theorem}[test]
  bla
\end{theorem}

\begin{definition}
  
\end{definition}

normal:~\autoref{normal}, star:~\autoref{star}, dagger:~\autoref{dagger} 

\begin{testthm}
  
\end{testthm}

\begin{lemma}
  bla
\end{lemma}

\end{document}