% !Mode:: "TeX:DE:UTF-8:Main"

%This example shows how one can patch sectioning command and toc entries
%to add tags.
%The patches are layout/option dependant
%With other document options (e.g. chapterprefix) or
%if the sectioning commands are redefined more/different patches are perhaps needed

%no page break involved. So the example works in lua and generic mode

\documentclass{scrbook}
\usepackage[english]{babel}

\usepackage{tagpdf}

\tagpdfifpdftexT
 {
  %set language / can also be done with hyperref
  \pdfcatalog{/Lang (en-US)}
  \usepackage[T1]{fontenc}
 }

\tagpdfifluatexT
 {
  %set language / can also be done with hyperref
  \pdfextension catalog{/Lang (en-US)}
  \usepackage{fontspec}
  \usepackage{luacode}
 }


\tagpdfsetup{tabsorder=structure,
             activate-all,
             uncompress
             }

\usepackage{lipsum}%\textheight3cm

%%%%%%%%%%%%%%%
%Marking the toc entries
%around the whole entry so only structure:
\newcommand\tagscrtocentry[1]{\tagstructbegin{tag=TOCI}#1\tagstructend}

%leaf so structure and mc:
\newcommand\tagscrtocpagenumber[1]{%
 \tagstructbegin{tag=Reference}%
 \tagmcbegin{tag=Reference}%
 #1%
 \tagmcend
 \tagstructend}

\DeclareTOCStyleEntry[
   entryformat=\tagscrtocentry,
   pagenumberformat=\tagscrtocpagenumber]{tocline}{chapter}
\DeclareTOCStyleEntry[
   entryformat=\tagscrtocentry,
   pagenumberformat=\tagscrtocpagenumber]{tocline}{section}
\DeclareTOCStyleEntry[
   entryformat=\tagscrtocentry,
   pagenumberformat=\tagscrtocpagenumber]{tocline}{subsection}
\DeclareTOCStyleEntry[
   entryformat=\tagscrtocentry,
   pagenumberformat=\tagscrtocpagenumber]{tocline}{subsubsection}
\DeclareTOCStyleEntry[
   entryformat=\tagscrtocentry,
   pagenumberformat=\tagscrtocpagenumber]{tocline}{paragraph}



\renewcommand{\addtocentrydefault}[3]{%
 \ifstr{#3}{}{}
   {%\
   \ifstr{#2}{}
    {%
     \addcontentsline{toc}{#1}
      {%
       \protect\nonumberline
       \tagstructbegin{tag=P}%
       \tagmcbegin{tag=P}%
        #3%
       \tagmcend
       \tagstructend
      }%
    }%
    {%
    \addcontentsline{toc}{#1}{%
     \tagstructbegin{tag=Lbl}%
     \tagmcbegin{tag=Lbl}%
     \protect\numberline{#2}%
     \tagmcend\tagstructend
     \tagstructbegin{tag=P}%
     \tagmcbegin{tag=P}%
      #3%
     \tagmcend
     \tagstructend
     }%
    }%
   }}%

% the dots must be marked too
\makeatletter
\renewcommand*{\TOCLineLeaderFill}[1][.]{%
  \leaders\hbox{$\m@th
    \mkern \@dotsep mu\hbox{\tagmcbegin{artifact}#1\tagmcend}\mkern \@dotsep
    mu$}\hfill
}

%%%%%%%%%
% Sectioning commands
%%%%%%%%

\ExplSyntaxOn
\prop_new:N   \g_tag_section_level_prop
\prop_gput:Nnn \g_tag_section_level_prop {chapter}{H1}
\prop_gput:Nnn \g_tag_section_level_prop {section}{H2}
\prop_gput:Nnn \g_tag_section_level_prop {subsection}{H3}
\prop_gput:Nnn \g_tag_section_level_prop {subsubsection}{H4}
\prop_gput:Nnn \g_tag_section_level_prop {paragraph}{H5}

%new 0.6, as attributes are local we have to put \tagmcbegin everywhere.
\renewcommand{\chapterlinesformat}[3]
 {
  \@hangfrom
   {
    \tagstructbegin{tag=\prop_item:Nn\g_tag_section_level_prop{chapter}}
    \tl_if_empty:nF{#2}
     {
      \tagmcbegin    {tag=\prop_item:Nn\g_tag_section_level_prop{chapter}}
      #2
      \tagmcend
     }
   }
   {\tagmcbegin    {tag=\prop_item:Nn\g_tag_section_level_prop{chapter}}
    #3\tagmcend\tagstructend}%
 }

%unnumbered sections level give an empty mc, need to think about it.
\renewcommand{\sectionlinesformat}[4]
 {
  \@hangfrom
   {\hskip #2
    \tagstructbegin{tag=\prop_item:Nn\g_tag_section_level_prop{#1}}
    \tl_if_empty:nF{#3}
    {
     \tagmcbegin    {tag=\prop_item:Nn\g_tag_section_level_prop{#1}}
     #3
     \tagmcend
    }
   }
   {\tagmcbegin    {tag=\prop_item:Nn\g_tag_section_level_prop{#1}}
    #4
    \tagmcend\tagstructend}%
 }
 
\ExplSyntaxOff
\AfterTOCHead{\tagstructbegin{tag=TOC}}
\AfterStartingTOC{\tagstructend} %end TOC


\begin{document}
%I don't want to handle pagestyles, so set everything to empty:
\pagestyle{empty}\renewcommand\chapterpagestyle{empty}

\tagstructbegin{tag=Document}

\tableofcontents

\chapter{chapter}
\addchap{chapter}
\section{section}
\subsection{subsection}
\subsubsection{subsubsection}

 \tagstructbegin{tag=P,actualtext=abc!}
   \tagmcbegin{tag=P}
    a paragraph\par x
   \tagmcend
 \tagstructend

\tagstructend   %Document
\end{document} 