%D \module
%D   [       file=strc-sec,
%D        version=2008.10.20,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Sectioning,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Structure Macros / Sectioning}

\unprotect

\ifdefined \v!block \else \def\v!block{block} \fi

% compatibility issue:
%
% \def\setfullsectionnumber #1{}
% \def\preparefullnumber    #1{}
% \def\fullsectionnumber    {1--1--1}
% \def\makesectionnumber    [#1]{}
% \def\makesectionformat    {}
% \def\sectionformat        {1--1-1-1-1-1-1}
% \def\composedsectionnumber{}
% \def\@@kolist{}

% \setuphead[section]   [separator=\separatorlist{?,!,*}]
% \setuphead[subsection][separator=\separatorlist{??,!!,**}]
%
% \let\spr\separatorlist % this will enable this feature
%
% \setuphead[section]   [separator={?,!,*}]
% \setuphead[subsection][separator={??,!!,**}]
%
% \setupheads[separator={A,B,C,D,E,F}]
% \chapter{test}
% \section{test} \subsection{test} \subsection{test}
% \section{test} \subsection{test} \subsection{test}

% lua interface / names and interface might change

\def\setstructurelevel         #1#2{\ctxlua{structures.sections.setlevel("#1","#2")}}  % name, level|parent
\def\getstructurelevel           #1{\ctxlua{structures.sections.getcurrentlevel("#1")}}% name
\def\setstructurenumber        #1#2{\ctxlua{structures.sections.setnumber(#1,"#2")}}   % level, number (+/-)
\def\getstructurenumber          #1{\ctxlua{structures.sections.getnumber(#1)}}        % level
\def\getsomestructurenumber    #1#2{\ctxlua{structures.sections.getnumber(#1,"#2")}}   % level, what
\def\getfullstructurenumber      #1{\ctxlua{structures.sections.fullnumber(#1)}}       % level
\def\getsomefullstructurenumber#1#2{\ctxlua{structures.sections.fullnumber(#1,"#2")}}
\def\getspecificstructuretitle   #1{\ctxlua{structures.sections.structuredata("#1","titledata.title",nil,"\headparameter\s!catcodes")}}%

% structure heads (like \startchapter)

% \c!deeptextcommand, \c!deepnumbercommand: undefined !
% \c!before \c!after \c!distance
% \c!page \c!header  \c!text \c!footer=,
% \c!numbercommand \c!textcommand \c!ownnumber \c!number
% \c!file \c!grid \c!margintext
% \c!expansion \c!xmlsetup \s!catcode

\installcommandhandler \??nh {head} \??nh

\let\setupheads\setuphead % will go

\appendtoks
    \ifx\currentheadparent\empty
        \edef\currentheaddefault{\headparameter\c!default}%
        \edef\currentheadsection{\headparameter\c!section}%
        \ifx\currenthead\currentheaddefault
          \let\currentheadparent\currentheadsection
        \else\ifx\currentheaddefault\empty
          \let\currentheadparent\currentheadsection
        \else
          \let\currentheadparent\currentheaddefault
        \fi\fi
        \normalexpanded {%
            \setheadparameter{\c!label}{\currenthead}%
            \setheadparameter{\c!coupling}{\currenthead}%
            \setheadparameter{\s!parent}{\??nh\currentheadparent}%
            \definemarking[\currenthead]         [\currentheadsection]%
            \definemarking[\currenthead\v!number][\currentheadsection]%
            \setupmarking [\currenthead]         [\c!filtercommand=\noexpand\sectionheadmarkingtitle {\currenthead}]%
            \setupmarking [\currenthead\c!number][\c!filtercommand=\noexpand\sectionheadmarkingnumber{\currenthead}]%
        }%
        \doifelselist\currenthead\donothing
          {\definelist[\currenthead][\c!prefix=\v!no]}%
    \else
        \normalexpanded {%
            \setheadparameter{\c!label}{\currenthead}%
            \setheadparameter{\c!coupling}{\currentheadparent}%
            \definemarking[\currenthead]         [\currentheadparent]%
            \definemarking[\currenthead\v!number][\currentheadparent\c!number]%
        }%
        \doifelselist\currenthead\donothing
          {\normalexpanded{\definelist[\currenthead][\currentheadparent][\c!prefix=\v!no]}}%
    \fi
    \presetlabeltext[\currenthead=]%
    \the\everysetuphead
\to \everydefinehead

\appendtoks
   \setstructurelevel\currenthead{\thenamedheadlevel\currenthead}%
\to \everydefinehead

\appendtoks
    % beware, this is a global register
    \begingroup
    \edef\currentsectionheadcoupling{\sectionheadcoupling\currenthead}%
    \edef\currentsectionheadsection {\sectionheadsection \currentsectionheadcoupling}%
    \edef\currentsectionlevel       {\sectionlevel       \currentsectionheadsection}%
    \ctxlua{structures.sections.register("\currenthead",{
        coupling = "\currentsectionheadcoupling",
        section  = "\currentsectionheadsection",
        level    = \currentsectionlevel,
    })}%
    \endgroup
\to \everydefinehead

\appendtoks
 % \setevalue{\e!next \currenthead}{\donexthead [\currenthead]}%
   \setevalue{\e!start\currenthead}{\dostarthead[\currenthead]}%
   \setevalue{\e!stop \currenthead}{\dostophead [\currenthead]}%
\to \everydefinehead

\appendtoks
   \doifelse{\headparameter\c!ownnumber}\v!yes
     {\setevalue\currenthead{\dohandleheadown[\currenthead]}}
     {\setevalue\currenthead{\dohandleheadnop[\currenthead]}}%
\to \everysetuphead

% structure sections (the parents of chapter etc)

\let\firstsectionname\empty
\let\lastsectionname \empty

\let\resetallstructuremarks            \relax
\let\resetcurrentstructuremarks        \relax
\let\resetcurrentstructuremarkswithpage\relax

\def\resetallstructuremarks            {\resetmarking[\firstsectionname]} % will become option (was \v!section-1)
\def\resetcurrentstructuremarks        {\resetmarking[\lastsectionname]}  % will become option
%def\resetcurrentstructuremarkswithpage{\resetmarking[\lastsectionname]}  % will become option

% -2=text -1=manual 0=block 1+=structurelevel

\newcount\maxstructuredepth

\def\setnextsectionlevel#1%
  {\global\advance\maxstructuredepth\plusone
   \setevalue{\??nh:\c!level:#1}{\the\maxstructuredepth}}

\def\sectionlevel#1%
  {\csname\??nh:\c!level:\ifcsname\??nh:\c!level:#1\endcsname#1\else\v!none\fi\endcsname}

\setvalue{\??nh:\c!level:\v!block}{0}
\setvalue{\??nh:\c!level:\v!none }{-1}
\setvalue{\??nh:\c!level:\v!text }{-2}

\newtoks\everydefinesection

\unexpanded\def\definesection[#1]%
  {\ifcsname\??nh:\c!level:#1\endcsname \else
     \edef\currentsection{#1}% not used, will go
     \edef\currenthead{#1}%
     \setnextsectionlevel{#1}%
     \setstructurelevel{#1}{\sectionlevel{#1}}%
     \normalexpanded{\setheadparameter{\s!parent}{\??nh\lastsectionname}}% TO BE CHECKED
     \the\everydefinesection
     % so far for these default inheritances
     \definemarking[#1]%
     \ifnum\maxstructuredepth>\plusone
       \normalexpanded{\noexpand\relatemarking[#1][\lastsectionname]}% so, the parent will reset the child
     \fi
     \xdef\lastsectionname{#1}%
     \ifx\firstsectionname\empty
        \glet\firstsectionname\lastsectionname
     \fi
   \fi}

\unexpanded\def\setupsection
  {\dotripleempty\dosetupsection}

\def\dosetupsection[#1][#2][#3]%
  {\ifcsname\??nh:\c!level:#1\endcsname
     \dodosetupsection[#1][#2][#3]%
   \else
     \dodosetupsection[\sectionheadsection{#1}][#2][#3]%
   \fi}

\def\dodosetupsection[#1][#2][#3]%
  {\pushmacro\currenthead
   \ifthirdargument
   % \getparameters[\??nh#1#2][#3]% ? probably sectionblock
     \edef\currenthead{#1#2}%     % not used at any more in mkiv (sets now)
     \setupcurrenthead[#3]%
   \else
   % \getparameters[\??nh#1][#2]%
     \edef\currenthead{#1}%
     \setupcurrenthead[#2]%
   \fi
   \popmacro\currenthead}

% we share the parameters as sections are roots of heads so eventually we can
% consider \definesection -> \definehead with one argument

\appendtoks
    % This is a rather practical default that we don't want to
    % be part of the parent chain lookup mechanism; it's also
    % mkii compatible. Somewhat weird that it's part of the
    % top level structure but it will be flattened anyway.
    \let\currenthead\currentsection %
    \setheadparameter\c!textstyle  {\strictheadparameter\c!style}%
    \setheadparameter\c!textcolor  {\strictheadparameter\c!color}%
    \setheadparameter\c!numberstyle{\strictheadparameter\c!style}%
    \setheadparameter\c!numbercolor{\strictheadparameter\c!color}%
\to \everydefinesection

% head -> head

\def\sectionheadmarkingtitle #1#2{\ctxlua{structures.marks.title("#1","#2")}}
\def\sectionheadmarkingnumber#1#2{\ctxlua{structures.marks.number("#1","#2")}}

\def\sectionheadcoupling#1{\namedheadparameter{#1}\c!coupling}
\def\sectionheadsection #1{\namedheadparameter{#1}\c!section}

% head construction

\unexpanded\def\dohandleheadown{\dodoubleempty\dodohandleheadown} % [ref] {nr} {title}
\unexpanded\def\dohandleheadnop{\dodoubleempty\dodohandleheadnop} % [ref] {title}
\unexpanded\def\dostarthead    {\dotripleempty\dodostarthead}     % [settings] [userdata]

\newconditional\currentstructureown

\newtoks\everybeforehead % hook, todo: before/after keys
\newtoks\everyafterhead  % hook, todo: before/after keys

\unexpanded\def\dodohandleheadown[#1][#2]#3#4%
  {\settrue\currentstructureown
   \triggerautostructurelevel
   \dohandlehead{#1}{\c!reference={#2},\c!ownnumber={#3},\c!title={#4}}{}} % name ref nr title --

\unexpanded\def\dodohandleheadnop[#1][#2]% for taco: [key=value] variant
  {\setfalse\currentstructureown
   \triggerautostructurelevel
   \doifassignmentelse{#2}\dodohandleheadnopA\dodohandleheadnopB{#1}{#2}}

\unexpanded\def\dodohandleheadnopA#1#2%
  {\dohandlehead{#1}{#2}{}}

\unexpanded\def\dodohandleheadnopB#1#2#3%
  {\dohandlehead{#1}{\c!reference={#2},\c!title={#3}}{}} % name ref nr title --

\unexpanded\def\dodostarthead[#1][#2][#3]% for the moment no grouping, too annoying with page breaks
  {\setfalse\currentstructureown
  %\globalpushmacro\currenthead % this does not work out well
   \xdef\currenthead{#1}%
   \headparameter\c!beforesection % beware, no users vars set yet
   \the\everybeforehead
   \dohandlehead{#1}{#2}{#3}% name -- -- -- userdata (we might move the tagged to here)
   \headparameter\c!insidesection}

\unexpanded\def\dostophead[#1]%
  {\dostoptagged\dostoptagged
  %\globalpopmacro\currenthead % so we do a hard recover
   \xdef\currenthead{#1}% recover
   \headparameter\c!aftersection
   \the\everyafterhead}

% \unexpanded\def\donexthead[#1][#2][#3]% obsolete
%   {\setfalse\currentstructureown
%    \xdef\currenthead{#1}%
%    \dohandlehead{#1}{#2}{#3}} % name -- -- -- userdata

% \newconditional\structurereversesectionnumbers  % todo: key/val

\newconditional\headtolist
\newconditional\headdoincrement
\newconditional\headdoplace
\newconditional\headleaveempty
\newconditional\headhidden
\newconditional\headshownumber
\newconditional\headisdisplay

\setvalue{\??nh:\c!incrementnumber:\v!yes  }{\settrue \headdoincrement\settrue \headtolist}
\setvalue{\??nh:\c!incrementnumber:\v!no   }{\setfalse\headdoincrement\setfalse\headtolist}
\setvalue{\??nh:\c!incrementnumber:\v!list }{\setfalse\headdoincrement\settrue \headtolist}
\setvalue{\??nh:\c!incrementnumber:\s!empty}{\settrue \headdoincrement\settrue \headtolist}

\def\setheadincrement
  {\edef\currentheadincrement{\headparameter\c!incrementnumber}%
   \ifcsname\??nh:\c!incrementnumber:\currentheadincrement\endcsname
     \csname\??nh:\c!incrementnumber:\currentheadincrement\endcsname
   \else
     \settrue \headdoincrement\settrue \headtolist
     % \filterheadnumber
   \fi}

\def\filterheadnumber
  {\settrue\headdoincrement
   \settrue\headtolist
   \ifx\currentproduct\empty
     % todo : filter from other toc (number, file, title)
     % use  : \currentheadincrement as spec
   \fi}

\setvalue{\??nh:\c!placehead:\v!yes}%
  {\setfalse\headleaveempty
   \settrue \headdoplace
   \setfalse\headhidden}

\setvalue{\??nh:\c!placehead:\v!empty}%
  {\settrue \headleaveempty
   \settrue \headdoplace
   \setfalse\headhidden}

\setvalue{\??nh:\c!placehead:\v!no}%
  {\settrue \headleaveempty
   \setfalse\headdoplace
   \setfalse\headhidden}

\setvalue{\??nh:\c!placehead:\v!hidden}%
  {\settrue \headleaveempty
   \setfalse\headdoplace
   \settrue \headhidden}

\def\setheadplacement
  {\executeifdefined
     {\??nh:\c!placehead:\headparameter\c!placehead}
     {\getvalue{\??nh:\c!placehead:\v!yes}}}

\def\setheaddisplay
  {\doifelsevalue{\??ns:\headparameter\c!alternative}\v!horizontal
     {\setfalse\headisdisplay}
     {\settrue \headisdisplay}}

\def\dosettructureheadnumbercontent
  {\setsystemmode  \v!sectionnumber
   \settrue\headshownumber} % why ?

\def\doresettructureheadnumbercontent
  {\resetsystemmode\v!sectionnumber
   \setfalse\headshownumber} % why ?

\def\setheadnumber
  {\doifelse{\sectionblockparameter\c!number}\v!yes % todo
     {\doifelse{\headparameter\c!number}\v!yes
        {\settrue\headshownumber}
        {\setfalse\headshownumber}}
     {\setfalse\headshownumber}}

\unexpanded\def\theheadsynchonization
  {\currentstructuresynchronize}

% BEWARE: \marking[section]{my text} does not work as we use list indices instead
% so we need a 'keep track of raw set option' (or maybe a funny internal prefix)

% \unexpanded\def\setheadmarking
%   {\normalexpanded{\noexpand\setmarking[\currenthead]{\currentstructurelistnumber}}}

\unexpanded\def\setheadmarking % li:: so that we can use \marking[section]{Taco needed this}
  {\normalexpanded{\noexpand\setmarking[\currenthead]{li::\currentstructurelistnumber}}}

\let\deepstructurenumbercommand\relax
\let\deepstructuretitlecommand \relax

\unexpanded\def\fullheadnumber
  {\edef\currentheadlabeltag{\currentsectionblock\c!label}%
   \dostarttagged\t!sectionnumber\empty
   \labeltexts
     {\headparameter\currentheadlabeltag}
     {\ifx\deepstructurenumbercommand\relax
        \structurenumber
      \else
        \normalexpanded{\noexpand\deepstructurenumbercommand{\structurenumber}}%
      \fi}%
   \dostoptagged}

\unexpanded\def\fullheadtitle
  {\dostarttagged\t!sectiontitle\empty
   \ifx\deepstructuretitlecommand\relax
     \structuretitle
   \else
     \normalexpanded{\noexpand\deepstructuretitlecommand{\structuretitle}}%
   \fi
   \dostoptagged}

\let\currenthead        \empty
\let\currentheadcoupling\empty
\let\currentheadsection \empty
\let\currentheadlevel   \!!zerocount
\let\currentheadcounter \!!zerocount

% here we could inherit as well but it's a bit complex

\def\doregisterhead#1#2#3% name data userdata
  {\structurecomponent
    %[\c!label={\headparameter\c!label}, % why { }
     [\c!label={\headparameter{\currentsectionblock\c!label}},
      \c!incrementnumber=\ifconditional\headdoincrement\v!yes\else\v!no\fi, % not that needed
      \c!saveinlist=\ifconditional\headtolist\v!yes\else\v!no\fi,
      \c!level=\currentheadlevel,
      \c!name=#1,
      \c!number=\ifconditional\headdoincrement\ifconditional\headshownumber\v!yes\else\v!no\fi\else\v!no\fi,
      \c!bookmark=,
      \c!marking=,
      \c!list=,
      \c!expansion=\headparameter\c!expansion,
      \c!xmlsetup=\headparameter\c!xmlsetup,
      \s!catcodes=\headparameter\s!catcodes,
      \c!sectionresetset=\headparameter\c!sectionresetset,
      \c!sectionseparatorset=\headparameter\c!sectionseparatorset,
      \c!sectionconversionset=\headparameter\c!sectionconversionset,
      \c!sectionconversion=\headparameter\c!conversion, % just for compatibility
      \c!sectionstarter=\headparameter\c!sectionstarter,
      \c!sectionstopper=\headparameter\c!sectionstopper,
      \c!sectionset=\headparameter\c!sectionset,
      \c!sectionsegments=\headparameter\c!sectionsegments,
      \c!reference=\headparameter\c!reference,
      \c!referenceprefix=\headparameter\c!referenceprefix,
      \c!backreference=,
      \c!command=,
      #2]%
     [#3]%
   \reportcurrentstructure}

\unexpanded\def\placeheadtext  {\dosingleempty\place_head_text  } % use with care
\unexpanded\def\placeheadnumber{\dosingleempty\place_head_number} % use with care

\ifdefined\setupheadcomponentfont \else

    \unexpanded\def\setupheadcomponentfont#1#2%
      {\dontconvertfont
       \dosetheadattributes\c!style\c!color
       \dosetheadattributes#1#2%
       \setupinterlinespace}

\fi

\def\place_head_text[#1]%
  {\dontleavehmode
   \begingroup
   \edef\currenthead{#1}%
   \setupheadcomponentfont\c!textstyle\c!textcolor
   \relax
   \getspecificstructuretitle{\thenamedheadlevel{#1}}%
   \endgraf
   \endgroup}

\def\place_head_number[#1]%
  {\dontleavehmode
   \begingroup
   \edef\currenthead{#1}%
   \setupheadcomponentfont\c!numberstyle\c!numbercolor
   \relax
   \getfullstructurenumber{\thenamedheadlevel{#1}}%
   \endgraf
   \endgroup}

\ifdefined\presetnumberheadalternative \else \let\presetnumberheadalternative\relax \fi
\ifdefined\setautostructurelevel       \else \let\setautostructurelevel      \relax \fi
\ifdefined\triggerautostructurelevel   \else \let\triggerautostructurelevel  \relax \fi

\def\dohandlehead#1#2#3% name data userdata (we can move #1 to the caller)
  {\xdef\currenthead        {#1}%
   \xdef\currentheadcoupling{\sectionheadcoupling\currenthead}%
   \xdef\currentheadsection {\sectionheadsection \currentheadcoupling}%
   \xdef\currentheadlevel   {\sectionlevel       \currentheadsection}%
   %writestatus\m!system{setup: \currenthead,\currentheadcoupling,\currentheadsection,\currentheadlevel}%
   %
   \setautostructurelevel
   \setheadincrement
   \setheadplacement
   \setheaddisplay
   \setheadnumber
   %
   \unexpanded\def\\{\space}%
   \flushingcolumnfloatsfalse
   %
   % todo: also mark (for header)
   %
   % we might remove the lower level
   %
   % not here, after optional \page: \doregisterhead\currenthead{#2}{#3}%
   %
%    \xdef\currentheadcounter{\currentstructurecounter}% lua call
   %
   % \currentstructuresynchronize % will move
   %
   \edef\numberheaddistance   {\headparameter\c!distance   }% compatibility
   \edef\numberheadalternative{\headparameter\c!alternative}% compatibility
   \presetnumberheadalternative
   %
   \let\getheadnumber\empty
   \let\getheadtitle \empty
   \let\getheadsyncs \empty
   \ifconditional\headdoincrement
     \ifconditional\headdoplace
       \doheadspacingbeforeyes
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \let\getheadtitle\fullheadtitle
       \ifconditional\headshownumber
         \let\getheadnumber\fullheadnumber
         \placecurrentheadnumbertext
       \else
         \placecurrentheadtext
       \fi
       \doheadspacingafteryes
     \else\ifconditional\headhidden
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \placecurrentheadhidden % only something when tracing
     \else
       \doheadspacingbeforenop % toegevoegd ivm subpaginanr / tug sheets
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \placecurrentheadempty % just flush 'm
       \doheadspacingafternop
     \fi\fi
   \else
     \ifconditional\headdoplace
       \doheadspacingbeforeyes
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \let\getheadtitle\fullheadtitle
       \placecurrentheadtext
       \doheadspacingafteryes
     \else\ifconditional\headhidden
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \placecurrentheadhidden % only something when tracing
     \else
       % do nothing / should be vbox to 0pt
       \doheadspacingbeforenop
       \doregisterhead\currenthead{#2}{#3}% after optional \page
       \let\getheadsyncs\theheadsynchonization
       \placecurrentheadempty % just flush 'm
       \doheadspacingafternop
     \fi\fi
   \fi
   \flushingcolumnfloatstrue
   \setfalse\ignorehandlepagebreak
   % ignorespaces prevents spaces creeping in when after=\dontleavehmode
   \dostarttagged\t!sectioncontent\empty
   \ifconditional\headisdisplay % \ifdisplaysectionhead
     \ignorespaces
   \else
     \expandafter\GotoPar
   \fi}

% typesetting

\unexpanded\def\placecurrentheadnumbertext
  {\setheadmarking
   \getheadnumber/\getheadtitle
   \getheadsyncs}

\unexpanded\def\placecurrentheadtext
  {\setheadmarking
   \getheadtitle
   \getheadsyncs}

\unexpanded\def\placecurrentheadempty
  {\setheadmarking
   \getheadsyncs}

\unexpanded\def\placecurrentheadhidden
  {\setxvalue{\currenthead:hidden:attr}%
     {\headreferenceattributes}% can be used when making a box
   \setxvalue{\currenthead:hidden:sync}%
     {\noexpand\letgvalue{\currenthead:hidden:sync}\relax
      \noexpand\setmarking[\currentheadcoupling]{\currentstructurelistnumber}%
      \hbox\headreferenceattributes{}% otherwise no destination ... maybe tag ref as hidden and fall back on page reference
      \currentstructuresynchronize}} % and it's a node anyway

\def\synchronizehead           #1{\csname#1:hidden:sync\endcsname}
\def\theheadreferenceattributes#1{\csname#1:hidden:attr\endcsname}

\unexpanded\def\placerawheaddata  [#1]{\synchronizehead{#1}}
\unexpanded\def\placerawheadtext  [#1]{\getspecificstructuretitle{\thenamedheadlevel{#1}}}
\unexpanded\def\placerawheadnumber[#1]{\getfullstructurenumber{\thenamedheadlevel{#1}}}

% \setuphead[chapter][placehead=hidden]
% \chapter {test}
%
% %(\synchronizehead{chapter}) % \getheadsyncs
% %(\getfullstructurenumber{\thenamedheadlevel{chapter}})
% %(\getspecificstructuretitle{\thenamedheadlevel{chapter}})
%
% (\placerawheaddata  [chapter])
% (\placerawheadnumber[chapter])
% (\placerawheadtext  [chapter])

% pagebreaks

\newcount\precedingstructurelevel \precedingstructurelevel\plusone
\newconditional\ignorehandlepagebreak

\def\doheadspacingbeforeyes
  {\docheckheadbefore
   \dohandleheadpagebreakyes
   \headparameter\c!inbetween
   \dostarttagged\t!section\currenthead}

\def\doheadspacingbeforenop
  {\docheckheadbefore
   \dohandleheadpagebreaknop
   \headparameter\c!inbetween
   \dostarttagged\currenthead\empty}

\def\emptyheadcorrection
  {\ifconditional\headleaveempty % inlined \emptyheadcorrection (with after=\blank)
     \penalty10000 % first ... we need to adapt this all to vspacing
     \vskip-\lineheight
     \kern\zeropoint
     \prevdepth\strutdepth
   \fi}

\def\doheadspacingafteryes
  {\ifconditional\headisdisplay
     \dosomebreak\nobreak % needs to be adapted to vspacing
     \emptyheadcorrection
     \headparameter\c!after
   \fi}

\def\doheadspacingafternop
  {}

\newsignal\continuousheadsignal

\def\docheckheadbefore#1%
  {\ifhmode
     \scratchcounter\lastpenalty\unpenalty % no beauty in this
     \ifdim\lastskip=\continuousheadsignal
       % no page break
       \ifconditional\ignorehandlepagebreak
         \setfalse\ignorehandlepagebreak
       \else
         \global\precedingstructurelevel\currentheadlevel
         \nobreak
       \fi
       \global\settrue\continuoussectionhead
     \else
       \penalty\scratchcounter
       \global\setfalse\continuoussectionhead
       #1%
     \fi
   \else
     \global\setfalse\continuoussectionhead
     #1%
   \fi}

\def\dodocheckheadlayout#1#2%
  {\doifelselayouttextline{#1}
     {\doifsomething{\headparameter#2}{\expanded{\setuplayouttext[#1][\c!state=\headparameter#2]}}}
     \donothing}

\setvalue{\??nh:\??mk:n:\v!page }{}
\setvalue{\??nh:\??mk:n:\v!reset}{\resetcurrentstructuremarks}
\setvalue{\??nh:\??mk:y:\v!page }{} % to be checked: {\resetcurrentstructuremarks}
\setvalue{\??nh:\??mk:y:\v!reset}{\resetcurrentstructuremarks}

\def\docheckheadlayout
  {\doifelsenothing{\headparameter\c!page}
     {\getvalue{\??nh:\??mk:n:\headparameter\c!marking}}
     {\page[\headparameter\c!page]%
      \getvalue{\??nh:\??mk:y:\headparameter\c!marking}%
      \dodocheckheadlayout\v!header\c!header
      \dodocheckheadlayout\v!text  \c!text
      \dodocheckheadlayout\v!footer\c!footer}}

\def\currentstructurecounter {\ctxlua{structures.sections.depthnumber(\thenamedheadlevel\currenthead)}}
\def\previousstructurecounter{\ctxlua{structures.sections.depthnumber(\thenamedheadlevel\currenthead-1)}}

\def\dohandleheadpagebreaknop
  {\doifelse{\headparameter\c!continue}\v!yes
     {\ifnum\previousstructurecounter=\zerocount
        \docheckheadlayout
      \else\ifnum\currentstructurecounter>\zerocount
        \docheckheadlayout
      \fi\fi}%
     {\docheckheadlayout}}

\def\dohandleheadpagebreakyes
  {%[[\currenthead @\thenamedheadlevel\currenthead/prev:\previousstructurecounter/curr:\currentstructurecounter]]
   \ifconditional\ignorehandlepagebreak
     \setfalse\ignorehandlepagebreak
   \else
%      \ifnum\lastpenalty>\zerocount
%        \global\pagebreakdisabledtrue
%      \fi
     % beware, these numbers are not yet know here
     \doifelse{\headparameter\c!continue}\v!yes
       {\ifnum\previousstructurecounter=\zerocount
          \docheckheadlayout
        \else\ifnum\currentstructurecounter>\zerocount
          \docheckheadlayout
        \fi\fi}%
       {\docheckheadlayout}%
     \doifnot{\headparameter\c!aligntitle}\v!float\flushsidefloats
     \headparameter\c!before
     \relax
%      \ifpagebreakdisabled
%        \global\pagebreakdisabledfalse
%      \else
%        \dopreventbreakafterheadauto % not ok as it binds the prev par
%      \fi
     \doif{\headparameter\c!aligntitle}\v!float\indent
     \global\precedingstructurelevel\currentheadlevel
   \fi}

\settrue\autoheadbreak % todo: \vspacing[category:8] == keep_together

\def\dopreventbreakafterheadauto % used after \c!before
  {\ifconditional\autoheadbreak
      \vspacing[\v!samepage-\currentheadlevel]%
   \fi}

\def\dopreventbreakafterheadspec#1% see enumerations etc
  {\ifconditional\autoheadbreak
      \vspacing[\v!samepage-\the\numexpr\currentheadlevel+1\relax]% todo #1
   \fi}

\def\dohandlepagebreakX{\dopreventbreakafterheadspec} % no \let so we can redefine

% we do support negative numbers but it can have side effects that we won't
% catch
%
% \chapter{some} \setupheadnumber[chapter][3] \chapter{more}
% \setupheadnumber[section][8] \section{b} \section{c} \setupheadnumber[section][-1] \section{d}

\def\thenamedheadlevel#1%
  {\sectionlevel{\sectionheadsection{\sectionheadcoupling{#1}}}}

\unexpanded\def\setupheadnumber
  {\dodoubleargument\dosetupheadnumber}

\def\dosetupheadnumber[#1][#2]% todo: reset if at other level
  {\setstructurenumber{\thenamedheadlevel{#1}}{#2}}

\def\currentheadnumber{0} % ==> \currentheadnumber

\unexpanded\def\determineheadnumber[#1]%
  {\xdef\currentheadnumber{\getstructurenumber{\thenamedheadlevel{#1}}}}

% The previous macro is been replaced by the expandable:

\def\namedheadnumber      #1{\getstructurenumber    {\thenamedheadlevel{#1}}}
\def\somenamedheadnumber#1#2{\getsomestructurenumber{\thenamedheadlevel{#1}}{#2}}

\unexpanded\def\headnumber
  {\dodoubleempty\doheadnumber}

\def\doheadnumber[#1][#2]% simple case is just a number
  {\getsomefullstructurenumber{\iffirstargument\thenamedheadlevel{#1}\fi}{#2}}

\def\someheadnumber
  {\dodoubleempty\dosomeheadnumber}

\def\dosomeheadnumber[#1][#2]%
  {\dontleavehmode
   \begingroup
   \edef\currenthead{#1}%
   \getsomefullstructurenumber{\thenamedheadlevel{#1}}{#2}%
   \endgroup}

\let\sectioncountervalue\structurevalue

\def\currentheadtext{obsolete, use marks}

% list references, will be redone in lua when we need it

\let\startlistreferences\relax
\let\stoplistreferences \relax

% experimental

\newconditional\auto_structure_level

\appendtoks
    \settrue\auto_structure_levels
\to \everyenableelements

\def\setautostructurelevel
  {\ifconditional\auto_structure_level
     \ctxcommand{autonextstructurelevel(\number\currentheadlevel)}%
     \global\setfalse\auto_structure_level
   \fi}

\def\triggerautostructurelevel
  {\global\settrue\auto_structure_level}

\def\finalizeautostructurelevels
  {\ctxcommand{autofinishstructurelevels()}}

\unexpanded\def\finalizeautostructurelevel
  {\dostoptagged
   \dostoptagged}

\appendtoks
    \finalizeautostructurelevels
\to \everystoptext

\protect \endinput