%D \module
%D   [       file=strc-sbe,
%D        version=2008.10.20,
%D          title=\CONTEXT\ Structure Macros,
%D       subtitle=Section Block Environments,
%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 / Section Block Environments}

\unprotect

% \def\ChapterEntry#1#2#3%
%   {chapter : \hbox to \hsize{\strut\bf#2\hss#3}\endgraf\placelist[section]}
%
% \startfrontmatter % optional
%   \placelist[chapter][alternative=command,command=\ChapterEntry,criterium=text] \page
% \stopfrontmatter  % optional
%
% \startbodymatter % optional
%   \chapter{first}  \section{one}   test \section{two}  test \page
%   \chapter{second} \section{alpha} test \section{beta} test \page
% \stopbodymatter  % optional

\installcorenamespace{sectionblock}

\installcommandhandler \??sectionblock {sectionblock} \??sectionblock

\setupsectionblock
  [\c!number=\v!yes,
   \c!page=\v!right] % otherwise marks are reset too soon

\newtoks\everybeforesectionblock
\newtoks\everyaftersectionblock

\let\strc_sectionblock_define_normal\definesectionblock

\unexpanded\def\definesectionblock
  {\dotripleargument\strc_sectionblock_define}

\def\strc_sectionblock_define[#1][#2][#3]% singular plural settings
  {\strc_sectionblock_define_normal[#1][#3]%
  %\expandafter\newif\csname if#2\endcsname % obsolete
   \strc_sectionblock_set_environment{#1}\empty
   \setuvalue{\e!start#2}{\startsectionblock[#1]}%
   \setuvalue{\e!stop #2}{\stopsectionblock}}

\ifdefined \resetallstructuremarks \else
    \let\resetallstructuremarks\relax
\fi

\def\strc_sectionblock_handle_page
  {\edef\p_strc_sectionblock_page{\sectionblockparameter\c!page}%
   \ifx\p_strc_sectionblock_page\empty \else
      \page[\p_strc_sectionblock_page]%
   \fi}

\appendtoks
    \strc_sectionblock_handle_page
    \resetallstructuremarks
    \strc_sectionblock_get_environment\currentsectionblock
    \sectionblockparameter\c!before % don't move
    \dostarttagged\t!division\currentsectionblock % no parents
\to \everybeforesectionblock

\appendtoks
    \sectionblockparameter\c!after % don't move
    \strc_sectionblock_handle_page
    \dostoptagged
    \resetallstructuremarks
\to \everyaftersectionblock

\unexpanded\def\setsectionblock
  {\dodoubleempty\strc_sectionblock_set}

\def\strc_sectionblock_set[#1][#2]% used to set the default
  {\edef\currentsectionblock{#1}% from now on we assume a value
   \setupcurrentsectionblock[#2]%
   \clf_setsectionblock{#1}
      bookmark {\sectionblockparameter\c!bookmark}%
   \relax}

\let\currentsectionblock\empty % was \s!unknown

\unexpanded\def\startsectionblock
  {\dodoubleempty\strc_sectionblock_start}

\unexpanded\def\strc_sectionblock_start[#1][#2]%
  {%\ctxlua{structures.counters.check(0)}% we assume sane usage of \page, as this is the only workable place (in push)
   \begingroup
   \edef\currentsectionblock{#1}% from now on we assume a value
   \setupcurrentsectionblock[#2]%
   \clf_pushsectionblock{#1}
     bookmark {\sectionblockparameter\c!bookmark}%
   \relax
  %\csname #1true\endcsname % obsolete
   \setsystemmode\currentsectionblock
   \the\everybeforesectionblock\relax
   \showmessage\m!structures1\currentsectionblock}

\unexpanded\def\stopsectionblock
  {\showmessage\m!structures2\currentsectionblock
   \the\everyaftersectionblock\relax
   \clf_popsectionblock
   \endgroup}

%D \starttyping
%D \startsectionblockenvironment[frontpart]
%D   \setupnumber[userpage][numberconversion=romannumerals,start=1]
%D \stopsectionblockenvironment
%D
%D \startsectionblockenvironment[bodypart]
%D   \setupnumber[userpage][numberconversion=numbers,start=1]
%D \stopsectionblockenvironment
%D
%D \startsectionblockenvironment[backpart]
%D   \setupnumber[userpage][numberconversion=numbers,start=1]
%D \stopsectionblockenvironment
%D
%D \starttext
%D   \startfrontmatter \chapter{test} \stopfrontmatter
%D   \startbodymatter  \chapter{test} \stopbodymatter
%D   \startappendices  \chapter{test} \stopappendices
%D \stoptext
%D \stoptyping

\installcorenamespace{sectionblockenvironment}

\unexpanded\def\strc_sectionblock_set_environment#1#2%
  {\setvalue{\??sectionblockenvironment#1}{#2}}

\unexpanded\def\strc_sectionblock_get_environment#1%
  {\csname\??sectionblockenvironment#1\endcsname}

\unexpanded\setvalue{\e!start\v!sectionblockenvironment}%
  {\dosingleargument\strc_sectionblock_environment_start}

\letvalue{\e!stop\v!sectionblockenvironment}\relax

\def\strc_sectionblock_environment_start[#1]% evt \pushendofline \popendofline
  {\grabuntil{\e!stop\v!sectionblockenvironment}{\strc_sectionblock_set_environment{#1}}}

\protect \endinput