%D \module
%D   [     file=page-inj,
%D      version=2013.02.10,
%D        title=\CONTEXT\ Page Module,
%D     subtitle=Injections,
%D       author=Wolfgang Schuster \& Hans Hagen,
%D         date=\currentdate,
%D    copyright=Wolfgang Schuster \& Hans Hagen,
%D      license=see context related readme files (gpl)]

%D This module is based on an idea and prototype by Wolfgang but instead of
%D injectioning into a page constructor we injection it into the regular shipout
%D handler because that way we get page numbering. It's a sort of variation on
%D postponing but the content does not end up in the regular page flow, so it's
%D closer to page figures but without the usual page builder.
%D
%D This module is following the mkvi way of rendering setups and configuration and
%D is somewhat experimental. Probably more alternatives will be added. This could
%D become a delayed loaded module at some point (no real consequences).

\unprotect

\registerctxluafile{page-inj}{}

\installcorenamespace {pageinjection}
\installcorenamespace {pageinjectionalternative}
\installcorenamespace {pageinjectionrenderings}

\installframedcommandhandler \??pageinjection            {pageinjection}            \??pageinjection
\installcommandhandler       \??pageinjectionalternative {pageinjectionalternative} \??pageinjectionalternative

\let\page_boxes_flush_before\clf_flushpageinjectionsbefore
\let\page_boxes_flush_after \clf_flushpageinjectionsafter

\lettonothing\p_page_injections_delay
\lettonothing\p_page_injections_n
\lettonothing\p_page_injections_page
\lettonothing\p_page_injections_pagestate
\lettonothing\p_page_injections_state

\def\page_injections_flush_indeed
  {\begingroup
   \setbox\scratchbox\normalhpack
     {\inheritedpageinjectionframed{\texsetup\p_page_injectionalternative_rederingsetup}}%
   \printpaperwidth \wd\scratchbox
   \printpaperheight\ht\scratchbox
   \scrn_canvas_synchronize_only
   \invokepagehandler\v!normal{\box\scratchbox}%
   \endgroup
   \scrn_canvas_synchronize_reset}

\def\page_injections_flush_saved#name#parameters%
  {\begingroup
   \edef\currentpageinjection{#name}%
   \getdummyparameters[#parameters]%
   \edef\currentpageinjectionalternative          {\pageinjectionparameter           \c!alternative   }%
   \edef\p_page_injectionalternative_rederingsetup{\pageinjectionalternativeparameter\c!renderingsetup}%
   \page_injections_nextpage
   \page_injections_flush_indeed
   \endgroup}

\permanent\tolerant\protected\def\pageinjection[#1]#*[#2]% name parameters | settings parameters | name | parameters
  {\begingroup
   \ifhastok={#1}%
     \ifhastok={#2}%
        \page_injections_direct_settings_parameters{#1}{#2}%
     \else
        \page_injections_direct_parameters{#1}%
     \fi
   \else
     \ifhastok={#2}%
        \page_injections_direct_name_parameters{#1}{#2}%
     \else
        \page_injections_direct_name{#1}%
     \fi
   \fi}

\def\page_injections_direct_settings_parameters#settings% #parameters%
  {\lettonothing\currentpageinjection
   \checkpageinjectionparent
   \setupcurrentpageinjection[#settings]%
   \page_injections_direct_indeed}

\def\page_injections_direct_parameters% #parameters%
  {\lettonothing\currentpageinjection
   \checkpageinjectionparent
   \page_injections_direct_indeed}

\def\page_injections_direct_name_parameters#name% #parameters%
  {\edef\currentpageinjection{#name}%
   \checkpageinjectionparent
   \page_injections_direct_indeed}

\def\page_injections_direct_name#name%
  {\edef\currentpageinjection{#name}%
   \checkpageinjectionparent
   \page_injections_direct_indeed{}}

\def\page_injections_direct_indeed% #parameters%
  {\edef\p_page_injections_state{\pageinjectionparameter\c!state}%
   \edef\p_page_injections_delay{\pageinjectionparameter\c!delay}%
   \edef\p_page_injections_page {\pageinjectionparameter\c!page }%
   \ifx\p_page_injections_delay\v!yes
     \expandafter\page_injections_direct_indeed_yes
   \else
     \expandafter\page_injections_direct_indeed_nop
   \fi}

\def\page_injections_direct_indeed_yes#parameters%
  {\clf_savepageinjections
         name {\currentpageinjection}%
        state {\p_page_injections_state}%
     userdata {\normalunexpanded{#parameters}}%
   \relax
   \endgroup}

\def\page_injections_direct_indeed_nop#parameters%
  {\ifempty\p_page_injections_page
     \page
   \else
     \page[\p_page_injections_page]%
   \fi
   \getdummyparameters[#parameters]%
   \page_injections_place
   \endgroup}

\def\page_injections_place
  {\edef\currentpageinjectionalternative          {\pageinjectionparameter           \c!alternative   }%
   \edef\p_page_injectionalternative_rederingsetup{\pageinjectionalternativeparameter\c!renderingsetup}%
   \page_injections_nextpage
   \ifx\currentpageinjectionalternative\v!none \else % increment counter but don’t generate output
     \forgetparindent
     \dontcomplain
     \setconstant\shipoutfinalizemethod\zerocount % this is messy
     \page_injections_flush_indeed
   \fi}

\def\page_injections_nextpage
  {\edef\p_page_injections_pagestate{\pageinjectionparameter\c!pagestate}%
   \ifx\p_page_injections_pagestate\v!stop \else
     \edef\p_page_injections_n{\pageinjectionparameter\c!n}%
     \ifempty\p_page_injections_n
        \let\p_page_injections_n\plusone
     \fi
     \dorecurse\p_page_injections_n
       {\incrementcounter[\s!realpage]%
        \incrementcounter[\s!userpage]}%
   \fi}

\definepageinjectionalternative[\v!figure][\c!renderingsetup=\??pageinjectionrenderings:\v!figure]
\definepageinjectionalternative[\v!buffer][\c!renderingsetup=\??pageinjectionrenderings:\v!buffer]
\definepageinjectionalternative[\v!setups][\c!renderingsetup=\??pageinjectionrenderings:\s!setup ]

\startsetups[\??pageinjectionrenderings:\v!figure]
    \dontleavehmode\externalfigure[\dummyparameter\c!name][\c!factor=\v!max]
\stopsetups

\startsetups[\??pageinjectionrenderings:\s!setup]
    \setups[\dummyparameter\c!setups]% kind of redundant but fits in
\stopsetups

\startsetups[\??pageinjectionrenderings:\v!buffer]
    \getbuffer[\dummyparameter\c!name]%
\stopsetups

% \setuppaper
%   [\c!method=\v!pageinjection]

\setuppageinjection
  [      \c!width=\paperwidth,
        \c!height=\paperheight,
         \c!frame=\v!off,
        \c!offset=\v!overlay,
         \c!delay=\v!no,
         \c!state=\v!next,
   \c!alternative=\v!figure]

\definepageinjection[\v!previouspage][\c!delay=\v!yes,\c!state=\v!previous]
\definepageinjection[\v!nextpage]    [\c!delay=\v!yes,\c!state=\v!next]
\definepageinjection[\v!here]        % direct
\definepageinjection[\v!empty]       [\c!alternative=\v!none]

%definepageinjection[\v!chapter]     [\v!previouspage][\c!pagestate=\v!stop]

\protect \endinput

% \enabletrackers[pagebuilder.injections]
%
% \setuppageinjection[offset=2em]
%
% \definepageinjection[chapter][previouspage][pagestate=stop]
% \definepageinjection[later]  [delay=yes,state=+2]
%
% \useMPlibrary[dum]
%
% \starttext
%
% \startchapter[title={Insert pages before/after the current page}]
%
% 	\dorecurse{10}{one: \input ward\par}
%
% 	\pageinjection[previouspage][name=dummy-1]
%
% 	\dorecurse{20}{two: \input ward\par} \page
%
% 	\pageinjection[nextpage][name=dummy-2]
%  	\pageinjection[later]   [name=dummy-4]
%  	\pageinjection[delay=yes,state=+2][name=dummy-5]
%
% 	\dorecurse{100}{three: \input ward\par}
%
% \stopchapter
%
% \startbuffer[whatever]
%     \dorecurse{10}{whatever #1 }
% \stopbuffer
%
% \startchapter[title={Insert pages at the current location}]
%
% 	\dorecurse{10}{\input ward\par}
%
% 	\pageinjection[direct][name=dummy-3]
% 	\pageinjection[direct][alternative=buffer,name=whatever]
%
% 	\dorecurse{10}{\input ward\par}
%
% \stopchapter
%
% \setuphead
%   [chapter]
%   [beforesection={\pageinjection[empty]},
%    insidesection={\pageinjection[chapter][name=\structureuservariable{image}]}]
%
% \startchapter[title={Combine both mechanism}][name=dummy-4]
%
% 	\dorecurse{10}{\input ward\par}
%
% \stopchapter
%
% \stoptext