%D \module
%D   [      file=s-present-stepwise, % was s-pre-60
%D        version=2004.03.15,
%D          title=\CONTEXT\ Style File,
%D       subtitle=Presentation Environment Stepwise,
%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.

% use lua instead of global mess

\startmodule[present-stepwise]

\unprotect

\startmode[paper,print]
    \let\StartSteps\relax
    \let\StopSteps \relax
    \let\FlushStep \relax
    \let\ResetStep \relax
    \let\StartBusy \relax
    \let\StopBusy  \relax
    \endinput
\stopmode

\newcount\c_module_pre_steps_current
\newcount\c_module_pre_steps_maximum
\newcount\c_module_pre_steps_nesting_step
\newcount\c_module_pre_steps_nesting_steps
\newcount\c_module_pre_steps_nesting_busy

\def\StepCounter   {\the\c_module_pre_steps_current}
\def\StepMaximum   {\the\c_module_pre_steps_maximum}
\def\StepLayer     {step:\the\c_module_pre_steps_current}
\def\NextStepLayer {step:\the\numexpr\c_module_pre_steps_current+\plusone\relax}
\def\FirstStepLayer{step:1}

\useJSscripts[stp]

\startsetups[set-stepper]

    \ifnum\getvariable{stepper}{nofsteps}>\c_module_pre_steps_maximum

        \dostepwiserecurse {\numexpr\c_module_pre_steps_maximum+\plusone\relax} {\getvariable{stepper}{nofsteps}} {1} {
            \doifnotmode{nosteps,nostep} {
                \expanded{\defineviewerlayer[step:\recurselevel][state=stop,scope=global]}
            }
        }

        \global\c_module_pre_steps_maximum\getvariable{stepper}{nofsteps}\relax

    \fi

\stopsetups

\setvariables
  [stepper]
  [set=\setups{set-stepper},
   nofsteps=50]

\defineviewerlayer[step:busy][state=start]

\definereference [SetupStepper]  [JS(SetupStepper{step,\StepMaximum})]
\definereference [ResetStepper]  [JS(ResetStepper)]
\definereference [CheckStepper]  [JS(CheckStepper{\StepCounter})]
\definereference [InvokeStepper] [JS(InvokeStepper)]

% todo: roll back blank

\unexpanded\def\ResetStep
  {\iftrialtypesetting\else
     \global\c_module_pre_steps_current\zerocount
   \fi}

\unexpanded\def\NextStep
  {\iftrialtypesetting\else
     \global\advance\c_module_pre_steps_current\plusone
   \fi}

\unexpanded\def\PrevStep
  {\iftrialtypesetting\else
     \global\advance\c_module_pre_steps_current\minusone
   \fi}

\unexpanded\def\FlushStep
  {\iftrialtypesetting\else
     \StopStep
     \NextStep
     \StartStep
   \fi}

\unexpanded\def\StartStep
  {\iftrialtypesetting\else
     \global\advance\c_module_pre_steps_nesting_step\plusone
     \ifcase\c_module_pre_steps_nesting_step\or
       \startviewerlayer[\StepLayer]%
     \fi
   \fi
   \ignorespaces}

\unexpanded\def\StopStep
  {\removeunwantedspaces
   \iftrialtypesetting\else
     \ifcase\c_module_pre_steps_nesting_step\or
       \stopviewerlayer
     \fi
     \global\advance\c_module_pre_steps_nesting_step\minusone
   \fi}

\unexpanded\def\StartSteps
  {\iftrialtypesetting\else
     \global\advance\c_module_pre_steps_nesting_steps\plusone
     \ifcase\c_module_pre_steps_nesting_steps\or
       \ResetStep
       \NextStep
       \StartStep
     \fi
   \fi}

\unexpanded\def\StopSteps
  {\iftrialtypesetting\else
     \ifcase\c_module_pre_steps_nesting_steps\or
       \StopStep
       \PrevStep
     \fi
     \global\advance\c_module_pre_steps_nesting_steps\minusone
   \fi}

\unexpanded\def\StartBusy
  {\iftrialtypesetting\else
     \global\advance\c_module_pre_steps_nesting_busy\plusone
     \ifcase\c_module_pre_steps_nesting_busy\or
       \startviewerlayer[step:busy]
     \fi
   \fi
   \ignorespaces}

\unexpanded\def\StopBusy
  {\removeunwantedspaces
   \iftrialtypesetting\else
     \ifcase\c_module_pre_steps_nesting_busy\or
       \stopviewerlayer
     \fi
     \global\advance\c_module_pre_steps_nesting_busy\minusone
   \fi}

%D Handy:

\unexpanded\def\StartLocalSteps
  {\ResetStep}

\unexpanded\def\StopLocalSteps
  {}

\unexpanded\def\StartLocalStep
  {\NextStep
   \StartStep}

\unexpanded\def\StopLocalStep
  {\StopStep}

\appendtoks
    \ResetStep
\to \everyaftershipout

\setupinteraction
  [%openaction=SetupStepper,
   closeaction=ResetStepper,
   openpageaction=CheckStepper,
   closepageaction=ResetStepper]

\defineoverlay[invoke][\overlaybutton{InvokeStepper}]

\setupbackgrounds
  [text]
  [background=invoke]

% bonus

\useMPlibrary[nav]

\definepalet
  [navplus]
  [attach=interactioncolor,
   comment=interactioncolor]

\setupcomment
  [symbol={comment-normal,comment-down},
   textlayer=\StepLayer,
   option=buffer,
   height=\textheight,
   width=\textwidth,
   margin=0pt]

\setupattachments
  [symbol={attach-normal,attach-down},
   textlayer=\StepLayer]

%D used as (given some definitions):
%D
%D \starttyping
%D \StartLocalSteps
%D     \startcombination[both]
%D         {\StartLocalStep\placestreamlayer[left]\StopLocalStep}  {}
%D         {\StartLocalStep\placestreamlayer[right]\StopLocalStep} {}
%D     \stopcombination
%D \StopLocalSteps
%D \stoptyping

\protect

\stopmodule