%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Module:    ZzTeX Error Handling
%
% Synopsis:
%
% Author:    Paul C. Anagnostopoulos
% Created:   13 August 1989
%
% Copyright 1989--2020 by Paul C. Anagnostopoulos
% under The MIT License (opensource.org/licenses/MIT)
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%                       Remarks & Errors
%                       ------- - ------


\def \remark #1{%                               {text}
  \messagenl{_ZzTeX: #1_}}

\def \warning #1#2{%                            {help-id}{text}
  \zsethelp{#1}%
  \zerrmsg{warning}{#2}}

\def \error #1#2{%                              {help-id}{text}
  \zsethelp{#1}%
  \zerrmsg{error}{#2}%
  \remark{Continuing from an error may cause unpredictable results.}}

\def \zzerror #1{%                              {text}
  \zerrmsg{internal error}{#1}%
  \remark{Continuing from an internal error will cause erroneous results.}}

\def \zerrmsg #1#2{%                            {prefix}{text}
  {\newlinechar = `\_%
   \errmessage{ZzTeX #1: #2}}}

%%%\def \zerrcontext #1{%
%%%  \listtop{\znext}{\zblockstack}%
%%%  \writelog{ZzTeX context: #1 \znext\space \the\typesizename
%%%                           \the\typestyle \the\typeencoding.}}
%%%
%%%\def \context {%
%%%  \zerrcontext{???}%
%%%  \zend}

%                       To-Do Facility
%                       ----- --------


\definecount{\ztodocount}{0}


%~ The |\todo| command accepts a note that is stored in the composite
%~ cross-reference file as a reminder of something that needs to
%~ be done later. ZzExplore can display a list of the outstanding
%~ to-dos.

\long\def \todo #1{%                                    {note}
  \zwritetodo{#1}%
  \ztodo #1\zmark
  \global\increment \ztodocount}

\long\def \ztodo #1#2\zmark{%                           {char1}{rest of message}
  \if \codeeqlp{#1}{!}%
    {\errorcontextlines = 0
     \def \znext {#2}%
     \zerrmsg{to-do}{\expandafter\zdefof \meaning\znext\zmark\space
                     [\the\divisionname]}}%
  \else\if \codeeqlp{#1}{.}%
    \def \znext {#2}%
    \writelog{ZzTeX to-do: \expandafter\zdefof \meaning\znext\zmark\space
                           [\the\divisionname]}%
  \else\if \codeeqlp{#1}{?}%
    \def \znext {#2}%
    \messagenl{_ZzTeX to-do: To come: \expandafter\zdefof \meaning\znext\zmark\space 
                             [\the\divisionname]_}%
    \if \DVIWindoinuse \colorspecial{ifview color push rgb 1 0 0}\fi
    ???%
    \if \DVIWindoinuse \colorspecial{ifview color pop}\fi
  \else
    \def \znext {#1#2}%
    \messagenl{_ZzTeX to-do: \expandafter\zdefof \meaning\znext\zmark\space
                             [\the\divisionname]_}%
  \fi\fi\fi}

% Write a todo entry into the cross-reference file.

\long\def \zwritetodo #1{%                      {message}
  \zbeginhidewrite
    \def \znext {#1}%
    \edef \znext {\noexpand\xref{todo}{\noexpand\folio}{}
                                {\expandafter\zdefof \meaning\znext\zmark}
                                {\the\divisionname}}%
    \znext
   \zendhidewrite}

% There is nothing to do with each entry in the cross-reference file
% when it is loaded.

\long\def \xreftodo #1#2#3#4{}

% This macro is invoked at the end of the run.

\def \ztodomsg {%
  \if \posp{\ztodocount}%
    \remark{Number of to-do reminders encountered: \the\ztodocount}%
  \fi}


%                       Help Text
%                       ---- ----


\def \zsethelp #1{%
  \if \definedp{\=zH:#1}%
    \global\errhelp = \expandafterthrice{\name{\=zH:#1}}%
  \else
    \global\errhelp = {No additional help is available.}%
  \fi}