%
% CoDi: Commutative Diagrams for TeX
% Copyright (c) 2015-2020 Paolo Brasolin <paolo.brasolin@gmail.com>
% SPDX-License-Identifier: MIT
%
% This file is part of CoDi 1.0.0, released on 2020/06/06 under MIT license.
%

% καθαρίζω • (katharízo)
%   1. clean, wash
%   2. peel, descale
%   3. (slang) kill

% Katharizo is a detokenization/sanitation mechanism.
% It produces "safe" strings from tokens.

% ,-- input          input hook
% `-> expander ---.  performs expansion according to
% ,---[expand]----'    macro expansion configuration
% `-> expanded ---.  pre-sanitation hook
% ,-- sanitizer <-'  performs detokenization and sanitation according to
% `---[replace]---.    character replacement configuration
% ,-- sanitized <-'  pre-output hook
% `-> output         output hook

%==[ input stage ]==============================================================

\pgfqkeys{/katharizo/input}{
  .forward to=/katharizo/expander
}

%==[ expansion stage ]==========================================================

\pgfqkeys{/katharizo/expand}{.is choice,
  once/.style={/katharizo/expander/.style={/katharizo/expanded/.expand once={##1}}},
  full/.style={/katharizo/expander/.style={/katharizo/expanded/.expanded={##1}}},
  none/.style={/katharizo/expander/.style={/katharizo/expanded={##1}}},
  none % default is no expansion
}

\pgfqkeys{/katharizo/expanded}{
  .forward to=/katharizo/sanitizer
}

%==[ sanitation stage ]=========================================================

\pgfqkeys{/katharizo}{
  replace charcode/.code args={#1 with #2}{%
    % TODO: would a \string be of any use? or at least a stringification?
    \pgfkeys{/katharizo/replacements/characters/#1/.initial={#2}}%
  },
  remove charcode/.style={/katharizo/replace charcode={{#1} with {}}},
  remove charcodes/.style args={#1}{%
    /katharizo/remove charcodes loop={#1 \kD},
  },
  remove charcodes loop/.code args={#1 #2\kD}{%
    % \message{|||#1|#2|||}
    \ifx\relax#1\else\pgfkeys{/katharizo/remove charcode={#1}}\fi
    \ifx\relax#2\else\pgfkeys{/katharizo/remove charcodes loop={#2\kD}}\fi
  },
  replace character/.code args={#1 with #2}{%
    \edef\kDFoo{\number`#1}% TODO: can I inline this?
    % TODO: would a \string be of any use? or at least a stringification?
    \pgfkeys{/katharizo/replacements/characters/\kDFoo/.initial={#2}}%
  },
  remove character/.style={/katharizo/replace character={{#1} with {}}},
  remove characters/.code args={#1#2}{%
    \ifx\relax#1\else\pgfkeys{/katharizo/remove character={#1}}\fi
    \ifx\relax#2\else\pgfkeys{/katharizo/remove characters={#2}}\fi
  },
  remove characters={(),.:},
  remove charcode=92,% \ backslash
}

\pgfqkeys{/katharizo}{
  sanitizer/.code={
    % TODO: token replacement routine? Would that be useful?
    \kDKatharizoStringify#1\kD
    \expandafter\kDKatharizoSanitize\the\kDKatharizoStringified\kD
    \pgfkeysalso{/katharizo/sanitized/.expanded=\the\kDKatharizoSanitized}
    % \message{^^J:::\the\kDKatharizoSanitized:::^^J}
  }
}

\pgfqkeys{/katharizo/sanitized}{
  .forward to=/katharizo/output
}

%==[ output stage ]=============================================================

% NOTE: this must be defined/hooked before calling input
\pgfqkeys{/katharizo/output}{
  .code={}
}

\newtoks\kDKatharizoStringified

\def\kDKatharizoStringify#1\kD{
  \def\kDFoo{#1}
  \edef\kDFoo{\meaning\kDFoo}
  \def\kDAct##1:->##2\kD{##2}
  \edef\kDFoo{\expandafter\kDAct\kDFoo\kD}
  \kDKatharizoStringified\expandafter{\kDFoo}
}

\newtoks\kDKatharizoSanitized

\def\kDKatharizoSanitize#1\kD{
  \pgfkeysifdefined{/katharizo/replacements/characters/32}%
    {\edef\kDKatharizoSSpace{\pgfkeysvalueof{/katharizo/replacements/characters/32}}}%
    {\edef\kDKatharizoSSpace{\space}}%
  \def\kDKatharizoSAppendSpace
    {\edef\kDAct{\noexpand\kDKatharizoSanitized={\the\kDKatharizoSanitized\kDKatharizoSSpace}}\kDAct}
  \kDKatharizoSanitized={}
  \kDKatharizoSString#1 \kD}% NOTE: the whitespace is a mandatory string terminator

\def\kDKatharizoSString#1 #2\kD{%
  \ifx\relax#1\else                       % if string head word is not empty
    \kDKatharizoSWord#1\kD                % parse string head word
    \if#2\space\else                      % if string tail is not the space terminator
      \ifx\relax#2\else                   %   if string tail is not empty
        \kDKatharizoSAppendSpace\fi\fi\fi %     append space substitute to output
  \ifx\relax#2\else                       % if string tail is not empty
    \kDKatharizoSString#2\kD\fi}          %   recurse on string tail

\def\kDKatharizoSWord#1#2\kD{%
  \kDKatharizoSCharacter#1\kD   % parse word head character
  \ifx\relax#2\else             % if word tail is not empty
    \kDKatharizoSWord#2\kD\fi}  %   recurse on word tail

\def\kDKatharizoSCharacter#1\kD{%
  \pgfkeysifdefined{/katharizo/replacements/characters/\number`#1}%
    {\edef\kDFoo{\pgfkeysvalueof{/katharizo/replacements/characters/\number`#1}}}%
    {\edef\kDFoo{#1}}%
  \edef\kDAct{\noexpand\kDKatharizoSanitized={\the\kDKatharizoSanitized\kDFoo}}%
  \kDAct}