%% Copyright 2023 Francesco Lambertini
  %
  % This work may be distributed and/or modified under the
  % conditions of the LaTeX Project Public License, either version 1.3c
  % of this license or any later version.
  % The latest version of this license is in
  %   http://www.latex-project.org/lppl.txt
  % and version 1.3c or later is part of all distributions of LaTeX
  % version 2023/04/17 or later.
  %
  % This work has the LPPL maintenance status `maintained'.
  % 
  % The Current Maintainer of this work is Francesco Lambertini.
  %
  % This work consists of the files quickreaction.sty, quickreaction.tex and quickreaction.pdf.
  %
  % v1.02.01 2023/04/17
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{quickreaction}[2023/04/17]

\RequirePackage{tikz}
\RequirePackage{xparse}

\usetikzlibrary{matrix}
\usetikzlibrary{positioning}

\DeclareOption{iupac}{%
\renewcommand{\printatom}[1]{%
\fontsize{8pt}{10pt}\selectfont{\ensuremath{\mathsf{#1}}}}
\setchemfig{
cram rectangle=false,
cram width=2.5pt,
cram dash width=0.5pt,
cram dash sep=1.5pt,
atom sep=16pt,
bond offset=1pt,
double bond sep=2pt,
bond join = true,
bond style={line width=0.5pt}
}
}
\ProcessOptions\relax

\makeatletter
\newcommand{\settomaxwidth}[1]{\saltyarrow@settomax{\wd}{#1}}
\newcommand{\saltyarrow@settomax}[3]{%
\newdimen\pippo
\pippo=1cm
  #2\pippo
  \@for\next:=#3\do{%
    \sbox\z@{\next}%
    \ifdim#1\z@>#2%
      #2=#1\z@
    \fi}%
}
\makeatother

\newlength{\saltyarrowmax}

\newlength{\fixrow}

\NewDocumentEnvironment{quickreaction}{O{} O{} b}{%
%
\newbox\fixa
\newbox\fixb
\savebox{\fixa}{#1}
\savebox{\fixb}{#2}
\def\a{\the\dp\fixa}
\def\aa{\the\ht\fixa}
\def\b{\the\dp\fixb}
\def\bb{\the\ht\fixb}
\pgfmathsetlength{\fixrow}{(\a+\aa-\b-\bb)/2)}
%
\newcommand{\reactionbody}{#3}
    \begin{tikzpicture}[baseline=(current  bounding  box.center)]
     \matrix (reaction) [%
     ampersand replacement=\&,
     matrix of nodes,
     column sep=\pgflinewidth, 
     row sep=\pgflinewidth, 
     nodes={anchor=center},
     ] {\reactionbody};
     \end{tikzpicture}%
     }{}

\NewDocumentCommand{\quickarrow}{O{} O{}}{%
\newcommand{\argone}{#1}%
\newcommand{\argtwo}{#2}%
\settomaxwidth{\saltyarrowmax}{\argone, \argtwo}%
\begin{tikzpicture}
 \draw [-stealth] (-0.5,0) -- node[anchor=center] (X) {} (\the\saltyarrowmax,0); 
     \node (A) [above= 0pt of X] {\argone};
     \node (B) [below= 0pt of X] {\argtwo};
    \phantom{ \node (AA) [below= 0pt of X] {\argone};}
    \phantom{ \node (BB) [above= 0pt of X] {\argtwo};}
\end{tikzpicture}
}