%% superderive.sty -- stepwise algebraic derivation figures
%% Third sibling of superfig / supertensor. Same house style and
%% role/cursor/warning discipline. Primitives are rewrite steps,
%% not nodes or tensor faces.
%%
%% Options:  cjk    XeLaTeX + fandol
%%           en     English meaning-box rails
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{superderive}[2026/08/17 v1.0 stepwise derivation figures]

\newif\ifder@cjk\der@cjkfalse
\newif\ifder@en\der@enfalse
\DeclareOption{cjk}{\der@cjktrue}
\DeclareOption{en}{\der@entrue}
\DeclareOption{zh}{\der@enfalse}
\ProcessOptions\relax

\RequirePackage{amsmath}
\RequirePackage{amssymb}
\RequirePackage{xcolor}
\RequirePackage{etoolbox}
\RequirePackage{array}
\RequirePackage{tikz}
\usetikzlibrary{calc,positioning,arrows.meta,fit}

\ifder@cjk
  \RequirePackage[UTF8,fontset=fandol]{ctex}
\fi

\pgfdeclarelayer{sdbg}
\pgfdeclarelayer{sdfg}
\pgfsetlayers{sdbg,main,sdfg}

\definecolor{sdTeal}{HTML}{4F8FA5}
\definecolor{sdOrange}{HTML}{EE995B}
\definecolor{sdCoral}{HTML}{C95B5B}
\definecolor{sdViolet}{HTML}{8A74B5}
\definecolor{sdGray}{HTML}{85898F}
\definecolor{sdInk}{HTML}{1A1A1A}

\newcommand{\sdsetrole}[2]{%
  \edef\sd@newrole{#2}%
  \ifcsname sd@role@#1\endcsname
    \edef\sd@oldrole{\csname sd@role@#1\endcsname}%
    \ifx\sd@oldrole\sd@newrole\else
      \PackageWarning{superderive}{Role `#1' was already mapped to
        `\sd@oldrole' and cannot be remapped to `\sd@newrole'}%
    \fi
  \else
    \expandafter\gdef\csname sd@role@#1\endcsname{#2}%
  \fi}
\newcommand{\sdrole}[1]{%
  \ifcsname sd@role@#1\endcsname\csname sd@role@#1\endcsname\else sdGray\fi}
\newcommand{\sdcheckrole}[1]{%
  \ifcsname sd@role@#1\endcsname\else
    \PackageWarning{superderive}{Undeclared role `#1' -- drawn in neutral gray.
      Declare it with \string\sdsetrole}%
  \fi}
\sdsetrole{neutral}{sdGray}
\sdsetrole{keep}{sdTeal}
\sdsetrole{rewrite}{sdOrange}
\sdsetrole{cancel}{sdCoral}
\sdsetrole{intro}{sdViolet}
\sdsetrole{warn}{sdCoral}

\newcommand{\sdlevelpct}[1]{\ifcase#1 0\or30\or55\or80\else55\fi}

\tikzset{
  sd stage/.style = {font=\small\bfseries, text=black!55, inner sep=2pt},
  sd note/.style  = {font=\scriptsize, text=black!55, inner sep=2pt, align=left},
  sd arrow/.style = {-{Stealth[length=2.2mm,width=1.6mm]}, draw=black!45, line width=0.5pt},
  sd term/.style  = {draw=black!60, line width=0.5pt, rounded corners=1.5pt,
                     inner sep=6pt, font=\small, text=sdInk, align=center},
  sd reason/.style= {font=\scriptsize, text=black!55, align=left,
                     draw=black!18, fill=black!3, rounded corners=1.5pt,
                     inner xsep=6pt, inner ysep=5pt},
}

\newlength{\sdgutter}\setlength{\sdgutter}{6mm}
\newlength{\sdrowgap}\setlength{\sdrowgap}{5mm}
\newlength{\sdblockgap}\setlength{\sdblockgap}{9mm}
\newlength{\sd@railx}\newlength{\sd@cx}\newlength{\sd@cy}
\newlength{\sd@ycur}\newlength{\sd@bandh}\newlength{\sd@tmpx}\newlength{\sd@tmpy}
\newif\ifder@inrow
\newif\ifder@first
\newcount\sd@ncols

\newcommand{\sdlayoutreset}{%
  \global\sd@railx=0pt \global\sd@ycur=0pt
  \global\sd@cx=0pt \global\sd@cy=0pt \global\sd@bandh=0pt
  \global\der@inrowfalse
  \global\sd@ncols=0
  \gdef\sd@rowlist{}\gdef\sd@alllist{}\gdef\sd@rowname{}%
  \gdef\sd@lastnode{}}
\sdlayoutreset
\newcommand{\sdleftrail}[1]{\global\sd@railx=\dimexpr#1\relax}
\newcommand{\sdvgap}[1]{\global\advance\sd@ycur by -\dimexpr#1\relax}
\newcommand{\sdgap}[1]{\global\advance\sd@cx by \dimexpr#1\relax}

\newcommand{\sd@lower}[1]{%
  \pgfextracty{\sd@tmpy}{\pgfpointanchor{#1}{south}}%
  \ifdim\sd@tmpy<\sd@ycur \global\sd@ycur=\sd@tmpy \fi}
\newcommand{\sd@regall}[1]{\xdef\sd@alllist{\sd@alllist(#1)}}
\newcommand{\sd@regrow}[1]{%
  \xdef\sd@rowlist{\sd@rowlist(#1)}\sd@regall{#1}%
  \gdef\sd@lastnode{#1}}
\newcommand{\sd@needrow}[1]{%
  \ifder@inrow\else
    \PackageError{superderive}{\string#1\space needs an open \string\sdrow}%
      {Close placement only works between \string\sdrow\space and \string\sdrowend.}%
  \fi}
\newcommand{\sd@leadgap}[1]{%
  \ifder@first
    \global\der@firstfalse
  \else
    \global\advance\sd@cx by \dimexpr#1\relax
  \fi}

\newcommand{\sdstage}[2]{%
  \dimen0=\sd@ycur \advance\dimen0 by -\sdblockgap
  \node[sd stage, anchor=north west] (#1) at (\the\sd@railx,\the\dimen0) {#2};
  \sd@regall{#1}\sd@lower{#1}}

% \sdrow{name} or \sdrow[height]{name}
\newcommand{\sdrow}[2][16mm]{%
  \gdef\sd@rowlist{}\gdef\sd@rowname{#2}\gdef\sd@lastnode{}%
  \global\der@inrowtrue\global\der@firsttrue
  \pgfmathsetlengthmacro{\sd@bh}{#1}%
  \global\sd@bandh=\sd@bh
  \global\sd@cx=\sd@railx
  \dimen0=\sd@ycur \advance\dimen0 by -\sdrowgap \advance\dimen0 by -0.5\sd@bandh
  \global\sd@cy=\dimen0}

\newcommand{\sdrowend}{%
  \ifdefempty{\sd@rowlist}%
    {\PackageWarning{superderive}{Empty \string\sdrow\space `\sd@rowname'}}%
    {\edef\sd@do{\noexpand\node[inner sep=0pt, outer sep=0pt,
        fit={\sd@rowlist}] (\sd@rowname) {};}\sd@do
     \sd@regall{\sd@rowname}\sd@lower{\sd@rowname}}%
  \global\der@inrowfalse}

\newcommand{\sdbbox}[1]{%
  \edef\sd@do{\noexpand\node[inner sep=0pt, outer sep=0pt,
    fit={\sd@alllist}] (#1) {};}\sd@do}
\newcommand{\sdtrack}[1]{\sd@regall{#1}\sd@lower{#1}}
\newcommand{\sdtopformula}[2]{%
  \sdbbox{sd@bbt}%
  \node[above=6mm of sd@bbt, anchor=south, font=\large] (#1) {#2};
  \sd@regall{#1}}

\pgfkeys{
  /sd/term/.cd,
  role/.store in=\sd@role,
  level/.store in=\sd@level,
  gap/.store in=\sd@gap,
  role=rewrite, level=2, gap=\sdgutter,
}

% \sdstep[keys]{name}{lhs}{rhs}
\newcommand{\sdstep}[4][]{%
  \sd@needrow{\sdstep}%
  \begingroup
  \pgfkeys{/sd/term/.cd,#1}%
  \sdcheckrole{\sd@role}%
  \edef\sd@col{\sdrole{\sd@role}}%
  \sd@leadgap{\sd@gap}%
  \node[anchor=west, inner sep=0pt] (#2) at (\the\sd@cx,\the\sd@cy) {%
    \begin{tikzpicture}[baseline=(sd@mid)]
      \node[sd term, fill=\sd@col!\sdlevelpct{\sd@level}] (sd@L) {$\displaystyle #3$};
      \node[sd term, fill=\sd@col!\sdlevelpct{\sd@level},
            right=\sdgutter of sd@L] (sd@R) {$\displaystyle #4$};
      \coordinate (sd@mid) at ($(sd@L.east)!0.5!(sd@R.west)$);
      \begin{pgfonlayer}{sdbg}
        \draw[sd arrow] (sd@L.east) -- (sd@R.west);
      \end{pgfonlayer}
    \end{tikzpicture}};%
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#2}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#2}%
  \endgroup}

% \sdreason{step-name}{text} -- hangs off the named step, or the last step.
\newcommand{\sdreason}[2]{%
  \sd@needrow{\sdreason}%
  \sd@leadgap{\sdgutter}%
  \node[sd reason, anchor=west, text width=38mm] (#1-why)
    at (\the\sd@cx,\the\sd@cy) {#2};%
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#1-why}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#1-why}}

% \sdcancel[keys]{name}{math}
\newcommand{\sdcancel}[3][]{%
  \sd@needrow{\sdcancel}%
  \begingroup
  \pgfkeys{/sd/term/.cd,role=cancel,#1}%
  \sdcheckrole{\sd@role}%
  \edef\sd@col{\sdrole{\sd@role}}%
  \sd@leadgap{\sd@gap}%
  \node[sd term, fill=\sd@col!\sdlevelpct{\sd@level}, anchor=west] (#2)
    at (\the\sd@cx,\the\sd@cy) {$\displaystyle #3$};%
  \draw[\sd@col, line width=0.8pt]
    ($(#2.west)+(1.2mm,0)$) -- ($(#2.east)+(-1.2mm,0)$);
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#2}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#2}%
  \endgroup}

% \sdsubst[keys]{name}{from}{to}
\newcommand{\sdsubst}[4][]{%
  \sd@needrow{\sdsubst}%
  \begingroup
  \pgfkeys{/sd/term/.cd,role=rewrite,#1}%
  \sdcheckrole{\sd@role}%
  \edef\sd@col{\sdrole{\sd@role}}%
  \sd@leadgap{\sd@gap}%
  \node[anchor=west, inner sep=0pt] (#2) at (\the\sd@cx,\the\sd@cy) {%
    \begin{tikzpicture}[baseline=(sd@mid)]
      \node[sd term, fill=sdCoral!30] (sd@F) {$\displaystyle #3$};
      \draw[sdCoral, line width=0.7pt]
        ($(sd@F.west)+(1mm,0)$) -- ($(sd@F.east)+(-1mm,0)$);
      \node[sd term, fill=\sd@col!\sdlevelpct{\sd@level},
            right=\sdgutter of sd@F] (sd@T) {$\displaystyle #4$};
      \coordinate (sd@mid) at ($(sd@F.east)!0.5!(sd@T.west)$);
      \draw[sd arrow] (sd@F.east) -- (sd@T.west);
    \end{tikzpicture}};%
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#2}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#2}%
  \endgroup}

% \sdbox[keys]{name}{math}
\newcommand{\sdbox}[3][]{%
  \sd@needrow{\sdbox}%
  \begingroup
  \pgfkeys{/sd/term/.cd,role=keep,#1}%
  \sdcheckrole{\sd@role}%
  \edef\sd@col{\sdrole{\sd@role}}%
  \sd@leadgap{\sd@gap}%
  \node[sd term, fill=\sd@col!\sdlevelpct{\sd@level}, anchor=west] (#2)
    at (\the\sd@cx,\the\sd@cy) {$\displaystyle #3$};%
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#2}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#2}%
  \endgroup}

% \sdcol{name}{illegal}{legal} -- one contrast pair per figure.
\newcommand{\sdcol}[3]{%
  \sd@needrow{\sdcol}%
  \global\advance\sd@ncols by 1
  \ifnum\sd@ncols>1
    \PackageWarning{superderive}{Contrast column `#1' is the second pair
      in the figure. The budget is one illegal/legal pair}%
  \fi
  \sd@leadgap{\sdgutter}%
  \node[anchor=west, inner sep=0pt] (#1) at (\the\sd@cx,\the\sd@cy) {%
    \begin{tikzpicture}[baseline=(sd@mid)]
      \node[sd term, fill=sdCoral!30] (sd@B) {$\displaystyle #2$};
      \node[font=\scriptsize, text=sdCoral, above=1pt of sd@B] {\sd@lblillegal};
      \node[sd term, fill=sdTeal!30, right=8mm of sd@B] (sd@G) {$\displaystyle #3$};
      \node[font=\scriptsize, text=sdTeal, above=1pt of sd@G] {\sd@lbllegal};
      \coordinate (sd@mid) at ($(sd@B.east)!0.5!(sd@G.west)$);
    \end{tikzpicture}};%
  \pgfextractx{\sd@tmpx}{\pgfpointanchor{#1}{east}}%
  \global\sd@cx=\sd@tmpx
  \sd@regrow{#1}}

\ifder@en
  \def\sd@lblidea{Idea}\def\sd@lblrw{Rewrite}\def\sd@lblcaveat{Caveat}
  \def\sd@lblillegal{illegal}\def\sd@lbllegal{legal}
\else
  \def\sd@lblidea{思路}\def\sd@lblrw{改写}\def\sd@lblcaveat{注意}
  \def\sd@lblillegal{非法}\def\sd@lbllegal{合法}
\fi
\newcommand{\sdsetlabels}[3]{\def\sd@lblidea{#1}\def\sd@lblrw{#2}\def\sd@lblcaveat{#3}}
\newlength{\sd@raillen}
\ifder@en
  \setlength{\sd@raillen}{5.4em}
\else
  \setlength{\sd@raillen}{3.2em}
\fi

\newcommand{\sdmeaningbox}[6]{%
  \node[below=4mm of #3, anchor=north,
        draw=black!18, fill=black!3, rounded corners=1.5pt,
        inner xsep=9pt, inner ysep=8pt, text width=#2] (#1) {%
    \small
    \setlength{\tabcolsep}{0pt}%
    \renewcommand{\arraystretch}{1.25}%
    \begin{tabular}{@{}p{\sd@raillen}@{\hspace{7pt}}p{\dimexpr#2-\sd@raillen-7pt\relax}@{}}
      \ifblank{#4}{}{\textbf{\sd@lblidea} & \raggedright\arraybackslash #4 \\}
      \ifblank{#5}{}{\textbf{\sd@lblrw} & \raggedright\arraybackslash #5 \\}
      \ifblank{#6}{}{\textbf{\sd@lblcaveat} & \raggedright\arraybackslash #6 \\}
    \end{tabular}};}

\newcommand{\sdsignature}[2]{%
  \node[below=2.2mm of #2, font=\scriptsize, text=black!45] (#2-sig) {#1};}

\endinput