% Babelbidi: Bidi extensions for Babel.
%
% Copyright (C) 2026 Amer Amikhteh
%
% This file is part of the Babelbidi package.
%
% This work is free software: you may redistribute it and/or modify
% it under the terms of the LaTeX Project Public License as published
% by the LaTeX Project, either version 1.3c of the License, or
% (at your option) any later version.
%
% This work is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
%
% The full license text is available at:
% https://www.latex-project.org/lppl/
%
% This work is "maintained" by Amer Amikhteh.
%
% The current maintainer of this work is Amer Amikhteh.

\ProvidesFile{babelbidi-api.def}[2026/11/01 v0.2.0 Bidi API for Babelbidi]

\makeatletter


% ------------------------------------------
% Determining text direction
% ------------------------------------------

\providecommand{\if@RTL}{\ifnum\bbl@thetextdir>\z@}
\providecommand{\@RTLtrue}{\chardef\bbl@thetextdir\@ne}
\providecommand{\@RTLfalse}{\chardef\bbl@thetextdir\z@}

\providecommand{\bbd@main@dir}{0}

\providecommand{\if@RTLmain}{%
    \ifnum\bbd@main@dir>\z@
}

\providecommand{\@RTLmaintrue}{%
    \gdef\bbd@main@dir{1}%
}

\providecommand{\@RTLmainfalse}{%
    \gdef\bbd@main@dir{0}%
}

\AddToHook{begindocument}{%
    \ifnum\bbl@thetextdir>\z@
        \@RTLmaintrue
    \else
        \@RTLmainfalse
    \fi
}%

% ------------------------------------------
% basic bidi commands
% ------------------------------------------

\def\bbd@setdir#1{%
    \bbl@bodydir{#1}%
    \bbl@pardir{#1}% Must precede the text direction.
    \bbl@textdir{#1}%
}

\ProvideDocumentCommand{\setLTR}{}{\bbd@setdir{0}}
\ProvideDocumentCommand{\setRTL}{}{\bbd@setdir{1}}


% On TeXXeT engines beginL/R are primitives used by Babel itself.
\ifLuaTeX
    \ProvideDocumentCommand{\beginR}{}{%
        \begingroup
        \bbl@textdir{1}%
    }%

    \ProvideDocumentCommand{\beginL}{}{%
        \begingroup
        \bbl@textdir{0}%
    }%

    \ProvideDocumentCommand{\endR}{}{\endgroup}
    \ProvideDocumentCommand{\endL}{}{\endgroup}
\fi


% ------------------------------------------
% Core APIs
% ------------------------------------------

\long\def\bbd@inline#1#2{%
    \leavevmode
    {%
        \bbl@textdir{#1}%
        #2%
    }%
}
\ProvideDocumentCommand{\RLE}{+m}{\bbd@inline{1}{#1}}
\ProvideDocumentCommand{\LRE}{+m}{\bbd@inline{0}{#1}}

\ProvideDocumentEnvironment{RTL}{}
{%
    \par
    \begingroup
    \bbl@pardir{1}%
    \bbl@textdir{1}%
    \bbl@bodydir{1}
}
{%
    \par
    \endgroup
}%


\ProvideDocumentEnvironment{LTR}{}
{%
    \par
    \begingroup
    \bbl@pardir{0}%
    \bbl@textdir{0}%
    \bbl@bodydir{0}
}
{%
    \par
    \endgroup
}%


% ------------------------------------------
% Aliases
% ------------------------------------------

\DeclareCommandCopy{\RL}{\RLE}
\DeclareCommandCopy{\LR}{\LRE}
\DeclareCommandCopy{\setRL}{\setRTL}
\DeclareCommandCopy{\unsetLTR}{\setRTL}
\DeclareCommandCopy{\setLR}{\setLTR}
\DeclareCommandCopy{\unsetRTL}{\setLTR}


% ------------------------------------------
% Primitive-style boxes: retain to/spread, \setbox and verbatim scanning.
% The content must not be read as a macro argument.
% ------------------------------------------

\def\bbd@box#1#2#3#{%
    % Babel has no box-direction setter. Set the box's own direction
    % while scanning it, then synchronize its content through Babel.
    #1\ifLuaTeX bdir #2 \fi#3\bgroup
    \bbd@setdir{#2}\let\bbd@box@brace
}
\ProvideDocumentCommand{\hboxL}{}{\bbd@box\hbox{0}}
\ProvideDocumentCommand{\hboxR}{}{\bbd@box\hbox{1}}
\ProvideDocumentCommand{\vboxL}{}{\bbd@box\vbox{0}}
\ProvideDocumentCommand{\vboxR}{}{\bbd@box\vbox{1}}
\ProvideDocumentCommand{\vtopL}{}{\bbd@box\vtop{0}}
\ProvideDocumentCommand{\vtopR}{}{\bbd@box\vtop{1}}

% ------------------------------------------
% Explicit footnote direction, independent of the surrounding language.
% Resolve footnotemark/text at use time, including later hyperref patches.
% ------------------------------------------

% luabidi's Polyglossia compatibility fallback; preserve any real formatter.
\ProvideDocumentCommand{\localnumeral}{s m}{%
    \IfBooleanTF{#1}%
    {\expandafter\@arabic\csname c@#2\endcsname}%
    {#2}%
}

\def\bbd@footnotemark#1{%
    \IfNoValueTF{#1}%
    {\footnotemark}%
    {\footnotemark[#1]}%
}

\ProvideDocumentCommand{\bbd@fn@mark@lr}{o}{%
    \bbd@footnotemark{#1}%
}

\ProvideDocumentCommand{\bbd@fn@mark@rl}{o}{%
    \bbd@footnotemark{#1}%
}


\def\bbd@footnote@dir#1{%
    \ifPDFTeX
        % The paragraph direction is set before \@makefntext starts it.
        % Do not open a TeXXeT run spanning several footnote paragraphs.
        \bbl@pardir{#1}%
        \ifnum#1=\z@
            \@RTLfalse
        \else
            \@RTLtrue
        \fi
    \else
        \bbd@setdir{#1}%
    \fi
}


\long\def\bbd@footnote#1#2#3{%
    \begingroup
    % Remember the first explicit footnote direction in pdfTeX.
    \ifPDFTeX
        \bbd@pdf@remember@fn@dir{#1}%
    \fi
    % Select the footnote mark.
    \ifnum#1=\z@
        \let\bbd@mark\bbd@fn@mark@lr
    \else
        \let\bbd@mark\bbd@fn@mark@rl
    \fi
    \IfNoValueTF{#2}%
    {\bbd@mark}%
    {\bbd@mark[#2]}%
    % Apply the requested direction to the footnote text.
    \let\bbd@explicit@makefntext\@makefntext
    \long\def\@makefntext##1{%
        \bbd@setdir{#1}%
        \bbd@explicit@makefntext{##1}%
    }%
    \IfNoValueTF{#2}%
    {\footnotetext{{\bbd@footnote@dir{#1}#3}}}%
    {\footnotetext[#2]{{\bbd@footnote@dir{#1}#3}}}%
    \endgroup
}


\ProvideDocumentCommand{\LTRfootnote}{o +m}{%
    \bbd@footnote{0}{#1}{#2}%
}

\ProvideDocumentCommand{\RTLfootnote}{o +m}{%
    \bbd@footnote{1}{#1}{#2}%
}


% ------------------------------------------
% Footnote rules
% ------------------------------------------

\let\bbd@default@footnoterule\footnoterule

\newlength\bbd@fn@rulewidth
\setlength\bbd@fn@rulewidth{.4\columnwidth}

% An expandable register alias also supports \the and direct assignment.
\providecommand{\footnoterulewidth}{\bbd@fn@rulewidth}


\def\bbd@fn@rule#1{%
    \kern-3\p@
    \nointerlineskip
    \hboxL to \columnwidth{%
        \ifnum#1=\@ne
            \hfil
        \fi
        \vrule
        width \footnoterulewidth
        height .4\p@
        depth \z@
        \ifnum#1=\z@
            \hfil
        \fi
    }%
    \kern2.6\p@
}


\def\bbd@fn@rule@left{%
    \bbd@fn@rule{0}%
}

\def\bbd@fn@rule@right{%
    \bbd@fn@rule{1}%
}

\def\bbd@fn@rule@full{%
    \kern-3\p@
    \hrule\@width\textwidth
    \kern2.6\p@
}


\ProvideDocumentCommand{\leftfootnoterule}{}{%
    \global\let\footnoterule\bbd@fn@rule@left
}

\ProvideDocumentCommand{\rightfootnoterule}{}{%
    \global\let\footnoterule\bbd@fn@rule@right
}

\ProvideDocumentCommand{\textwidthfootnoterule}{}{%
    \global\let\footnoterule\bbd@fn@rule@full
}


% ------------------------------------------
% Automatic footnote rule
% ------------------------------------------

% pdfTeX fallback:
% remember the first explicitly directed footnote inserted for the page.
\ifPDFTeX

    % -1 means that no explicitly directed footnote has been seen yet.
    \newcount\bbd@pdf@fn@dir
    \bbd@pdf@fn@dir=-1

    \def\bbd@pdf@remember@fn@dir#1{%
        \ifnum\bbd@pdf@fn@dir<\z@
            \global\bbd@pdf@fn@dir=#1\relax
        \fi
    }

    \def\bbd@pdf@reset@fn@dir{%
        \global\bbd@pdf@fn@dir=-1\relax
    }

    % Reset after the current page has been shipped out.
    \AddToHook{shipout/after}{%
        \bbd@pdf@reset@fn@dir
    }

    \def\bbd@fn@rule@auto{%
        \ifnum\bbd@pdf@fn@dir=\@ne
            \bbd@fn@rule{1}%
        \else
            \bbd@fn@rule{0}%
        \fi
    }

    \ProvideDocumentCommand{\autofootnoterule}{}{%
        \global\let\footnoterule\bbd@fn@rule@auto
    }

\fi


% LuaTeX:
% inspect the first hlist line in the footins node list.
\ifLuaTeX

    \newcount\bbd@fn@rule@dir

    \def\bbd@fn@rule@auto{%
        \bbd@fn@rule@dir=\z@
        \directlua{
            local box = tex.box['footins']
            local line = table.swapped(node.subtypes('hlist')).line

            if box and box.list then
            for n in node.traverse(box.list) do
            if n.id == node.id('hlist')
            and n.subtype == line then
            tex.count['bbd@fn@rule@dir'] = n.direction
            break
            end
            end
            end
        }%
        \bbd@fn@rule{\the\bbd@fn@rule@dir}%
    }

    \ProvideDocumentCommand{\autofootnoterule}{}{%
        \global\let\footnoterule\bbd@fn@rule@auto
    }

\fi

% XeTeX deliberately has no definition here.
% \autofootnoterule is supplied by bidi.



\makeatother

\endinput