%
% babelbidi-logos.sty
%
% 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 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.
%

\NeedsTeXFormat{LaTeX2e}[2020-10-01]
\ProvidesPackage{babelbidi-logos}
[2026/11/11 v0.1.0 Standalone engine logos for BabelBidi]

\RequirePackage{iftex}
\RequirePackage{xspace}
\RequirePackage{xkeyval}

% ------------------------------------------
% Package options
% ------------------------------------------

% auto: retain automatic graphics detection.
% simple: disable graphics-based construction and all reflection.
\newif\ifbbd@logo@simple
\bbd@logo@simplefalse

\DeclareOptionX{style}[auto]{%
    \edef\bbd@logo@style@option{#1}%
    \def\bbd@logo@style@auto{auto}%
    \def\bbd@logo@style@simple{simple}%
    \ifx\bbd@logo@style@option\bbd@logo@style@auto
        \bbd@logo@simplefalse
    \else
        \ifx\bbd@logo@style@option\bbd@logo@style@simple
            \bbd@logo@simpletrue
        \else
            \PackageError{babelbidi-logos}%
            {Invalid style value '#1'}%
            {Use style=auto or style=simple.}%
        \fi
    \fi
}

\ProcessOptionsX\relax

% ------------------------------------------
% Saved base logos
% ------------------------------------------

% Copy robust commands together with their implementations.
% A plain \let is not sufficient for arbitrary robust definitions.
% Capture the definitions supplied by packages loaded before this one.
\NewCommandCopy\bbd@logo@base@tex\TeX
\NewCommandCopy\bbd@logo@base@latex\LaTeX
\NewCommandCopy\bbd@logo@base@latexe\LaTeXe

% ------------------------------------------
% Standalone fallback
% ------------------------------------------

% Do not guess a language or a font.
% Use textLR if supplied by the surrounding bidi system.
% Otherwise only keep the logo together in a horizontal box.
\def\bbd@logo@plain#1{%
    \leavevmode
    \@ifundefined{textLR}{%
        \hbox{#1}%
    }{%
        \textLR{\hbox{#1}}%
    }%
}

% ------------------------------------------
% BabelBidi language context
% ------------------------------------------

\def\bbd@logo@babelbidi#1{%
    \@ifundefined{dateenglish}{%
        \@ifundefined{bbd@main@latin}{%
            \bbd@logo@plain{#1}%
        }{%
            \foreignlanguage{\bbd@main@latin}{%
                \ifTUTeX
                    \@ifundefined{latinfont}{}{\latinfont}%
                \fi
                #1%
            }%
        }%
    }{%
        \foreignlanguage{english}{#1}%
    }%
}

% ------------------------------------------
% Babel language context (without BabelBidi)
% ------------------------------------------

\def\bbd@logo@babel#1{%
    \@ifundefined{dateenglish}{%
        \bbd@logo@plain{#1}%
    }{%
        \foreignlanguage{english}{#1}%
    }%
}

% ------------------------------------------
% Polyglossia language context
% ------------------------------------------

% textenglish is normally defined when English is loaded.
% Do not load English or infer a Latin language automatically.
\def\bbd@logo@polyglossia#1{%
    \@ifundefined{textenglish}{%
        \bbd@logo@plain{#1}%
    }{%
        \textenglish{#1}%
    }%
}

% ------------------------------------------
% Internal logo context
% ------------------------------------------

% Detect language support at use time, not at package load time.
\def\bbd@logo@context#1{%
    \@ifpackageloaded{babelbidi}{%
        \bbd@logo@babelbidi{#1}%
    }{%
        \@ifpackageloaded{polyglossia}{%
            \bbd@logo@polyglossia{#1}%
        }{%
            \@ifpackageloaded{babel}{%
                \bbd@logo@babel{#1}%
            }{%
                \bbd@logo@plain{#1}%
            }%
        }%
    }%
}

% Keep xspace outside the group and all context wrappers.
% Composite logos must use the saved base commands, not the public
% wrappers: otherwise language contexts and xspace would be nested.
\def\bbd@logo@latin#1{%
    \begingroup
    \let\TeX\bbd@logo@base@tex
    \let\LaTeX\bbd@logo@base@latex
    \let\LaTeXe\bbd@logo@base@latexe
    \bbd@logo@context{#1}%
    \endgroup
    \xspace
}

% ------------------------------------------
% Graphics branch selection
% ------------------------------------------

% Choose the branch once, while loading this package.
% The simple style overrides graphics/graphicx detection.
% Loading graphics/graphicx later does not change this choice.
\newif\ifbbd@logo@graphics

\ifbbd@logo@simple
    \bbd@logo@graphicsfalse
\else
    \@ifpackageloaded{graphics}
    {\bbd@logo@graphicstrue}
    {\bbd@logo@graphicsfalse}
\fi

% ==========================================
% Engine logo construction
% ==========================================

\ifbbd@logo@graphics

    % ------------------------------------------
    % Logos with graphics
    % ------------------------------------------

    \def\bbd@xetex@reflect#1{%
        \reflectbox{#1}%
    }

    % A vertically reflected U with its baseline corrected.
    % The lowercase a is centred inside the reflected U.
    % Use the normal medium series: a light series is not provided
    % by every font family (for example, TeX Gyre Termes).
    \def\bbd@logo@lua@ua{%
        \begingroup
        \scriptsize
        \setbox\z@=\hbox{%
            \scalebox{1.7}[-1.2]{%
                {\mdseries U}%
            }%
        }%
        \setbox\z@=\hbox{%
            \raise\dp\z@\box\z@
        }%
        \hbox{%
            \rlap{%
                \hbox to \wd\z@{%
                    \hss
                    \raise.2ex\hbox{a}%
                    \hss
                }%
            }%
            \box\z@
        }%
        \endgroup
    }

    \def\bbd@logo@lua@kern{-.08}
    \def\bbd@luatex@logo#1#2{%
        \leavevmode
        \hbox{%
            L%
            \kern-.22em
            \raise.38ex\hbox{%
                \bbd@logo@lua@ua
            }%
            \kern#1em
            #2%
        }%
    }

    \def\bbd@logo@pdf@kern{-.10em}
    \def\bbd@pdftex@logo#1#2{%
        \leavevmode
        \hbox{%
            P%
            \kern-.25em
            \raise-.18ex\hbox{%
                \scriptsize
                \reflectbox{D}%
                \kern-.06em
                f%
            }%
            \kern#1%
            #2%
        }%
    }

\else

    % ------------------------------------------
    % Logos without graphics
    % ------------------------------------------

    % Select the simple/auto reflection policy at package load time.
    % In auto mode, look up the bidi helper when the logo is used.
    \ifbbd@logo@simple
        \def\bbd@xetex@reflect#1{#1}
    \else
        \def\bbd@xetex@reflect#1{%
            \@ifundefined{bidi@reflect@box}
            {#1}
            {\bidi@reflect@box{#1}}%
        }
    \fi

    \def\bbd@logo@lua@kern{-.16}
    \def\bbd@luatex@logo#1#2{%
        \leavevmode
        \hbox{%
            L%
            \kern-.1em
            \raise.28ex\hbox{%
                \scriptsize Ua%
            }%
            \kern#1em
            #2%
        }%
    }

    \def\bbd@logo@pdf@kern{-.08em}
    \def\bbd@pdftex@logo#1#2{%
        \leavevmode
        \hbox{%
            P%
            \kern-.12em
            \raise-.42ex\hbox{%
                \scriptsize Df%
            }%
            \kern#1%
            #2%
        }%
    }

\fi

% ------------------------------------------
% Shared XeTeX / XeLaTeX construction
% ------------------------------------------

% Preserve the wider simple-style spacing; choose it once at load time.
\ifbbd@logo@simple
    \def\bbd@logo@xelatex@kern{0}
\else
    \def\bbd@logo@xelatex@kern{-.1667}
\fi

\def\bbd@xetex@logo#1#2{%
    \leavevmode
    $\smash{\hbox{%
                X%
                \lower.5ex\hbox{%
                    \kern-.125em
                    \bbd@xetex@reflect{E}%
                }%
                \kern#1em #2%
            }}$%
}

% ==========================================
% Public base logos
% ==========================================

\DeclareDocumentCommand{\TeX}{}{%
    \bbd@logo@latin{\bbd@logo@base@tex}%
}

\DeclareDocumentCommand{\LaTeX}{}{%
    \bbd@logo@latin{\bbd@logo@base@latex}%
}

% LaTeXe contains LaTeX: wrap the whole logo, not its inner component.
\DeclareDocumentCommand{\LaTeXe}{}{%
    \bbd@logo@latin{\bbd@logo@base@latexe}%
}

% ==========================================
% Public engine logos
% ==========================================

% Existing commands with these names are deliberately redefined.
\DeclareDocumentCommand{\XeTeX}{}{%
    \bbd@logo@latin{%
        \bbd@xetex@logo{-.1667}{\TeX}%
    }%
}

\DeclareDocumentCommand{\XeLaTeX}{}{%
    \bbd@logo@latin{%
        \bbd@xetex@logo{\bbd@logo@xelatex@kern}{\LaTeX}%
    }%
}

\DeclareDocumentCommand{\LuaTeX}{}{%
    \bbd@logo@latin{%
        \bbd@luatex@logo{\bbd@logo@lua@kern}{\TeX}%
    }%
}

\DeclareDocumentCommand{\pdfTeX}{}{%
    \bbd@logo@latin{%
        \bbd@pdftex@logo{\bbd@logo@pdf@kern}{\TeX}%
    }%
}

% LaTeX variants have different spacing in the two branches.
\ifbbd@logo@graphics

    \DeclareDocumentCommand{\LuaLaTeX}{}{%
        \bbd@logo@latin{%
            \bbd@luatex@logo{-.02}{\LaTeX}%
        }%
    }

    \DeclareDocumentCommand{\pdfLaTeX}{}{%
        \bbd@logo@latin{%
            \bbd@pdftex@logo{+.02em}{\LaTeX}%
        }%
    }

\else

    \DeclareDocumentCommand{\LuaLaTeX}{}{%
        \bbd@logo@latin{%
            \bbd@luatex@logo{-.01}{\LaTeX}%
        }%
    }

    \DeclareDocumentCommand{\pdfLaTeX}{}{%
        \bbd@logo@latin{%
            \bbd@pdftex@logo{0em}{\LaTeX}%
        }%
    }

\fi

\endinput