\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{mkessler-vocab}[2021-09-06 - Package for emphasizing vocabulary]
%%%%%%%%%%%%%%%%%%
%%Provides a \vocab<[name in index]>{vocabulary} command to print vocabulary in bold blue and automatically index it.

\newif\ifenglish\englishtrue
\DeclareOption{german}{\englishfalse}
\DeclareOption{english}{\englishtrue}
\DeclareOption*{\PackageWarning{mkessler-vocab}{Unknown '\CurrentOption'}}
\ProcessOptions\relax

%%%%Management of vocabulary and corresponding index
\RequirePackage{imakeidx}
\makeindex[columns=2, title=\ifenglish Index\else Stichwortverzeichnis\fi, intoc]

%Emphasize \vocabulary
\RequirePackage{xparse}
\RequirePackage{expl3}
\ExplSyntaxOn
\NewDocumentCommand{\vocab}{O{} m}{
    \textbf{\color{blue} #2}
    \ifthenelse{\isempty{#1}}{\index{\text_titlecase_first:n{#2}}}{\index{#1}}
}
\ExplSyntaxOff