\documentclass[11pt, a4paper]{article}
% \usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage{mathtools}
\usepackage{esdiff} % derivatives
\usepackage{braket}
\usepackage{graphicx}
\usepackage{etoolbox}
\usepackage{substr}
\usepackage{xcolor}
\usepackage{float}
\usepackage[hidelinks]{hyperref}
\usepackage{subcaption}
\hypersetup{colorlinks   = true,    % Colours links instead of ugly boxes
            urlcolor     = blue,    % Colour for external hyperlinks
            linkcolor    = cyan,    % Colour of internal links
            citecolor    = red      % Colour of citations 
            }
% \usepackage[version=4,arrows=pgf-filled]{mhchem}
\usepackage{siunitx}
\sisetup{output-decimal-marker = {,}}
\sisetup{separate-uncertainty}
\sisetup{per-mode = power}
\sisetup{exponent-product=\ensuremath{\cdot}}

\DeclarePairedDelimiter\abs{\lvert}{\rvert}
\DeclareMathOperator{\e}{e}

\usepackage{translations}

\newcommand{\TODO}[1]{{\color{red}#1}}

% put an explanation above an equal sign
% [1]: equality sign (or anything else)
% 2: text (not in math mode!)
\newcommand{\explUnderEq}[2][=]{%
    \underset{\substack{\uparrow\\\mathrlap{\text{\hspace{-1em}#2}}}}{#1}}
\newcommand{\explOverEq}[2][=]{%
    \overset{\substack{\mathrlap{\text{\hspace{-1em}#2}}\\\downarrow}}{#1}}

%
% TRANSLATION COMMANDS
%
% The lower case commands use \fqname based keys, the upper case absolute keys.
% Example:
%   \dt[example]{german}{Beispiel}  % defines the key \fqname:example
%   \ger[example]{Beispiel}         % defines the key \fqname:example
%   \DT[example]{german}{Beispiel}  % defines the key example
%   \Ger[example]{Beispiel}         % defines the key example
%
% For ease of use in the ttext environment and the optional argument of the \Part, \Section, ... commands,
% all "define translation" commands use \fqname as default key

% Get a translation
% expandafter required because the translation commands dont expand anything
% shortcuts for translations
% 1: key
\newcommand{\gt}[1]{\expandafter\GetTranslation\expandafter{\fqname:#1}}
\newcommand{\GT}[1]{\expandafter\GetTranslation\expandafter{#1}}

\newcommand{\IfTranslationExists}{
    \IfTranslation{\languagename}
}
\newcommand{\iftranslation}[1]{\expandafter\IfTranslationExists\expandafter{\fqname:#1}}

% Define a new translation
% [1]: key, 2: lang, 3: translation
\newcommand{\dt}[3][\fqname]{
    % hack because using expandafter on the second arg didnt work
    \def\tempaddtranslation{\addtranslation{#2}}
    \ifstrequal{#1}{\fqname}{
        \expandafter\tempaddtranslation\expandafter{\fqname}{#3}
    }{
        \expandafter\tempaddtranslation\expandafter{\fqname:#1}{#3}
    }
}
\newcommand{\DT}[3][\fqname]{
    % hack because using expandafter on the second arg didnt work
    \def\tempaddtranslation{\addtranslation{#2}}
    \ifstrequal{#1}{\fqname}{
        \expandafter\tempaddtranslation\expandafter{\fqname}{#3}
    }{
        \expandafter\tempaddtranslation\expandafter{#1}{#3}
    }
}
% [1]: key, 2: translation
\newcommand{\ger}[2][\fqname]{\dt[#1]{german}{#2}}
\newcommand{\eng}[2][\fqname]{\dt[#1]{english}{#2}}

\newcommand{\GER}[2][\fqname]{\DT[#1]{german}{#2}}
\newcommand{\ENG}[2][\fqname]{\DT[#1]{english}{#2}}

% use this to define text in different languages for the key <env arg>
% the translation for <env arg> when the environment ends.
% (temporarily change fqname to the \fqname:<env arg> to allow
% the use of \eng and \ger without the key parameter)
\newenvironment{ttext}[1]{
    \edef\realfqname{\fqname}
    \edef\fqname{\fqname:#1}
}{
    \expandafter\GT\expandafter{\fqname} \\
    \edef\fqname{\realfqname}
}

% "automate" sectioning
% start <section>, get heading from translation, set label
% fqname is the fully qualified name: the keys of all previous sections joined with a ':'
% [1]: code to run after setting \fqname, but before the \part, \section etc
% 2: key
\newcommand{\Part}[2][desc]{
    \newpage
    \def\partname{#2}
    \def\sectionname{}
    \def\subsectionname{}
    \def\subsubsectionname{}
    \edef\fqname{\partname}
    #1
    \part{\GT{\fqname}} 
    \label{sec:\fqname}
}
\newcommand{\Section}[2][]{
    \def\sectionname{#2}
    \def\subsectionname{}
    \def\subsubsectionname{}
    \edef\fqname{\partname:\sectionname}
    #1
    \section{\GT{\fqname}} 
    \label{sec:\fqname}
}
% \newcommand{\Subsection}[1]{\Subsection{#1}{}}
\newcommand{\Subsection}[2][]{
    \def\subsectionname{#2}
    \def\subsubsectionname{}
    \edef\fqname{\partname:\sectionname:\subsectionname}
    #1
    \subsection{\GT{\fqname}}
    \label{sec:\fqname}
}
\newcommand{\Subsubsection}[2][]{
    \def\subsubsectionname{#2}
    \edef\fqname{\partname:\sectionname:\subsectionname:\subsubsectionname}
    #1
    \subsubsection{\GT{\fqname}}
    \label{sec:\fqname}
}

\usepackage{xstring}

\newcommand{\insertEquationLine}[2]{
    \par\noindent\ignorespaces
    % \textcolor{gray}{\hrule}
    \vspace{0.5\baselineskip}
    % \fbox{
    \begin{minipage}{0.3\textwidth}
        \iftranslation{#1}{
            \raggedright
            \gt{#1}
        }{} 
        \iftranslation{#1_desc}{
           \\ {\color{darkgray} \gt{#1_desc}}
        }{}
    \end{minipage}
    % }
    \hfill
    \fbox{
    \begin{minipage}{0.6\textwidth}
        % \vspace{-\baselineskip}  % remove the space that comes from starting a new paragraph
        #2 %
        \noindent\iftranslation{#1_defs}{
            \begingroup
                \color{darkgray} 
                \gt{#1_defs}
                % \edef\temp{\GT{#1_defs}}
                % \expandafter\StrSubstitute\expandafter{\temp}{:}{\\}
            \endgroup
        }{}
        % \vspace{-\baselineskip}  % remove the space that comes from starting a new paragraph
    \end{minipage}
    }
    \textcolor{lightgray}{\hrule}
    \vspace{0.5\baselineskip}
    % \par
    % \hrule
}

\newcommand{\insertEquation}[2]{
    \insertEquationLine{#1}{
        \begin{align}
            \label{eq:\fqname:#1}
            #2
        \end{align}
    }
}

\newcommand{\insertFLAlign}[2]{  % eq name, #cols, eq
    \insertEquationLine{#1}{%
        \begin{flalign}%
            % dont place label when one is provided
            % \IfSubStringInString{label}\unexpanded{#3}{}{
            %     \label{eq:#1}
            % }
            #2%
        \end{flalign}
    }
}

\newcommand{\insertAlignedAt}[3]{  % eq name, #cols, eq
    \insertEquationLine{#1}{%
        \begin{alignat}{#2}%
            % dont place label when one is provided
            % \IfSubStringInString{label}\unexpanded{#3}{}{
            %     \label{eq:#1}
            % }
            #3%
        \end{alignat}
    }
}

\newenvironment{formula}[1]{
    % key
    \newcommand{\desc}[4][english]{
        % language, name, description, definitions
        \dt[#1]{##1}{##2}
        \ifblank{##3}{}{\dt[#1_desc]{##1}{##3}}
        \ifblank{##4}{}{\dt[#1_defs]{##1}{##4}}
    }
    \newcommand{\eq}[1]{
        \insertEquation{#1}{##1}
    }
    \newcommand{\eqAlignedAt}[2]{
        \insertAlignedAt{#1}{##1}{##2}
    }
    \newcommand{\eqFLAlign}[1]{
        \insertFLAlign{#1}{##1}
    }
}{\ignorespacesafterend}

\title{Formelsammlung}
\author{Matthias Quintern}
\date{\today}

\begin{document}

\maketitle
\tableofcontents
\newpage
\setcounter{page}{1}

% \nuwcommand{\eq}[4][desc]{
%     \vspace*{0.1cm}
%     \begin{minipage}{0.3\textwidth}
%         \raggedright
%         .#2 \\
%         \ifstrequal{#1}{desc}{}{
%             {\color{gray}#1}
%         }
%     \end{minipage}
%     \begin{minipage}{0.7\textwidth}
%         \begin{align}
%             \label{eq:#4}
%             #3
%         \end{align}
%     \end{minipage}
%     \newline
% }


% \newcommand{\eqd}[5][desc]{
%     \vspace*{0.1cm}
%     \begin{minipage}{0.3\textwidth}
%         \raggedright
%         .#2 \\
%         \ifstrequal{#1}{desc}{}{
%             {\color{gray}#1}
%         }
%     \end{minipage}
%     \begin{minipage}{0.7\textwidth}
%         \begin{align}
%             \label{eq:#5}
%             #3
%         \end{align}
%         {\color{gray}with: #4}
%     \end{minipage}
%     \newline
% }
\IfSubStringInString{lol}{lol\frac{asdsd}{lol} & l}{YES!}{
    NO!
}
\input{translations.tex}

\input{trigonometry.tex}
    
\input{quantum_mechanics.tex}
\input{atom.tex}

\input{quantum_computing.tex}

%\newpage
% \bibliographystyle{plain}
% \bibliography{ref}
\end{document}