main.tex

\documentclass[twoside,symmetric,a4paper]{tufte-book}
\usepackage{lipsum}
\usepackage{tikz}
\usepackage{xifthen}
\usepackage{xcolor}
\usepackage{fontawesome}
\usepackage{microtype}
\usepackage{hyperref}

\newenvironment{loggentry}[2]% date, heading
{\noindent\textbf{#2}\marginnote{#1}\par}{\vspace{0.5cm}}


\newcommand{\book}[1]
{
    \footnote{\faBook\enspace {#1}}
}

\newcommand{\music}[1]
{
    \footnote{\faMusic\enspace {#1}}
}

\newcommand{\yt}[1]
{
    \footnote{\faYoutube\enspace \href{https://www.youtube.com/watch?v=#1}{{#1}}}
}

\newcommand{\travel}[1]
{
    \footnote{\faPlane\enspace {#1}}
}

\newcommand{\movie}[1]
{
    \footnote{\faPlayCircle\enspace {#1}}
}


\def\?#1{}

\pgfmathtruncatemacro{\StartYear}{2020}
\pgfmathtruncatemacro{\EndYear}{2020}

\newcommand{\writetitle}{0}
\newcommand{\mytitle}[1]
{   \ifthenelse{\writetitle=1}{#1}{}
}


\newread\mysource

\begin{document}
\begingroup% T&H Typography
\raggedleft\vspace*{\baselineskip}
{\Large Author}\\[0.167\textheight]
{\bfseries Journaling}\\[\baselineskip]
{\textcolor{Red}{\Huge DEAR DIARY}}\\[\baselineskip]
\vfill
{\Large Do not read.}\par
\vspace*{3\baselineskip}
\endgroup

\foreach \Year in {\StartYear,...,\EndYear}
{
   \chapter{\Year}
    \foreach \Month in {Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec}
    {
        \IfFileExists{\Year/\Month/entries}
        {
            \section{\Month}
            \foreach \Day in {01,...,31}
            {
                \IfFileExists{\Year/\Month/\Day}
                {
                    \openin\mysource=\Year/\Month/\Day.tex
                    \read\mysource to \firstline
                    \closein\mysource
                    \xdef\writetitle{1}
                    \begin{loggentry}{\Year\ - \Month\ - \Day}{\firstline}    
                        \xdef\writetitle{0}
                        \input{\Year/\Month/\Day}
                    \end{loggentry} 
                }
                {
                }
            }
        }
        {
        }
    }
}

\end{document}