\documentclass{book}
\usepackage{amsfonts}
\usepackage{amsmath}
\usepackage[gen]{eurosym}
\usepackage{textcomp}
\usepackage{graphicx}
\usepackage{etoolbox}
\usepackage{titleps}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{float}
% use hidelinks to remove boxes around links to be similar to Texinfo TeX
\usepackage[hidelinks]{hyperref}

\makeatletter
\newcommand{\Texinfothechapterheading}{}
\newtitlemark{\Texinfothechapterheading}%
\newcommand{\Texinfoheadingchaptername}{\chaptername}
\newtitlemark{\Texinfoheadingchaptername}%
\newcommand{\Texinfosettitle}{Title \leavevmode{}\\ for a manual}%

\newcommand{\Texinfounnumberedchapter}[1]{\chapter*{#1}
\addcontentsline{toc}{chapter}{\protect\textbf{#1}}%
\renewcommand{\Texinfothechapterheading}{}%
\chaptermark{#1}%
}%

\newcommand{\Texinfounnumberedpart}[1]{\part*{#1}
\addcontentsline{toc}{part}{\protect\textbf{#1}}%
}%

\newcommand{\Texinfounnumberedsection}[1]{\section*{#1}
\addcontentsline{toc}{section}{\protect\textbf{#1}}%
\sectionmark{#1}%
}%

\newcommand{\Texinfounnumberedsubsection}[1]{\subsection*{#1}
\addcontentsline{toc}{subsection}{\protect\textbf{#1}}%
}%

\newcommand{\Texinfounnumberedsubsubsection}[1]{\subsubsection*{#1}
\addcontentsline{toc}{subsubsection}{\protect\textbf{#1}}%
}%

\newcommand{\Texinfochapter}[1]{\chapter{#1}
\renewcommand{\Texinfothechapterheading}{\Texinfoheadingchaptername{} \thechapter{} }%
}%

% redefine the \mainmatter command such that it does not clear page
% as if in double page
\renewcommand\mainmatter{\clearpage\@mainmattertrue\pagenumbering{arabic}}
\newenvironment{Texinfopreformatted}{%
  \par\GNUTobeylines\obeyspaces\frenchspacing\parskip=\z@\parindent=\z@}{}
{\catcode`\^^M=13 \gdef\GNUTobeylines{\catcode`\^^M=13 \def^^M{\null\par}}}
\newenvironment{Texinfoindented}{\begin{list}{}{}\item\relax}{\end{list}}

% used for substitutions in commands
\newcommand{\Texinfoplaceholder}[1]{}

\newpagestyle{single}{\sethead[\Texinfothechapterheading{}\chaptertitle{}][][\thepage]
                              {\Texinfothechapterheading{}\chaptertitle{}}{}{\thepage}}

\newpagestyle{double}{\sethead[\thepage{}][][\Texinfosettitle]
                              {\Texinfothechapterheading{}\chaptertitle{}}{}{\thepage}}

% allow line breaking at underscore
\let\Texinfounderscore\_
\renewcommand{\_}{\Texinfounderscore\discretionary{}{}{}}
\renewcommand{\includegraphics}[1]{\fbox{FIG \detokenize{#1}}}

\makeatother
% set default for @setchapternewpage
\makeatletter
\patchcmd{\chapter}{\if@openright\cleardoublepage\else\clearpage\fi}{\Texinfoplaceholder{setchapternewpage placeholder}\clearpage}{}{}
\makeatother
\pagestyle{single}%


\pagestyle{double}%

\begin{document}
\Texinfochapter{{chap}}

\newpage{}%
\phantom{blabla}%

More text

\newpage{}%
\phantom{blabla}%

Another page
\end{document}
