% Chapter designs, implemented with memoir's heading hooks.
% Copyright 2019, 2026 Adib Hasan. Part of BOOKbangla; LPPL 1.3c or later.

% Register a normal memoir style, so \chapterstyle{...} remains an override.
% Only the heading is decorated: \thechapter and reference values stay plain.
\makechapterstyle{classic}{%
  \renewcommand*\printchaptername{}%
  \renewcommand*\chapternamenum{}%
  \renewcommand*\printchapternum{%
    \hfill\begin{tikzpicture}[every node/.style={outer sep=0pt}]
      \node[outer sep=0pt,text width=2.4cm,minimum height=2.5cm,
        fill=bookbanglaaccent,font=\color{white}\bfseries\fontsize{75}{80}\selectfont,
        align=center] (bookbanglanumber) {\thechapter};
      \node[rotate=90,anchor=south,font=\color{black}\bfseries\Large]
        at ([xshift=-5pt]bookbanglanumber.west) {\@chapapp};
    \end{tikzpicture}\par}
  \renewcommand*\afterchapternum{\par\nobreak\vskip-30pt}
  \renewcommand*\chaptitlefont{\bfseries\color{bookbanglaaccent}\fontsize{22}{24}\selectfont}
  \renewcommand*\afterchaptertitle{%
    \par\nobreak\vskip8pt
    {\color{bookbanglaaccent}\hrule height2.5pt\vskip3pt\hrule height.4pt}%
    \nobreak\vskip\afterchapskip}}
\chapterstyle{classic}

% The alternatives draw on Hansen, VZ34 and BlueBox in Lars Madsen's
% memoir showcase: https://ctan.org/pkg/memoirchapstyles. Their compositions
% are adapted for Bangla, monochrome printing and multiline titles.
% Keep the numbered/unnumbered distinction local to memoir's heading group.
\newif\ifbookbangla@numberedchapter
\newcommand*\bookbangla@structuredchapter{%
  \renewcommand*\printchaptername{}%
  \renewcommand*\chapternamenum{}%
  \renewcommand*\printchapternum{\bookbangla@numberedchaptertrue}%
  \renewcommand*\printchapternonum{\bookbangla@numberedchapterfalse}%
  \renewcommand*\afterchapternum{}%
  \renewcommand*\chapnumfont{\normalfont\bfseries\fontsize{52}{56}\selectfont}
  \renewcommand*\chaptitlefont{\normalfont\bfseries\fontsize{26}{34}\selectfont
    \hyphenpenalty=10000\exhyphenpenalty=10000}}

\makechapterstyle{modern}{%
  \bookbangla@structuredchapter
  \renewcommand*\printchaptertitle[1]{%
    \begin{tikzpicture}[every node/.style={outer sep=0pt}]
      % Reserve the opening's height even for a short or unnumbered title.
      \path[use as bounding box] (0,0) rectangle (\linewidth,-96pt);
      \ifbookbangla@numberedchapter
        \node[anchor=north east,inner sep=0pt,
          text=bookbanglaaccent!25!white,
          font=\normalfont\bfseries\fontsize{120}{120}\selectfont]
          at (\linewidth,10pt) {\thechapter};
        \node[anchor=north west,inner sep=0pt,font=\normalfont\large]
          at (0,0) {\@chapapp};
      \fi
      \node[anchor=north east,inner sep=0pt,text width=.92\linewidth,
        align=right,font=\chaptitlefont] at (\linewidth,-36pt) {##1};
    \end{tikzpicture}}}

\makechapterstyle{minimal}{%
  \bookbangla@structuredchapter
  \renewcommand*\printchaptertitle[1]{%
    \begin{tikzpicture}[every node/.style={outer sep=0pt}]
      \node[anchor=north west,inner sep=0pt,
        text width=\dimexpr\linewidth-82pt\relax,
        align=left,font=\chaptitlefont] (bookbanglatitle)
        at (82pt,0) {##1};
      \ifbookbangla@numberedchapter
        \node[anchor=north east,inner sep=0pt,font=\normalfont\small]
          at (54pt,0) {\@chapapp};
        \node[anchor=north east,inner sep=0pt,font=\chapnumfont]
          (bookbanglanumber) at (54pt,-17pt) {\thechapter};
      \else
        \coordinate (bookbanglanumber) at (54pt,-54pt);
      \fi
      % Extend the divider to whichever is taller: the title or the number.
      \coordinate (bookbanglaheadingbottom) at (current bounding box.south);
      \draw[bookbanglaaccent,line width=1.2pt]
        (66pt,2pt)--(66pt,0 |- bookbanglaheadingbottom);
      \path[use as bounding box] (0,0);
    \end{tikzpicture}}}

\makechapterstyle{ruled}{%
  \bookbangla@structuredchapter
  \renewcommand*\printchaptertitle[1]{%
    \begin{tikzpicture}[every node/.style={outer sep=0pt}]
      \ifbookbangla@numberedchapter
        \node[anchor=north west,inner xsep=9pt,inner ysep=6pt,
          minimum width=58pt,minimum height=64pt,
          fill=bookbanglaaccent,text=white,font=\chapnumfont]
          (bookbanglanumber) at (0,0) {\thechapter};
        \node[anchor=south west,inner sep=0pt,font=\normalfont\large]
          at ([xshift=12pt,yshift=8pt]bookbanglanumber.south east) {\@chapapp};
        \draw[bookbanglaaccent,line width=1.2pt]
          (bookbanglanumber.south east)--(\dimexpr\linewidth-.6pt\relax,0 |- bookbanglanumber.south);
        \coordinate (bookbanglatitletop) at ([yshift=-18pt]bookbanglanumber.south west);
      \else
        \draw[bookbanglaaccent,line width=1.2pt] (.6pt,0)--(\dimexpr\linewidth-.6pt\relax,0);
        \coordinate (bookbanglatitletop) at (0,-18pt);
      \fi
      \node[anchor=north west,inner sep=0pt,text width=\linewidth,
        align=left,font=\chaptitlefont] at (bookbanglatitletop) {##1};
    \end{tikzpicture}}}
\endinput