#!/usr/bin/env nix
#! nix shell --impure --expr ``
#! nix with (builtins.getFlake "git+file://${toString ./.}/..").packages.${builtins.currentSystem};
#! nix let fonts = [
#! nix   pkgs.comic-mono
#! nix   pkgs.crimson
#! nix   pkgs.dejavu_fonts
#! nix   pkgs.fira-code
#! nix   pkgs.freefont_ttf
#! nix   pkgs.gyre-fonts # TrueType substitutes for standard PostScript fonts
#! nix   pkgs.hack-font
#! nix   pkgs.liberation_ttf
#! nix   pkgs.lmodern
#! nix   pkgs.noto-fonts-emoji
#! nix   pkgs.tex-gyre.adventor
#! nix   pkgs.tex-gyre.bonum
#! nix   pkgs.tex-gyre.chorus
#! nix   pkgs.tex-gyre.cursor
#! nix   pkgs.tex-gyre.heros
#! nix   pkgs.tex-gyre.pagella
#! nix   pkgs.tex-gyre.schola
#! nix   pkgs.tex-gyre.termes
#! nix   pkgs.unifont
#! nix ]; in
#! nix [
#! nix    (pkgs.writeShellScriptBin "interpreter" ''
#! nix      # used by luaotfload (lualatex)
#! nix      export OSFONTDIR="${lib.concatStringsSep "//:" (map toString fonts)}"
#! nix      exec bash "$@"
#! nix    '')
#! nix     pandoc
#! nix     pdftk
#! nix     qpdf
#! nix     (pkgs.texlive.combine {
#! nix       inherit (pkgs.texlive)
#! nix         collection-fontsrecommended
#! nix         collection-langenglish
#! nix         collection-langfrench
#! nix         collection-latexrecommended
#! nix         collection-luatex
#! nix         pdfbook2
#! nix         pdfcrop
#! nix         pdfjam
#! nix         scheme-basic
#! nix         tex-gyre
#! nix         ;
#! nix     })
#! nix ]
#! nix ``
#! nix --command interpreter

epubPath=$1
epubDir=$(realpath -e "$(dirname "$epubPath")")
styleDir=$(realpath -e "$(dirname "$0")")/styles
outDir=$epubDir/pdf
pdfFile="$outDir"/out.pdf
rm -rf "$outDir"
mkdir -p "$outDir"

# Converting EPUB to PDF
set -eux
pandoc \
  --embed-resources \
  --include-in-header "$styleDir"/epub.header.tex \
  --filter "$epubDir"/filter \
  --number-sections \
  --pdf-engine lualatex \
  --standalone \
  --toc \
  --toc-depth 6 \
  --top-level-division chapter \
  -V documentclass=scrbook \
  -V classoption=english \
  -V mainfont="TeX Gyre Termes" \
  -V fontsize=13pt \
  -V papersize=a5 \
  -i "$epubPath" \
  -t pdf \
  -o "$pdfFile"

# Slicing on chapters and splitting into chunks of at most 18 pages (for easy binding)
  mkdir -p "$outDir"/sections
  pdftk "$pdfFile" dump_data | grep '^BookmarkPageNumber:' |
  {
    sectionNum=1
    sectionBegin=1
    splitSection () {
      qpdf \
        "$pdfFile" \
        "$outDir"/sections/sectionNum="$sectionNum".pages="$sectionPages".chunk=%d.pdf \
        --pages "$pdfFile" "$sectionPages" -- \
        --split-pages=18
    }
    while read -r _BookmarkPageNumber sectionEnd; do
      test "$sectionEnd" != 1 || continue
      sectionPages=$sectionBegin-$((sectionEnd-1))
      splitSection
      sectionNum=$((sectionNum+1))
      sectionBegin=$sectionEnd
    done
    sectionPages="$sectionBegin"-r1
    splitSection
  }

# Converting to booklet
  find "$outDir"/sections -type f |
  sort -n |
  while read -r pdfSection; do
    # Margins have already been set correctly by the geometry package in header.tex
    # pdfbook2 fails to move the .pdf over filesystems
    pdfbook2 --no-crop \
      --paper "${paper:-a4paper}" \
      --outer-margin "${outerMargin:-80}" \
      --inner-margin "${innerMargin:-150}" \
      --top-margin "${topmargin:-30}" \
      --bottom-margin "${bottomMargin:-30}" \
      "$pdfSection"
    rm "$pdfSection"

    # Split odd and even pages to print in the same direction
      pdftk "${pdfSection%.pdf}"-book.pdf cat oddSouth output "${pdfSection%.pdf}".book.odds.pdf
      pdftk "${pdfSection%.pdf}"-book.pdf cat even output "${pdfSection%.pdf}".book.even.pdf
    rm "${pdfSection%.pdf}"-book.pdf
  done