#!/usr/bin/env zsh

###
: '
Scans several pages using `scanpage` and combines them into a single PDF file.
'
###

# change this to your preferred PDF viewer
_viewer="zathura"

###

trap _ctrlc INT

function _cleanup() {
  # cleanup _tmpdir
  rm -rf $_tmpdir
}
function _ctrlc() {
  echo "cancelled by SIGINT/^C"
  _cleanup
  exit 1
}



_cmd=""
_file=""
_landscape=false
_silent=false
_tmpdir=""

usage () {
  echo 'Scans several pages using `scanpage` and combines them into a single PDF file.

options:
  -h, --help
    prints this message
  -l, --landscape
    rotates the pages 90° left for landscape scans
  -o, --outfile FILE
    writes the scan to FILE instead of using a temporary file
  -r, --rotate
    same as -l
  -s, --silent
    silently write output file, don’t open it
  --viewer CMD
    uses CMD as PDF viewer'
}

###~begin option parsing
zparseopts -A _OPTS -D -E -- h l o: r --help -outfile: -landscape -rotate -viewer:
if [ ! -z "$@" ] ; then
  usage
  exit 1
fi

for opt in "${(@k)_OPTS}"; do
  case $opt in
    -h|--help)
      usage
      exit 0
      ;;
    -l|-r|--landscape|--rotate)
      _landscape=true
      ;;
    -o|--outfile)
      _file="$_OPTS[$opt]"
      ;;
    -s|--silent)
      _silent=true
      ;;
    --viewer)
      _viewer="$_OPTS[$opt]"
      ;;
  esac
done
###~end option parsing

# setup temporary directory for scans; we deffo need it for the intermediate,
# single page files this time
_tmpdir=`mktemp -d`

# check file ending if outfile is specified (and add it), else use tmpfile
if [ ! -z $_file ] ; then
  if [[ ! "$_file" =~ ".*\.pdf" ]] ; then _file="${_file}.pdf"; fi
else
  _file="${_tmpdir}/$(date +%Y-%m-%d).pdf"
fi

i=1
done=false
while ! $done
do
  echo "Starting scan …"
  scanpage -s$( ( $_landscape ) && print "l")o ${_tmpdir}/$(printf "%0*d" 3 ${i}).png
  echo "Page $i scanned. Insert next page and hit <Enter>. ^D to finish the document."
  let i++
  read
  [ "$?" -eq "1" ] && done=true
done

# concatenate scanned pages
echo "Concatenating pages …"
magick "$_tmpdir/*.png" "${_file}"
pushd $_tmpdir
ps2pdf -dPDFSETTINGS=/ebook "${_file}"
popd

( $_silent ) || $_viewer "${_file}.pdf" >/dev/null 2>/dev/null

_cleanup