a5toa4

#!/usr/bin/env bash
set +vx
# a5toa4 - Print an A5/Statement size document on A4/Letter for booklet folding
# Required: coreutils(cat mktemp) ghostscript(psselect pdf2ps ps2pdf)
#           psutils(pstops/psnup)

Usage(){ # $1: code for exit
	cat <<-EOS
		a5toa4 - Print A5/Statement document on A4/Letter pages for booklet folding
		Usage: a5toa4 [<Options>] <a5.pdf> [<a4.pdf>]
		Options:  -h/--help:                  Display this help text
		          -v/--verbose:               Verbose output of processing steps
              -l/--letter:                Use Letter & Statement, not A4 & A5
		          -s/--split & -r/--reverse:  See below
		Print the resulting A4/Letter document on a single-sided printer by:
		  1. Printing all the even pages.
		  2. Reinserting the stack of printed pages in such a way that the blank
		     sides will now be used to print the rest of the pages in step 3.
		  3. Printing all the odd pages.
		If -s/--split is given, the printing can be done by:
		  1. Printing the first half of the N pages, from 1 to N/2.
		  2. See step 2 above.
		  3. Printing the second half of the N pages, from N/2+1 to N.
		If -r/--reverse is given, the order of printing in step 3 is reversed, as
		  appropriate for normal full-duplex printing (not the whole stack of
		  papers gets flipped, just individual pages automatically).
		For more than 1 copy, be sure to select COLLATE before printing!
		For printing on Letter size paper, select FIT TO PAGE before printing!
	EOS
	[[ $1 ]] && exit $1
}

# process commandline
verbose=0 split=0 reverse=0 in= out= stdout=/dev/null half=a5 full=a4
while (($#))
do
	case $1 in
	-l|--letter) half=statement full=letter ;;
	-h|--help) Usage 0 ;;
	-v|--verbose) verbose=1 stdout=/dev/stdout ;;
	-s|--split) split=1 ;;
	-r|--reverse) reverse=1 ;;
	*) [[ $out ]] && echo "Too many arguments" && Usage 1
		[[ $in ]] && out=$1 || in=$1
		[[ ! -f $in ]] &&
			echo "Filename of ${half^} sized pdf required, not a file: '$in'" &&
			Usage 2
	esac
	shift
done
[[ -z $in ]] && echo "No filename for ${half^} sized pdf given" && Usage 3
[[ -z $out ]] &&
	out=$(basename "$in") out=${out%.pdf} out=${out%.PDF} out+=_${full^}.pdf

missingcmd=
for cmd in psselect pdf2ps ps2pdf psnup
do type -P $cmd &>/dev/null || missingcmd+=" $cmd"
done
[[ $missingcmd ]] &&
	echo "Missing commands:$missingcmd, install ghostscript/psutils" &&
	exit 4

((verbose)) && echo "Convert ${half^} pdf to ps..."
tmp=$(mktemp -d) papersize=$(</etc/papersize)
[[ ! $full = $papersize ]] &&
	restore='echo -n "Set " && echo $papersize |sudo tee /etc/papersize' &&
	echo -n "Set " && echo $full |sudo tee /etc/papersize
trap "rm -r -- '$tmp'; $restore" EXIT QUIT
! pdf2ps "$in" "$tmp/a5.ps" && echo "Problem converting $in" && exit 5

# Get number of pages
cd "$tmp"
p=$(psselect -p- a5.ps 2>&1 >/dev/null) p=${p#*Wrote } p=${p%% *}
((!p)) && echo "No pages found in $in" && exit 6

# p: number pages in A5/Statement document; n: full number of A5/Statement-pages (multiple of 4)
((n=p,r=p%4)) && ((r=4-r,n+=r))
# s: number of A4/Letter-sheets; m: number of A4/Letter page sides
((s=n/4,m=n/2))
i=0
while ((i++<n))
do ((i>p)) && range+='_ ' || range+="$i "
done

# Normal full-duplex range: n,1 2,n-1 (-2,+2 +2,-2)
# Reverse full-duplex range: n,1 n/2,n/2+1 (-2,+2 -2,+2)
i=0 range=($range) nor= rev=
((na=n,nb=1,nc=2,nd=n-1,ra=n,rb=1,rc=n/2,rd=n/2+1))
while ((nb<m))
do  # lower all indexes by 1 for zero-based array
	nor+="${range[na-1]} ${range[nb-1]} ${range[nc-1]} ${range[nd-1]} "
	rev+="${range[ra-1]} ${range[rb-1]} ${range[rc-1]} ${range[rd-1]} "
	((na-=2,nb+=2,nc+=2,nd-=2,ra-=2,rb+=2,rc-=2,rd+=2))
done
nor=${nor% } rev=${rev% }
((reverse)) && r=$rev || r=$nor

if ((s>1 && split))
then  # Split requested and more than 1 sheet
	# Take the odd A4/Letter pages and then the even A4/Letter pages
	i=0 odd= even= na=($nor) ra=($rev)
	while ((i<n))
	do
		odd+="${na[i]} ${na[i+1]} "
		even+="${na[i+2]} ${na[i+3]} "
		reven+="${ra[i+2]} ${ra[i+3]} "
		((i+=4))
	done
	snor=$odd${even% }
	srev=$odd${reven% }
	((reverse)) && r=$srev || r=$snor
fi

# Put the A5/Statement pages on A4/Letter
((verbose)) && echo "Convert ${half^} ps to ${full^}..."
r=${r// /,}
! psselect -p $r a5.ps a5c.ps &>"$stdout" &&
	echo "Reordering failed" && exit 7
	[[ $full = a4 ]] && size='-Pa5 -pa4' ||
		size='-W5.5in -H8.5in -w8.5in -h11in'
! PAPERSIZE=$full psnup -2 $size a5c.ps a4.ps &>"$stdout" &&
	echo "Conversion ${half^} to ${full^} failed" && exit 8
#pstops -pa4 "2:0L(21cm,0cm)+1L(21cm,14.85cm)" a5c.ps a4.ps
#pstops -w11in -h8.5in "2:0L(21cm,1cm)+1L(21cm,6in)" a5c.ps a4.ps

cd - >/dev/null
((verbose)) && echo "Convert ${full^} ps to pdf..."
! PAPERSIZE=$full ps2pdf "$tmp/a4.ps" "$out" &>"$stdout" &&
	echo "Conversion ${full^} ps to pdf failed" && exit 9

if ((verbose))
then
	echo "All done! Now print the booklet '$out' by:"
	if ((split))
	then
		echo "- printing pages 1-$s"
		echo "- reinserting the stack of sheets for printing the blank sides"
		echo "- printing pages $((s+1))-$((s+s)) (REVERSE if needed by printer!)"
	else
		echo "printing the document with a full-duplex printer, or:"
		echo "- printing the even pages"
		echo "- reinserting the stack of sheets for printing the blank sides"
		echo "- printing the odd pages (REVERSE if needed by printer!)"
	fi
	echo "For more than 1 copy, select COLLATE before printing!"
fi

exit 0