#!/bin/sh
#---------------
# A parametrized replacement for psnup -2 using pstops.
#
# The script computes bounding boxes using gs and deduces optimized reductions
# on two pages per sheet with given margins or scaling. Pages can be arranged
# for various kinds of folding or binding.
#---------------
# Requires: gs, bc, pstops, psbook, pdftops
#---------------

VERSION=2009-12-02

# Output parameters

PAPER=a4
WIDTH=597   # 210mm
HEIGHT=845  # 297mm
MARGIN=30
INNER=1
SCALE=
TWO=false
BIND=top
BBRANGE=-
SIG=
IN=
OUT=
DASHQ=-q
VERBOSE=false
BB_ODD=
BB_EVEN=

# Parse the command line

while [ $# -gt 0 ]; do
	case "$1" in
	--help)
		cat <<EOF
usage: livre.sh [options] input output
The input can be in PostScript or PDF, possibly gzipped.
options:
  --margin SIZE    compute scaling to get SIZE-point margins (default: 30)
  --scale FACTOR   use the given scaling FACTOR (overrides --margin)
  --inner FACTOR   set inner margin to FACTOR times the outer one (default: 1)
  --two            input is two-sided
  --top            output should be bound at the top (default)
  --left           output should be bound on the left
  --book           output should be folded into a booklet
  --sig N          select the signature for psbook (implies --book)
  --bbrange PAGES  only use the specified PAGES for bounding box computation
  --bbox BBOX      provide the bounding box explictly, disable its computation
                     (use this twice if the input is two-sided)
  --verbose        do not use quiet mode
  --version        print version number and exit
EOF
		exit 0
		;;
	--version)
		echo $VERSION
		exit 0
		;;
	--margin)
		shift
		MARGIN="$1"
		;;
	--scale)
		shift
		SCALE="$1"
		;;
	--inner)
		shift
		INNER="$1"
		;;
	--two*)
		TWO=true
		;;
	--top|--left|--book)
		BIND=${1#--}
		;;
	--sig)
		shift
		SIG="-s$1"
		BIND=book
		;;
	--bbrange)
		shift
		BBRANGE="$1"
		;;
	--bbox)
		shift
		if [ -z "$BB_ODD" ]; then
			BB_ODD="$1"
		else
			TWO=true
			BB_EVEN="$1"
		fi
		;;
	--verbose)
		DASHQ=
		VERBOSE=true
		;;
	-*)
		echo "unknown option: $1" >&2
		exit 1
		;;
	*)
		if [ -z "$IN" ]
		then IN="$1"
		elif [ -z "$OUT" ]
		then OUT="$1"
		else echo "unused argument: $1" >&2
		fi
	esac
	shift
done

if [ -z "$IN" ]; then
	echo "missing input file" >&2
	exit 1
fi

# Make a teporary file if needed

TMP=

make_ps ()
{
	case $(file -bL "$IN") in
	"PostScript document"*)
		;;
	"PDF document"*)
		$VERBOSE && echo "converting to PS..." >&2
		TMP2=$(mktemp)
		pdftops "$IN" "$TMP2"
		test -n "$TMP" && rm "$TMP"
		TMP="$TMP2"
		IN="$TMP"
		;;
	"gzip compressed "*)
		$VERBOSE && echo "unzipping..." >&2
		TMP2=$(mktemp)
		gunzip < "$IN" > "$TMP2"
		test -n "$TMP" && rm "$TMP"
		TMP="$TMP2"
		IN="$TMP"
		make_ps
		;;
	*)
		echo "Unknown file type!" >&2
		exit 1
	esac
}

make_ps

# Extract the bounding box for all pages of a given file.

read_bbox()
{
	gs -sDEVICE=bbox -sPAPERSIZE=$PAPER -r300x300 -q -dBATCH -dNOPAUSE "$1" 2>&1 | awk '
function min(x,y) { if (x < y) return x; else return y }
function max(x,y) { if (x > y) return x; else return y }
BEGIN {
	left = top = 10000;
	right = bottom = 0
}
/%%BoundingBox:/ {
	left = min(left, $2);
	top = min(top, $3);
	right = max(right, $4);
	bottom = max(bottom, $5);
}
END { print left, top, right, bottom }
'
}

# Compute the maximum scaling factor given the bounding box

max_scale()
{
	bc <<EOF
scale = 3
hfactor = (($HEIGHT - (2 + $INNER) * $MARGIN) / 2) / ($3 - $1)
vfactor = ($WIDTH - 2 * $MARGIN) / ($4 - $2)
if (hfactor < vfactor) print hfactor else print vfactor
EOF
}

# Make a pstops specification

spec_left()
{
	bc <<EOF
scale = 3
factor = $1
shift_x = $WIDTH / 2 + ($3 + $5) * factor / 2
vmargin = ($HEIGHT - 2 * ($4 - $2) * factor) / (2 + $INNER)
shift_y = vmargin - $2 * factor + $6 * (($4 - $2) * factor + $INNER * vmargin)
print "L@", factor, "(", shift_x, ",", shift_y, ")"
EOF
}

spec_right()
{
	bc <<EOF
scale = 3
factor = $1
shift_x = $WIDTH / 2 - ($3 + $5) * factor / 2
vmargin = ($HEIGHT - 2 * ($4 - $2) * factor) / (2 + $INNER)
shift_y = vmargin + $4 * factor + $6 * (($4 - $2) * factor + $INNER * vmargin)
print "R@", factor, "(", shift_x, ",", shift_y, ")"
EOF
}

# Compute the bounding boxes for even and odd pages

if [ -z "$BB_ODD" ]; then
	$VERBOSE && echo "computing the bounding box..." >&2
	if $TWO; then
		BB_ODD=$(psselect -o -p"$BBRANGE" "$IN" 2>/dev/null | read_bbox -)
		BB_EVEN=$(psselect -e -p"$BBRANGE" "$IN" 2>/dev/null | read_bbox -)
	else
		if [ "$BBRANGE" = "-" ]; then
			BB_ODD=$(read_bbox "$IN")
		else
			BB_ODD=$(psselect -p"$BBRANGE" "$IN" 2>/dev/null | read_bbox -)
		fi
	fi
fi

test -z "$BB_EVEN" && BB_EVEN="$BB_ODD"

if $VERBOSE; then
	if $TWO; then
		echo "bounding box (odd): $BB_ODD"
		echo "bounding box (even): $BB_ODD"
	else
		echo "bounding box: $BB_ODD"
	fi
fi
		

# Deduce the scaling factor if needed

if [ -z "$SCALE" ]; then
	if $TWO; then
		SCALE=$(bc <<EOF
scale=3
s1=$(max_scale $BB_ODD)
s2=$(max_scale $BB_EVEN)
if (s1 < s2) print s1 else print s2
EOF
)
	else
		SCALE=$(max_scale $BB_ODD)
	fi
fi
	
$VERBOSE && echo "scale: $SCALE" >&2

# Process the file according to the chosen style

command()
{
	$VERBOSE && echo "-- $*"
	$*
}

case $BIND in
top)
	command pstops $DASHQ -p$PAPER "2:\
0$(spec_left $SCALE $BB_ODD 0)+1$(spec_left $SCALE $BB_EVEN 1)" "$IN" "$OUT"
	;;
left)
	command pstops $DASHQ -p$PAPER "4:\
0$(spec_left $SCALE $BB_ODD 0)+1$(spec_left $SCALE $BB_EVEN 1),\
2$(spec_right $SCALE $BB_ODD 1)+3$(spec_right $SCALE $BB_EVEN 0)" "$IN" "$OUT"
	;;
book)
	psbook $DASHQ $SIG $IN | command pstops $DASHQ -p$PAPER "4:\
0$(spec_left $SCALE $BB_EVEN 0)+1$(spec_left $SCALE $BB_ODD 1),\
2$(spec_right $SCALE $BB_EVEN 1)+3$(spec_right $SCALE $BB_ODD 0)" /dev/stdin "$OUT"
esac

test -n "$TMP" && rm "$TMP" || true