#!/bin/sh -e

name="$1"
[ -n "$name" ] || {
    echo "Usage: $0 <output.pdf>"
    exit 1
}
name=$(readlink -f "$name")

D=`mktemp -d`
cd "$D"
echo "Output file directory: $D"
PAGE=0
while true; do
    PAGE=$((PAGE+1))
    scanimage --device-name=genesys --format=png --progress --resolution 150 --mode Gray -x 210 -y 297 | convert -rotate 180 -modulate 120 -level 30,60% - cur.png
    FNAME=page`printf '%02i' $PAGE`
    pngquant 4 < cur.png > $FNAME.png
    convert $FNAME.png $FNAME.pdf
    echo "Insert next page and press Enter; q to stop"
    read x
    [ "$x" = q ] && break || true
done

# pdfmerge does not get along with just one input file
if [ $PAGE -eq 1 ]; then
    mv page*.pdf "$name"
else
    pdfmerge page*.pdf "$name"
fi

rm -rf "$D"