preparePDFComment

#!/bin/bash 

#This is a small script modifying page $2 such as it has double size with the right column empty for comments. It makes use of pdftk and pdfjam. The Outputfile may not be the same as the inputfile

PDFPATH=$1
PAGE=$2
OUTFILE=$3

function modifyPDF { 
        PDFPATH=$1
        PAGE=$2
        OUTFILE=$3
        #three alternatives for extracting the page which has to be edited and adding an empty page
        #pdftk $PDFPATH cat $PAGE output /tmp/editpage.pdf 
        #pdfjam /tmp/editpage.pdf '1,{}' --outfile /tmp/editpage.pdf
        #pdfjam --quiet $PDFPATH "'$PAGE,{}'" --outfile /tmp/editpage.pdf
        #pdfjam --quiet --landscape --nup 2x1 /tmp/editpage.pdf  --outfile /tmp/editpageA3.pdf
        pdfjam --quiet --landscape --nup 2x1 $PDFPATH $PAGE,{} --outfile /tmp/editpageA3.pdf

        NPAGES=$(pdftk $PDFPATH dump_data | /bin/grep -i NumberOfPages | sed 's/[^0-9]*//')

        if [ $PAGE == "1" ]
        then 
                pdftk A=$PDFPATH B=/tmp/editpageA3.pdf cat B A2-end output $OUTFILE
        elif [ $PAGE == $NPAGES ]
        then
                pdftk A=$PDFPATH B=/tmp/editpageA3.pdf cat A1-$(($NPAGES-1)) B output $OUTFILE
        else
                pdftk A=$PDFPATH B=/tmp/editpageA3.pdf cat "A1-$(($PAGE-1))" B "A$(($PAGE+1))-end" output $OUTFILE
        fi

        rm /tmp/editpageA3.pdf
}

function modifyAll {
        PDFPATH=$1
        OUTFILE=$2
        PAGES=""
        NPAGES=$(pdftk $PDFPATH dump_data | /bin/grep -i NumberOfPages | sed 's/[^0-9]*//')
        for ((i=1; i<=$NPAGES; i++))
        do
                PAGES=${PAGES}"$i"",{},"
        done
        # Remove last character
        PAGES=${PAGES%?}
        pdfjam --quiet --landscape --nup 2x1 $PDFPATH $PAGES --outfile $OUTFILE
}

if [ -z "$OUTFILE" ]
then
        OUTFILE="comments.pdf"
fi
        
if [ "$PAGE" = "all" ]
then
        modifyAll $PDFPATH $OUTFILE
else
        modifyPDF $PDFPATH $PAGE $OUTFILE
fi