#!/bin/bash

function help () {
   echo "Usage: $0 <inputfile> [<outputfile>]"
   echo "Takes a pdf file, removes any vertical scanner lines, and outputs it as output.pdf if not otherwise specified"
   echo " -e     remove lines on even pages. First page is page 0 (even)"
   echo " -o     remove lines on odd pages. First page is page 0 (even)"
   echo " -a     remove lines on all pages"
   echo " -c     increase contrast of pdf file"
   echo " -h     display this output"
   exit 1
}

while getopts 'eoaclh' opt ; do
   case "$opt" in
#      v) verbosity=VERBOSE ;;
#      q) verbosity=QUIET;;
      e) even='true';;
      o) odd='true';;
      a) even='true'; odd='true';;
      c) contrast='true';;
      h) help ;;
   esac
done

input_file=${@:$OPTIND:1}
output_file=${@:($OPTIND +1):1}
output_file=${output_file:-'output.pdf'}

if [ -z "$input_file" ]; then
   help
fi

tmp_dir=$(mktemp -d -t processor-images-XXXXX)

pdfimages -j "$input_file" "$tmp_dir/page"

for file in "$tmp_dir"/page-*.jpg
do
   filename="${file##*/}"
   page_nr="${filename:5:3}"
   page_nr=$(echo $page_nr | sed 's/^0*//') # Remove leading zeros
   if [ -z "$page_nr" ]
   then
      page_nr=0
   fi

   echo "Pagenr: $page_nr"
   if [ "$contrast" = 'true' ]
   then
      echo "Increase contrast"
      mogrify -level 25% $file
   fi

   page_even='true'; [ $((page_nr%2)) -eq 1 ] && page_even='false'
   if ( [ "$page_even" = 'true' ] && [ "$even" = 'true' ] ) || ( [ "$page_even" = 'false' ] && [ "$odd" = 'true' ] )
   then
      echo Remove line
      mogrify -morphology bottomhat "1x100:0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0" -negate $file
   fi
done

convert $tmp_dir/page-*.jpg "$output_file"
rm -rf $tmp_dir
echo "Done! Saved output to $output_file"