Use ScanSnap's 'Scan to Searchable PDF' even with PDFs not created by ScanSnap

makeAnyPdfSearchable.rb

#! /usr/bin/env ruby

require 'tmpdir'

def fixed?(fn) fn =~ /\.searchable\.pdf/; end

def searchable_fn(fn)
  return fn if fixed?(fn)
  "#{File.dirname(fn)}/#{File.basename(fn, File.extname(fn))}.searchable.pdf"
end

def have_fix?(fn)
  return false if fixed?(fn)
  return File.exists?(searchable_fn(fn))
end

$fn = ARGV.shift
$fn = searchable_fn($fn) if have_fix?($fn)

def needs_creator_fixed?
  info=`pdfinfo #{$fn.inspect}`.split("\n").
      grep(/Creator/).first !~ /ABBYY FineReader/
end

def fix_creator
  log "Fixing creator"
  Dir.mktmpdir {|d|
    pdftk_desc = "#{d}/pdftk_desc.txt"
    File.open(pdftk_desc, "w") {|w| 
      w.puts(<<EODESC)
InfoKey: Creator
InfoValue: ABBYY FineReader for ScanSnap (Mac edition)
EODESC
    }
    nfn = searchable_fn($fn)
    system "pdftk #{$fn.inspect} update_info #{pdftk_desc} output #{nfn.inspect}"
    $fn = nfn
  }
end

def does_pdf_file_contain_text?
  text=`pdftotext #{$fn.inspect} /dev/stdout`
  text =~ /\w+/
end 

def log(m)
  puts "[#{$0.gsub(/.*?(\w+$)/, "\\1")}] #{m}"
end

def make_searchable
  log "Invoking PDF OCR"
  system "open -a 'Scan to Searchable PDF' #{$fn.inspect}"
end


if !does_pdf_file_contain_text?
  log "Not yet searchable"
  if needs_creator_fixed?
    fix_creator
    raise "Failed to fix creator" if needs_creator_fixed?
  end
  make_searchable
  $stdout.write "Hit enter when OCR is finished..."
  $stdin.gets
end