#!/usr/bin/env bash

TMP_DIR=$(mktemp -d -p "" emulate_duplex_scan.XXXXXXXXXX)

cleanup()
{
  rm -rf "$TMP_DIR" 
} 
trap cleanup EXIT

help()
{
   echo "$(basename $0) PDF-sourcefile_A PDF-sourcefile_B PDF-destfile"
}

ARGC=$#

file_A=$1
file_B=$2
output_file=$3

if [ $ARGC -ne 3 ]; then
   help
   exit 1
fi

pdfseparate "$file_A" $TMP_DIR/scan-separated-%d-A.pdf
pdfseparate "$file_B" $TMP_DIR/scan-separated-%d-B.pdf

pdfunite $TMP_DIR/scan-separated-*-*.pdf "$output_file"