#!/bin/sh

# InterleaveDoubleSidedBook.sh
# Fri Jun 12 01:29:15 PDT 2009
# Chieh Cheng
# http://www.CynosureX.com/

# GNU General Public License (GPL) Version 2, June 1991

  scriptName=`basename "$0"`

function usage ()
{
  echo "  Usage:   ${scriptName} \"PDF 1\" \"PDF 2\" \"output PDF\""
}

  if [ $# -eq 3 ]
  then
    pdf1="$1"
    pdf2="$2"
    output="$3"

    if [ -f "${pdf1}" ] && [ -f "${pdf2}" ]
    then
      date

      tempDir=`GetTempDirPath.ksh "${scriptName}"`

      echo "Extracting pages from ${pdf1} . . ."
      pdftk "${pdf1}" burst output "${tempDir}/First_%05d.pdf"
      echo "Extracting pages from ${pdf2} . . ."
      pdftk "${pdf2}" burst output "${tempDir}/Second_%05d.pdf"

      cwd=`pwd`
      cd "${tempDir}"

      echo "Interleaving pages from ${pdf1} . . ."
      ls -1 First_*.pdf > "FirstList.txt"
      for file in `cat "FirstList.txt" | sort`
      do
        num=`echo ${file} | sed "s/^.*_//" | sed "s/.pdf//"`
        page=`expr ${num} \* 2 - 1`
        str=`NumberToString.sh ${page} 5`
        mv "${file}" "Page_${str}.pdf"
      done

      echo "Interleaving pages from ${pdf2} . . ."
      page=0
      ls -1 Second_*.pdf > "SecondList.txt"
      for file in `cat "SecondList.txt" | sort -r`
      do
#        num=`echo ${file} | sed "s/^.*_//" | sed "s/.pdf//"`
#        page=`expr ${num} \* 2`
        page=`expr ${page} + 2`
        str=`NumberToString.sh ${page} 5`
        mv "${file}" "Page_${str}.pdf"
      done

      echo "Creating ${output} . . ."
      pages=""
      ls -1 Page_*.pdf > "PageList.txt"
      for file in `cat "PageList.txt" | sort`
      do
        pages="${pages} ${file}"
      done
      pdftk ${pages} cat output "output.pdf"

      cd "${cwd}"
      mv "${tempDir}/output.pdf" "${output}"
      rm -r "${tempDir}"

      date
    else
      "${pdf1} and/or ${pdf2} do not exist."
    fi
  else
    usage
  fi