#!/usr/bin/perl

# Accept two PDFs as input.
# Base = the baseline PDF
# Test = the new PDF that is being tested.
# Turn the PDFs into images using Ghostscript,
# then use imagemagick to compare and highlight differences
# Turn the resulting images into a PDF and concatenate them.

# Sample usage:
#   ./pdfcomp.pl -basefile LGNP.FIN.WFG1911.STND.OUTPDF.PDF -testfile LGNT.FIN.WFG1911.STND.OUTPDF.PDF

use warnings;
use strict;
use Getopt::Long;
use File::Path;
use Parallel::ForkManager;
my $pm = new Parallel::ForkManager ( 3 );

my $maxFuzz = 100;    # The biggest fuzz factor I'm willing to accept.
my $fileName_Base   = "NULL";
my $fileName_Test   = "NULL";
my $numPages        = 0;    # How many pages should I compare? If value is left at 0, I default to looking at all pages.
my $baseStart       = 1;    # What page of the base file should I start looking at?
my $testStart       = 1;    # What page of the test file should I start looking at?
my $noClean;                  # Clean up the test and base images after comparing them?
my $noLog;                    # Don't write to the log file. This isn't implemented yet.
my $logFile         = "pdfcomp.log";
my $outFile         = "pdfcomp.pdf";
my $verbose;          # If set, then don't tell ghostscript to be quiet, don't add "-q" flag.
my $fuzzFactor  = 0;  # how much of a fuzz factor to tell Imagemagic to apply when doing the compare
my $chunkSize   = 100;# how many pages to compare at a time
my $pixelThreshold = 0; # How many pixels can be differnt in images before a diff PDF is created for the pages.
my $forkOkay;         # Use forking. Makes the standard output and log a mess, but can speed up compare on large files
my $printHelp;        # Print a "usage" statement describing inputs


# Grab the command line arguments so they can be printed to the log
#
my $cmdParms = " ";
my $numArgs = $#ARGV;
foreach my $argnum (0 .. $#ARGV) {
   #print "@ARGV[$argnum]\n";
   $cmdParms = $cmdParms . $ARGV[$argnum] . " ";
}

# Set internal variables using the command line options
#
GetOptions
(
 "basefile=s"  => \$fileName_Base,
 "testfile=s"  => \$fileName_Test,
 "numpages=s"  => \$numPages,
 "basestart=s" => \$baseStart,
 "teststart=s" => \$testStart,
 "logname=s"   => \$logFile,
 "noclean"     => \$noClean,
 "nolog"       => \$noLog,
 "outfile=s"   => \$outFile,
 "verbose"     => \$verbose,
 "fuzz=s"      => \$fuzzFactor,
 "chunksize=s" => \$chunkSize,
 "pixelcnt=s"  => \$pixelThreshold,
 "fork"        => \$forkOkay,
 "help"        => \$printHelp
);


# Print out "usage" statement
#
if ( ( $printHelp ) or ( $fileName_Base eq "NULL" ) or ( $fileName_Test eq "NULL" ) )
{
    print "Usage: pdfcomp.pl -basefile=filename -testfile=filename -numpages=# -basestart=# \n";
    print "-teststart=# -logname=filename -noclean -nolog -outfile=filename -verbose\n";
    print "-chunksize=# -fork -help\n\n";
    print "-basefile:   The baseline file to test against. Prompted if missing.\n";
    print "-testfile:   The new file being tested. Prompted if missing.\n";
    print "-numpages:   The number of pages to compare. Optional, default is all pages.\n";
    print "-basestart:  Which page to start comparing in the base file. Optional, defaults to first page.\n";
    print "-teststart:  Which page to start comparing in the test file. Optional, defaults to first page.\n";
    print "-logname:    Over ride the default log file name. Optional, defaults to $logFile.\n";
    print "-nolog:      Don't print a log file. Optional.\n";
    print "-noclean:    Don't clean up the intermediate image and PDF files in the images directory. Optional.\n";
    print "-outfile:    Over ride the default pdf output file name. Optional, defaults to $outFile.\n";
    print "-verbose:    Print a lot more information to the screen and log file. Optional.\n";
    print "-chunksize:  Over ride the default number of pages per a loop. Optional, defaults to $chunkSize.\n";
    print "-pixelcnt:   When comparing pages, how many pixels must be different to have a diff PDF created.\n";
    print "             Optional, defaults to 0.\n";
    # print "-fork:       Okay to use forking to speed up processing large files. Optional.\n";
    print "-help:       Print this usage statement. Optional\n\n";
}

# Check for the input BASE and TEST file.
#
if ( $fileName_Base eq "NULL" )
{
    print "What is the name of the BASE file? ";
    $fileName_Base = <STDIN>;
    chomp $fileName_Base;
}
die "I can't find the input file $fileName_Base." unless ( -e $fileName_Base );

if ( $fileName_Test eq "NULL" )
{
    print "What is the name of the TEST file? ";
    $fileName_Test = <STDIN>;
    chomp $fileName_Test;
}
die "I can't find the input file $fileName_Test." unless ( -e $fileName_Test );

# Detect if input files are PDF or Postscript
#
my $baseHeadCommand = "head -n 1 $fileName_Base";
my $testHeadCommand = "head -n 1 $fileName_Test";
my $baseLineOne = `$baseHeadCommand`;
my $testLineOne = `$testHeadCommand`;
my $fileTypeBase = "NULL";
my $fileTypeTest = "NULL";

if ( $baseLineOne =~ /PDF-/ )
{
  $fileTypeBase = "pdf";
}
elsif ( $baseLineOne =~ /PS-Adobe-/ )
{
  $fileTypeBase = "ps";
}
else
{
  $fileTypeTest = "INVALID";
  print "Unknown file type: $testLineOne\n";
  die ( "I give up.\n" );
}

if ( $testLineOne =~ /PDF-/ )
{
  $fileTypeTest = "pdf";
}
elsif ( $testLineOne =~ /PS-Adobe-/ )
{
  $fileTypeTest = "ps";
}
else
{
  $fileTypeTest = "INVALID";
  print "Unknown file type: $testLineOne\n";
  die ( "I give up.\n" );
}


# Validation of input variables.
#
#print "fuzzFactor=$fuzzFactor\n";
if ( $fuzzFactor > $maxFuzz )
{
  print "Fuzz Factor of $fuzzFactor is too high, I'm reseting it to $maxFuzz.\n";
  $fuzzFactor = $maxFuzz;
}
if ( $fuzzFactor < 0 )
{
  print "Fuzz Factor of $fuzzFactor is too low, I'm reseting it to 0.\n";
  $fuzzFactor = 0;
}

# Test that I can write to the current directory
#
open ( TEMP, ">pdfcompTemp$$.txt" ) || die ( "ABEND: Error opening temp file, make sure you run this job from a file system you have permission to write to. Error: $!" );
print TEMP "Making sure I can create files on the current file system. If you see this than I can.\n";
close ( TEMP );
unlink "pdfcompTemp$$.txt";


# Open the log file
#
unless ( $noLog )
{
    print "Opening log file $logFile.\n";
    open( STDOUT, "| tee $logFile" ) or die "Failed to dup STDOUT to $logFile: $!";
    open( STDERR, ">&STDOUT" ) or die "Failed to dup STDERR: $!";
}

print "Command line parameters: $cmdParms\n";;
$|++;


# Look at input PDFs, find page counts.
#
my $basePageCnt = 0;
my $testPageCnt = 0;
if ( $fileTypeBase eq "pdf" )
{
  print "Using pdfinfo to find the page count for $fileName_Base, this could take a while...\n";
  my $pdfcommand = "pdfinfo $fileName_Base | grep '^Pages:'";
  $basePageCnt = `$pdfcommand`;
  $basePageCnt =~ /Pages:\s*(\d+)/;
  $basePageCnt = $1;
  print "Base PDF page count: $basePageCnt\n";
}
elsif ( $fileTypeBase eq "ps" )
{
  print "Using grep to find the page count of the Postscript, this could take a while...\n";
  my $pdfcommand = "grep -c %%Page:  $fileName_Base";
  $basePageCnt = `$pdfcommand`;
  print "Base PS page count: $basePageCnt\n";
}
else
{
  print "Unknown file type, I'm quiting: $fileTypeBase.\n";
  die;
}

if ( $fileTypeTest eq "pdf" )
{
  print "Using pdfinfo to find the page count for $fileName_Test, this could take a while...\n";
  my $pdfcommand = "pdfinfo $fileName_Test | grep '^Pages:'";
  $testPageCnt = `$pdfcommand`;
  $testPageCnt =~ /Pages:\s*(\d+)/;
  $testPageCnt = $1;
  print "Base PDF page count: $testPageCnt\n";
}
elsif ( $fileTypeTest eq "ps" )
{
  print "Using grep to find the page count for $fileName_Test, this could take a while...\n";
  my $pdfcommand = "grep -c %%Page:  $fileName_Test";
  $testPageCnt = `$pdfcommand`;
  print "Test PS page count: $testPageCnt\n";
}
else
{
  print "Unknown file type, I'm quit: $fileTypeTest.\n";
  die;
}

$basePageCnt += 0;
$testPageCnt += 0;
print "WARNING: Base and Test PDFs do not have the same number of pages: Base:$basePageCnt, Test:$testPageCnt.\n" unless ( $basePageCnt eq $testPageCnt );
print "WARNING: BASE PDF has less pages then you asked to be compared.\n"   unless ( $basePageCnt >= $numPages );
print "WARNING: TEST PDF has less pages then you asked to be compared.\n"   unless ( $testPageCnt >= $numPages );


# Deciding the range of pages to compare.
#
if ( ( $numPages == "0" ) or ( $numPages > ( $basePageCnt + $baseStart )  ) or ( $numPages > ( $testPageCnt + $testStart) ) )
{
    $numPages = $basePageCnt;
    if ( $testPageCnt < $basePageCnt )
    {
        $numPages = $testPageCnt;
    }
}

print "I have decided to compare $numPages pages.\n";
my $baseStop = $baseStart + ( $numPages - 1 );
my $testStop = $testStart + ( $numPages - 1 );
print "For the BASE file I will be looking at page $baseStart through $baseStop.\n";
print "For the TEST file I will be looking at page $testStart through $testStop.\n";

# Clean up any previous runs
#
my $imageDir = "images";
if ( -d "./$imageDir" )
{
    print "\nI found a previous $imageDir directory. I am deleting it and all the files in it...\n";
    rmtree( $imageDir, 0, 1);
}
mkdir "$imageDir";


# Convert the PDFs to Images
#
my $quietFlag;
if ( $verbose )
{
  $quietFlag = " ";             # if "verbose" then don't pass in the "be quit" flag to ghost script
}
else
{
  $quietFlag = " -q ";
}

# Calculate how many pages the current loop should look at
#
#print "numPage:$numPages\n";
#print "chunkSize:$chunkSize\n";
if ( $numPages <  $chunkSize )
{
  $chunkSize = $numPages - 1;    #  Make sure the chunksize isn't larger then the actual number of pages
}

if ( ( $fileTypeBase eq "ps" ) or ( $fileTypeTest eq "ps" ) )
{
  $chunkSize = $testPageCnt - 1;
  print "* Postscript files cannot be compared in pieces, I have to compare the whole file.\n";
}

if ( $verbose ) { print "chunkSize:$chunkSize\n"; }

# base start and stop
my $curBaseStart   = $baseStart;                   if ( $verbose ) { print "curBaseStart:$curBaseStart\n"; }
my $curBaseEnd   = $baseStart + $chunkSize - 1;        if ( $verbose ) { print "curBaseEnd:$curBaseEnd\n"; }

# test start and stop
my $curTestStart = $testStart;                     if ( $verbose ) { print "curTestStart:$curTestStart\n"; }
my $curTestEnd   = $testStart + $chunkSize - 1;        if ( $verbose ) { print "curTestEnd:$curTestEnd\n"; }

# set up loop variables
my $loopCnt = 0;
my $diffCnt  = 0;           # Count of the number of pages found with differences
my $pdfList  = " ";     # List of the pdf pages that had differences, used by Ghostscript to create one big final pdf.

while ( $curBaseEnd <= $baseStop )
{
  $loopCnt++;
  print "\n***Loop $loopCnt\n";


  # Make sure the current chunks stop pages are not greater then the
  # end page the user asked for.
  #
  if ( $curBaseEnd > $baseStop )
  {
    $curBaseEnd = $baseStop;
  }
  if ( $curTestEnd > $testStop )
  {
    $curTestEnd = $testStop;
  }

  # Fork to run the two Ghost scripts in seperate threads
  #
#  if ( $forkOkay )
  # {
    # Forks and returns the pid for the child:
#    my $pid = $pm->start and next;
#  }


  # For the two Ghostscripts so the can run together.
  # For BASE and TEST turn the current chunk of pages into images
  #
  if ( $verbose ) { print "Forking to run both ghostscript commands."; }
  my $pid = fork();
  if ( not defined $pid )
  {
    die ( "I was unable to fork: $!")
  }
  elsif ( $pid == 0 )
  {
    # I am the child process.
    my $gsCommand = "gs" . $quietFlag . "-dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 -dFirstPage#$curBaseStart -dLastPage#$curBaseEnd -sOutputFile=./$imageDir/base_chunk${loopCnt}_%05d.png $fileName_Base";
    if ( $verbose )
    {
      print "\nConverting BASELINE PDFs to images: $gsCommand\n";
    }
    else
    {
        print "\nRunning ghostscript on BASE file.";
    }
    system "$gsCommand";
    if ( $verbose ) { print "ghostscript is finished converting BASE, chunk $loopCnt, pdf to images.\n"; }
    exit(0);
  }
  else
  {
    # I am the parent process.
    my $gsCommand = "gs" . $quietFlag . "-dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 -dFirstPage#$curTestStart -dLastPage#$curTestEnd -sOutputFile=./$imageDir/test_chunk${loopCnt}_%05d.png $fileName_Test";
    if ( $verbose )
    {
      print "\nConverting TEST PDFs to images: $gsCommand\n";
    }
    else
    {
        print "\nRunning ghostscript on TEST file.\n";
    }
    system "$gsCommand";
    if ( $verbose ) { print "ghostscript is finished converting TEST, chunk $loopCnt, pdf to images.\n"; }
    waitpid($pid,0);
  }

  # if ( $forkOkay )
  # {
  # $pm->finish; # Terminates the child process
  #}


  # Loop through the images using ImageMagick to look for differences
  #
  my $imageCnt = 0;     # Loop counter
  my $chunkTotalCnt = $curBaseEnd - $curBaseStart + 1; # For last chunk this won't be the chunk size

  for ( $imageCnt = 1; $imageCnt <= $chunkTotalCnt; $imageCnt++ )
  {
    my $numSufix = sprintf( "%05d", $imageCnt ); # recreate the file sufix numbers coming out of the ghostscript commands.

    # recreate the file names coming out of Ghostscript, make a similar name for difference PDF
    #
    my $file_base = "./$imageDir/base_chunk${loopCnt}_" . $numSufix . ".png";
    my $file_test = "./$imageDir/test_chunk${loopCnt}_" . $numSufix . ".png";
    my $file_diff = "./$imageDir/diff_chunk${loopCnt}_" . $numSufix . ".png";

    # Find the md5sum for the current base and test page
    #
    my $md5Command = "md5sum $file_base";
    my $base_md5 = `$md5Command`;
    my @base_md5_array = split(/ /, $base_md5 );
    #print "base_md5: $base_md5_array[0]\n";

       $md5Command = "md5sum $file_test";
    my $test_md5 = `$md5Command`;
    my @test_md5_array = split(/ /, $test_md5 );
    #print "test_md5: $test_md5_array[0]\n";

    #  If md5sum is the same, don't bother making a compare image
    #  else, make the compare image.
    #
    my $curPagecnt = $curBaseStart + $imageCnt - 1;   # the current pages number in the full file, not just this chunk

    if ( $base_md5_array[0] eq $test_md5_array[0] )
    {
      #print "$i: Base page $numBase and test page $numTest have same md5sum, skipping compare.\n";
      #if ( $verbose )
      #{
        print  "$curPagecnt: Same md5sum, not comparing.\n";
      #}
      #print LOG "$i: Same (md5sum)\n";
    }
    else
    {
      #my $imCommand = "/apps/ImageMagick-6.3.9/bin/compare -metric AE $file_base $file_test -highlight-color Red $file_diff";
      my $imCommand = "/apps/ImageMagick-6.3.9/bin/compare -metric AE -fuzz " . $fuzzFactor . "% $file_base $file_test $file_diff";
      #print "$i: Comparing: $imCommand\n";
      print "$curPagecnt: Comparing...";
      my $imDiff = `$imCommand 2>&1 1>/dev/null`;       # grab the STDOUT get the number of different pixels. Throw the STDERR away.
      chomp $imDiff;
      #system  "$imCommand";
      print "Pages differ by $imDiff pixels, ";

      if ( $imDiff == $pixelThreshold )
      {
          print "below threshold of $pixelThreshold\n";
          unless ( $noClean )
          {
            if ( $verbose ) {   print "     Deleting the compare image.\n"; }
            unlink $file_diff unless ( $noClean );
          }
      }
      else
      {
        $diffCnt++;
        print "creating diff pdf\n";
        my $convertCmd = "/apps/ImageMagick-6.3.9/bin/convert $file_diff $file_diff.pdf";
        #print $convertCmd . "\n";
        system ( $convertCmd );
        $pdfList = $pdfList . " $file_diff.pdf";
        #print LOG "$i: differnt. (pixel cnt=$imDiff)\n";
      } # end else ( imagemagic found image differences.
    } # end else (md5 didn't match
  } # end for (looping through current chunks images)


  # Update the current chunks counts so the loop can look at the next chunk.
  #
  $curBaseStart = $curBaseEnd + 1;
  $curTestStart = $curTestEnd + 1;
  $curBaseEnd += $chunkSize;
  $curTestEnd += $chunkSize;

 #if ( $forkOkay )
  #{
    $pm->finish; # Terminates the child process
  #}
}

print "$diffCnt of $numPages pages had differences.\n";

# Concatenating all the Pdfs into one
#
if ( $diffCnt > 0 )
{
    print "Creating difference pdf $outFile.\n";
    my $catCmd = "gs -q -sPAPERSIZE=letter -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=$outFile $pdfList";
    system ( $catCmd );
}
else
{
    print "All pages match. I'm not creating a difference pdf.\n";
}


# Delete the base and test images for current page
#
unless ( $noClean )
{
    print "\nRemoving intermediate files.\n";
    rmtree( $imageDir, 0, 1);
}

print "\nDone.\n";