#!/usr/bin/perl -w
# Perl script to CRC32 files and validate them
# Useful for anime stuff...
#
# Copyright (c) 2007, ryan <ryan@paluminum.net> or <yeknod@gmail.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without 
# modification, are permitted provided that the following conditions are met:
#  * Redistributions of source code must retain the above copyright notice, 
#    this list of conditions and the following disclaimer.
#  * Redistributions in binary form must reproduce the above copyright notice, 
#    this list of conditions and the following disclaimer in the documentation 
#    and/or other materials provided with the distribution.
#  * Neither the name of the author nor the names of its contributors may be 
#    used to endorse or promote products derived from this software without 
#    specific prior written permission.
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# run with -h switch for usage instructions and help

use constant VERSION => '0.2';

use Digest;
use Switch;
use File::Find;

# Flags, and global declarations (don't change these, they're set by command line options)
my $scanned = 0;  # files scanned
my $passed  = 0;  # if -v, files that are valid.
my $vidonly = 0;  # only hash/check video files.

my $verify = 0;
my $isfile = 0;
my $isdir  = 0;

my $dirname = "";
my $filename = "";
my $outfile = "";

if( $#ARGV == -1 ) {
  &show_usage;
  exit;
}

for( my $i=-1; $i<$#ARGV; $i++ ) {
  my $cur = $ARGV[$i];
  switch($cur) {
    case "-v" { $verify = 1; }
    
    case "-d" {
      if( $isfile || $isdir ) { last }; 
      $isdir = 1;
      $dirname = $ARGV[++$i];
      (-d $dirname) or die "Directory $dirname does not exist!\n";
    }

    case "-f" {
      if( $isfile || $isdir ) { last };
      $isfile = 1;
      $filename = $ARGV[++$i];
      (-f $filename) or die "File $filename does not exist!\n";
    }

    case "-h" {
      &show_usage;
      exit;
    }

    case "-o" {
      $outfile = $ARGV[++$i];
      if( !(-e $outfile) ) {
        open( OUT, ">$outfile" );
        close(OUT);
      }
    }

    case "-vid" {
      $vidonly = 1;
    }

  }
} 

# Do the actual stuff here:
if( $isfile ) {
  &check_file($filename);
} elsif( $isdir ) {
  find(\&scan_directory, $dirname);
  &output("\n$scanned files hashed.\n");
  ($verify && $scanned > 0) && &output("$passed/$scanned files are valid (" . ($passed/$scanned)*100 . "%)\n");
}

#####  Subroutines for doing stuff  #####

sub crc32 {
  my ($file) = @_;
  open( FILE, $file );
  my $dig = Digest->new("CRC-32");
  $dig->addfile(FILE);
  close FILE;
  return uc($dig->hexdigest());
}

sub check_file {
  my ($file) = @_;
  return unless ((-f $file));

  if( $vidonly && !($file =~ /(\.avi|\.mkv|\.ogm|\.mp4|\.wmv)$/i) ) {
    return;
  }

  &output("Hashing $file... ");
  my $hash = crc32($file);
  &output($hash);
  if( $verify && $file =~ /\[([0-9ABCDEF]{8})\]/ ) {
    &output (" ... ");
    if( $file =~ /\[$hash\]/i ) {
      &output ("OK!");
      $passed++;
    } else {
      &output ("FAILED!");
    }
  }
  &output( "\n" );
  $scanned++;
}

sub scan_directory {
  my $arg = $_;
  if( !(-d $arg) ) { 
    &check_file($arg);
  } elsif( -d $arg ) {
    &output ("\nStepping into " . $File::Find::name . "...\n");
  }
}

sub show_usage {
  my $ver = VERSION;
  print <<USAGE;
 Ryan's CRC32 checker $ver
 usage:  $0 <options>
 options:
   -f <file>       Get the CRC32 of a file
   -d <directory>  Get the CRC32 of all files in a directory 
   -v              Verifies the CRC32 value by checking the filename for a match
   -vid            Only check video files (avi, mkv, ogm, mp4, wmv)
   -o <file>       Output to file (appends)
 example:
   $0 -v -f [Conclave-Mendoi]_ef_-_a_tale_of_memories_05_[H264][1C06C6C4].mkv
USAGE
}

sub output {
  my ($arg) = @_;
  if( $outfile ne "" ) {
    open( OUT, ">>$outfile" );
    print OUT $arg;
    close(OUT);
  } else {
    print $arg;
  }
}