#!/path/to/perl -w
use strict;

if($#ARGV!=1){
	&usage();
	exit(1);
}

my $filename=$ARGV[0];
my $parts=$ARGV[1];

my $totallength = &getsize($filename);
my @part = &calculateparts($totallength, $parts);
&readfile($filename, @part);

exit(0);

sub getsize{
	# Read file and get it's TOTAL size
	 open(FILE, $filename)         or die "can't open $filename: $!";
	 binmode(FILE);               
	 binmode(STDOUT);            
	 my $totallength=0;
	 while (read(FILE, my $buff, 8 * 2**10)) {
	 	$totallength = $totallength + length $buff;
	 }
	 close (FILE) || die "Can't close\n";
	 return $totallength;
}

sub calculateparts{
	# Calculate how many parts are needed
	# and how many bytes should be in each part
	my ($totallength, $parts) = @_;
	my $bytecount = $totallength/$parts;
	if ($bytecount == int $bytecount){
		for (my $count=1; $count <= $parts; $count++){
#			print "Part number $count will be $bytecount bytes long\n";
			$part[$count] = $bytecount;
		}
	} else {
		my $difference = $totallength - int ($bytecount) * $parts;
		my $addition = int ($bytecount) + 1;
		for (my $count=1; $count <= $parts; $count++){
			if ($difference > 0){
#				print "Part number $count will be $addition bytes long\n";
				$part[$count] = $addition;
				$difference--;
			} else {
#				print "Part number $count will be " . int ($bytecount) . " bytes long\n";
				$part[$count] = $bytecount;
			}
		}
		
	}
	return @part;
}

sub readfile{
	my ($filename, @part) = @_;
	my $filename2 = $filename;
	$filename2 =~(s/(.*)\..*/$1/);
	my $count=1;
	open (IN,"$filename")    || die "can't open $filename for reading $!";
	while(<IN>) {
		my $rv = read(IN, my $buffer, 4096) || die "Couldn't read from $filename $!\n";
		# $rv is the number of bytes read,
		# $buffer holds the data read
		if (!$part[$count]) {last;}		
#print "part[count] is $part[$count]\n";
#		if ($rv != $part[$count]){print "Number of bytes read:  $rv\n";}
		my $filename3 = "$filename2.$count";
		open (OUT, ">$filename3");
			print OUT $buffer;
		close (OUT);
		my $pos = tell(IN);
		print "I'm $pos bytes from the start of $filename.\n";
		$count++;
	}
	close(IN)  || die "Can't close $filename:$!";
}

sub usage{
	$0 =~(s/.*\\(.*)\..*/$1/);
	my $Filename = uc($0);
	if ($^O =~ /Win/) { system"CLS"; } else { system"CLEAR";}
	print "\nUSAGE:\n";
	print "\n\t$Filename <filename> <parts>\n";
	print "\twhere:\n\n";
	print "\t<filename> is the file to be chopped\n";
	print "\t<parts> are the number of pieces to chop it into\n";
	print "\n";
	print "\tERRORLEVEL is set to 0 on Normal Exit\n";
}