#!/usr/bin/perl
# Usage: perl enchunk.pl InputDirectory 700MB chunk*
#

use File::Copy;
my $Dir = shift();
my $ChunkSize = shift();
my $OutputName = shift();
my $LenBaseDir = length($Dir) + 1;

my %Units = ("KB"=>1024,"MB"=>1024**2,"GB"=>1024**3,"TB"=>1024**4);
if($ChunkSize =~ /(\d+)(\w+)/){
    $BaseNum = $1;
    $Unit = $2;
    if(!$Units{$Unit}){
	die("Unknown unit \"$Unit\": Try using one of:" . join(",",keys(%Units)) . "\n");
    }
    $ChunkSize = $BaseNum * $Units{$Unit};
}
printf("Chunk size: %d bytes\n", $ChunkSize);

$BytesDone = 0;
$Chunk = 1;
$Files = 0;
GetOutputDir($Dir);
%OkayDirs;

ProcessDir($Dir,0);
printf("Done, %d files, %d chunks\n", $Files, $Chunk);

sub ProcessDir(){
    my ($Dir,$Level) = @_;
    my $Indent = " " x $Level;
    print "Dir: $Indent$Dir\n";
    opendir(my $dp, $Dir) || return;
    while($File = readdir($dp)){
	$FullFile = "$Dir/$File";
	if(-d $FullFile){
	    if($File ne "." && $File ne ".."){
		ProcessDir($FullFile, $Level+1);
	    }
	}
	elsif(-f $FullFile)
	{
	    $BytesDone += -s $FullFile;
	    if($BytesDone >= $ChunkSize){
		$Chunk++;
		GetOutputDir();
		$BytesDone = 0;
	    }
	    $Partial = substr($FullFile, $LenBaseDir);
	    $Output = "$OutputDir/$Partial";
	    CheckCreateDir($Output);
	    copy($FullFile, $Output) || die("$!\n");
	    $Files++;
	}
    }
    closedir($dp);
}

sub GetOutputDir(){
    $OutputDir = $OutputName;
    $OutputDir =~ s/\*/$Chunk/g;
}
sub CheckCreateDir(){
    my $Dir = shift();
    return if($OkayDirs{$Dir});

    @Parts = split(/[\/\\]/, $Dir);
    pop(@Parts);
    $Test = "";
    foreach $Part(@Parts){
	$Test .= "$Part/";
	if(! -d $Test){
	    mkdir($Test);
	    $OkayDirs{$Test} = 1;
	}
    }
}