package ChunkReader;

sub new
{
    my $class = shift;
    my %args  = @_;
    
    $args{threshold} = 2048 
        unless defined $args{threshold};

    return bless {%args}, $class;
}

sub open
{
    my $self = shift;
    my $file = shift || $self->{file};
    
    my $handle;
    
    open $handle, "<", $file
        or die "cannot open '$self->{file}\n'";
        
    $self->{handle} = $handle;
}

sub chunk
{
    my $self = shift;

    my $handle = $self->{handle} || die "File not open!\n";
    my $chunk  = $self->{lastline};
    
    # reset last line
    $self->{lastline} = undef;
    
    while ( my $line = <$handle> )
    {
        if ( ( length($chunk) + length($line) ) > $self->{threshold} ) 
        {
            # unless we already read a chunk 
            # (when a single line is bigger than the threshold)
            unless ( $chunk )
            {
                #return the line 
                return $line;
            }
            else
            {
                # save the last line for further use
                # and return the chunk
                $self->{lastline} = $line;
                return $chunk;
            }
        }
        else 
        {
            # append line and keep going
            $chunk .= $line;
        }
    }
    
    #end of file
    return $chunk;
}

1;