#!/usr/bin/perl

use 5.14.0;
use strict;
use warnings;
use Cwd qw(abs_path);
use File::Basename qw(basename);
use File::Copy qw(copy);
use POSIX qw(ceil);

sub usage {
	say "Usage: " . basename($0) . " [ infile ] [ outdir ]";
	exit;
}

if (!$ARGV[0] || !$ARGV[1]) { usage(); }
elsif (! -f $ARGV[0] || ! -d $ARGV[1]) { usage(); }

my $limit = int((4294967295 / 1024 / 1024));
my $infile = abs_path($ARGV[0]);
my $outfile;
my $outdir = abs_path($ARGV[1]);

chomp(my @free = split(' ',
`df --block-size=1 "$outdir" | tail --lines 1`));
my $free = int(($free[3] / 1024 / 1024));
my $size = ceil(((stat($infile))[7] / 1024 / 1024));

say "$free megabytes free in $outdir";
say "$infile is $size megabytes";

if ($size > $free) {
	say "Not enough free space in '$outdir'";
	exit;
}

if ($size > $limit) {
	my $parts = ceil(( $size / $limit ));
	my $last = $parts;
	my $skip = 0;
	foreach my $n (1 .. $parts) {

		$outfile = $outdir . '/' . basename($infile) . '.part' .
		$n;

		if (-f $outfile) {
			say "${outfile}: already exists!";
			exit;
		}

		say "${outfile}: writing...";

		if ($n == 1) {
			system('dd', 'if=' . "$infile", 'of=' . "$outfile",
			'bs=1MB', 'count=' . $limit);
			$skip += $limit;
		} elsif ($n == $last) {
			system('dd', 'if=' . "$infile", 'of=' . "$outfile",
			'bs=1MB', 'skip=' . "$skip");
		} else {
			system('dd', 'if=' . "$infile", 'of=' . "$outfile",
			'bs=1MB', 'skip=' . "$skip", 'count=' . $limit);
			$skip += $limit;
		}

		if ($? != 0 && $? != 2) {
			say "Something went wrong with 'dd': $!";
			exit;
		}
	}
} else {
	$outfile = $outdir . '/' . basename($infile);

	if (! -f $outfile) {
		say "${outfile}: writing...";
		copy($infile, $outfile) or die "Can't copy '$infile': $!";
	} else { say "${outfile}: already exists!"; exit; }
}

say "\nDone copying file!";