#!/usr/bin/perl
# extract a tarball without having to care what it was compressed with

use strict;
use warnings;

use File::Temp qw(tempdir);
use File::Path qw(remove_tree);
use Getopt::Long qw(:config no_ignore_case bundling);

sub usage()
{
	print STDERR <<EOF 
Usage: untar [-U] <tar file>
EOF
}

my $safe = 1;
my $simulate = 0;
my $tar = "tar";

GetOptions(
	"simulate|dry-run|n" => sub { die "-n not supported at the moment\n" }, #\$simulate,
	"unsafe|U" => sub { $safe = 0; }
) or usage, exit 2;

my $tarfile = shift @ARGV
	or die "No file name specified\n";

my @flags = ("-x");

my %flags_for_extension = (
	'tar.bz2' => '-j',
	'tbz' => '-j',
	'tar.gz' => '-z',
	'tgz' => '-z',
	'tar.xz' => '--use-compress-program=xz',
	'txz' => '--use-compress-program=xz',
	'tar.lzma' => '--use-compress-program=xz',
	'tlzma' => '--use-compress-program=xz',
	'tar' => undef
);

my @extensions = keys %flags_for_extension;

my $known_extension = 0;
my $tarfile_without_extension = $tarfile;
foreach my $extension (keys %flags_for_extension) {
	if ($tarfile =~ m/^(.*)\Q.$extension\E$/) {
		$known_extension = 1;
		$tarfile_without_extension = $1;
		my $flags_for_this_extension = $flags_for_extension{$extension};
		if (defined($flags_for_this_extension)) {
			push @flags, $flags_for_this_extension;
		}
		last;
	}
}

my $tempdir;
if ($safe) {
	$tempdir = tempdir $tarfile_without_extension . ".XXXX", DIR => "."
		or die "untar: Cannot create temporary directory: $!\n";

    #print STDERR "untar: Safe mode, expanding into " . $tempdir . "\n";
    print STDERR "untar: Safe mode, expanding into temporary directory\n";
	push @flags, "-C", $tempdir;
}
else {
	print STDERR "untar: Unsafe mode, expanding into current directory\n";
}

if (!$known_extension) {
	die "untar: Cannot untar $tarfile: unknown file extension\n";
}

push @flags, "-f", $tarfile;

my $status = system $tar, @flags;
if ($status != 0) {
	print STDERR "untar: Cannot untar $tar: $?\n";
	if (defined $tempdir) {
		print STDERR "untar: Removing temporary directory $tempdir\n";
		remove_tree($tempdir);
	}
}

sub file_description {
	my $file = shift @_;
	my $type;
	if (-d $file) {
		$type = "directory";
	}
	elsif (-f $file) {
		$type = "file";
	}
	else {
		$type = "special file";
	}
	$type;
}

if ($safe) {
	if (opendir TEMPDIR, $tempdir) {
		my @files = grep { $_ ne "." and $_ ne ".." } readdir TEMPDIR;
		if (scalar @files == 1) {
            # archive contained a single file or directory,
            # the file is in a temporary directory,
            # try to rename it to the name it has in the archive
			my $src = $tempdir . "/" . $files[0];
			my $dst = $files[0];
			my $srctype = file_description($src);
			if (-e $dst) {
                # desired name is already in use...
				my $dsttype = file_description($dst);
				print STDERR "untar: Original name was $dst, but there is already a $dsttype called that\n";
				if (-d $src) {
					print STDERR "untar: Extracted files are in $src\n";
				}
				else {
					print STDERR "untar: Extracted file is $src\n";
				}
			}
			else {
                # desired name is available, rename it...
                if (rename $src, $dst and ! -e $src) {
                    if (-d $dst) {
                        # it was a single directory
                        print STDERR "untar: Extracted files are in $dst\n";
                    }
                    elsif (-e $dst) {
                        # it was a single file
                        print STDERR "untar: Extracted $dst\n";
                    }
                    else {
                        print STDERR "untar: Unexpected error: No files found\n";
                    }
                    # the archive contents have now been moved out of the temporary directory,
                    # clean up the temporary directory
                    remove_tree($tempdir);
				}
				else {
					print STDERR "untar: Move failed: $!\n";
                    if (-e $src) {
                        print STDERR "untar: Extracted files are in $src\n";
                    }
				}
			}
		}
		else {
			my $src = $tempdir;
			my $dst = $tarfile_without_extension;
			print STDERR "untar: Archive contained multiple files\n";
			print STDERR "untar: Trying to move extracted files into $dst\n";
			if (-e $dst) {
				my $dsttype = file_description($dst);
				print STDERR "untar: Original name was $dst, but there is already a $dsttype called that\n";
				print STDERR "untar: Extracted files are in $src\n";
			}
			else {
				if (rename $src, $dst and ! -e $src) {
					print STDERR "untar: Extracted files are in $dst\n";
				}
				else {
					print STDERR "untar: Move failed: $!\n";
					print STDERR "untar: Extracted files are in $dst\n";
				}
			}
		}
	}
	else {
		print STDERR "untar: Temporary directory disappeared\n";
	}
}