package Devel::CheckOS;

use strict;
use warnings;
use Exporter;

use vars qw(@ISA @EXPORT_OK %EXPORT_TAGS);

our $VERSION = '1.81';

@ISA = qw(Exporter);
@EXPORT_OK = qw(os_is os_isnt die_if_os_is die_if_os_isnt die_unsupported list_platforms list_family_members);
%EXPORT_TAGS = (
    all      => \@EXPORT_OK,
    booleans => [qw(os_is os_isnt die_unsupported)],
    fatal    => [qw(die_if_os_is die_if_os_isnt)]
);

=head1 NAME

Devel::CheckOS - check what OS we're running on

=head1 DESCRIPTION

A learned sage once wrote on IRC:

   $^O is stupid and ugly, it wears its pants as a hat

Devel::CheckOS provides a more friendly interface to $^O, and also lets
you check for various OS "families" such as "Unix", which includes things
like Linux, Solaris, AIX etc.

It spares perl the embarrassment of wearing its pants on its head by
covering them with a splendid Fedora.

=head1 SYNOPSIS

    use Devel::CheckOS qw(os_is);
    print "Hey, I know this, it's a Unix system\n" if(os_is('Unix'));

    print "You've got Linux 2.6\n" if(os_is('Linux::v2_6'));

=head1 USING IT IN Makefile.PL or Build.PL

If you want to use this from Makefile.PL or Build.PL, do
not simply copy the module into your distribution as this may cause
problems when PAUSE and search.cpan.org index the distro.  Instead, use
the use-devel-assertos script.

=head1 FUNCTIONS

Devel::CheckOS implements the following functions, which load subsidiary
OS-specific modules on demand to do the real work.  They can be exported
by listing their names after C<use Devel::CheckOS>.  You can also export
groups of functions thus:

    use Devel::CheckOS qw(:booleans); # export the boolean functions
                                      # and 'die_unsupported'
    
    use Devel::CheckOS qw(:fatal);    # export those that die on no match

    use Devel::CheckOS qw(:all);      # export everything

=head2 Boolean functions

=head3 os_is

Takes a list of OS names.  If the current platform matches any of them,
it returns true, otherwise it returns false.  The names can be a mixture
of OSes and OS families, eg ...

    os_is(qw(Unix VMS)); # Unix is a family, VMS is an OS

=cut

sub os_is {
    my @targets = @_;
    my $rval = 0;
    foreach my $target (@targets) {
        die("Devel::CheckOS: $target isn't a legal OS name\n")
            unless($target =~ /^\w+(::\w+)*$/);
        eval "use Devel::AssertOS::$target";
        if(!$@) {
            no strict 'refs';
            $rval = 1 if(&{"Devel::AssertOS::${target}::os_is"}());
        }
    }
    return $rval;
}

=head3 os_isnt

If the current platform matches any of the parameters it returns false,
otherwise it returns true.

=cut

sub os_isnt {
    my @targets = @_;
    my $rval = 1;
    foreach my $target (@targets) {
        $rval = 0 if(os_is($target));
    }
    return $rval;
}

=head2 Fatal functions

=head3 die_if_os_isnt

As C<os_is()>, except that it dies instead of returning false.  The die()
message matches what the CPAN-testers look for to determine if a module
doesn't support a particular platform.

=cut

sub die_if_os_isnt {
    os_is(@_) ? 1 : die_unsupported();
}

=head3 die_if_os_is

As C<os_isnt()>, except that it dies instead of returning false.

=cut

sub die_if_os_is {
    os_isnt(@_) ? 1 : die_unsupported();
}

=head2 And some utility functions ...

=head3 die_unsupported

This function simply dies with the message "OS unsupported", which is what
the CPAN testers look for to figure out whether a platform is supported or
not.

=cut

sub die_unsupported { die("OS unsupported\n"); }

=head3 list_platforms

When called in list context,
return a list of all the platforms for which the corresponding
Devel::AssertOS::* module is available.  This includes both OSes and OS
families, and both those bundled with this module and any third-party
add-ons you have installed.

In scalar context, returns a hashref keyed by platform with the filename
of the most recent version of the supporting module that is available to you.
This is to make sure that the use-devel-assertos script Does The Right Thing
in the case where you have installed the module in one version of perl, then
upgraded perl, and installed it again in the new version.  Sometimes the old
version of perl and all its modules will still be hanging around and perl
"helpfully" includes the old perl's search path in its own.

Unfortunately, on some platforms this list may have file case
broken.  eg, some platforms might return 'freebsd' instead of 'FreeBSD'.
This is because they have case-insensitive filesystems so things
should Just Work anyway.

=cut

my ($re_Devel, $re_AssertOS);

sub list_platforms {
    # need to lazily load these cos the module gets use()d in Makefile.PL,
    # at which point pre-reqs might not be installed. This function isn't
    # used in Makefile.PL so we can live without 'em.
    eval " # only load these if needed
        use File::Find::Rule;
        use File::Spec;
    ";
    die($@) if($@);
    
    if (!$re_Devel) {
        my $case_flag = File::Spec->case_tolerant ? '(?i)' : '';
        $re_Devel    = qr/$case_flag ^Devel$/x;
        $re_AssertOS = qr/$case_flag ^AssertOS$/x;
    }

    # sort by mtime, so oldest last
    my @modules = sort {
        (stat($a->{file}))[9] <=> (stat($b->{file}))[9]
    } map {
        my (undef, $dir_part, $file_part) = File::Spec->splitpath($_);
        $file_part =~ s/\.pm$//;
        my (@dirs) = grep {+length} File::Spec->splitdir($dir_part);
        foreach my $i (reverse 1..$#dirs) {
            next unless $dirs[$i] =~ $re_AssertOS
                && $dirs[$i - 1] =~ $re_Devel;
            splice @dirs, 0, $i + 1;
            last;
        }
        {
            module => join('::', @dirs, $file_part),
            file   => File::Spec->canonpath($_)
        }
    } File::Find::Rule->file()->name('*.pm')->in(
        grep { -d }
        map { File::Spec->catdir($_, qw(Devel AssertOS)) }
        @INC
    );

    my %modules = map {
        $_->{module} => $_->{file}
    } @modules;

    if(wantarray()) {
        return sort keys %modules;
    } else {
        return \%modules;
    }
}

=head3 list_family_members

Takes the name of an OS 'family' and returns a list of all its members.
In list context, you get a list, in scalar context you get an arrayref.

If called on something that isn't a family, you get an empty list (or
a ref to an empty array).

=cut

sub list_family_members {
    my $family = shift() ||
        die(__PACKAGE__."::list_family_members needs a parameter\n");

    # this will die if it's the wrong OS, but the module is loaded ...
    eval qq{use Devel::AssertOS::$family};
    # ... so we can now query it
    my @members = eval qq{
        no strict 'refs';
	&{"Devel::AssertOS::${family}::matches"}()
    };
    return wantarray() ? @members : \@members;
}

=head1 PLATFORMS SUPPORTED

To see the list of platforms for which information is available, run this:

    perl -MDevel::CheckOS -e 'print join(", ", Devel::CheckOS::list_platforms())'

Note that capitalisation is important.  These are the names of the
underlying Devel::AssertOS::* modules
which do the actual platform detection, so they have to
be 'legal' filenames and module names, which unfortunately precludes
funny characters, so platforms like OS/2 are mis-spelt deliberately.
Sorry.

Also be aware that not all of them have been properly tested.  I don't
have access to most of them and have had to work from information
gleaned from L<perlport> and a few other places.  For a complete list of
OS families, see L<Devel::CheckOS::Families>.

If you want to add your own OSes or families, see L<Devel::AssertOS::Extending>
and please feel free to upload the results to the CPAN.

=head1 BUGS and FEEDBACK

I welcome feedback about my code, including constructive criticism.
Bug reports should be made using L<https://github.com/DrHyde/perl-modules-Devel-CheckOS/issues>.

You will need to include in your bug report the exact value of $^O, what
the OS is called (eg Windows Vista 64 bit Ultimate Home Edition), and,
if relevant, what "OS family" it should be in and who wrote it.

If you are feeling particularly generous you can encourage me in my
open source endeavours by buying me something from my wishlist:
  L<http://www.cantrell.org.uk/david/wishlist/>

=head1 SEE ALSO

$^O in L<perlvar>

L<perlport>

L<Devel::AssertOS>

L<Devel::AssertOS::Extending>

L<Probe::Perl>

The use-devel-assertos script

L<Module::Install::AssertOS>

=head1 AUTHOR

David Cantrell E<lt>F<david@cantrell.org.uk>E<gt>

Thanks to David Golden for the name and ideas about the interface, and
to the cpan-testers-discuss mailing list for prompting me to write it
in the first place.

Thanks to Ken Williams, from whose L<Module::Build> I lifted some of the
information about what should be in the Unix family.

Thanks to Billy Abbott for finding some bugs for me on VMS.

Thanks to Matt Kraai for information about QNX.

Thanks to Kenichi Ishigaki and Gabor Szabo for reporting a bug on Windows,
and to the former for providing a patch.

Thanks to Paul Green for some information about VOS.

Thanks to Yanick Champoux for a patch to let Devel::AssertOS support
negative assertions.

Thanks to Brian Fraser for adding Android support.

Thanks to Dale Evans for Debian detection, a bunch of Mac OS X specific version
detection modules, and perl 5.6 support.

=head1 SOURCE CODE REPOSITORY

L<git://github.com/DrHyde/perl-modules-Devel-CheckOS.git>

=head1 COPYRIGHT and LICENCE

Copyright 2007-2012 David Cantrell

This software is free-as-in-speech software, and may be used, distributed, and modified under the terms of either the GNU General Public Licence version 2 or the Artistic Licence. It's up to you which one you use. The full text of the licences can be found in the files GPL2.txt and ARTISTIC.txt, respectively.

=head1 HATS

I recommend buying a Fedora from L<http://hatsdirect.com/>.

=head1 CONSPIRACY

This module is also free-as-in-mason software.

=cut

1;
