#!/usr/bin/perl

use strict;

use Getopt::Long;

use File::Spec;

my $link;

my $target;

my $help;

my $force = 0;

sub usage($);

sub help();

sub usage_error();

my %optmap = (  'link' => \$link,

			    'target' => \$target,

			    'force' => \$force, 

                'help' => \$help);

GetOptions(\%optmap,

          'link=s',

          'target=s',

          'force!',

          'help!') 

          or usage_error();

if ($help) {

	help();

}

usage_error(), unless (defined($link) && defined($target));

my $junction_help = `junction /?`;

die("Need command \"junction\". Not found\n"), if ($junction_help =~ /is not recognised/);

die("Directory \"$target\" not found\n"), unless -d "$target";

my ($vol,$dir,$file) = File::Spec->splitpath($target);

my @subst_lines = `subst`;

foreach (@subst_lines) {

    my $line = $_;

    chomp($line);

    $line =~ /^(.:)\\: => (.*)$/;

    die("Cannot parse output of 'subst'. Bailing out confused."), unless (defined($1) and defined($2));    

    my $subst_drive = $1;

    my $subst_targ = $2;

    if (lc($subst_drive) eq lc($vol)) {

        print("Target $target is in a substituted drive: $line\n");

        $target = File::Spec->catfile(($subst_targ,$dir),$file);

        print("Target $target will be used\n");

        last;

    }

}

if ( -e "$link") {

    print("\"$link\" already exists. ");

    if (!$force) {

        my $choice;

        while($choice ne 'y' and $choice ne 'n') {

            print "Delete? (y/n)? ";

            $choice = <STDIN>;

            chomp($choice);

            $choice = lc($choice);

        }

        $force = $choice eq 'y';

    }    

    if ($force) {

        system("junction -d \"$link\" > nul");

        if ($?) {

            die("Cannot delete \"$link\": $!\n");

        }

        else {

            print "Deleted \"$link\"\n";

        }

    }

} 

system("junction \"$link\" \"$target\" > nul");

if ($?) {

    die("Cannot cteate junction \"$link\" -> \"$target\": $!\n");

}

else {

    print("Created junction \"$link\" -> \"$target\"\n");

}

exit 0;

sub usage($)

{

    my $error = shift;

    my $fh = $error == 0 ? *STDOUT : *STDERR;

    print $fh "make_junction.pl\n" .

            "Create a Windows junction (a.k.a symbolic link)\n" .

            "usage:\n" .

            "  make_junction.pl --help\n" .

            "  make_junction.pl --link=LINKDIR --target=TARGDIR\n " .

            "options:\n" .

            "  --help                        Display this help and exit\n" .

            "  --link=LINKDIR                LINKDIR specifies the junction to be created. Last component is the junction. The rest must exist\n" .

            "  --target=TARGDIR              TARGDIR is directory to which the junction will point.\n" .

            "                                If TARGDIR is in a substed drive, the real path will be used.\n";

    exit $error;            

}

sub help()

{

    usage(0);

}

sub usage_error()

{

    usage(1);

}             

# EOF