#!/usr/bin/perl
use strict;
use warnings;
use 5.01;

# get the locales available on the system
my @avail_locales = map { chomp; s/\.utf8//; $_ } qx( locale -a | grep \.utf8 );

# add items without country code to facilitate lookups
my %extended_localelist;
for my $loc (@avail_locales) {
    ( my $lang = $loc ) =~ s/_[A-Z]+//;
    @extended_localelist{$loc, $lang} = (1, 1);
}

# get the union of /usr/share/locale-langpack and /usr/share/locale
my %translation_dirs;
opendir my $dh, '/usr/share/locale-langpack' or die $!;
$translation_dirs{$_} = 1 for readdir $dh;
opendir $dh, '/usr/share/locale' or die $!;
$translation_dirs{$_} = 1 for readdir $dh;

# get the intersection of available translation_dirs and the extended locale list
my %intersection;
for ( keys %extended_localelist ) {
    $intersection{$_} = 1 if $translation_dirs{$_};
}

# Remove items without country code if country code items in the same language
# exist, since gettext won't find a translation under e.g. 'de_DE' if the
# first item in LANGUAGE is 'de' (see https://launchpad.net/bugs/700213).
# 'en' is kept, though, since it's always the last item in LANGUAGE per design.
my %count;
for ( keys %intersection ) {
    next if /^en[^a-z]/;
    ( my $not_country = $_ ) =~ s/_[A-Z]+//;
    $count{$not_country} ++;
}
for ( keys %count ) {
    if ( $count{$_} > 1 and $intersection{$_} ) {
        delete $intersection{$_};
    }
}

# print the resulting list of language options
say for sort keys %intersection;