#!/usr/bin/perl -w

use strict;
use Config;

die "usage: $0 file(s)\n" unless scalar @ARGV;

## check whether the used version of Perl has been compiled
## with thread support
unless ($Config{useithreads})
{
    die "The used version Perl does not support threads!\n";
}

require threads;
require Lingua::Lid;

my $max_threads = 2;
my $nr = 0;

## while there are files given as arguments left...
while (@ARGV)
{
    my $file = shift(@ARGV);

    ## ...create a thread that identifies the file's language
    ## and charset and returns the determined results in
    ## scalar context when it is requested to join() to the
    ## main thread of control again.
    threads->create({ context => "scalar" }, sub {

        ## identify language and charset of the file using
        ## lid's lid_ffile
        my $res = Lingua::Lid::lid_ffile($file);

        return {
            file   => $file,

            ## $res will be undef if no result could be
            ## computed
            result => $res,

            ## in this case, Lingua::Lid::errstr() will
            ## return the error message reported by lid's
            ## lid_strerror() function.
            errstr => Lingua::Lid::errstr()
        };
    });

    ## if the maximum amount of concurrent threads has been
    ## reached or no files are left to identify, join all
    ## threads and print their results.
    if (scalar @ARGV % $max_threads == 0 || ! scalar @ARGV)
    {
        foreach my $thread (threads->list())
        {
            my $rv = $thread->join();

            printf("%02d: %s: %s\n",
                ++$nr,
                $rv->{file},
                $rv->{result} ?
                    join(", ", $rv->{result}->{language},
                               $rv->{result}->{isocode},
                               $rv->{result}->{encoding})
                    : "ERROR: $rv->{errstr}"
            );
        }
    }
}