#!/usr/bin/perl

=pod

=head1 NAME

rina - run if no activity


=head1 SYNOPSIS

... | B<rina> [-v] [-t timeout] I<command>


=head1 OPTIONS

=over 9

=item B<-v>

Verbose. Print when I<command> is run.

=back


=head1 DESCRIPTION

B<rina> monitors a pipe. If there is no activity on the pipe for
I<timeout> seconds, it runs I<command>.


=head1 EXAMPLE

Restart networking if Google's DNS does not repond to ping:

  ping 8.8.8.8 | rina -t 20 /etc/init.d/networking restart

=head1 AUTHOR

Copyright (C) 2017 Ole Tange,
http://ole.tange.dk and Free Software Foundation, Inc.


=head1 LICENSE

Copyright (C) 2012 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.


=head1 DEPENDENCIES

B<rina> uses B<perl>.


=head1 SEE ALSO

B<perl>


=cut

use Getopt::Long;
use Time::HiRes;
use POSIX qw(strftime);

Getopt::Long::Configure("bundling","require_order");
get_options_from_array(\@ARGV);

my $in_fh = *STDIN;
$|=1;

set_fh_non_blocking($in_fh);

while(1) {
    my $newline = "";
    my $t;
    sleep(1);
    if(read($in_fh,$dummy,32768)) { next; }
    for($t = $opt::timeout || 10; $t; $t--) {
	sleep(1);
	if(read($in_fh,$dummy,32768)) { last; }
	$newline = "\n";
	@opt::verbose and print "$t ";
    }
    @opt::verbose and print $newline;
    if(not $t) {
	# run_command
	@opt::verbose and print iso8601(Time::HiRes::time())," Running @ARGV\n";
	system(@ARGV);
	wait();
	@opt::verbose and print iso8601(Time::HiRes::time())," Done @ARGV\n";
    }
    while(read($in_fh,$dummy,32768)) { }
}

while(1){
    my $t = $opt::timeout || 10;
    my $newline = "";
    sleep(1);
    if(not read($in_fh,$dummy,32768)) {
	$newline = "\n";
	@opt::verbose and print "$t";
	if(not $t--) {
	    # run_command
	    @opt::verbose and print $newline;
	    @opt::verbose and print iso8601(Time::HiRes::time())," Running @ARGV\n";
	    system(@ARGV);
	    wait();
	    @opt::verbose and print iso8601(Time::HiRes::time())," Done @ARGV\n";
	}
    }
    @opt::verbose and print $newline;
    # empty_buffer
    while(read($in_fh,$dummy,32768)) { }
}

sub iso8601 {
    my $time = shift;
    my $tz = strftime("%z", localtime($time));
    $tz =~ s/(\d{2})(\d{2})/$1:$2/;
    my $ms = sprintf "%03d", int(($time - int($time))*1000);

    return strftime("%Y-%m-%dT%H:%M:%S.".$ms, localtime($time)). $tz;
}

sub set_fh_non_blocking {
    # Set filehandle as non-blocking
    # Inputs:
    #   $fh = filehandle to be blocking
    # Returns:
    #   N/A
    my $fh = shift;
    $Global::use{"Fcntl"} ||= eval "use Fcntl qw(:DEFAULT :flock); 1;";
    my $flags;
    # Get the current flags on the filehandle
    fcntl($fh, &F_GETFL, $flags) || die $!;
    # Add non-blocking to the flags
    $flags |= &O_NONBLOCK;
    # Set the flags on the filehandle
    fcntl($fh, &F_SETFL, $flags) || die $!;
}

sub options_hash {
    # Returns:
    #   %hash = the GetOptions config
    return
	("debug|D=s" => \$opt::D,
	 "verbose|v" => \@opt::verbose,
	 "timeout|t=s" => \$opt::timeout,
	);
}

sub get_options_from_array {
    # Run GetOptions on @array
    # Input:
    #   $array_ref = ref to @ARGV to parse
    #   @keep_only = Keep only these options
    # Uses:
    #   @ARGV
    # Returns:
    #   true if parsing worked
    #   false if parsing failed
    #   @$array_ref is changed
    my ($array_ref, @keep_only) = @_;
    if(not @$array_ref) {
	# Empty array: No need to look more at that
	return 1;
    }
    # A bit of shuffling of @ARGV needed as GetOptionsFromArray is not
    # supported everywhere
    my @save_argv;
    my $this_is_ARGV = (\@::ARGV == $array_ref);
    if(not $this_is_ARGV) {
	@save_argv = @::ARGV;
	@::ARGV = @{$array_ref};
    }
    # If @keep_only set: Ignore all values except @keep_only
    my %options = options_hash();
    if(@keep_only) {
	my (%keep,@dummy);
	@keep{@keep_only} = @keep_only;
	for my $k (grep { not $keep{$_} } keys %options) {
	    # Store the value of the option in @dummy
	    $options{$k} = \@dummy;
	}
    }
    my $retval = GetOptions(%options);
    if(not $this_is_ARGV) {
	@{$array_ref} = @::ARGV;
	@::ARGV = @save_argv;
    }
    return $retval;
}