use Downtime::Monitor;

my sub keep-line(Str $line) { $line !~~ /^PING/ }

my sub parse-line(Str $line) {
    given $line {
        when /time\=([\d|\.]+)/ { Duration.new($0.Real / 1000) }
        when /timeout/ { "error: timeout" }
        default { "error: $_" }
    }
}

class PingMonitor does Monitor {
    has Supply $.events;
    has Str @!args;
    has Proc::Async $!proc;

    method new(Str $host, Duration $interval, Duration $timeout) {
        my @args = (
            "-i", $interval.Str,
            "-W", ($timeout * 1000).Str,
            $host,
        );
        self.bless(:@args);
    }

    submethod BUILD(:@!args) {
        $!events = Supply.new;
    }

    method start {
        $!proc = Proc::Async.new("stdbuf", "-oL", "-eL", "ping", @!args);
        $!proc.stdout.grep(&keep-line).act: { $!events.emit(parse-line($_)) };
        $!proc.start;
    }

    method stop {
        $!proc.kill;
    }
}