use strict;
use warnings;

use Async::Event::Interval;
use Data::Dumper;
use IPC::Shareable;
use JSON;
use LWP::UserAgent;

my $ua = LWP::UserAgent->new;
my $url = 'http://tesla:55556';

# Create a shared scalar string that will hold JSON
# data that gets updated by the async event below, which
# runs in a separate, unrelated process

tie my $fetched_data, 'IPC::Shareable', {
    key     => 'TESLA',
    create  => 1,
    destroy => 1,
};

$fetched_data = '';

# Create an async event that runs in the background. The
# 0 parameter means it won't run on an interval, we have to
# manually start it each iteration of the loop. We 'start'
# it here to send it off on its first run so we have initial
# data

my $tesla_event = Async::Event::Interval->new(0, \&update_data);
$tesla_event->start;

my $previous_time = time;
my $previous_tesla_data = {charge => -1};

while (1) {
    # If the background URL fetch is done, start it again. It's probably wise
    # to time yours to run just prior to your 60 second loop cycle timer
    # expiring. No sense constantly hitting the site every second if you
    # don't need the data that quick!

    $tesla_event->start if $tesla_event->waiting;

    my $current_time = time;

    if ($current_time - $previous_time > 3) {
        my $tesla_data = decode_json($fetched_data);

        if ($tesla_data->{charge} != $previous_tesla_data->{charge}) {
            # Do stuff with the result
            print Dumper $tesla_data;

            $previous_tesla_data = $tesla_data;
        }

        $previous_time = $current_time;
    }
}

sub update_data {
    my $server_response = $ua->get($url);

    if ($server_response->is_success) {
        $fetched_data = $server_response->decoded_content;
    }
}

##</code><code>##

$VAR1 = {
          'fetching' => 0,
          'charge' => 0,
          'charging' => 0,
          'online' => 0,
          'error' => 0,
          'gear' => 0,
          'garage' => 0,
          'rainbow' => 0
        };
$VAR1 = {
          'fetching' => 0,
          'charge' => 61,
          'charging' => 0,
          'online' => 1,
          'error' => 0,
          'gear' => 0,
          'garage' => 1,
          'rainbow' => 0
        };