Send email alerts to drink admins if a drink machine's temperature drops too low

drink-temp-alert.php

<?php

# Script for alerting drink admins if a machine is gonna freeze.
#
# Requires a WebDrink API key: https://webdrink.csh.rit.edu/#/settings
#
# Should be run as a cron job on san.csh.rit.edu: 
# 	*/10 * * * * php /users/u18/bencentra/scripts/drink-temp-alert.php

$apiKey = "API_KEY_HERE";

$threshold = 32;

$machines = array(
	"Little Drink" => 1,
	"Big Drink" => 2
	// "Snack" => 3
);

$recipients = array(
	"[email protected]"
);

function getMachineTemp($machineId) {
	$url = "https://webdrink.csh.rit.edu/api/index.php?request=temps/machines";
	$url .= "&api_key=$apiKey&limit=1&machine_id=$machineId";
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $url);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	$output = curl_exec($ch);
	curl_close($ch);
	$result = json_decode($output, true);
	return $result["data"][0][1];
}

function sendEmail($to, $machine, $temperature) {
	$subject = "$machine Temperature Alert";
	$message = "Head's up, $machine is currently $temperature degrees.";
	$headers = "From: [email protected]";
	mail($to, $subject, $message, $headers);
}

foreach($machines as $machine => $id) {
	$file = __DIR__ . "/$machine.txt";
	$temperature = getMachineTemp($id);
	if ($temperature < $threshold) {
		if (!file_exists($file)) {
			foreach($recipients as $recipient) {
				sendEmail($recipient, $machine, $temperature);
			}
			file_put_contents($file, $temperature);
		}
	} 
	else {
		if (file_exists($file)) {
			unlink($file);
		}
	}
}

?>