moha/hooks/scripts/availability.php

<?php

class availability
{
	public $hookname = "availability";
	public $initialized = true;
	// by default all devices are listening for availability

	function __construct()
	{
		global $devices;
		$this->iterate();
	}

	private function iterate()
	{
		global $indexDevices;
		foreach ($indexDevices as &$value)
		{
			$value->properties["availability"]["functions"][] = array($this,"callback");
		}
	}

	// callback fonction. Is called with these 3 parameters
	// $device 	-> calling device
	// $property 	-> parameter passed by mqtt
	// $value 	-> value of the parameter
	public function callBack($device, $property, $value)
	{
		switch($property)
		{
			case "availability":			// theorically can't be other, but ....
				if ($device->availability != $value)
				{
					//echo "==========>>>>>> Availability $value" . EOL;
					//if (!empty($device->availability))
					//{
						$log = ALERT;
					//}else
					//{
					//	$log = INFO;
					//}
					//$device->availability = $value;
					logger($log, sprintf(_("Device: %s/%s is %s"), $device->topic, $device->friendlyName, bool2string($value)), __FILE__ . ":" . __LINE__);
				}
			break;
		}
	}
}

$hooks["availability"] = new availability();
?>