vikbooking / admin / helpers / src / event / observer.php

observer.php in VikBooking Hotel Booking Engine & PMS trunk, at admin/helpers/src/event/observer.php

140 lines 3.6 KB

Raw Download Zip

1	<?php
2	/**
3	* @package VikBooking
4	* @subpackage core
5	* @author E4J s.r.l.
6	* @copyright Copyright (C) 2025 E4J s.r.l. All Rights Reserved.
7	* @license http://www.gnu.org/licenses/gpl-2.0.html GNU/GPL
8	* @link https://vikwp.com
9	*/
10
11	// No direct access
12	defined('ABSPATH') or die('No script kiddies please!');
13
14	/**
15	* Observer design pattern implementation as trait for a better reusability.
16	*
17	* @since 1.18.15 (J) - 1.8.15 (WP)
18	*/
19	trait VBOEventObserver
20	{
21	/**
22	* A list of subscribers, grouped per event.
23	*
24	* @var array
25	*/
26	protected $listeners = [];
27
28	/**
29	* Subscribes the provided callback to the given event.
30	*
31	* @param string $event The event to observe.
32	* @param mixed $callback The callback to invoke.
33	*
34	* @return self
35	*/
36	public function subscribe(string $event, $callback)
37	{
38	if (!isset($this->listeners[$event]))
39	{
40	// create event repository for the first time
41	$this->listeners[$event] = [];
42	}
43
44	// make sure we have a valid callback
45	if (is_callable($callback))
46	{
47	// generate callback ID
48	$callbackId = $this->getCallbackId($callback);
49
50	// internally register the callback
51	$this->listeners[$event][$callbackId] = $callback;
52	}
53
54	return $this;
55	}
56
57	/**
58	* Unsubscribes the provided callback from the given event.
59	*
60	* @param string $event The observed event.
61	* @param mixed $callback The registered callback.
62	*
63	* @return self
64	*/
65	public function unsubscribe(string $event, $callback)
66	{
67	// make sure we have a valid callback
68	if (is_callable($callback))
69	{
70	// generate callback ID
71	$callbackId = $this->getCallbackId($callback);
72
73	// unset registered callback, if any
74	if (isset($this->listeners[$event][$callbackId]))
75	{
76	unset($this->listeners[$event][$callbackId]);
77	}
78	}
79
80	return $this;
81	}
82
83	/**
84	* Notifies all the subscribers when a certain event is triggered.
85	*
86	* @param string $event The fired event.
87	* @param mixed ...$args Arguments to pass to the function.
88	*
89	* @return A list of return values.
90	*/
91	public function notify(string $event, &...$args)
92	{
93	$return = [];
94
95	// iterate all the event subscribers
96	foreach ($this->listeners[$event] ?? [] as $callback)
97	{
98	// invoke callback function and register returned value
99	$return[] = call_user_func_array($callback, $args);
100	}
101
102	// get rid of NULL values
103	return array_values(array_filter($return, fn($v) => $v !== null));
104	}
105
106	/**
107	* Generates a unique and reusable identifier according to the provided callback.
108	*
109	* @param mixed $callback The registered callback.
110	*
111	* @return string
112	*/
113	private function getCallbackId($callback)
114	{
115	if ($callback instanceof \Closure \|\| is_object($callback))
116	{
117	return spl_object_hash($callback);
118	}
119
120	if (is_string($callback))
121	{
122	return $callback;
123	}
124
125	if (is_array($callback))
126	{
127	[$target, $method] = $callback;
128
129	if (is_object($target))
130	{
131	return spl_object_hash($target) . '::' . $method;
132	}
133
134	return $target . '::' . $method;
135	}
136
137	throw new \InvalidArgumentException('Invalid callback provided.', 400);
138	}
139	}
140