wp-parsely / src / Telemetry / Tracks / class-tracks-pixel.php

class-tracks-pixel.php in Parse.ly 3.20.3, at src/Telemetry/Tracks/class-tracks-pixel.php

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1	<?php
2	/**
3	* Telemetry: Tracks Pixel class
4	*
5	* @package Parsely\Telemetry
6	* @since 3.12.0
7	*/
8
9	declare(strict_types=1);
10
11	namespace Parsely\Telemetry;
12
13	use Parsely\Utils\Utils;
14	use WP_Error;
15
16	/**
17	* Handles all operations related to the Tracks pixel.
18	*
19	* @since 3.12.0
20	*/
21	class Tracks_Pixel {
22	/**
23	* Base URL of the Tracks pixel.
24	*/
25	protected const PIXEL_BASE_URL = 'https://pixel.wp.com/t.gif';
26
27	/**
28	* Class singleton instance.
29	*
30	* @var ?Tracks_Pixel
31	*/
32	protected static $instance = null;
33
34	/**
35	* Events queued to be sent to the Tracks pixel.
36	*
37	* @var array<Tracks_Event>
38	*/
39	protected $events = array();
40
41	/**
42	* Constructor.
43	*
44	* @since 3.12.0
45	*/
46	public function __construct() {
47	// Track events asynchronously (inject pixels in the footer).
48	add_action( 'admin_footer', array( $this, 'render_tracking_pixels' ) );
49	// Synchronously track any remaining events that could not be added to
50	// the footer.
51	add_action( 'shutdown', array( $this, 'record_remaining_events' ) );
52	}
53
54	/**
55	* Instantiates the singleton.
56	*
57	* @since 3.12.0
58	*
59	* @return Tracks_Pixel
60	*/
61	public static function instance(): Tracks_Pixel {
62	if ( is_null( self::$instance ) ) {
63	self::$instance = new Tracks_Pixel();
64	}
65
66	return self::$instance;
67	}
68
69	/**
70	* Enqueues an event to be recorded asynchronously.
71	*
72	* @since 3.12.0
73	*
74	* @param Tracks_Event $event The event to record.
75	* @return bool\|WP_Error True if the event was enqueued for recording.
76	* False if the event is not recordable.
77	* WP_Error if the event is generating an error.
78	*/
79	public function record_event_asynchronously( Tracks_Event $event ) {
80	$is_event_recordable = $event->is_recordable();
81
82	if ( true !== $is_event_recordable ) {
83	return $is_event_recordable;
84	}
85
86	self::instance()->events[] = $event;
87
88	return true;
89	}
90
91	/**
92	* Records an event synchronously (using a GET request).
93	*
94	* @since 3.12.0
95	*
96	* @param Tracks_Event $event The event to record.
97	* @return bool\|WP_Error True if recording the event succeeded.
98	* False if the event is not recordable.
99	* WP_Error if any error occurred.
100	*/
101	public function record_event_synchronously( Tracks_Event $event ) {
102	$is_event_recordable = $event->is_recordable();
103
104	if ( true !== $is_event_recordable ) {
105	return $is_event_recordable;
106	}
107
108	$pixel_url = self::instance()->generate_pixel_url( $event );
109
110	if ( null === $pixel_url ) {
111	return new WP_Error(
112	'invalid_pixel',
113	'cannot generate tracks pixel for given input',
114	array( 'status' => 400 )
115	);
116	}
117
118	// Add the Request Timestamp and URL terminator just before the HTTP
119	// request.
120	$pixel_url .= '&_rt=' . Utils::get_timestamp() . '&_=_';
121
122	$request = wp_safe_remote_get(
123	$pixel_url,
124	array(
125	'blocking' => false,
126	'redirection' => 2,
127	'httpversion' => '1.1',
128	'timeout' => 1,
129	)
130	);
131
132	if ( is_wp_error( $request ) ) {
133	return $request;
134	}
135
136	return true;
137	}
138
139	/**
140	* Outputs a Tracks pixel for every registered event.
141	*
142	* @since 3.12.0
143	*/
144	public function render_tracking_pixels(): void {
145	foreach ( $this->events as $event ) {
146	$pixel_url = $this->generate_pixel_url( $event );
147
148	if ( null === $pixel_url ) {
149	continue;
150	}
151
152	echo '<img style="position: fixed;" src="', esc_url( $pixel_url ), '" />';
153	}
154
155	$this->events = array();
156	}
157
158	/**
159	* Generates a Tracks pixel URL that will record an event when accessed.
160	*
161	* @since 3.12.0
162	*
163	* @param Tracks_Event $event The event for which to generate the pixel URL.
164	* @return ?string The pixel URL or null if an error occurred.
165	*/
166	protected function generate_pixel_url( Tracks_Event $event ): ?string {
167	$event_data = $event->get_data();
168
169	if ( is_wp_error( $event_data ) ) {
170	return null;
171	}
172
173	$args = get_object_vars( $event_data );
174
175	// Request Timestamp and URL Terminator must be added just before the
176	// HTTP request or not at all.
177	unset( $args['_rt'], $args['_'] );
178
179	return esc_url_raw(
180	self::PIXEL_BASE_URL . '?' . http_build_query( $args )
181	);
182	}
183
184	/**
185	* Records any remaining events synchronously.
186	*
187	* @since 3.12.0
188	*/
189	public function record_remaining_events(): void {
190	foreach ( $this->events as $event ) {
191	self::instance()->record_event_synchronously( $event );
192	}
193	}
194	}
195