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

class-tracks-pixel.php in Parse.ly 3.16.2, 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 WP_Error;
14
15	use function Parsely\Utils\get_timestamp;
16
17	/**
18	* Handles all operations related to the Tracks pixel.
19	*
20	* @since 3.12.0
21	*/
22	class Tracks_Pixel {
23	/**
24	* Base URL of the Tracks pixel.
25	*/
26	protected const PIXEL_BASE_URL = 'https://pixel.wp.com/t.gif';
27
28	/**
29	* Class singleton instance.
30	*
31	* @var ?Tracks_Pixel
32	*/
33	protected static $instance = null;
34
35	/**
36	* Events queued to be sent to the Tracks pixel.
37	*
38	* @var array<Tracks_Event>
39	*/
40	protected $events = array();
41
42	/**
43	* Constructor.
44	*
45	* @since 3.12.0
46	*/
47	public function __construct() {
48	// Track events asynchronously (inject pixels in the footer).
49	add_action( 'admin_footer', array( $this, 'render_tracking_pixels' ) );
50	// Synchronously track any remaining events that could not be added to
51	// the footer.
52	add_action( 'shutdown', array( $this, 'record_remaining_events' ) );
53	}
54
55	/**
56	* Instantiates the singleton.
57	*
58	* @since 3.12.0
59	*
60	* @return Tracks_Pixel
61	*/
62	public static function instance(): Tracks_Pixel {
63	if ( is_null( self::$instance ) ) {
64	self::$instance = new Tracks_Pixel();
65	}
66
67	return self::$instance;
68	}
69
70	/**
71	* Enqueues an event to be recorded asynchronously.
72	*
73	* @since 3.12.0
74	*
75	* @param Tracks_Event $event The event to record.
76	* @return bool\|WP_Error True if the event was enqueued for recording.
77	* False if the event is not recordable.
78	* WP_Error if the event is generating an error.
79	*/
80	public function record_event_asynchronously( Tracks_Event $event ) {
81	$is_event_recordable = $event->is_recordable();
82
83	if ( true !== $is_event_recordable ) {
84	return $is_event_recordable;
85	}
86
87	self::instance()->events[] = $event;
88
89	return true;
90	}
91
92	/**
93	* Records an event synchronously (using a GET request).
94	*
95	* @since 3.12.0
96	*
97	* @param Tracks_Event $event The event to record.
98	* @return bool\|WP_Error True if recording the event succeeded.
99	* False if the event is not recordable.
100	* WP_Error if any error occurred.
101	*/
102	public function record_event_synchronously( Tracks_Event $event ) {
103	$is_event_recordable = $event->is_recordable();
104
105	if ( true !== $is_event_recordable ) {
106	return $is_event_recordable;
107	}
108
109	$pixel_url = self::instance()->generate_pixel_url( $event );
110
111	if ( null === $pixel_url ) {
112	return new WP_Error(
113	'invalid_pixel',
114	'cannot generate tracks pixel for given input',
115	array( 'status' => 400 )
116	);
117	}
118
119	// Add the Request Timestamp and URL terminator just before the HTTP
120	// request.
121	$pixel_url .= '&_rt=' . get_timestamp() . '&_=_';
122
123	$request = wp_safe_remote_get(
124	$pixel_url,
125	array(
126	'blocking' => false,
127	'redirection' => 2,
128	'httpversion' => '1.1',
129	'timeout' => 1,
130	)
131	);
132
133	if ( is_wp_error( $request ) ) {
134	return $request;
135	}
136
137	return true;
138	}
139
140	/**
141	* Outputs a Tracks pixel for every registered event.
142	*
143	* @since 3.12.0
144	*/
145	public function render_tracking_pixels(): void {
146	foreach ( $this->events as $event ) {
147	$pixel_url = $this->generate_pixel_url( $event );
148
149	if ( null === $pixel_url ) {
150	continue;
151	}
152
153	echo '<img style="position: fixed;" src="', esc_url( $pixel_url ), '" />';
154	}
155
156	$this->events = array();
157	}
158
159	/**
160	* Generates a Tracks pixel URL that will record an event when accessed.
161	*
162	* @since 3.12.0
163	*
164	* @param Tracks_Event $event The event for which to generate the pixel URL.
165	* @return ?string The pixel URL or null if an error occurred.
166	*/
167	protected function generate_pixel_url( Tracks_Event $event ): ?string {
168	$event_data = $event->get_data();
169
170	if ( is_wp_error( $event_data ) ) {
171	return null;
172	}
173
174	$args = get_object_vars( $event_data );
175
176	// Request Timestamp and URL Terminator must be added just before the
177	// HTTP request or not at all.
178	unset( $args['_rt'], $args['_'] );
179
180	return esc_url_raw(
181	self::PIXEL_BASE_URL . '?' . http_build_query( $args )
182	);
183	}
184
185	/**
186	* Records any remaining events synchronously.
187	*
188	* @since 3.12.0
189	*/
190	public function record_remaining_events(): void {
191	foreach ( $this->events as $event ) {
192	self::instance()->record_event_synchronously( $event );
193	}
194	}
195	}
196