convertkit / includes / class-convertkit-output-restrict-content.php

class-convertkit-output-restrict-content.php in Kit (formerly ConvertKit) – Email Newsletter, Email Marketing, Membership, Subscribers and Landing Pages 2.3.2, at includes/class-convertkit-output-restrict-content.php

845 lines 27.1 KB

Raw Download Zip

1	<?php
2	/**
3	* ConvertKit Output Restrict Content class.
4	*
5	* @package ConvertKit
6	* @author ConvertKit
7	*/
8
9	/**
10	* Restricts (or displays) a single Page, Post or Custom Post Type's content
11	* based on the Post's "Restrict Content" configuration.
12	*
13	* @since 2.1.0
14	*/
15	class ConvertKit_Output_Restrict_Content {
16
17	/**
18	* Holds the success message to display on screen as a notification.
19	*
20	* @since 2.1.0
21	*
22	* @var bool\|string
23	*/
24	private $success = false;
25
26	/**
27	* Holds the WP_Error object if an API call / authentication failed,
28	* to display on screen as a notification.
29	*
30	* @since 2.1.0
31	*
32	* @var bool\|WP_Error
33	*/
34	private $error = false;
35
36	/**
37	* Holds the ConvertKit Plugin Settings class
38	*
39	* @since 2.1.0
40	*
41	* @var bool\|ConvertKit_Settings
42	*/
43	private $settings = false;
44
45	/**
46	* Holds the ConvertKit Restrict Content Settings class
47	*
48	* @since 2.1.0
49	*
50	* @var bool\|ConvertKit_Settings_Restrict_Content
51	*/
52	private $restrict_content_settings = false;
53
54	/**
55	* Holds the ConvertKit Post Settings class
56	*
57	* @since 2.1.0
58	*
59	* @var bool\|ConvertKit_Post
60	*/
61	private $post_settings = false;
62
63	/**
64	* Holds the Post ID
65	*
66	* @since 2.1.0
67	*
68	* @var bool\|int
69	*/
70	private $post_id = false;
71
72	/**
73	* Holds the ConvertKit API class
74	*
75	* @since 2.1.0
76	*
77	* @var bool\|ConvertKit_API
78	*/
79	private $api = false;
80
81	/**
82	* Holds the token returned from calling the subscriber_authentication_send_code API endpoint.
83	*
84	* @since 2.1.0
85	*
86	* @var bool\|string
87	*/
88	private $token = false;
89
90	/**
91	* Constructor. Registers actions and filters to possibly limit output of a Page/Post/CPT's
92	* content on the frontend site.
93	*
94	* @since 2.1.0
95	*/
96	public function __construct() {
97
98	// Initialize classes that will be used.
99	$this->settings = new ConvertKit_Settings();
100	$this->restrict_content_settings = new ConvertKit_Settings_Restrict_Content();
101
102	add_action( 'init', array( $this, 'maybe_run_subscriber_authentication' ), 1 );
103	add_action( 'init', array( $this, 'maybe_run_subscriber_verification' ), 2 );
104	add_filter( 'the_content', array( $this, 'maybe_restrict_content' ) );
105	add_filter( 'get_previous_post_where', array( $this, 'maybe_change_previous_post_where_clause' ), 10, 5 );
106	add_filter( 'get_next_post_where', array( $this, 'maybe_change_next_post_where_clause' ), 10, 5 );
107	add_filter( 'get_previous_post_sort', array( $this, 'maybe_change_previous_next_post_order_by_clause' ), 10, 3 );
108	add_filter( 'get_next_post_sort', array( $this, 'maybe_change_previous_next_post_order_by_clause' ), 10, 3 );
109
110	}
111
112	/**
113	* Checks if the request is a Restrict Content request with an email address.
114	* If so, calls the API depending on the Restrict Content resource that's required:
115	* - tag: subscribes the email address to the tag, storing the subscriber ID in a cookie and redirecting
116	* - product: calls the API to send the subscriber a magic link by email containing a code. See maybe_run_subscriber_verification()
117	* for logic once they click the link in the email or enter the code on screen.
118	*
119	* @since 2.1.0
120	*/
121	public function maybe_run_subscriber_authentication() {
122
123	// Bail if no nonce was specified.
124	if ( ! array_key_exists( '_wpnonce', $_REQUEST ) ) {
125	return;
126	}
127
128	// Bail if the nonce failed validation.
129	if ( ! wp_verify_nonce( sanitize_key( $_REQUEST['_wpnonce'] ), 'convertkit_restrict_content_login' ) ) {
130	$this->error = new WP_Error( 'convertkit_output_restrict_content_error', __( 'Invalid nonce specified. Please try again.', 'convertkit' ) );
131	return;
132	}
133
134	// If the Plugin API keys have not been configured, we can't get this subscriber's ID by email.
135	if ( ! $this->settings->has_api_key_and_secret() ) {
136	return;
137	}
138
139	// Initialize the API.
140	$this->api = new ConvertKit_API( $this->settings->get_api_key(), $this->settings->get_api_secret(), $this->settings->debug_enabled() );
141
142	// Sanitize inputs.
143	$email = sanitize_text_field( $_REQUEST['convertkit_email'] );
144	$resource_type = sanitize_text_field( $_REQUEST['convertkit_resource_type'] );
145	$resource_id = absint( sanitize_text_field( $_REQUEST['convertkit_resource_id'] ) );
146
147	// Run subscriber authentication / subscription depending on the resource type.
148	switch ( $resource_type ) {
149	case 'product':
150	// Send email to subscriber with a link to authenticate they have access to the email address submitted.
151	$result = $this->api->subscriber_authentication_send_code(
152	$email,
153	$this->get_url()
154	);
155
156	// Bail if an error occured.
157	if ( is_wp_error( $result ) ) {
158	$this->error = $result;
159	return;
160	}
161
162	// Clear any existing subscriber ID cookie, as the authentication flow has started by sending the email.
163	$subscriber = new ConvertKit_Subscriber();
164	$subscriber->forget();
165
166	// Store the token so it's included in the subscriber code form.
167	$this->token = $result;
168
169	// Show a message telling the subscriber to check their email and click the link in the email.
170	$this->success = $this->restrict_content_settings->get_by_key( 'email_check_text' );
171	break;
172
173	case 'tag':
174	// Tag the subscriber.
175	$result = $this->api->tag_subscribe( $resource_id, $email );
176
177	// Bail if an error occured.
178	if ( is_wp_error( $result ) ) {
179	$this->error = $result;
180	return;
181	}
182
183	// Clear any existing subscriber ID cookie, as the authentication flow has started by sending the email.
184	$subscriber = new ConvertKit_Subscriber();
185	$subscriber->forget();
186
187	// Fetch the subscriber ID from the result.
188	$subscriber_id = $result['subscription']['subscriber']['id'];
189
190	// Store subscriber ID in cookie and redirect.
191	$this->store_subscriber_id_in_cookie_and_redirect( $subscriber_id );
192	break;
193
194	}
195
196	}
197
198	/**
199	* Checks if the request contains a token and subscriber_code i.e. the subscriber clicked
200	* the link in the email sent by the maybe_run_subscriber_authentication() function above.
201	*
202	* This calls the API to verify the token and subscriber code, which tells us that the email
203	* address supplied truly belongs to the user, and that we can safely trust their subscriber ID
204	* to be valid.
205	*
206	* @since 2.1.0
207	*/
208	public function maybe_run_subscriber_verification() {
209
210	// phpcs:disable WordPress.Security.NonceVerification.Recommended
211	// Bail if the expected token and subscriber code is missing.
212	if ( ! array_key_exists( 'token', $_REQUEST ) ) {
213	return;
214	}
215	if ( ! array_key_exists( 'subscriber_code', $_REQUEST ) ) {
216	return;
217	}
218
219	// If the Plugin API keys have not been configured, we can't get this subscriber's ID by email.
220	if ( ! $this->settings->has_api_key_and_secret() ) {
221	return;
222	}
223
224	// Store the token so it's included in the subscriber code form if verification fails.
225	$this->token = sanitize_text_field( $_REQUEST['token'] );
226
227	// Initialize the API.
228	$this->api = new ConvertKit_API( $this->settings->get_api_key(), $this->settings->get_api_secret(), $this->settings->debug_enabled() );
229
230	// Verify the token and subscriber code.
231	$subscriber_id = $this->api->subscriber_authentication_verify(
232	sanitize_text_field( $_REQUEST['token'] ),
233	sanitize_text_field( $_REQUEST['subscriber_code'] )
234	);
235	// phpcs:enable
236
237	// Bail if an error occured.
238	if ( is_wp_error( $subscriber_id ) ) {
239	$this->error = $subscriber_id;
240	return;
241	}
242
243	// Store subscriber ID in cookie and redirect.
244	$this->store_subscriber_id_in_cookie_and_redirect( $subscriber_id );
245
246	}
247
248	/**
249	* Displays (or hides) content on a singular Page, Post or Custom Post Type's Content,
250	* depending on whether the visitor is an authenticated ConvertKit subscriber and has
251	* subscribed to the ConvertKit Product or Tag.
252	*
253	* @since 2.1.0
254	*
255	* @param string $content Post Content.
256	* @return string Post Content with content restricted/not restricted
257	*/
258	public function maybe_restrict_content( $content ) {
259
260	// Bail if the Restrict Content setting is not enabled on this Page.
261	if ( ! $this->is_restricted_content() ) {
262	return $content;
263	}
264
265	// Get resource type (Product or Tag) that the visitor must be subscribed against to access this content.
266	$resource_type = $this->get_resource_type( $this->post_id );
267
268	// Return the Post Content, unedited, if the Resource Type is false.
269	if ( ! $resource_type ) {
270	return $content;
271	}
272
273	// Get resource ID (Product ID or Tag ID) that the visitor must be subscribed against to access this content.
274	$resource_id = $this->get_resource_id( $this->post_id );
275
276	// Return the full Post Content, unedited, if the Resource ID is false, as this means
277	// no restrict content setting has been defined for this Post.
278	if ( ! $resource_id ) {
279	return $content;
280	}
281
282	// Return if this request is after the user entered their email address,
283	// which means we're going through the authentication flow.
284	if ( $this->in_authentication_flow() ) {
285	return $this->restrict_content( $content, $resource_type, $resource_id );
286	}
287
288	// Get the subscriber ID, either from the request or an existing cookie.
289	$subscriber_id = $this->get_subscriber_id_from_request();
290
291	// If no subscriber ID exists, the visitor cannot view the content.
292	if ( ! $subscriber_id ) {
293	return $this->restrict_content( $content, $resource_type, $resource_id );
294	}
295
296	// If the subscriber is not subscribed to the product, restrict the content.
297	if ( ! $this->subscriber_has_access( $subscriber_id, $resource_type, $resource_id ) ) {
298	// Show an error before the call to action, to tell the subscriber why they still cannot
299	// view the content.
300	$this->error = new WP_Error(
301	'convertkit_restrict_content_subscriber_no_access',
302	esc_html( $this->restrict_content_settings->get_by_key( 'no_access_text' ) )
303	);
304
305	return $this->restrict_content( $content, $resource_type, $resource_id );
306	}
307
308	// If here, the subscriber has subscribed to the product.
309	// Show the full Post Content.
310	return $content;
311
312	}
313
314	/**
315	* Changes how WordPress' get_adjacent_post() function queries Pages, to determine what
316	* the previous Page link is when using the Previous navigation block on a Page that
317	* has the Restrict Content setting defined.
318	*
319	* By default, get_adjacent_post() will query by post_date, which we change to menu_order.
320	*
321	* @since 2.1.0
322	*
323	* @param string $where The `WHERE` clause in the SQL.
324	* @param bool $in_same_term Whether post should be in a same taxonomy term.
325	* @param array $excluded_terms Array of excluded term IDs.
326	* @param string $taxonomy Taxonomy. Used to identify the term used when `$in_same_term` is true.
327	* @param WP_Post $post WP_Post object.
328	* @return string Modified `WHERE` clause
329	*/
330	public function maybe_change_previous_post_where_clause( $where, $in_same_term, $excluded_terms, $taxonomy, $post ) { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter
331
332	// Bail if the Restrict Content setting is not enabled on this Page.
333	if ( ! $this->is_restricted_content() ) {
334	return $where;
335	}
336
337	// Bail if the Page doesn't match the current Page being viewed, or has no parent Page.
338	if ( ! $this->has_parent_page( $post ) ) {
339	return $where;
340	}
341
342	// Build replacement where statement.
343	$new_where = 'p.post_parent = ' . $post->post_parent . ' AND p.menu_order < ' . $post->menu_order;
344
345	// Replace existing where statement with new statement.
346	$where = 'WHERE ' . $new_where . ' ' . substr( $where, strpos( $where, 'AND' ) );
347
348	// Return.
349	return $where;
350
351	}
352
353	/**
354	* Changes how WordPress' get_adjacent_post() function queries Pages, to determine what
355	* the next Page link is when using the Previous navigation block on a Page that
356	* has the Restrict Content setting defined.
357	*
358	* By default, get_adjacent_post() will query by post_date, which we change to menu_order.
359	*
360	* @since 2.1.0
361	*
362	* @param string $where The `WHERE` clause in the SQL.
363	* @param bool $in_same_term Whether post should be in a same taxonomy term.
364	* @param array $excluded_terms Array of excluded term IDs.
365	* @param string $taxonomy Taxonomy. Used to identify the term used when `$in_same_term` is true.
366	* @param WP_Post $post WP_Post object.
367	* @return string Modified `WHERE` clause
368	*/
369	public function maybe_change_next_post_where_clause( $where, $in_same_term, $excluded_terms, $taxonomy, $post ) { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter
370
371	// Bail if the Restrict Content setting is not enabled on this Page.
372	if ( ! $this->is_restricted_content() ) {
373	return $where;
374	}
375
376	// Bail if the Page doesn't match the current Page being viewed, or has no parent Page.
377	if ( ! $this->has_parent_page( $post ) ) {
378	return $where;
379	}
380
381	// Build replacement where statement.
382	$new_where = 'p.post_parent = ' . $post->post_parent . ' AND p.menu_order > ' . $post->menu_order;
383
384	// Replace existing where statement with new statement.
385	$where = 'WHERE ' . $new_where . ' ' . substr( $where, strpos( $where, 'AND' ) );
386
387	// Return.
388	return $where;
389
390	}
391
392	/**
393	* Changes how WordPress' get_adjacent_post() function orders Pages, to determine what
394	* the next and previous Page links are when using Previous / Next navigation blocks
395	* on a Page that has the Restrict Content setting defined.
396	*
397	* By default, get_adjacent_post() will sort by Post Date, which we change to Page Order
398	* (called menu_order in WordPress).
399	*
400	* @since 2.1.0
401	*
402	* @param string $order_by SQL ORDER BY statement.
403	* @param WP_Post $post WordPress Post.
404	* @param string $order Order.
405	* @return string Modified SQL ORDER BY statement.
406	*/
407	public function maybe_change_previous_next_post_order_by_clause( $order_by, $post, $order ) {
408
409	// Bail if the Restrict Content setting is not enabled on this Page.
410	if ( ! $this->is_restricted_content() ) {
411	return $order_by;
412	}
413
414	// Bail if the Page doesn't match the current Page being viewed, or has no parent Page.
415	if ( ! $this->has_parent_page( $post ) ) {
416	return $order_by;
417	}
418
419	// Order by Page order (menu_order), highest to lowest, instead of post_date.
420	return 'ORDER BY p.menu_order ' . $order . ' LIMIT 1';
421
422	}
423
424	/**
425	* Stores the given subscriber ID in the ck_subscriber_id cookie, and redirects
426	* to the current URL, removing any query parameters (such as tokens), and appending
427	* a ck-cache-bust query parameter to beat caching plugins.
428	*
429	* @since 2.3.2
430	*
431	* @param string\|int $subscriber_id Subscriber ID (int if restrict by tag, signed subscriber id string if restrict by product).
432	*/
433	private function store_subscriber_id_in_cookie_and_redirect( $subscriber_id ) {
434
435	// Store subscriber ID in cookie.
436	// We don't need to use validate_and_store_subscriber_id() as we just validated the subscriber via authentication above.
437	$subscriber = new ConvertKit_Subscriber();
438	$subscriber->set( $subscriber_id );
439
440	// We append a query parameter to the URL to prevent caching plugins and
441	// aggressive cache hosting configurations from serving a cached page, which would
442	// result in maybe_restrict_content() not showing an error message or permitting
443	// access to the content.
444	$url = add_query_arg(
445	array(
446	'ck-cache-bust' => microtime(),
447	),
448	$this->get_url()
449	);
450
451	// Redirect to the Post without parameters.
452	// This will then run maybe_restrict_content() to get the subscriber's ID from the cookie,
453	// and determine if the content can be displayed.
454	wp_safe_redirect( $url );
455	exit;
456
457	}
458
459	/**
460	* Returns the URL for the current request, excluding any query parameters.
461	*
462	* @since 2.1.0
463	*
464	* @return string URL.
465	*/
466	private function get_url() {
467
468	$url = wp_parse_url( get_site_url() . $_SERVER['REQUEST_URI'] );
469	return $url['scheme'] . '://' . $url['host'] . $url['path'];
470
471	}
472
473	/**
474	* Determines if the request is for a WordPress Page that has the Restrict Content
475	* setting defined.
476	*
477	* @since 2.1.0
478	*
479	* @return bool
480	*/
481	private function is_restricted_content() {
482
483	// Bail if not a singular Post Type.
484	if ( ! is_singular() ) {
485	return false;
486	}
487
488	// If a Post ID is already defined in this class, this check has already been performed,
489	// and the Post's settings class has been initialized.
490	if ( $this->post_id ) {
491	return true;
492	}
493
494	// Get Post ID.
495	$this->post_id = get_the_ID();
496
497	// Initialize Settings and Post Setting classes.
498	$this->post_settings = new ConvertKit_Post( $this->post_id );
499
500	// If the Plugin API keys have not been configured, we can't determine the validity of this subscriber ID
501	// or which resource(s) they have access to.
502	if ( ! $this->settings->has_api_key_and_secret() ) {
503	return false;
504	}
505
506	// Return whether the Post's settings are set to restrict content.
507	return $this->post_settings->restrict_content_enabled();
508
509	}
510
511	/**
512	* Determines if the user entered a valid email address, and need to be prompted
513	* to enter a code sent to their email address.
514	*
515	* @since 2.1.0
516	*
517	* @return bool
518	*/
519	private function in_authentication_flow() {
520
521	return ( $this->token !== false );
522
523	}
524
525	/**
526	* Checks if the given WordPress Page matches the Page ID viewed, and has a parent.
527	*
528	* @since 2.1.0
529	*
530	* @param WP_Post $post WordPress Post.
531	* @return bool Has parent page
532	*/
533	private function has_parent_page( $post ) {
534
535	// Bail if the Page doesn't match the current Page being viewed.
536	// This prevents us accidentally interfering with other previous / next link queries, which shouldn't happen
537	// as we check if we're viewing a restricted content page above.
538	if ( $post->ID !== $this->post_id ) {
539	return false;
540	}
541
542	// Bail if the Page doesn't have a parent Page.
543	// We don't want to modify the default sort behaviour in this instance.
544	if ( $post->post_parent === 0 ) {
545	return false;
546	}
547
548	return true;
549
550	}
551
552	/**
553	* Get the Post's Restricted Content resource type.
554	*
555	* @since 2.1.0
556	*
557	* @param int $post_id Post ID.
558	* @return bool\|string Resource Type (product).
559	*/
560	private function get_resource_type( $post_id ) {
561
562	// Get resource type.
563	$resource_type = $this->post_settings->get_restrict_content_type();
564
565	/**
566	* Define the ConvertKit Resource Type that the visitor must be subscribed against
567	* to access this content, overriding the Post setting.
568	*
569	* Return false or an empty string to not restrict content.
570	*
571	* @since 2.1.0
572	*
573	* @param string $resource_type Resource Type (product)
574	* @param int $post_id Post ID
575	*/
576	$resource_type = apply_filters( 'convertkit_output_restrict_content_get_resource_type', $resource_type, $post_id );
577
578	// If resource type is blank, set it to false.
579	if ( empty( $resource_type ) ) {
580	$resource_type = false;
581	}
582
583	// Return.
584	return $resource_type;
585
586	}
587
588	/**
589	* Get the Post's Restricted Content resource ID.
590	*
591	* @since 2.1.0
592	*
593	* @param int $post_id Post ID.
594	* @return int Resource ID (product ID).
595	*/
596	private function get_resource_id( $post_id ) {
597
598	// Get resource ID.
599	$resource_id = $this->post_settings->get_restrict_content_id();
600
601	/**
602	* Define the ConvertKit Resource ID that the visitor must be subscribed against
603	* to access this content, overriding the Post setting.
604	*
605	* Return 0 to not restrict content.
606	*
607	* @since 2.1.0
608	*
609	* @param int $resource_id Resource ID
610	* @param int $post_id Post ID
611	*/
612	$resource_id = apply_filters( 'convertkit_output_restrict_content_get_resource_id', $resource_id, $post_id );
613
614	// Return.
615	return $resource_id;
616
617	}
618
619	/**
620	* Determines if the given subscriber has an active subscription to
621	* the given resource and its ID.
622	*
623	* @since 2.1.0
624	*
625	* @param string\|int $subscriber_id Signed Subscriber ID or Subscriber ID.
626	* @param string $resource_type Resource Type (product).
627	* @param int $resource_id Resource ID (Product ID).
628	* @return bool Can view restricted content
629	*/
630	private function subscriber_has_access( $subscriber_id, $resource_type, $resource_id ) { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter
631
632	// Initialize the API.
633	$this->api = new ConvertKit_API( $this->settings->get_api_key(), $this->settings->get_api_secret(), $this->settings->debug_enabled() );
634
635	// Depending on the resource type, determine if the subscriber has access to it.
636	// This is deliberately a switch statement, because we will likely add in support
637	// for restrict by tag and form later.
638	switch ( $resource_type ) {
639	case 'product':
640	// Get products that the subscriber has access to.
641	$result = $this->api->profile( $subscriber_id );
642
643	// If an error occured, the subscriber ID is invalid.
644	if ( is_wp_error( $result ) ) {
645	return false;
646	}
647
648	// If no products exist, there's no access.
649	if ( ! $result['products'] \|\| ! count( $result['products'] ) ) {
650	return false;
651	}
652
653	// Return if the subscriber is not subscribed to the product.
654	if ( ! in_array( absint( $resource_id ), $result['products'], true ) ) {
655	return false;
656	}
657
658	// If here, the subscriber is subscribed to the product.
659	return true;
660
661	case 'tag':
662	// Get tags that the subscriber has been assigned.
663	$tags = $this->api->get_subscriber_tags( $subscriber_id );
664
665	// If an error occured, the subscriber ID is invalid.
666	if ( is_wp_error( $tags ) ) {
667	return false;
668	}
669
670	// If no tags exist, there's no access.
671	if ( ! count( $tags ) ) {
672	return false;
673	}
674
675	// Iterate through the subscriber's tags to see if they have the required tag.
676	foreach ( $tags as $tag ) {
677	if ( $tag['id'] === absint( $resource_id ) ) {
678	// Subscriber has the required tag assigned to them - grant access.
679	return true;
680	}
681	}
682
683	// If here, the subscriber does not have the tag.
684	return false;
685	}
686
687	// If here, the subscriber does not have access.
688	return false;
689
690	}
691
692	/**
693	* Gets the subscriber ID from the request (either the cookie or the URL).
694	*
695	* @since 2.1.0
696	*
697	* @return int\|string Subscriber ID or Signed ID
698	*/
699	public function get_subscriber_id_from_request() {
700
701	// Use ConvertKit_Subscriber class to fetch and validate the subscriber ID.
702	$subscriber = new ConvertKit_Subscriber();
703	$subscriber_id = $subscriber->get_subscriber_id();
704
705	// If an error occured, the subscriber ID in the request/cookie is not a valid subscriber.
706	if ( is_wp_error( $subscriber_id ) ) {
707	return 0;
708	}
709
710	return $subscriber_id;
711
712	}
713
714	/**
715	* Restrict the given Post Content by showing a preview of the content, and appending
716	* the call to action to subscribe or authenticate.
717	*
718	* @since 2.1.0
719	*
720	* @param string $content Post Content.
721	* @param string $resource_type Resource Type (product).
722	* @param int $resource_id Resource ID (Product ID).
723	* @return string Post Content preview with call to action
724	*/
725	private function restrict_content( $content, $resource_type, $resource_id ) {
726
727	return $this->get_content_preview( $content ) . $this->get_call_to_action( $this->post_id, $resource_type, $resource_id );
728
729	}
730
731	/**
732	* Returns a preview of the given content for visitors that don't have access to restricted content.
733	*
734	* The preview is determined by:
735	* - A single <!--more--> tag being placed between WordPress paragraphs when using the Classic Editor.
736	* Content before the tag will be returned as the preview, unless 'noteaser' is enabled.
737	* - A single 'Read More' block being placed between WordPress blocks when using the Gutenberg Editor.
738	* Content before the Read More block will be returned as the preview, unless 'Hide th excerpt
739	* on the full content page' is enabled.
740	*
741	* No preview content is returned if the above conditions are not met.
742	*
743	* @since 2.1.0
744	*
745	* @param string $content Post Content.
746	* @return string Post Content Preview.
747	*/
748	private function get_content_preview( $content ) {
749
750	global $post;
751
752	// Check if the content contains a <!--more--> tag, which the editor might have placed
753	// in the content through WordPress' Classic Editor.
754	$content_breakdown = get_extended( $content );
755
756	// If the <!-- more --> tag exists, the 'extended' key will contain the restricted content.
757	if ( ! empty( $content_breakdown['extended'] ) ) {
758	// Return the preview content.
759	return $content_breakdown['main'];
760	}
761
762	// Check if the content contains a 'Read More' block, which the editor might have placed
763	// in the content through the Gutenberg Editor.
764	$block_editor_tag = '<span id="more-' . $post->ID . '"></span>';
765	if ( strpos( $content, $block_editor_tag ) !== false ) {
766	// Split content into an array by the tag.
767	$content_breakdown = explode( $block_editor_tag, $content );
768
769	// Return the content before the tag.
770	// If noteaser is enabled, this will correctly be blank.
771	return $content_breakdown[0];
772	}
773
774	// If here, there is no preview content available. Don't return any content.
775	return '';
776
777	}
778
779	/**
780	* Returns the HTML output for the call to action for visitors not subscribed to the required
781	* resource type and ID.
782	*
783	* @since 2.1.0
784	*
785	* @param int $post_id Post ID.
786	* @param string $resource_type Resource Type (product).
787	* @param int $resource_id Resource ID (Product ID).
788	* @return string HTML
789	*/
790	private function get_call_to_action( $post_id, $resource_type, $resource_id ) { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter
791
792	// Read success and error notices from this class.
793	$success = $this->success;
794	$error = $this->error;
795
796	// Only load styles if the Disable CSS option is off.
797	if ( ! $this->settings->css_disabled() ) {
798	// Enqueue styles.
799	wp_enqueue_style( 'convertkit-restrict-content', CONVERTKIT_PLUGIN_URL . 'resources/frontend/css/restrict-content.css', array(), CONVERTKIT_PLUGIN_VERSION );
800	}
801
802	// This is deliberately a switch statement, because we will likely add in support
803	// for restrict by tag and form later.
804	switch ( $resource_type ) {
805	case 'product':
806	// Output product code form if this request is after the user entered their email address,
807	// which means we're going through the authentication flow.
808	if ( $this->in_authentication_flow() ) { // phpcs:ignore WordPress.Security.NonceVerification
809	ob_start();
810	include CONVERTKIT_PLUGIN_PATH . '/views/frontend/restrict-content/product-code.php';
811	return trim( ob_get_clean() );
812	}
813
814	// Output product restricted message and email form.
815	// Get Product.
816	$products = new ConvertKit_Resource_Products( 'restrict_content' );
817	$product = $products->get_by_id( $resource_id );
818
819	// Get commerce.js URL and enqueue.
820	$url = $products->get_commerce_js_url();
821	if ( $url ) {
822	wp_enqueue_script( 'convertkit-commerce', $url, array(), CONVERTKIT_PLUGIN_VERSION, true );
823	}
824
825	// Output.
826	ob_start();
827	$button = $products->get_html( $resource_id, $this->restrict_content_settings->get_by_key( 'subscribe_button_label' ) );
828	include CONVERTKIT_PLUGIN_PATH . '/views/frontend/restrict-content/product.php';
829	return trim( ob_get_clean() );
830
831	case 'tag':
832	// Output.
833	ob_start();
834	include CONVERTKIT_PLUGIN_PATH . '/views/frontend/restrict-content/tag.php';
835	return trim( ob_get_clean() );
836
837	default:
838	return '';
839
840	}
841
842	}
843
844	}
845