thinkrank / includes / seo / class-feed-manager.php

class-feed-manager.php in ThinkRank AI SEO – AI SEO Plugin for WordPress: Schema, XML Sitemaps, Meta Tags, Search Console & Local SEO 2.7.0, at includes/seo/class-feed-manager.php

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1	<?php
2	/**
3	* What ThinkRank does to the site's RSS feeds.
4	*
5	* @package ThinkRank
6	* @since 2.7.0
7	*/
8
9	declare(strict_types=1);
10
11	namespace ThinkRank\SEO;
12
13	if (!defined('ABSPATH')) {
14	exit;
15	}
16
17	/**
18	* Feed controls: shorten entries, sign them, and keep them out of the index.
19	*
20	* WordPress publishes a feed of every site, and content scrapers read it to
21	* republish posts wholesale. The standard defence — shipped by The SEO
22	* Framework, Yoast and Rank Math — is three small controls, and ThinkRank had
23	* none of them, which made a ThinkRank site the easy target among the big
24	* plugins.
25	*
26	* - Shorten entries to an excerpt. A scraper that copies the feed gets an
27	* intro rather than the article.
28	* - Sign each entry with a link home. The useful half: a scraped copy
29	* carries a link back to the original, which is worth more than the copy
30	* costs.
31	* - Keep feeds out of the index. A feed URL competing with the post it
32	* duplicates helps nobody. Deliberately a choice rather than a hardcode:
33	* podcast sites need their feed indexable, which is the caveat The SEO
34	* Framework documents for its own version of this.
35	*
36	* All three default off, so an upgrade changes nothing about what an existing
37	* site already publishes to its subscribers. A brand-new install is seeded with
38	* the signature and the noindex on ({@see Activator::seed_feed_defaults()}),
39	* which is where matching the competitors' out-of-the-box posture belongs.
40	*
41	* @since 2.7.0
42	*/
43	class Feed_Manager {
44
45	/**
46	* Site identity settings, read once per request.
47	*
48	* @since 2.7.0
49	* @var array\|null
50	*/
51	private $settings = null;
52
53	/**
54	* Register the feed hooks.
55	*
56	* @since 2.7.0
57	* @return void
58	*/
59	public function init(): void {
60	// Early, so the header is set before anything can start the body.
61	add_action('template_redirect', [$this, 'maybe_noindex_feed'], 1);
62
63	add_filter('the_content_feed', [$this, 'filter_content'], 20);
64	add_filter('the_excerpt_rss', [$this, 'filter_excerpt'], 20);
65	}
66
67	/**
68	* Ask crawlers not to index a feed.
69	*
70	* A header rather than a robots.txt rule: a disallowed URL is never fetched,
71	* so the crawler never learns it is not to be indexed and the URL can still
72	* surface from links elsewhere. `follow` is kept so the links inside the
73	* feed still count.
74	*
75	* @since 2.7.0
76	* @return void
77	*/
78	public function maybe_noindex_feed(): void {
79	if (!is_feed() \|\| headers_sent()) {
80	return;
81	}
82
83	if (empty($this->settings()['feed_noindex'])) {
84	return;
85	}
86
87	header('X-Robots-Tag: noindex, follow', true);
88	}
89
90	/**
91	* The body of a feed entry.
92	*
93	* @since 2.7.0
94	* @param mixed $content Entry content.
95	* @return mixed
96	*/
97	public function filter_content($content) {
98	// Untyped: this value belongs to whoever filtered it before us, and
99	// coercing another plugin's object or null to a string would drop it.
100	if (!is_string($content)) {
101	return $content;
102	}
103
104	$settings = $this->settings();
105
106	if (!empty($settings['feed_excerpt_only'])) {
107	$excerpt = $this->excerpt();
108
109	if ('' !== $excerpt) {
110	$content = $excerpt;
111	}
112	}
113
114	return $content . $this->source_link($settings);
115	}
116
117	/**
118	* The excerpt of a feed entry.
119	*
120	* Signed as well as the body: which of the two a reader sees depends on the
121	* feed template and on the site's Reading setting, and an unsigned entry is
122	* exactly the one a scraper wants.
123	*
124	* @since 2.7.0
125	* @param mixed $excerpt Entry excerpt.
126	* @return mixed
127	*/
128	public function filter_excerpt($excerpt) {
129	if (!is_string($excerpt)) {
130	return $excerpt;
131	}
132
133	return $excerpt . $this->source_link($this->settings());
134	}
135
136	/**
137	* The line that points a scraped copy back here.
138	*
139	* @since 2.7.0
140	* @param array $settings Site identity settings.
141	* @return string HTML, or '' when the feature is off.
142	*/
143	private function source_link(array $settings): string {
144	if (empty($settings['feed_source_link'])) {
145	return '';
146	}
147
148	$post_id = get_the_ID();
149
150	if (!$post_id) {
151	return '';
152	}
153
154	$permalink = (string) get_permalink($post_id);
155	$home = home_url('/');
156
157	if ('' === $permalink) {
158	return '';
159	}
160
161	$html = sprintf(
162	'<p>%s</p>',
163	sprintf(
164	/* translators: 1: link to the original post, 2: link to the site. */
165	esc_html__('The post %1$s first appeared on %2$s.', 'thinkrank'),
166	'<a href="' . esc_url($permalink) . '">' . esc_html(get_the_title($post_id)) . '</a>',
167	'<a href="' . esc_url($home) . '">' . esc_html(get_bloginfo('name')) . '</a>'
168	)
169	);
170
171	/**
172	* Filter the source line appended to each feed entry.
173	*
174	* @since 2.7.0
175	*
176	* @param string $html The line, as HTML.
177	* @param int $post_id Post the entry describes.
178	*/
179	$filtered = apply_filters('thinkrank_feed_source_link', $html, $post_id);
180
181	// Same reasoning as filter_content() above, from the other side: a
182	// caller who returns an array gets `Array to string conversion` and the
183	// literal string "Array" appended to every entry in the feed. Take the
184	// filtered value only when it is one, and keep our own line otherwise.
185	if (is_string($filtered)) {
186	$html = $filtered;
187	}
188
189	// Feed bodies are wrapped in CDATA by the feed templates, and a literal
190	// ]]> inside one ends the section early and breaks the whole document.
191	return str_replace(']]>', ']]>', $html);
192	}
193
194	/**
195	* The excerpt to stand in for a full entry.
196	*
197	* Falls back to one derived from the content when the author wrote none,
198	* because the point of the setting is that the full text does not go out.
199	*
200	* @since 2.7.0
201	* @return string
202	*/
203	private function excerpt(): string {
204	$post_id = get_the_ID();
205
206	if (!$post_id) {
207	return '';
208	}
209
210	// Core already shortens entries when the Reading setting says
211	// "Summary". Shortening an excerpt again would cut a short entry down
212	// to almost nothing, so this defers to it.
213	if (get_option('rss_use_excerpt')) {
214	return '';
215	}
216
217	$excerpt = trim((string) get_the_excerpt($post_id));
218
219	return '' === $excerpt ? '' : wpautop($excerpt);
220	}
221
222	/**
223	* Site identity settings, read once.
224	*
225	* @since 2.7.0
226	* @return array
227	*/
228	private function settings(): array {
229	if (null === $this->settings) {
230	$this->settings = $this->load_settings();
231	}
232
233	return $this->settings;
234	}
235
236	/**
237	* Read the settings.
238	*
239	* Its own method so the filters can be exercised without a settings store;
240	* what matters here is which switch changed which part of an entry.
241	*
242	* @since 2.7.0
243	* @return array
244	*/
245	protected function load_settings(): array {
246	return (array) (new Site_Identity_Manager())->get_settings('site', null);
247	}
248	}
249