subscriptions.php 31.9 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
<?php // phpcs:ignore WordPress.Files.FileName.InvalidClassFileName)
/**
 * Module Name: Subscriptions
 * Module Description: Let visitors subscribe to new posts and comments via email
 * Sort Order: 9
 * Recommendation Order: 8
 * First Introduced: 1.2
 * Requires Connection: Yes
 * Requires User Connection: Yes
 * Auto Activate: No
 * Module Tags: Social
 * Feature: Engagement
 * Additional Search Queries: subscriptions, subscription, email, follow, followers, subscribers, signup
 */

// phpcs:disable Universal.Files.SeparateFunctionsFromOO.Mixed -- TODO: Move classes to appropriately-named class files.

use Automattic\Jetpack\Connection\XMLRPC_Async_Call;

add_action( 'jetpack_modules_loaded', 'jetpack_subscriptions_load' );

/**
 * Loads the Subscriptions module.
 */
function jetpack_subscriptions_load() {
	Jetpack::enable_module_configurable( __FILE__ );
}

/**
 * Cherry picks keys from `$_SERVER` array.
 *
 * @since 6.0.0
 *
 * @return array An array of server data.
 */
function jetpack_subscriptions_cherry_pick_server_data() {
	$data = array();

	foreach ( $_SERVER as $key => $value ) {
		if ( ! is_string( $value ) || 0 === strpos( $key, 'HTTP_COOKIE' ) ) {
			continue;
		}

		if ( 0 === strpos( $key, 'HTTP_' ) || in_array( $key, array( 'REMOTE_ADDR', 'REQUEST_URI', 'DOCUMENT_URI' ), true ) ) {
			$data[ $key ] = $value;
		}
	}

	return $data;
}

/**
 * Main class file for the Subscriptions module.
 */
class Jetpack_Subscriptions {
	/**
	 * Whether Jetpack has been instantiated or not.
	 *
	 * @var bool
	 */
	public $jetpack = false;

	/**
	 * Hash of the siteurl option.
	 *
	 * @var string
	 */
	public static $hash;

	/**
	 * Singleton
	 *
	 * @static
	 */
	public static function init() {
		static $instance = false;

		if ( ! $instance ) {
			$instance = new Jetpack_Subscriptions();
		}

		return $instance;
	}

	/**
	 * Jetpack_Subscriptions constructor.
	 */
	public function __construct() {
		$this->jetpack = Jetpack::init();

		// Don't use COOKIEHASH as it could be shared across installs && is non-unique in multisite.
		// @see: https://twitter.com/nacin/status/378246957451333632 .
		self::$hash = md5( get_option( 'siteurl' ) );

		add_filter( 'jetpack_xmlrpc_methods', array( $this, 'xmlrpc_methods' ) );

		// @todo remove sync from subscriptions and move elsewhere...

		// Add Configuration Page.
		add_action( 'admin_init', array( $this, 'configure' ) );

		// Catch subscription widget submits.
		if ( isset( $_REQUEST['jetpack_subscriptions_widget'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Nonce checked in widget_submit() for logged in users.
			add_action( 'template_redirect', array( $this, 'widget_submit' ) );
		}

		// Set up the comment subscription checkboxes.
		add_filter( 'comment_form_submit_field', array( $this, 'comment_subscribe_init' ), 10, 2 );

		// Catch comment posts and check for subscriptions.
		add_action( 'comment_post', array( $this, 'comment_subscribe_submit' ), 50, 2 );

		// Adds post meta checkbox in the post submit metabox.
		add_action( 'post_submitbox_misc_actions', array( $this, 'subscription_post_page_metabox' ) );

		add_action( 'transition_post_status', array( $this, 'maybe_send_subscription_email' ), 10, 3 );

		add_filter( 'jetpack_published_post_flags', array( $this, 'set_post_flags' ), 10, 2 );

		add_filter( 'post_updated_messages', array( $this, 'update_published_message' ), 18, 1 );

		// Set "social_notifications_subscribe" option during the first-time activation.
		add_action( 'jetpack_activate_module_subscriptions', array( $this, 'set_social_notifications_subscribe' ) );

		// Hide subscription messaging in Publish panel for posts that were published in the past
		add_action( 'init', array( $this, 'register_post_meta' ), 20 );
		add_action( 'transition_post_status', array( $this, 'maybe_set_first_published_status' ), 10, 3 );
	}

	/**
	 * Jetpack_Subscriptions::xmlrpc_methods()
	 *
	 * Register subscriptions methods with the Jetpack XML-RPC server.
	 *
	 * @param array $methods Methods being registered.
	 */
	public function xmlrpc_methods( $methods ) {
		return array_merge(
			$methods,
			array(
				'jetpack.subscriptions.subscribe' => array( $this, 'subscribe' ),
			)
		);
	}

	/**
	 * Disable Subscribe on Single Post
	 * Register post meta
	 */
	public function subscription_post_page_metabox() {
		if (
			/**
			 * Filter whether or not to show the per-post subscription option.
			 *
			 * @module subscriptions
			 *
			 * @since 3.7.0
			 *
			 * @param bool true = show checkbox option on all new posts | false = hide the option.
			 */
			! apply_filters( 'jetpack_allow_per_post_subscriptions', false ) ) {
			return;
		}

		if ( has_filter( 'jetpack_subscriptions_exclude_these_categories' ) || has_filter( 'jetpack_subscriptions_include_only_these_categories' ) ) {
			return;
		}

		global $post;
		$disable_subscribe_value = get_post_meta( $post->ID, '_jetpack_dont_email_post_to_subs', true );
		// only show checkbox if post hasn't been published and is a 'post' post type.
		if ( get_post_status( $post->ID ) !== 'publish' && get_post_type( $post->ID ) === 'post' ) :
			// Nonce it.
			wp_nonce_field( 'disable_subscribe', 'disable_subscribe_nonce' );
			?>
			<div class="misc-pub-section">
				<label for="_jetpack_dont_email_post_to_subs"><?php esc_html_e( 'Jetpack Subscriptions:', 'jetpack' ); ?></label><br>
				<input type="checkbox" name="_jetpack_dont_email_post_to_subs" id="jetpack-per-post-subscribe" value="1" <?php checked( $disable_subscribe_value, 1, true ); ?> />
				<?php esc_html_e( 'Don&#8217;t send this to subscribers', 'jetpack' ); ?>
			</div>
			<?php
		endif;
	}

	/**
	 * Checks whether or not the post should be emailed to subscribers
	 *
	 * It checks for the following things in order:
	 * - Usage of filter jetpack_subscriptions_exclude_these_categories
	 * - Usage of filter jetpack_subscriptions_include_only_these_categories
	 * - Existence of the per-post checkbox option
	 *
	 * Only one of these can be used at any given time.
	 *
	 * @param string $new_status Tthe "new" post status of the transition when saved.
	 * @param string $old_status The "old" post status of the transition when saved.
	 * @param object $post obj The post object.
	 */
	public function maybe_send_subscription_email( $new_status, $old_status, $post ) {

		if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
			return;
		}

		// Make sure that the checkbox is preseved.
		if ( ! empty( $_POST['disable_subscribe_nonce'] ) && wp_verify_nonce( $_POST['disable_subscribe_nonce'], 'disable_subscribe' ) ) { // phpcs:ignore WordPress.Security.ValidatedSanitizedInput -- WP Core doesn't unslash or sanitize nonces either.
			$set_checkbox = isset( $_POST['_jetpack_dont_email_post_to_subs'] ) ? 1 : 0;
			update_post_meta( $post->ID, '_jetpack_dont_email_post_to_subs', $set_checkbox );
		}
	}

	/**
	 * Message used when publishing a post.
	 *
	 * @param array $messages Message array for a post.
	 */
	public function update_published_message( $messages ) {
		global $post;
		if ( ! $this->should_email_post_to_subscribers( $post ) ) {
			return $messages;
		}

		$view_post_link_html = sprintf(
			' <a href="%1$s">%2$s</a>',
			esc_url( get_permalink( $post ) ),
			__( 'View post', 'jetpack' )
		);

		$messages['post'][6] = sprintf(
			/* translators: Message shown after a post is published */
			esc_html__( 'Post published and sending emails to subscribers.', 'jetpack' )
		) . $view_post_link_html;
		return $messages;
	}

	/**
	 * Determine if a post should notifiy subscribers via email.
	 *
	 * @param object $post The post.
	 */
	public function should_email_post_to_subscribers( $post ) {
		$should_email = true;
		if ( get_post_meta( $post->ID, '_jetpack_dont_email_post_to_subs', true ) ) {
			return false;
		}

		// Only posts are currently supported.
		if ( 'post' !== $post->post_type ) {
			return false;
		}

		// Private posts are not sent to subscribers.
		if ( 'private' === $post->post_status ) {
			return false;
		}

		/**
		 * Array of categories that will never trigger subscription emails.
		 *
		 * Will not send subscription emails from any post from within these categories.
		 *
		 * @module subscriptions
		 *
		 * @since 3.7.0
		 *
		 * @param array $args Array of category slugs or ID's.
		 */
		$excluded_categories = apply_filters( 'jetpack_subscriptions_exclude_these_categories', array() );

		// Never email posts from these categories.
		if ( ! empty( $excluded_categories ) && in_category( $excluded_categories, $post->ID ) ) {
			$should_email = false;
		}

		/**
		 * ONLY send subscription emails for these categories
		 *
		 * Will ONLY send subscription emails to these categories.
		 *
		 * @module subscriptions
		 *
		 * @since 3.7.0
		 *
		 * @param array $args Array of category slugs or ID's.
		 */
		$only_these_categories = apply_filters( 'jetpack_subscriptions_exclude_all_categories_except', array() );

		// Only emails posts from these categories.
		if ( ! empty( $only_these_categories ) && ! in_category( $only_these_categories, $post->ID ) ) {
			$should_email = false;
		}

		return $should_email;
	}

	/**
	 * Retrieve which flags should be added to a particular post.
	 *
	 * @param array  $flags Flags to be added.
	 * @param object $post A post object.
	 */
	public function set_post_flags( $flags, $post ) {
		$flags['send_subscription'] = $this->should_email_post_to_subscribers( $post );
		return $flags;
	}

	/**
	 * Jetpack_Subscriptions::configure()
	 *
	 * Jetpack Subscriptions configuration screen.
	 */
	public function configure() {
		// Create the section.
		add_settings_section(
			'jetpack_subscriptions',
			__( 'Jetpack Subscriptions Settings', 'jetpack' ),
			array( $this, 'subscriptions_settings_section' ),
			'discussion'
		);

		/** Subscribe to Posts */

		add_settings_field(
			'jetpack_subscriptions_post_subscribe',
			__( 'Follow Blog', 'jetpack' ),
			array( $this, 'subscription_post_subscribe_setting' ),
			'discussion',
			'jetpack_subscriptions'
		);

		register_setting(
			'discussion',
			'stb_enabled'
		);

		/** Subscribe to Comments */

		add_settings_field(
			'jetpack_subscriptions_comment_subscribe',
			__( 'Follow Comments', 'jetpack' ),
			array( $this, 'subscription_comment_subscribe_setting' ),
			'discussion',
			'jetpack_subscriptions'
		);

		register_setting(
			'discussion',
			'stc_enabled'
		);

		/** Email me whenever: Someone follows my blog */
		/* @since 8.1 */

		add_settings_section(
			'notifications_section',
			__( 'Someone follows my blog', 'jetpack' ),
			array( $this, 'social_notifications_subscribe_section' ),
			'discussion'
		);

		add_settings_field(
			'jetpack_subscriptions_social_notifications_subscribe',
			__( 'Email me whenever', 'jetpack' ),
			array( $this, 'social_notifications_subscribe_field' ),
			'discussion',
			'notifications_section'
		);

		register_setting(
			'discussion',
			'social_notifications_subscribe',
			array( $this, 'social_notifications_subscribe_validate' )
		);

		/** Subscription Messaging Options */

		register_setting(
			'reading',
			'subscription_options',
			array( $this, 'validate_settings' )
		);

		add_settings_section(
			'email_settings',
			__( 'Follower Settings', 'jetpack' ),
			array( $this, 'reading_section' ),
			'reading'
		);

		add_settings_field(
			'invitation',
			__( 'Blog follow email text', 'jetpack' ),
			array( $this, 'setting_invitation' ),
			'reading',
			'email_settings'
		);

		add_settings_field(
			'comment-follow',
			__( 'Comment follow email text', 'jetpack' ),
			array( $this, 'setting_comment_follow' ),
			'reading',
			'email_settings'
		);
	}

	/**
	 * Discussions setting section blurb.
	 */
	public function subscriptions_settings_section() {
		?>
		<p id="jetpack-subscriptions-settings"><?php esc_html_e( 'Change whether your visitors can subscribe to your posts or comments or both.', 'jetpack' ); ?></p>

		<?php
	}

	/**
	 * Post Subscriptions Toggle.
	 */
	public function subscription_post_subscribe_setting() {

		$stb_enabled = get_option( 'stb_enabled', 1 );
		?>

		<p class="description">
			<input type="checkbox" name="stb_enabled" id="jetpack-post-subscribe" value="1" <?php checked( $stb_enabled, 1 ); ?> />
			<?php
			echo wp_kses(
				__(
					"Show a <em>'follow blog'</em> option in the comment form",
					'jetpack'
				),
				array( 'em' => array() )
			);
			?>
		</p>
		<?php
	}

	/**
	 * Comments Subscriptions Toggle.
	 */
	public function subscription_comment_subscribe_setting() {

		$stc_enabled = get_option( 'stc_enabled', 1 );
		?>

		<p class="description">
			<input type="checkbox" name="stc_enabled" id="jetpack-comment-subscribe" value="1" <?php checked( $stc_enabled, 1 ); ?> />
			<?php
			echo wp_kses(
				__(
					"Show a <em>'follow comments'</em> option in the comment form",
					'jetpack'
				),
				array( 'em' => array() )
			);
			?>
		</p>

		<?php
	}

	/**
	 * Someone follows my blog section
	 *
	 * @since 8.1
	 */
	public function social_notifications_subscribe_section() {
		// Atypical usage here. We emit jquery to move subscribe notification checkbox to be with the rest of the email notification settings.
		?>
		<script type="text/javascript">
			jQuery( function( $ )  {
				var table = $( '#social_notifications_subscribe' ).parents( 'table:first' ),
					header = table.prevAll( 'h2:first' ),
					newParent = $( '#moderation_notify' ).parent( 'label' ).parent();

				if ( ! table.length || ! header.length || ! newParent.length ) {
					return;
				}

				newParent.append( '<br/>' ).append( table.end().parent( 'label' ).siblings().andSelf() );
				header.remove();
				table.remove();
			} );
		</script>
		<?php
	}

	/**
	 * Someone follows my blog Toggle
	 *
	 * @since 8.1
	 */
	public function social_notifications_subscribe_field() {
		$checked = (int) ( 'on' === get_option( 'social_notifications_subscribe', 'on' ) );
		?>

		<label>
			<input type="checkbox" name="social_notifications_subscribe" id="social_notifications_subscribe" value="1" <?php checked( $checked ); ?> />
			<?php
				/* translators: this is a label for a setting that starts with "Email me whenever" */
				esc_html_e( 'Someone follows my blog', 'jetpack' );
			?>
		</label>
		<?php
	}

	/**
	 * Validate "Someone follows my blog" option
	 *
	 * @since 8.1
	 *
	 * @param String $input the input string to be validated.
	 * @return string on|off
	 */
	public function social_notifications_subscribe_validate( $input ) {
		// If it's not set (was unchecked during form submission) or was set to off (during option update), return 'off'.
		if ( ! $input || 'off' === $input ) {
			return 'off';
		}

		// Otherwise we return 'on'.
		return 'on';
	}

	/**
	 * Validate settings for the Subscriptions module.
	 *
	 * @param array $settings Settings to be validated.
	 */
	public function validate_settings( $settings ) {
		global $allowedposttags;

		$default = $this->get_default_settings();

		// Blog Follow.
		$settings['invitation'] = trim( wp_kses( $settings['invitation'], $allowedposttags ) );
		if ( empty( $settings['invitation'] ) ) {
			$settings['invitation'] = $default['invitation'];
		}

		// Comments Follow (single post).
		$settings['comment_follow'] = trim( wp_kses( $settings['comment_follow'], $allowedposttags ) );
		if ( empty( $settings['comment_follow'] ) ) {
			$settings['comment_follow'] = $default['comment_follow'];
		}

		return $settings;
	}

	/**
	 * HTML output helper for Reading section.
	 */
	public function reading_section() {
		echo '<p id="follower-settings">';
		esc_html_e( 'These settings change emails sent from your blog to followers.', 'jetpack' );
		echo '</p>';
	}

	/**
	 * HTML output helper for Invitation section.
	 */
	public function setting_invitation() {
		$settings = $this->get_settings();
		echo '<textarea name="subscription_options[invitation]" class="large-text" cols="50" rows="5">' . esc_textarea( $settings['invitation'] ) . '</textarea>';
		echo '<p><span class="description">' . esc_html__( 'Introduction text sent when someone follows your blog. (Site and confirmation details will be automatically added for you.)', 'jetpack' ) . '</span></p>';
	}

	/**
	 * HTML output helper for Comment Follow section.
	 */
	public function setting_comment_follow() {
		$settings = $this->get_settings();
		echo '<textarea name="subscription_options[comment_follow]" class="large-text" cols="50" rows="5">' . esc_textarea( $settings['comment_follow'] ) . '</textarea>';
		echo '<p><span class="description">' . esc_html__( 'Introduction text sent when someone follows a post on your blog. (Site and confirmation details will be automatically added for you.)', 'jetpack' ) . '</span></p>';
	}

	/**
	 * Get default settings for the Subscriptions module.
	 */
	public function get_default_settings() {
		$site_url    = get_home_url();
		$display_url = preg_replace( '(^https?://)', '', untrailingslashit( $site_url ) );

		return array(
			/* translators: Both %1$s and %2$s is site address */
			'invitation'     => sprintf( __( "Howdy,\nYou recently subscribed to <a href='%1\$s'>%2\$s</a> and we need to verify the email you provided. Once you confirm below, you'll be able to receive and read new posts.\n\nIf you believe this is an error, ignore this message and nothing more will happen.", 'jetpack' ), $site_url, $display_url ),
			'comment_follow' => __( "Howdy.\n\nYou recently followed one of my posts. This means you will receive an email when new comments are posted.\n\nTo activate, click confirm below. If you believe this is an error, ignore this message and we'll never bother you again.", 'jetpack' ),
		);
	}

	/**
	 * Reeturn merged `subscription_options` option with module default settings.
	 */
	public function get_settings() {
		return wp_parse_args( (array) get_option( 'subscription_options' ), $this->get_default_settings() );
	}

	/**
	 * Jetpack_Subscriptions::subscribe()
	 *
	 * Send a synchronous XML-RPC subscribe to blog posts or subscribe to post comments request.
	 *
	 * @param string $email being subscribed.
	 * @param array  $post_ids (optional) defaults to 0 for blog posts only: array of post IDs to subscribe to blog's posts.
	 * @param bool   $async    (optional) Should the subscription be performed asynchronously?  Defaults to true.
	 * @param array  $extra_data Additional data passed to the `jetpack.subscribeToSite` call.
	 *
	 * @return true|WP_Error true on success
	 *  invalid_email   : not a valid email address
	 *  invalid_post_id : not a valid post ID
	 *  unknown_post_id : unknown post
	 *  not_subscribed  : strange error.  Jetpack servers at WordPress.com could subscribe the email.
	 *  disabled        : Site owner has disabled subscriptions.
	 *  active          : Already subscribed.
	 *  pending         : Tried to subscribe before but the confirmation link is never clicked. No confirmation email is sent.
	 *  unknown         : strange error.  Jetpack servers at WordPress.com returned something malformed.
	 *  unknown_status  : strange error.  Jetpack servers at WordPress.com returned something I didn't understand.
	 */
	public function subscribe( $email, $post_ids = 0, $async = true, $extra_data = array() ) {
		if ( ! is_email( $email ) ) {
			return new WP_Error( 'invalid_email' );
		}

		if ( ! $async ) {
			$xml = new Jetpack_IXR_ClientMulticall();
		}

		foreach ( (array) $post_ids as $post_id ) {
			$post_id = (int) $post_id;
			if ( $post_id < 0 ) {
				return new WP_Error( 'invalid_post_id' );
			} elseif ( $post_id && ! get_post( $post_id ) ) {
				return new WP_Error( 'unknown_post_id' );
			}

			if ( $async ) {
				XMLRPC_Async_Call::add_call( 'jetpack.subscribeToSite', 0, $email, $post_id, serialize( $extra_data ) ); //phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_serialize
			} else {
				$xml->addCall( 'jetpack.subscribeToSite', $email, $post_id, serialize( $extra_data ) ); //phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.serialize_serialize
			}
		}

		if ( $async ) {
			return;
		}

		// Call.
		$xml->query();

		if ( $xml->isError() ) {
			return $xml->get_jetpack_error();
		}

		$responses = $xml->getResponse();

		$r = array();
		foreach ( (array) $responses as $response ) {
			if ( isset( $response['faultCode'] ) || isset( $response['faultString'] ) ) {
				$r[] = $xml->get_jetpack_error( $response['faultCode'], $response['faultString'] );
				continue;
			}

			if ( ! is_array( $response[0] ) || empty( $response[0]['status'] ) ) {
				$r[] = new WP_Error( 'unknown' );
				continue;
			}

			switch ( $response[0]['status'] ) {
				case 'error':
					$r[] = new WP_Error( 'not_subscribed' );
					continue 2;
				case 'disabled':
					$r[] = new WP_Error( 'disabled' );
					continue 2;
				case 'active':
					$r[] = new WP_Error( 'active' );
					continue 2;
				case 'confirming':
					$r[] = true;
					continue 2;
				case 'pending':
					$r[] = new WP_Error( 'pending' );
					continue 2;
				default:
					$r[] = new WP_Error( 'unknown_status', (string) $response[0]['status'] );
					continue 2;
			}
		}

		return $r;
	}

	/**
	 * Jetpack_Subscriptions::widget_submit()
	 *
	 * When a user submits their email via the blog subscription widget, check the details and call the subsribe() method.
	 */
	public function widget_submit() {
		// Check the nonce.
		if ( is_user_logged_in() ) {
			check_admin_referer( 'blogsub_subscribe_' . get_current_blog_id() );
		}

		if ( empty( $_REQUEST['email'] ) || ! is_string( $_REQUEST['email'] ) ) {
			return false;
		}

		$redirect_fragment = false;
		if ( isset( $_REQUEST['redirect_fragment'] ) ) {
			$redirect_fragment = preg_replace( '/[^a-z0-9_-]/i', '', $_REQUEST['redirect_fragment'] ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput -- This is manually unslashing and sanitizing.
		}
		if ( ! $redirect_fragment || ! is_string( $redirect_fragment ) ) {
			$redirect_fragment = 'subscribe-blog';
		}

		$subscribe = self::subscribe(
			isset( $_REQUEST['email'] ) ? wp_unslash( $_REQUEST['email'] ) : null, // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- Validated inside self::subscribe().
			0,
			false,
			array(
				'source'         => 'widget',
				'widget-in-use'  => is_active_widget( false, false, 'blog_subscription', true ) ? 'yes' : 'no',
				'comment_status' => '',
				'server_data'    => jetpack_subscriptions_cherry_pick_server_data(),
			)
		);

		if ( is_wp_error( $subscribe ) ) {
			$error = $subscribe->get_error_code();
		} else {
			$error = false;
			foreach ( $subscribe as $response ) {
				if ( is_wp_error( $response ) ) {
					$error = $response->get_error_code();
					break;
				}
			}
		}

		switch ( $error ) {
			case false:
				$result = 'success';
				break;
			case 'invalid_email':
				$result = $error;
				break;
			case 'blocked_email':
				$result = 'opted_out';
				break;
			case 'active':
				$result = 'already';
				break;
			case 'flooded_email':
				$result = 'many_pending_subs';
				break;
			case 'pending':
				$result = 'pending';
				break;
			default:
				$result = 'error';
				break;
		}

		$redirect = add_query_arg( 'subscribe', $result );

		/**
		 * Fires on each subscription form submission.
		 *
		 * @module subscriptions
		 *
		 * @since 3.7.0
		 *
		 * @param string $result Result of form submission: success, invalid_email, already, error.
		 */
		do_action( 'jetpack_subscriptions_form_submission', $result );

		wp_safe_redirect( "$redirect#$redirect_fragment" );
		exit;
	}

	/**
	 * Jetpack_Subscriptions::comment_subscribe_init()
	 *
	 * Set up and add the comment subscription checkbox to the comment form.
	 *
	 * @param string $submit_button HTML markup for the submit field.
	 */
	public function comment_subscribe_init( $submit_button ) {
		global $post;

		$comments_checked = '';
		$blog_checked     = '';

		// Check for a comment / blog submission and set a cookie to retain the setting and check the boxes.
		if ( isset( $_COOKIE[ 'jetpack_comments_subscribe_' . self::$hash . '_' . $post->ID ] ) ) {
			$comments_checked = ' checked="checked"';
		}

		if ( isset( $_COOKIE[ 'jetpack_blog_subscribe_' . self::$hash ] ) ) {
			$blog_checked = ' checked="checked"';
		}

		// Some themes call this function, don't show the checkbox again.
		remove_action( 'comment_form', 'subscription_comment_form' );

		// Check if Mark Jaquith's Subscribe to Comments plugin is active - if so, suppress Jetpack checkbox.

		$str = '';

		if ( false === has_filter( 'comment_form', 'show_subscription_checkbox' ) && 1 === (int) get_option( 'stc_enabled', 1 ) && empty( $post->post_password ) && 'post' === get_post_type() ) {
			// Subscribe to comments checkbox.
			$str             .= '<p class="comment-subscription-form"><input type="checkbox" name="subscribe_comments" id="subscribe_comments" value="subscribe" style="width: auto; -moz-appearance: checkbox; -webkit-appearance: checkbox;"' . $comments_checked . ' /> ';
			$comment_sub_text = __( 'Notify me of follow-up comments by email.', 'jetpack' );
			$str             .= '<label class="subscribe-label" id="subscribe-label" for="subscribe_comments">' . esc_html(
				/**
				 * Filter the Subscribe to comments text appearing below the comment form.
				 *
				 * @module subscriptions
				 *
				 * @since 3.4.0
				 *
				 * @param string $comment_sub_text Subscribe to comments text.
				 */
				apply_filters( 'jetpack_subscribe_comment_label', $comment_sub_text )
			) . '</label>';
			$str .= '</p>';
		}

		if ( 1 === (int) get_option( 'stb_enabled', 1 ) ) {
			// Subscribe to blog checkbox.
			$str          .= '<p class="comment-subscription-form"><input type="checkbox" name="subscribe_blog" id="subscribe_blog" value="subscribe" style="width: auto; -moz-appearance: checkbox; -webkit-appearance: checkbox;"' . $blog_checked . ' /> ';
			$blog_sub_text = __( 'Notify me of new posts by email.', 'jetpack' );
			$str          .= '<label class="subscribe-label" id="subscribe-blog-label" for="subscribe_blog">' . esc_html(
				/**
				 * Filter the Subscribe to blog text appearing below the comment form.
				 *
				 * @module subscriptions
				 *
				 * @since 3.4.0
				 *
				 * @param string $comment_sub_text Subscribe to blog text.
				 */
				apply_filters( 'jetpack_subscribe_blog_label', $blog_sub_text )
			) . '</label>';
			$str .= '</p>';
		}

		/**
		 * Filter the output of the subscription options appearing below the comment form.
		 *
		 * @module subscriptions
		 *
		 * @since 1.2.0
		 *
		 * @param string $str Comment Subscription form HTML output.
		 */
		$str = apply_filters( 'jetpack_comment_subscription_form', $str );

		return $str . $submit_button;
	}

	/**
	 * Jetpack_Subscriptions::comment_subscribe_init()
	 *
	 * When a user checks the comment subscribe box and submits a comment, subscribe them to the comment thread.
	 *
	 * @param int|string $comment_id Comment thread being subscribed to.
	 * @param string     $approved Comment status.
	 */
	public function comment_subscribe_submit( $comment_id, $approved ) {
		if ( 'spam' === $approved ) {
			return;
		}

		$comment = get_comment( $comment_id );
		if ( ! $comment ) {
			return;
		}

		// Set cookies for this post/comment.
		$this->set_cookies( isset( $_REQUEST['subscribe_comments'] ), $comment->comment_post_ID, isset( $_REQUEST['subscribe_blog'] ) ); // phpcs:ignore WordPress.Security.NonceVerification.Recommended

		if ( ! isset( $_REQUEST['subscribe_comments'] ) && ! isset( $_REQUEST['subscribe_blog'] ) ) {  // phpcs:ignore WordPress.Security.NonceVerification.Recommended
			return;
		}

		$post_ids = array();

		if ( isset( $_REQUEST['subscribe_comments'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended
			$post_ids[] = $comment->comment_post_ID;
		}

		if ( isset( $_REQUEST['subscribe_blog'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended
			$post_ids[] = 0;
		}

		$result = self::subscribe(
			$comment->comment_author_email,
			$post_ids,
			true,
			array(
				'source'         => 'comment-form',
				'widget-in-use'  => is_active_widget( false, false, 'blog_subscription', true ) ? 'yes' : 'no',
				'comment_status' => $approved,
				'server_data'    => jetpack_subscriptions_cherry_pick_server_data(),
			)
		);

		/**
		 * Fires on each comment subscription form submission.
		 *
		 * @module subscriptions
		 *
		 * @since 5.5.0
		 *
		 * @param NULL|WP_Error $result Result of form submission: NULL on success, WP_Error otherwise.
		 * @param array $post_ids An array of post IDs that the user subscribed to, 0 means blog subscription.
		 */
		do_action( 'jetpack_subscriptions_comment_form_submission', $result, $post_ids );
	}

	/**
	 * Jetpack_Subscriptions::set_cookies()
	 *
	 * Set a cookie to save state on the comment and post subscription checkboxes.
	 *
	 * @param bool $subscribe_to_post Whether the user chose to subscribe to subsequent comments on this post.
	 * @param int  $post_id If $subscribe_to_post is true, the post ID they've subscribed to.
	 * @param bool $subscribe_to_blog Whether the user chose to subscribe to all new posts on the blog.
	 */
	public function set_cookies( $subscribe_to_post = false, $post_id = null, $subscribe_to_blog = false ) {
		$post_id = (int) $post_id;

		/** This filter is already documented in core/wp-includes/comment-functions.php */
		$cookie_lifetime = apply_filters( 'comment_cookie_lifetime', 30000000 );

		/**
		 * Filter the Jetpack Comment cookie path.
		 *
		 * @module subscriptions
		 *
		 * @since 2.5.0
		 *
		 * @param string COOKIEPATH Cookie path.
		 */
		$cookie_path = apply_filters( 'jetpack_comment_cookie_path', COOKIEPATH );

		/**
		 * Filter the Jetpack Comment cookie domain.
		 *
		 * @module subscriptions
		 *
		 * @since 2.5.0
		 *
		 * @param string COOKIE_DOMAIN Cookie domain.
		 */
		$cookie_domain = apply_filters( 'jetpack_comment_cookie_domain', COOKIE_DOMAIN );

		if ( $subscribe_to_post && $post_id >= 0 ) {
			setcookie( 'jetpack_comments_subscribe_' . self::$hash . '_' . $post_id, 1, time() + $cookie_lifetime, $cookie_path, $cookie_domain, is_ssl(), true );
		} else {
			setcookie( 'jetpack_comments_subscribe_' . self::$hash . '_' . $post_id, '', time() - 3600, $cookie_path, $cookie_domain, is_ssl(), true );
		}

		if ( $subscribe_to_blog ) {
			setcookie( 'jetpack_blog_subscribe_' . self::$hash, 1, time() + $cookie_lifetime, $cookie_path, $cookie_domain, is_ssl(), true );
		} else {
			setcookie( 'jetpack_blog_subscribe_' . self::$hash, '', time() - 3600, $cookie_path, $cookie_domain, is_ssl(), true );
		}
	}

	/**
	 * Set the social_notifications_subscribe option to `off` when the Subscriptions module is activated in the first time.
	 *
	 * @since 8.1
	 *
	 * @return void
	 */
	public function set_social_notifications_subscribe() {
		if ( false === get_option( 'social_notifications_subscribe' ) ) {
			add_option( 'social_notifications_subscribe', 'off' );
		}
	}

	/**
	 * Save a flag when a post was ever published.
	 *
	 * It saves the post meta when the post was published and becomes a draft.
	 * Then this meta is used to hide subscription messaging in Publish panel.
	 *
	 * @param string $new_status Tthe "new" post status of the transition when saved.
	 * @param string $old_status The "old" post status of the transition when saved.
	 * @param object $post obj The post object.
	 */
	public function maybe_set_first_published_status( $new_status, $old_status, $post ) {
		$was_post_ever_published = get_post_meta( $post->ID, '_jetpack_post_was_ever_published', true );
		if ( ! $was_post_ever_published && 'publish' === $old_status && 'draft' === $new_status ) {
			update_post_meta( $post->ID, '_jetpack_post_was_ever_published', true );
		}
	}

	/**
	 * Checks if the current user can publish posts.
	 *
	 * @return bool
	 */
	public function first_published_status_meta_auth_callback() {
		if ( current_user_can( 'publish_posts' ) ) {
			return true;
		}
		return false;
	}

	/**
	 * Registers the 'post_was_ever_published' post meta for use in the REST API.
	 */
	public function register_post_meta() {
		$jetpack_post_was_ever_published = array(
			'type'          => 'boolean',
			'description'   => __( 'Whether the post was ever published.', 'jetpack' ),
			'single'        => true,
			'default'       => false,
			'show_in_rest'  => array(
				'name' => 'jetpack_post_was_ever_published',
			),
			'auth_callback' => array( $this, 'first_published_status_meta_auth_callback' ),
		);

		register_meta( 'post', '_jetpack_post_was_ever_published', $jetpack_post_was_ever_published );
	}

}

Jetpack_Subscriptions::init();

require __DIR__ . '/subscriptions/views.php';