init

wp-content/plugins/jetpack/modules/seo-tools/class-jetpack-seo-posts.php

@@ -0,0 +1,181 @@
+<?php
+/**
+ * Class containing utility static methods for managing SEO options for Posts and Pages.
+ *
+ * @package automattic/jetpack
+ */
+
+/**
+ * Provides static utility methods for managing SEO options for Posts and Pages.
+ */
+class Jetpack_SEO_Posts {
+	/**
+	 * Key of the post meta values that will be used to store post custom data.
+	 */
+	const DESCRIPTION_META_KEY = 'advanced_seo_description';
+	const HTML_TITLE_META_KEY  = 'jetpack_seo_html_title';
+	const NOINDEX_META_KEY     = 'jetpack_seo_noindex';
+	const POST_META_KEYS_ARRAY = array(
+		self::DESCRIPTION_META_KEY,
+		self::HTML_TITLE_META_KEY,
+		self::NOINDEX_META_KEY,
+	);
+
+	/**
+	 * Build meta description for post SEO.
+	 *
+	 * @param WP_Post|null $post Source of data for custom description.
+	 *
+	 * @return string Post description or empty string.
+	 */
+	public static function get_post_description( $post = null ) {
+		$post = get_post( $post );
+		if ( ! ( $post instanceof WP_Post ) ) {
+			return '';
+		}
+
+		if ( post_password_required() || ! is_singular() ) {
+			return '';
+		}
+
+		// Business users can overwrite the description.
+		$custom_description = self::get_post_custom_description( $post );
+
+		if ( ! empty( $custom_description ) ) {
+			return $custom_description;
+		}
+
+		if ( ! empty( $post->post_excerpt ) ) {
+			return $post->post_excerpt;
+		}
+
+		return $post->post_content;
+	}
+
+	/**
+	 * Returns post's custom meta description if it is set, and if
+	 * SEO tools are enabled for current blog.
+	 *
+	 * @param WP_Post|null $post Source of data for custom description.
+	 *
+	 * @return string Custom description or empty string
+	 */
+	public static function get_post_custom_description( $post = null ) {
+		$post = get_post( $post );
+		if ( ! ( $post instanceof WP_Post ) ) {
+			return '';
+		}
+
+		$custom_description = get_post_meta( $post->ID, self::DESCRIPTION_META_KEY, true );
+
+		if ( empty( $custom_description ) || ! Jetpack_SEO_Utils::is_enabled_jetpack_seo() ) {
+			return '';
+		}
+
+		return $custom_description;
+	}
+
+	/**
+	 * Gets a custom HTML title for a post if one is set, and if
+	 * SEO tools are enabled for the current blog.
+	 *
+	 * @param WP_Post|null $post Source of data for the custom HTML title.
+	 *
+	 * @return string Custom HTML title or an empty string if not set.
+	 */
+	public static function get_post_custom_html_title( $post = null ) {
+		$post = get_post( $post );
+		if ( ! ( $post instanceof WP_Post ) ) {
+			return '';
+		}
+
+		$custom_html_title = get_post_meta( $post->ID, self::HTML_TITLE_META_KEY, true );
+
+		if ( empty( $custom_html_title ) || ! Jetpack_SEO_Utils::is_enabled_jetpack_seo() ) {
+			return '';
+		}
+
+		return $custom_html_title;
+	}
+
+	/**
+	 * Gets the `jetpack_seo_noindex` setting for a post, if
+	 * SEO tools are enabled for the current blog.
+	 *
+	 * @param WP_Post|null $post Provided post or defaults to the global post.
+	 *
+	 * @return bool True if post should be marked as noindex, false otherwise.
+	 */
+	public static function get_post_noindex_setting( $post = null ) {
+		$post = get_post( $post );
+		if ( ! ( $post instanceof WP_Post ) ) {
+			return false;
+		}
+
+		$mark_as_noindex = get_post_meta( $post->ID, self::NOINDEX_META_KEY, true );
+
+		if ( empty( $mark_as_noindex ) || ! Jetpack_SEO_Utils::is_enabled_jetpack_seo() ) {
+			return false;
+		}
+
+		return (bool) $mark_as_noindex;
+	}
+
+	/**
+	 * Filter callback for `jetpack_sitemap_skip_post`; if a post has `jetpack_seo_noindex` set to true,
+	 * then exclude that post from the Jetpack sitemap.
+	 *
+	 * @param bool    $skip Whether to skip the post in the sitemap.
+	 * @param WP_Post $post The post to check.
+	 *
+	 * @return bool
+	 */
+	public static function exclude_noindex_posts_from_jetpack_sitemap( $skip, $post ) {
+		$exclude = self::get_post_noindex_setting( $post );
+		if ( $exclude ) {
+			$skip = true;
+		}
+		return $skip;
+	}
+
+	/**
+	 * Registers the following meta keys for use in the REST API:
+	 *   - self::DESCRIPTION_META_KEY
+	 *   - self::HTML_TITLE_META_KEY
+	 */
+	public static function register_post_meta() {
+		$description_args = array(
+			'type'         => 'string',
+			'description'  => __( 'Custom post description to be used in HTML <meta /> tag.', 'jetpack' ),
+			'single'       => true,
+			'default'      => '',
+			'show_in_rest' => array(
+				'name' => self::DESCRIPTION_META_KEY,
+			),
+		);
+
+		$html_title_args = array(
+			'type'         => 'string',
+			'description'  => __( 'Custom title to be used in HTML <title /> tag.', 'jetpack' ),
+			'single'       => true,
+			'default'      => '',
+			'show_in_rest' => array(
+				'name' => self::HTML_TITLE_META_KEY,
+			),
+		);
+
+		$noindex_args = array(
+			'type'         => 'boolean',
+			'description'  => __( 'Whether to hide the post from search engines and the Jetpack sitemap.', 'jetpack' ),
+			'single'       => true,
+			'default'      => false,
+			'show_in_rest' => array(
+				'name' => self::NOINDEX_META_KEY,
+			),
+		);
+
+		register_meta( 'post', self::DESCRIPTION_META_KEY, $description_args );
+		register_meta( 'post', self::HTML_TITLE_META_KEY, $html_title_args );
+		register_meta( 'post', self::NOINDEX_META_KEY, $noindex_args );
+	}
+}

wp-content/plugins/jetpack/modules/seo-tools/class-jetpack-seo-titles.php

@@ -0,0 +1,350 @@
+<?php
+/**
+ * Class containing utility static methods for managing SEO custom title formats.
+ *
+ * @package automattic/jetpack
+ */
+
+/*
+ * Each title format is an array of arrays containing two values:
+ *  - type
+ *  - value
+ *
+ * Possible values for type are: 'token' and 'string'.
+ * Possible values for 'value' are: any string in case that 'type' is set
+ * to 'string', or allowed token values for page type in case that 'type'
+ * is set to 'token'.
+ *
+ * Examples of valid formats:
+ *
+ * [
+ *  'front_page' => [
+ *      [ 'type' => 'string', 'value' => 'Front page title and site name:'],
+ *      [ 'type' => 'token', 'value' => 'site_name']
+ *  ],
+ *  'posts' => [
+ *      [ 'type' => 'token', 'value' => 'site_name' ],
+ *      [ 'type' => 'string', 'value' => ' | ' ],
+ *      [ 'type' => 'token', 'value' => 'post_title' ]
+ *  ],
+ *  'pages' => [],
+ *  'groups' => [],
+ *  'archives' => []
+ * ]
+ *  Custom title for given page type is created by concatenating all of the array 'value' parts.
+ *  Tokens are replaced with their corresponding values for current site.
+ *  Empty array signals that we are not overriding the default title for particular page type.
+ */
+
+/**
+ * Class containing utility static methods for managing SEO custom title formats.
+ */
+class Jetpack_SEO_Titles {
+	/**
+	 * Site option name used to store custom title formats.
+	 */
+	const TITLE_FORMATS_OPTION = 'advanced_seo_title_formats';
+
+	/**
+	 * Retrieves custom title formats from site option.
+	 *
+	 * @return array Array of custom title formats, or empty array.
+	 */
+	public static function get_custom_title_formats() {
+		if ( Jetpack_SEO_Utils::is_enabled_jetpack_seo() ) {
+			return get_option( self::TITLE_FORMATS_OPTION, array() );
+		}
+
+		return array();
+	}
+
+	/**
+	 * Returns tokens that are currently supported for each page type.
+	 *
+	 * @return array Array of allowed token strings.
+	 */
+	public static function get_allowed_tokens() {
+		return array(
+			'front_page' => array( 'site_name', 'tagline' ),
+			'posts'      => array( 'site_name', 'tagline', 'post_title' ),
+			'pages'      => array( 'site_name', 'tagline', 'page_title' ),
+			'groups'     => array( 'site_name', 'tagline', 'group_title' ),
+			'archives'   => array( 'site_name', 'tagline', 'date', 'archive_title' ),
+		);
+	}
+
+	/**
+	 * Used to modify the default title with custom SEO title.
+	 *
+	 * @param string $default_title Default title for current page.
+	 *
+	 * @return string A custom per-post title, custom title structure with replaced tokens, or default title.
+	 */
+	public static function get_custom_title( $default_title = '' ) {
+		// Don't filter title for unsupported themes.
+		if ( self::is_conflicted_theme() ) {
+			return $default_title;
+		}
+
+		$page_type = self::get_page_type();
+
+		// Keep default title if invalid page type is supplied.
+		if ( empty( $page_type ) ) {
+			return $default_title;
+		}
+
+		if ( ! Jetpack_SEO_Utils::is_enabled_jetpack_seo() ) {
+			return $default_title;
+		}
+
+		// If it's a singular -- page or post -- check for a meta title override.
+		if ( 'pages' === $page_type || 'posts' === $page_type ) {
+			$post = get_post();
+			if ( $post instanceof WP_Post ) {
+				$custom_title = get_post_meta( $post->ID, Jetpack_SEO_Posts::HTML_TITLE_META_KEY, true );
+				if ( ! empty( trim( $custom_title ) ) ) {
+					return esc_html( $custom_title );
+				}
+			}
+		}
+
+		$title_formats = self::get_custom_title_formats();
+
+		// Keep default title if user has not defined custom title for this page type.
+		if ( empty( $title_formats[ $page_type ] ) ) {
+			return $default_title;
+		}
+
+		$custom_title = '';
+		$format_array = $title_formats[ $page_type ];
+
+		foreach ( $format_array as $item ) {
+			if ( 'token' === $item['type'] ) {
+				$custom_title .= self::get_token_value( $item['value'] );
+			} else {
+				$custom_title .= $item['value'];
+			}
+		}
+
+		return esc_html( $custom_title );
+	}
+
+	/**
+	 * Returns string value for given token.
+	 *
+	 * @param string $token_name The token name value that should be replaced.
+	 *
+	 * @return string Token replacement for current site, or empty string for unknown token name.
+	 */
+	public static function get_token_value( $token_name ) {
+
+		switch ( $token_name ) {
+			case 'site_name':
+				return get_bloginfo( 'name' );
+
+			case 'tagline':
+				return get_bloginfo( 'description' );
+
+			case 'post_title':
+			case 'page_title':
+				return the_title_attribute( array( 'echo' => false ) );
+
+			case 'group_title':
+				return single_tag_title( '', false );
+
+			case 'date':
+			case 'archive_title':
+				return self::get_archive_title();
+
+			default:
+				return '';
+		}
+	}
+
+	/**
+	 * Returns page type for current page. We need this helper in order to determine what
+	 * user defined title format should be used for custom title.
+	 *
+	 * @return string|bool Type of current page or false if unsupported.
+	 */
+	public static function get_page_type() {
+
+		if ( is_front_page() ) {
+			return 'front_page';
+		}
+
+		if ( is_category() || is_tag() || is_tax() ) {
+			return 'groups';
+		}
+
+		if ( is_archive() && ! is_author() ) {
+			return 'archives';
+		}
+
+		if ( is_page() ) {
+			return 'pages';
+		}
+
+		if ( is_singular() ) {
+			return 'posts';
+		}
+
+		return false;
+	}
+
+	/**
+	 * Returns the value that should be used as a replacement for the `date` or `archive_title` tokens.
+	 * For date-based archives, a date is returned. Otherwise the `post_type_archive_title` is returned.
+	 *
+	 * The `archive_title` token was added after the `date` token to provide a more generic option
+	 * that would work for non date-based archives.
+	 *
+	 * @return string Token replaced string.
+	 */
+	public static function get_archive_title() {
+		// If archive year, month, and day are specified.
+		if ( is_day() ) {
+			return get_the_date();
+		}
+
+		// If archive year, and month are specified.
+		if ( is_month() ) {
+			return trim( single_month_title( ' ', false ) );
+		}
+
+		// Only archive year is specified.
+		if ( is_year() ) {
+			return get_query_var( 'year' );
+		}
+
+		// Not a date based archive.
+		// An example would be "Projects" for Jetpack's Portoflio CPT.
+		return post_type_archive_title( '', false );
+	}
+
+	/**
+	 * Checks if current theme is defining custom title that won't work nicely
+	 * with our custom SEO title override.
+	 *
+	 * @return bool True if current theme sets custom title, false otherwise.
+	 */
+	public static function is_conflicted_theme() {
+		/**
+		 * Can be used to specify a list of themes that use their own custom title format.
+		 *
+		 * If current site is using one of the themes listed as conflicting,
+		 * Jetpack SEO custom title formats will be disabled.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param array List of conflicted theme names. Defaults to empty array.
+		 */
+		$conflicted_themes = apply_filters( 'jetpack_seo_custom_title_conflicted_themes', array() );
+
+		return isset( $conflicted_themes[ get_option( 'template' ) ] );
+	}
+
+	/**
+	 * Checks if a given format conforms to predefined SEO title templates.
+	 *
+	 * Every format type and token must be specifically allowed.
+	 *
+	 * @see get_allowed_tokens()
+	 *
+	 * @param array $title_formats Template of SEO title to check.
+	 *
+	 * @return bool True if the formats are valid, false otherwise.
+	 */
+	public static function are_valid_title_formats( $title_formats ) {
+		$allowed_tokens = self::get_allowed_tokens();
+
+		if ( ! is_array( $title_formats ) ) {
+			return false;
+		}
+
+		foreach ( $title_formats as $format_type => $format_array ) {
+			if ( ! array_key_exists( $format_type, $allowed_tokens ) ) {
+				return false;
+			}
+
+			if ( '' === $format_array ) {
+				continue;
+			}
+
+			if ( ! is_array( $format_array ) ) {
+				return false;
+			}
+
+			foreach ( $format_array as $item ) {
+				if ( empty( $item['type'] ) || empty( $item['value'] ) ) {
+					return false;
+				}
+
+				if ( 'token' === $item['type'] ) {
+					if ( ! in_array( $item['value'], $allowed_tokens[ $format_type ], true ) ) {
+						return false;
+					}
+				}
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Sanitizes the arbitrary user input strings for custom SEO titles.
+	 *
+	 * @param array $title_formats Array of custom title formats.
+	 *
+	 * @return array The sanitized array.
+	 */
+	public static function sanitize_title_formats( $title_formats ) {
+		foreach ( $title_formats as &$format_array ) {
+			foreach ( $format_array as &$item ) {
+				if ( 'string' === $item['type'] ) {
+					// From `wp_strip_all_tags`, but omitting the `trim` portion since we want spacing preserved.
+					$item['value'] = preg_replace( '@<(script|style)[^>]*?>.*?</\\1>@si', '', $item['value'] );
+					$item['value'] = strip_tags( $item['value'] ); // phpcs:ignore WordPress.WP.AlternativeFunctions.strip_tags_strip_tags
+					$item['value'] = preg_replace( '/[\r\n\t ]+/', ' ', $item['value'] );
+				}
+			}
+		}
+		unset( $format_array );
+		unset( $item );
+
+		return $title_formats;
+	}
+
+	/**
+	 * Combines the previous values of title formats, stored as array in site options,
+	 * with the new values that are provided.
+	 *
+	 * @param array $new_formats Array containing new title formats.
+	 *
+	 * @return array $result Array of updated title formats, or empty array if no update was performed.
+	 */
+	public static function update_title_formats( $new_formats ) {
+		$new_formats = self::sanitize_title_formats( $new_formats );
+
+		// Empty array signals that custom title shouldn't be used.
+		$empty_formats = array(
+			'front_page' => array(),
+			'posts'      => array(),
+			'pages'      => array(),
+			'groups'     => array(),
+			'archives'   => array(),
+		);
+
+		$previous_formats = self::get_custom_title_formats();
+
+		$result = array_merge( $empty_formats, $previous_formats, $new_formats );
+
+		if ( update_option( self::TITLE_FORMATS_OPTION, $result ) ) {
+			return $result;
+		}
+
+		return array();
+	}
+}

wp-content/plugins/jetpack/modules/seo-tools/class-jetpack-seo-utils.php

@@ -0,0 +1,129 @@
+<?php
+/**
+ * Class containing utility static methods that other SEO tools are relying on.
+ *
+ * @package automattic/jetpack
+ */
+
+/**
+ * Class containing utility static methods that other SEO tools are relying on.
+ */
+class Jetpack_SEO_Utils {
+	/**
+	 * Site option name used to store front page meta description.
+	 */
+	const FRONT_PAGE_META_OPTION = 'advanced_seo_front_page_description';
+
+	/**
+	 * The LEGACY_META_OPTION is used to support legacy usage on WPcom simple sites (free or paid).
+	 * For WPorg JP sites, the JP seo-tools features were made free for all sites (free or paid).
+	 */
+	const LEGACY_META_OPTION = 'seo_meta_description';
+
+	/**
+	 * Used to check whether SEO tools are enabled for given site.
+	 *
+	 * @return bool True if SEO tools are enabled, false otherwise.
+	 */
+	public static function is_enabled_jetpack_seo() {
+		/**
+		 * Can be used by SEO plugin authors to disable the conflicting output of SEO Tools.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 5.0.0
+		 *
+		 * @param bool True if SEO Tools should be disabled, false otherwise.
+		 */
+		if ( apply_filters( 'jetpack_disable_seo_tools', false ) ) {
+			return false;
+		}
+
+		if ( defined( 'IS_WPCOM' ) && IS_WPCOM ) {
+			return wpcom_site_has_feature( 'advanced-seo', get_current_blog_id() );
+		}
+
+		return true;
+	}
+
+	/**
+	 * Checks if this option was set while it was freely available to all WPcom simple sites.
+	 *
+	 * @return bool True if we should enable legacy usage, false otherwise.
+	 */
+	public static function has_legacy_front_page_meta() {
+		return ! self::is_enabled_jetpack_seo() && get_option( self::LEGACY_META_OPTION );
+	}
+
+	/**
+	 * Returns front page meta description for current site.
+	 *
+	 * @return string Front page meta description string or empty string.
+	 */
+	public static function get_front_page_meta_description() {
+		if ( self::is_enabled_jetpack_seo() ) {
+			$front_page_meta = get_option( self::FRONT_PAGE_META_OPTION );
+			return $front_page_meta ? $front_page_meta : get_option( self::LEGACY_META_OPTION, '' );
+		}
+
+		// Support legacy usage for WPcom simple sites.
+		return get_option( self::LEGACY_META_OPTION, '' );
+	}
+
+	/**
+	 * Sanitizes the custom front page meta description input.
+	 *
+	 * @param string $value Front page meta string.
+	 *
+	 * @return string The sanitized string.
+	 */
+	public static function sanitize_front_page_meta_description( $value ) {
+		return wp_strip_all_tags( $value );
+	}
+
+	/**
+	 * Updates the site option value for front page meta description.
+	 *
+	 * @param string $value New value for front page meta description.
+	 *
+	 * @return string Saved value, or empty string if no update was performed.
+	 */
+	public static function update_front_page_meta_description( $value ) {
+		$front_page_description = self::sanitize_front_page_meta_description( $value );
+
+		/**
+		 * Can be used to limit the length of front page meta description.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param int Maximum length of front page meta description. Defaults to 300.
+		 */
+		$description_max_length = apply_filters( 'jetpack_seo_front_page_description_max_length', 300 );
+
+		if ( function_exists( 'mb_substr' ) ) {
+			$front_page_description = mb_substr( $front_page_description, 0, $description_max_length );
+		} else {
+			$front_page_description = substr( $front_page_description, 0, $description_max_length );
+		}
+
+		$can_set_meta       = self::is_enabled_jetpack_seo();
+		$legacy_meta_option = get_option( self::LEGACY_META_OPTION );
+		$has_old_meta       = ! empty( $legacy_meta_option );
+		$option_name        = self::has_legacy_front_page_meta() ? self::LEGACY_META_OPTION : self::FRONT_PAGE_META_OPTION;
+
+		$did_update = update_option( $option_name, $front_page_description );
+
+		if ( $did_update && $has_old_meta && $can_set_meta ) {
+			// Delete legacy option if user has switched to Business or eCommerce plan and updated the front page meta description.
+			delete_option( self::LEGACY_META_OPTION );
+		}
+
+		if ( $did_update ) {
+			return $front_page_description;
+		}
+
+		return '';
+	}
+}

wp-content/plugins/jetpack/modules/seo-tools/class-jetpack-seo.php

@@ -0,0 +1,286 @@
+<?php
+/**
+ * Main class file for the SEO Tools module.
+ *
+ * @package automattic/jetpack
+ */
+
+/**
+ * An SEO expert walks into a bar, bars, pub, public house, Irish pub, drinks, beer, wine, liquor, Grey Goose, Cristal...
+ */
+class Jetpack_SEO {
+	/**
+	 * Constructor.
+	 */
+	public function __construct() {
+		add_action( 'init', array( $this, 'init' ) );
+	}
+
+	/**
+	 * Initialization method for Jetpack_SEO.
+	 */
+	public function init() {
+		/**
+		 * Can be used to prevent SEO tools from inserting custom meta tags.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param bool true Should Jetpack's SEO Meta Tags be enabled. Defaults to true.
+		 */
+		if ( apply_filters( 'jetpack_seo_meta_tags_enabled', true ) ) {
+			add_action( 'wp_head', array( $this, 'meta_tags' ) );
+
+			// Add support for editing page excerpts in pages, regardless of theme support.
+			add_post_type_support( 'page', 'excerpt' );
+		}
+
+		/**
+		 * Can be used to prevent SEO tools from modifying site titles.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param bool true Should Jetpack SEO modify site titles. Defaults to true.
+		 */
+		if ( apply_filters( 'jetpack_seo_custom_titles', true ) ) {
+			// Overwrite page title with custom SEO meta title for themes that support title-tag.
+			add_filter( 'pre_get_document_title', array( 'Jetpack_SEO_Titles', 'get_custom_title' ) );
+
+			// Add overwrite support for themes that don't support title-tag.
+			add_filter( 'wp_title', array( 'Jetpack_SEO_Titles', 'get_custom_title' ) );
+		}
+
+		add_filter( 'jetpack_open_graph_tags', array( $this, 'set_custom_og_tags' ) );
+		Jetpack_SEO_Posts::register_post_meta();
+		// Exclude posts with 'jetpack_seo_noindex' set true from the Jetpack sitemap.
+		add_filter( 'jetpack_sitemap_skip_post', array( 'Jetpack_SEO_Posts', 'exclude_noindex_posts_from_jetpack_sitemap' ), 10, 2 );
+		add_action( 'rest_api_init', array( $this, 'add_custom_field_post_type_meta' ) );
+	}
+
+	/**
+	 * Add custom field meta to all public post types that don't already have it.
+	 */
+	public function add_custom_field_post_type_meta() {
+		/**
+		 * Filter the list of post types for which custom fields support is added.
+		 *
+		 * This filter allows modification of the post types that will be processed
+		 * to add support for custom fields if they do not already support it.
+		 *
+		 * @since 14.2
+		 *
+		 * @param array $post_types An array of post type names.
+		 */
+		$post_types = apply_filters(
+			'jetpack_seo_custom_field_post_types',
+			get_post_types(
+				array(
+					'public'   => true,
+					'show_ui'  => true,
+					'_builtin' => false,
+				)
+			)
+		);
+
+		foreach ( $post_types as $post_type ) {
+			if ( ! post_type_supports( $post_type, 'custom-fields' ) ) {
+				add_post_type_support( $post_type, 'custom-fields' );
+			}
+		}
+	}
+
+	/**
+	 * Helper method to fetch authors.
+	 */
+	private function get_authors() {
+		global $wp_query;
+
+		$authors = array();
+
+		foreach ( $wp_query->posts as $post ) {
+			$authors[] = get_the_author_meta( 'display_name', (int) $post->post_author );
+		}
+
+		$authors = array_unique( $authors );
+
+		return $authors;
+	}
+
+	/**
+	 * Constructs open graph tag data.
+	 *
+	 * @param array $tags Array of tag data.
+	 * @return array of tag data.
+	 */
+	public function set_custom_og_tags( $tags ) {
+		$custom_title = Jetpack_SEO_Titles::get_custom_title();
+
+		if ( ! empty( $custom_title ) ) {
+			$tags['og:title'] = $custom_title;
+		}
+
+		$post_custom_description = Jetpack_SEO_Posts::get_post_custom_description( get_post() );
+		$front_page_meta         = Jetpack_SEO_Utils::get_front_page_meta_description();
+
+		if ( class_exists( 'woocommerce' ) && is_shop() ) {
+			$shop_page_id = get_option( 'woocommerce_shop_page_id' );
+			if ( $shop_page_id ) {
+				$post_custom_description = Jetpack_SEO_Posts::get_post_custom_description( get_post( $shop_page_id ) );
+			}
+		}
+
+		if ( is_front_page() && ! empty( $front_page_meta ) ) {
+			$tags['og:description'] = $front_page_meta;
+		} elseif ( ! empty( $post_custom_description ) ) {
+			$tags['og:description'] = $post_custom_description;
+		}
+
+		return $tags;
+	}
+
+	/**
+	 * Outputs Jetpack's SEO <meta> tags.
+	 */
+	public function meta_tags() {
+		global $wp_query;
+
+		$post_count = is_countable( $wp_query->posts ) ? count( $wp_query->posts ) : 0;
+		$period     = '';
+		$template   = '';
+		$meta       = array();
+
+		/**
+		 * Can be used to specify a list of themes that set their own meta tags.
+		 *
+		 * If current site is using one of the themes listed as conflicting, inserting Jetpack SEO
+		 * meta tags will be prevented.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param array List of conflicted theme names. Defaults to empty array.
+		 */
+		$conflicted_themes = apply_filters( 'jetpack_seo_meta_tags_conflicted_themes', array() );
+
+		if ( isset( $conflicted_themes[ get_option( 'template' ) ] ) ) {
+			return;
+		}
+
+		$front_page_meta     = Jetpack_SEO_Utils::get_front_page_meta_description();
+		$description         = $front_page_meta ? $front_page_meta : get_bloginfo( 'description' );
+		$meta['description'] = trim( $description );
+
+		// Try to target things if we're on a "specific" page of any kind.
+		if ( is_singular() ) {
+			if ( ! ( is_front_page() && Jetpack_SEO_Utils::get_front_page_meta_description() ) ) {
+				$description = Jetpack_SEO_Posts::get_post_description( get_post() );
+
+				if ( $description ) {
+					$description         = wp_trim_words(
+						strip_shortcodes(
+							wp_strip_all_tags( $description, true )
+						)
+					);
+					$meta['description'] = $description;
+				}
+			}
+		} elseif ( is_author() ) {
+			$obj = get_queried_object();
+
+			$meta['description'] = sprintf(
+				/* translators: first property is an user's display name, the second is the site's title. */
+				_x( 'Read all of the posts by %1$s on %2$s', 'Read all of the posts by Author Name on Blog Title', 'jetpack' ),
+				isset( $obj->display_name ) ? $obj->display_name : __( 'the author', 'jetpack' ),
+				get_bloginfo( 'title' )
+			);
+		} elseif ( is_tag() || is_category() || is_tax() ) {
+			$obj         = get_queried_object();
+			$description = '';
+
+			if ( isset( $obj->term_id ) && isset( $obj->taxonomy ) ) {
+				$description = get_term_field( 'description', $obj->term_id, $obj->taxonomy, 'raw' );
+			}
+
+			if ( ! is_wp_error( $description ) && $description ) {
+				$meta['description'] = wp_trim_words( $description );
+			} else {
+				$authors = $this->get_authors();
+
+				$meta['description'] = wp_sprintf(
+					/* translators: %1$s: A post category. %2$l: Post authors. */
+					_x( 'Posts about %1$s written by %2$l', 'Posts about Category written by John and Bob', 'jetpack' ),
+					single_term_title( '', false ),
+					$authors
+				);
+			}
+		} elseif ( is_date() ) {
+			if ( is_year() ) {
+				$period = get_query_var( 'year' );
+
+				/* translators: %1$s: Number of posts published. %2$l: Post author. %3$s: A year date. */
+				$template = _nx(
+					'%1$s post published by %2$l in the year %3$s', // Singular.
+					'%1$s posts published by %2$l in the year %3$s', // Plural.
+					$post_count, // Number.
+					'10 posts published by John in the year 2012', // Context.
+					'jetpack'
+				);
+			} elseif ( is_month() ) {
+				$period = gmdate( 'F Y', mktime( 0, 0, 0, get_query_var( 'monthnum' ), 1, get_query_var( 'year' ) ) );
+
+				/* translators: %1$s: Number of posts published. %2$l: Post author. %3$s: A month/year date. */
+				$template = _nx(
+					'%1$s post published by %2$l during %3$s', // Singular.
+					'%1$s posts published by %2$l during %3$s', // Plural.
+					$post_count, // Number.
+					'10 posts publishes by John during May 2012', // Context.
+					'jetpack'
+				);
+			} elseif ( is_day() ) {
+				$period = gmdate(
+					'F j, Y',
+					mktime( 0, 0, 0, get_query_var( 'monthnum' ), get_query_var( 'day' ), get_query_var( 'year' ) )
+				);
+
+				/* translators: %1$s: Number of posts published. %2$l: Post author. %3$s: A month/day/year date. */
+				$template = _nx(
+					'%1$s post published by %2$l on %3$s', // Singular.
+					'%1$s posts published by %2$l on %3$s', // Plural.
+					$post_count, // Number.
+					'10 posts published by John on May 30, 2012', // Context.
+					'jetpack'
+				);
+			}
+
+			$authors             = $this->get_authors();
+			$meta['description'] = wp_sprintf( $template, $post_count, $authors, $period );
+		}
+
+		$mark_as_noindex = Jetpack_SEO_Posts::get_post_noindex_setting( get_post() );
+		if ( $mark_as_noindex ) {
+			$meta['robots'] = 'noindex';
+		}
+
+		/**
+		 * Can be used to edit the default SEO tools meta tags.
+		 *
+		 * @module seo-tools
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param array Array that consists of meta name and meta content pairs.
+		 */
+		$meta = apply_filters( 'jetpack_seo_meta_tags', $meta );
+
+		// Output them.
+		foreach ( $meta as $name => $content ) {
+			if ( ! empty( $content ) ) {
+				echo '<meta name="' . esc_attr( $name ) . '" content="' . esc_attr( $content ) . '" />' . "\n";
+			}
+		}
+	}
+}