$default_feed = get_default_feed();
	if ( empty( $feed ) ) {
		$feed = $default_feed;
	}

	$link = get_post_type_archive_link( $post_type );
	if ( ! $link ) {
		return false;
	}

	$post_type_obj = get_post_type_object( $post_type );
	if ( get_option( 'permalink_structure' ) && is_array( $post_type_obj->rewrite ) && $post_type_obj->rewrite['feeds'] ) {
		$link  = trailingslashit( $link );
		$link .= 'feed/';
		if ( $feed != $default_feed ) {
			$link .= "$feed/";
		}
	} else {
		$link = add_query_arg( 'feed', $feed, $link );
	}

	/**
	 * Filters the post type archive feed link.
	 *
	 * @since 3.1.0
	 *
	 * @param string $link The post type archive feed link.
	 * @param string $feed Feed type. Possible values include 'rss2', 'atom'.
	 */
	return apply_filters( 'post_type_archive_feed_link', $link, $feed );
}

/**
 * Retrieves the URL used for the post preview.
 *
 * Allows additional query args to be appended.
 *
 * @since 4.4.0
 *
 * @param int|WP_Post $post         Optional. Post ID or `WP_Post` object. Defaults to global `$post`.
 * @param array       $query_args   Optional. Array of additional query args to be appended to the link.
 *                                  Default empty array.
 * @param string      $preview_link Optional. Base preview link to be used if it should differ from the
 *                                  post permalink. Default empty.
 * @return string|null URL used for the post preview, or null if the post does not exist.
 */
function get_preview_post_link( $post = null, $query_args = array(), $preview_link = '' ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return;
	}

	$post_type_object = get_post_type_object( $post->post_type );
	if ( is_post_type_viewable( $post_type_object ) ) {
		if ( ! $preview_link ) {
			$preview_link = set_url_scheme( get_permalink( $post ) );
		}

		$query_args['preview'] = 'true';
		$preview_link          = add_query_arg( $query_args, $preview_link );
	}

	/**
	 * Filters the URL used for a post preview.
	 *
	 * @since 2.0.5
	 * @since 4.0.0 Added the `$post` parameter.
	 *
	 * @param string  $preview_link URL used for the post preview.
	 * @param WP_Post $post         Post object.
	 */
	return apply_filters( 'preview_post_link', $preview_link, $post );
}

/**
 * Retrieves the edit post link for post.
 *
 * Can be used within the WordPress loop or outside of it. Can be used with
 * pages, posts, attachments, revisions, global styles, templates, and template parts.
 *
 * @since 2.3.0
 * @since 6.3.0 Adds custom link for wp_navigation post types.
 *              Adds custom links for wp_template_part and wp_template post types.
 *
 * @param int|WP_Post $post    Optional. Post ID or post object. Default is the global `$post`.
 * @param string      $context Optional. How to output the '&' character. Default '&'.
 * @return string|null The edit post link for the given post. Null if the post type does not exist
 *                     or does not allow an editing UI.
 */
function get_edit_post_link( $post = 0, $context = 'display' ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return;
	}

	if ( 'revision' === $post->post_type ) {
		$action = '';
	} elseif ( 'display' === $context ) {
		$action = '&action=edit';
	} else {
		$action = '&action=edit';
	}

	$post_type_object = get_post_type_object( $post->post_type );

	if ( ! $post_type_object ) {
		return;
	}

	if ( ! current_user_can( 'edit_post', $post->ID ) ) {
		return;
	}

	$link = '';

	if ( 'wp_template' === $post->post_type || 'wp_template_part' === $post->post_type ) {
		$slug = urlencode( get_stylesheet() . '//' . $post->post_name );
		$link = admin_url( sprintf( $post_type_object->_edit_link, $post->post_type, $slug ) );
	} elseif ( 'wp_navigation' === $post->post_type ) {
		$link = admin_url( sprintf( $post_type_object->_edit_link, (string) $post->ID ) );
	} elseif ( $post_type_object->_edit_link ) {
		$link = admin_url( sprintf( $post_type_object->_edit_link . $action, $post->ID ) );
	}

	/**
	 * Filters the post edit link.
	 *
	 * @since 2.3.0
	 *
	 * @param string $link    The edit link.
	 * @param int    $post_id Post ID.
	 * @param string $context The link context. If set to 'display' then ampersands
	 *                        are encoded.
	 */
	return apply_filters( 'get_edit_post_link', $link, $post->ID, $context );
}

/**
 * Displays the edit post link for post.
 *
 * @since 1.0.0
 * @since 4.4.0 The `$css_class` argument was added.
 *
 * @param string      $text      Optional. Anchor text. If null, default is 'Edit This'. Default null.
 * @param string      $before    Optional. Display before edit link. Default empty.
 * @param string      $after     Optional. Display after edit link. Default empty.
 * @param int|WP_Post $post      Optional. Post ID or post object. Default is the global `$post`.
 * @param string      $css_class Optional. Add custom class to link. Default 'post-edit-link'.
 */
function edit_post_link( $text = null, $before = '', $after = '', $post = 0, $css_class = 'post-edit-link' ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return;
	}

	$url = get_edit_post_link( $post->ID );

	if ( ! $url ) {
		return;
	}

	if ( null === $text ) {
		$text = __( 'Edit This' );
	}

	$link = '<a class="' . esc_attr( $css_class ) . '" href="' . esc_url( $url ) . '">' . $text . '</a>';

	/**
	 * Filters the post edit link anchor tag.
	 *
	 * @since 2.3.0
	 *
	 * @param string $link    Anchor tag for the edit link.
	 * @param int    $post_id Post ID.
	 * @param string $text    Anchor text.
	 */
	echo $before . apply_filters( 'edit_post_link', $link, $post->ID, $text ) . $after;
}

/**
 * Retrieves the delete posts link for post.
 *
 * Can be used within the WordPress loop or outside of it, with any post type.
 *
 * @since 2.9.0
 *
 * @param int|WP_Post $post         Optional. Post ID or post object. Default is the global `$post`.
 * @param string      $deprecated   Not used.
 * @param bool        $force_delete Optional. Whether to bypass Trash and force deletion. Default false.
 * @return string|void The delete post link URL for the given post.
 */
function get_delete_post_link( $post = 0, $deprecated = '', $force_delete = false ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '3.0.0' );
	}

	$post = get_post( $post );

	if ( ! $post ) {
		return;
	}

	$post_type_object = get_post_type_object( $post->post_type );

	if ( ! $post_type_object ) {
		return;
	}

	if ( ! current_user_can( 'delete_post', $post->ID ) ) {
		return;
	}

	$action = ( $force_delete || ! EMPTY_TRASH_DAYS ) ? 'delete' : 'trash';

	$delete_link = add_query_arg( 'action', $action, admin_url( sprintf( $post_type_object->_edit_link, $post->ID ) ) );

	/**
	 * Filters the post delete link.
	 *
	 * @since 2.9.0
	 *
	 * @param string $link         The delete link.
	 * @param int    $post_id      Post ID.
	 * @param bool   $force_delete Whether to bypass the Trash and force deletion. Default false.
	 */
	return apply_filters( 'get_delete_post_link', wp_nonce_url( $delete_link, "$action-post_{$post->ID}" ), $post->ID, $force_delete );
}

/**
 * Retrieves the edit comment link.
 *
 * @since 2.3.0
 *
 * @param int|WP_Comment $comment_id Optional. Comment ID or WP_Comment object.
 * @return string|void The edit comment link URL for the given comment.
 */
function get_edit_comment_link( $comment_id = 0 ) {
	$comment = get_comment( $comment_id );

	if ( ! current_user_can( 'edit_comment', $comment->comment_ID ) ) {
		return;
	}

	$location = admin_url( 'comment.php?action=editcomment&amp;c=' ) . $comment->comment_ID;

	/**
	 * Filters the comment edit link.
	 *
	 * @since 2.3.0
	 *
	 * @param string $location The edit link.
	 */
	return apply_filters( 'get_edit_comment_link', $location );
}

/**
 * Displays the edit comment link with formatting.
 *
 * @since 1.0.0
 *
 * @param string $text   Optional. Anchor text. If null, default is 'Edit This'. Default null.
 * @param string $before Optional. Display before edit link. Default empty.
 * @param string $after  Optional. Display after edit link. Default empty.
 */
function edit_comment_link( $text = null, $before = '', $after = '' ) {
	$comment = get_comment();

	if ( ! current_user_can( 'edit_comment', $comment->comment_ID ) ) {
		return;
	}

	if ( null === $text ) {
		$text = __( 'Edit This' );
	}

	$link = '<a class="comment-edit-link" href="' . esc_url( get_edit_comment_link( $comment ) ) . '">' . $text . '</a>';

	/**
	 * Filters the comment edit link anchor tag.
	 *
	 * @since 2.3.0
	 *
	 * @param string $link       Anchor tag for the edit link.
	 * @param string $comment_id Comment ID as a numeric string.
	 * @param string $text       Anchor text.
	 */
	echo $before . apply_filters( 'edit_comment_link', $link, $comment->comment_ID, $text ) . $after;
}

/**
 * Displays the edit bookmark link.
 *
 * @since 2.7.0
 *
 * @param int|stdClass $link Optional. Bookmark ID. Default is the ID of the current bookmark.
 * @return string|void The edit bookmark link URL.
 */
function get_edit_bookmark_link( $link = 0 ) {
	$link = get_bookmark( $link );

	if ( ! current_user_can( 'manage_links' ) ) {
		return;
	}

	$location = admin_url( 'link.php?action=edit&amp;link_id=' ) . $link->link_id;

	/**
	 * Filters the bookmark edit link.
	 *
	 * @since 2.7.0
	 *
	 * @param string $location The edit link.
	 * @param int    $link_id  Bookmark ID.
	 */
	return apply_filters( 'get_edit_bookmark_link', $location, $link->link_id );
}

/**
 * Displays the edit bookmark link anchor content.
 *
 * @since 2.7.0
 *
 * @param string $link     Optional. Anchor text. If empty, default is 'Edit This'. Default empty.
 * @param string $before   Optional. Display before edit link. Default empty.
 * @param string $after    Optional. Display after edit link. Default empty.
 * @param int    $bookmark Optional. Bookmark ID. Default is the current bookmark.
 */
function edit_bookmark_link( $link = '', $before = '', $after = '', $bookmark = null ) {
	$bookmark = get_bookmark( $bookmark );

	if ( ! current_user_can( 'manage_links' ) ) {
		return;
	}

	if ( empty( $link ) ) {
		$link = __( 'Edit This' );
	}

	$link = '<a href="' . esc_url( get_edit_bookmark_link( $bookmark ) ) . '">' . $link . '</a>';

	/**
	 * Filters the bookmark edit link anchor tag.
	 *
	 * @since 2.7.0
	 *
	 * @param string $link    Anchor tag for the edit link.
	 * @param int    $link_id Bookmark ID.
	 */
	echo $before . apply_filters( 'edit_bookmark_link', $link, $bookmark->link_id ) . $after;
}

/**
 * Retrieves the edit user link.
 *
 * @since 3.5.0
 *
 * @param int $user_id Optional. User ID. Defaults to the current user.
 * @return string URL to edit user page or empty string.
 */
function get_edit_user_link( $user_id = null ) {
	if ( ! $user_id ) {
		$user_id = get_current_user_id();
	}

	if ( empty( $user_id ) || ! current_user_can( 'edit_user', $user_id ) ) {
		return '';
	}

	$user = get_userdata( $user_id );

	if ( ! $user ) {
		return '';
	}

	if ( get_current_user_id() == $user->ID ) {
		$link = get_edit_profile_url( $user->ID );
	} else {
		$link = add_query_arg( 'user_id', $user->ID, self_admin_url( 'user-edit.php' ) );
	}

	/**
	 * Filters the user edit link.
	 *
	 * @since 3.5.0
	 *
	 * @param string $link    The edit link.
	 * @param int    $user_id User ID.
	 */
	return apply_filters( 'get_edit_user_link', $link, $user->ID );
}

//
// Navigation links.
//

/**
 * Retrieves the previous post that is adjacent to the current post.
 *
 * @since 1.5.0
 *
 * @param bool         $in_same_term   Optional. Whether post should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return WP_Post|null|string Post object if successful. Null if global `$post` is not set.
 *                             Empty string if no corresponding post exists.
 */
function get_previous_post( $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	return get_adjacent_post( $in_same_term, $excluded_terms, true, $taxonomy );
}

/**
 * Retrieves the next post that is adjacent to the current post.
 *
 * @since 1.5.0
 *
 * @param bool         $in_same_term   Optional. Whether post should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return WP_Post|null|string Post object if successful. Null if global `$post` is not set.
 *                             Empty string if no corresponding post exists.
 */
function get_next_post( $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	return get_adjacent_post( $in_same_term, $excluded_terms, false, $taxonomy );
}

/**
 * Retrieves the adjacent post.
 *
 * Can either be next or previous post.
 *
 * @since 2.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param bool         $in_same_term   Optional. Whether post should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty string.
 * @param bool         $previous       Optional. Whether to retrieve previous post.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return WP_Post|null|string Post object if successful. Null if global `$post` is not set.
 *                             Empty string if no corresponding post exists.
 */
function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previous = true, $taxonomy = 'category' ) {
	global $wpdb;

	$post = get_post();

	if ( ! $post || ! taxonomy_exists( $taxonomy ) ) {
		return null;
	}

	$current_post_date = $post->post_date;

	$join     = '';
	$where    = '';
	$adjacent = $previous ? 'previous' : 'next';

	if ( ! empty( $excluded_terms ) && ! is_array( $excluded_terms ) ) {
		// Back-compat, $excluded_terms used to be $excluded_categories with IDs separated by " and ".
		if ( str_contains( $excluded_terms, ' and ' ) ) {
			_deprecated_argument(
				__FUNCTION__,
				'3.3.0',
				sprintf(
					/* translators: %s: The word 'and'. */
					__( 'Use commas instead of %s to separate excluded terms.' ),
					"'and'"
				)
			);
			$excluded_terms = explode( ' and ', $excluded_terms );
		} else {
			$excluded_terms = explode( ',', $excluded_terms );
		}

		$excluded_terms = array_map( 'intval', $excluded_terms );
	}

	/**
	 * Filters the IDs of terms excluded from adjacent post queries.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `get_next_post_excluded_terms`
	 *  - `get_previous_post_excluded_terms`
	 *
	 * @since 4.4.0
	 *
	 * @param int[]|string $excluded_terms Array of excluded term IDs. Empty string if none were provided.
	 */
	$excluded_terms = apply_filters( "get_{$adjacent}_post_excluded_terms", $excluded_terms );

	if ( $in_same_term || ! empty( $excluded_terms ) ) {
		if ( $in_same_term ) {
			$join  .= " INNER JOIN $wpdb->term_relationships AS tr ON p.ID = tr.object_id INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id";
			$where .= $wpdb->prepare( 'AND tt.taxonomy = %s', $taxonomy );

			if ( ! is_object_in_taxonomy( $post->post_type, $taxonomy ) ) {
				return '';
			}
			$term_array = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) );

			// Remove any exclusions from the term array to include.
			$term_array = array_diff( $term_array, (array) $excluded_terms );
			$term_array = array_map( 'intval', $term_array );

			if ( ! $term_array || is_wp_error( $term_array ) ) {
				return '';
			}

			$where .= ' AND tt.term_id IN (' . implode( ',', $term_array ) . ')';
		}

		if ( ! empty( $excluded_terms ) ) {
			$where .= " AND p.ID NOT IN ( SELECT tr.object_id FROM $wpdb->term_relationships tr LEFT JOIN $wpdb->term_taxonomy tt ON (tr.term_taxonomy_id = tt.term_taxonomy_id) WHERE tt.term_id IN (" . implode( ',', array_map( 'intval', $excluded_terms ) ) . ') )';
		}
	}

	// 'post_status' clause depends on the current user.
	if ( is_user_logged_in() ) {
		$user_id = get_current_user_id();

		$post_type_object = get_post_type_object( $post->post_type );
		if ( empty( $post_type_object ) ) {
			$post_type_cap    = $post->post_type;
			$read_private_cap = 'read_private_' . $post_type_cap . 's';
		} else {
			$read_private_cap = $post_type_object->cap->read_private_posts;
		}

		/*
		 * Results should include private posts belonging to the current user, or private posts where the
		 * current user has the 'read_private_posts' cap.
		 */
		$private_states = get_post_stati( array( 'private' => true ) );
		$where         .= " AND ( p.post_status = 'publish'";
		foreach ( $private_states as $state ) {
			if ( current_user_can( $read_private_cap ) ) {
				$where .= $wpdb->prepare( ' OR p.post_status = %s', $state );
			} else {
				$where .= $wpdb->prepare( ' OR (p.post_author = %d AND p.post_status = %s)', $user_id, $state );
			}
		}
		$where .= ' )';
	} else {
		$where .= " AND p.post_status = 'publish'";
	}

	$op    = $previous ? '<' : '>';
	$order = $previous ? 'DESC' : 'ASC';

	/**
	 * Filters the JOIN clause in the SQL for an adjacent post query.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `get_next_post_join`
	 *  - `get_previous_post_join`
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
	 *
	 * @param string       $join           The JOIN clause in the SQL.
	 * @param bool         $in_same_term   Whether post should be in the same taxonomy term.
	 * @param int[]|string $excluded_terms Array of excluded term IDs. Empty string if none were provided.
	 * @param string       $taxonomy       Taxonomy. Used to identify the term used when `$in_same_term` is true.
	 * @param WP_Post      $post           WP_Post object.
	 */
	$join = apply_filters( "get_{$adjacent}_post_join", $join, $in_same_term, $excluded_terms, $taxonomy, $post );

	/**
	 * Filters the WHERE clause in the SQL for an adjacent post query.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `get_next_post_where`
	 *  - `get_previous_post_where`
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
	 *
	 * @param string       $where          The `WHERE` clause in the SQL.
	 * @param bool         $in_same_term   Whether post should be in the same taxonomy term.
	 * @param int[]|string $excluded_terms Array of excluded term IDs. Empty string if none were provided.
	 * @param string       $taxonomy       Taxonomy. Used to identify the term used when `$in_same_term` is true.
	 * @param WP_Post      $post           WP_Post object.
	 */
	$where = apply_filters( "get_{$adjacent}_post_where", $wpdb->prepare( "WHERE p.post_date $op %s AND p.post_type = %s $where", $current_post_date, $post->post_type ), $in_same_term, $excluded_terms, $taxonomy, $post );

	/**
	 * Filters the ORDER BY clause in the SQL for an adjacent post query.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `get_next_post_sort`
	 *  - `get_previous_post_sort`
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$post` parameter.
	 * @since 4.9.0 Added the `$order` parameter.
	 *
	 * @param string $order_by The `ORDER BY` clause in the SQL.
	 * @param WP_Post $post    WP_Post object.
	 * @param string  $order   Sort order. 'DESC' for previous post, 'ASC' for next.
	 */
	$sort = apply_filters( "get_{$adjacent}_post_sort", "ORDER BY p.post_date $order LIMIT 1", $post, $order );

	$query        = "SELECT p.ID FROM $wpdb->posts AS p $join $where $sort";
	$key          = md5( $query );
	$last_changed = wp_cache_get_last_changed( 'posts' );
	if ( $in_same_term || ! empty( $excluded_terms ) ) {
		$last_changed .= wp_cache_get_last_changed( 'terms' );
	}
	$cache_key = "adjacent_post:$key:$last_changed";

	$result = wp_cache_get( $cache_key, 'post-queries' );
	if ( false !== $result ) {
		if ( $result ) {
			$result = get_post( $result );
		}
		return $result;
	}

	$result = $wpdb->get_var( $query );
	if ( null === $result ) {
		$result = '';
	}

	wp_cache_set( $cache_key, $result, 'post-queries' );

	if ( $result ) {
		$result = get_post( $result );
	}

	return $result;
}

/**
 * Retrieves the adjacent post relational link.
 *
 * Can either be next or previous post relational link.
 *
 * @since 2.8.0
 *
 * @param string       $title          Optional. Link title format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param bool         $previous       Optional. Whether to display link to previous or next post.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return string|void The adjacent post relational link URL.
 */
function get_adjacent_post_rel_link( $title = '%title', $in_same_term = false, $excluded_terms = '', $previous = true, $taxonomy = 'category' ) {
	$post = get_post();
	if ( $previous && is_attachment() && $post ) {
		$post = get_post( $post->post_parent );
	} else {
		$post = get_adjacent_post( $in_same_term, $excluded_terms, $previous, $taxonomy );
	}

	if ( empty( $post ) ) {
		return;
	}

	$post_title = the_title_attribute(
		array(
			'echo' => false,
			'post' => $post,
		)
	);

	if ( empty( $post_title ) ) {
		$post_title = $previous ? __( 'Previous Post' ) : __( 'Next Post' );
	}

	$date = mysql2date( get_option( 'date_format' ), $post->post_date );

	$title = str_replace( '%title', $post_title, $title );
	$title = str_replace( '%date', $date, $title );

	$link  = $previous ? "<link rel='prev' title='" : "<link rel='next' title='";
	$link .= esc_attr( $title );
	$link .= "' href='" . get_permalink( $post ) . "' />\n";

	$adjacent = $previous ? 'previous' : 'next';

	/**
	 * Filters the adjacent post relational link.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `next_post_rel_link`
	 *  - `previous_post_rel_link`
	 *
	 * @since 2.8.0
	 *
	 * @param string $link The relational link.
	 */
	return apply_filters( "{$adjacent}_post_rel_link", $link );
}

/**
 * Displays the relational links for the posts adjacent to the current post.
 *
 * @since 2.8.0
 *
 * @param string       $title          Optional. Link title format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function adjacent_posts_rel_link( $title = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	echo get_adjacent_post_rel_link( $title, $in_same_term, $excluded_terms, true, $taxonomy );
	echo get_adjacent_post_rel_link( $title, $in_same_term, $excluded_terms, false, $taxonomy );
}

/**
 * Displays relational links for the posts adjacent to the current post for single post pages.
 *
 * This is meant to be attached to actions like 'wp_head'. Do not call this directly in plugins
 * or theme templates.
 *
 * @since 3.0.0
 * @since 5.6.0 No longer used in core.
 *
 * @see adjacent_posts_rel_link()
 */
function adjacent_posts_rel_link_wp_head() {
	if ( ! is_single() || is_attachment() ) {
		return;
	}
	adjacent_posts_rel_link();
}

/**
 * Displays the relational link for the next post adjacent to the current post.
 *
 * @since 2.8.0
 *
 * @see get_adjacent_post_rel_link()
 *
 * @param string       $title          Optional. Link title format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function next_post_rel_link( $title = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	echo get_adjacent_post_rel_link( $title, $in_same_term, $excluded_terms, false, $taxonomy );
}

/**
 * Displays the relational link for the previous post adjacent to the current post.
 *
 * @since 2.8.0
 *
 * @see get_adjacent_post_rel_link()
 *
 * @param string       $title          Optional. Link title format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function prev_post_rel_link( $title = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	echo get_adjacent_post_rel_link( $title, $in_same_term, $excluded_terms, true, $taxonomy );
}

/**
 * Retrieves the boundary post.
 *
 * Boundary being either the first or last post by publish date within the constraints specified
 * by `$in_same_term` or `$excluded_terms`.
 *
 * @since 2.8.0
 *
 * @param bool         $in_same_term   Optional. Whether returned post should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param bool         $start          Optional. Whether to retrieve first or last post.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return array|null Array containing the boundary post object if successful, null otherwise.
 */
function get_boundary_post( $in_same_term = false, $excluded_terms = '', $start = true, $taxonomy = 'category' ) {
	$post = get_post();

	if ( ! $post || ! is_single() || is_attachment() || ! taxonomy_exists( $taxonomy ) ) {
		return null;
	}

	$query_args = array(
		'posts_per_page'         => 1,
		'order'                  => $start ? 'ASC' : 'DESC',
		'update_post_term_cache' => false,
		'update_post_meta_cache' => false,
	);

	$term_array = array();

	if ( ! is_array( $excluded_terms ) ) {
		if ( ! empty( $excluded_terms ) ) {
			$excluded_terms = explode( ',', $excluded_terms );
		} else {
			$excluded_terms = array();
		}
	}

	if ( $in_same_term || ! empty( $excluded_terms ) ) {
		if ( $in_same_term ) {
			$term_array = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) );
		}

		if ( ! empty( $excluded_terms ) ) {
			$excluded_terms = array_map( 'intval', $excluded_terms );
			$excluded_terms = array_diff( $excluded_terms, $term_array );

			$inverse_terms = array();
			foreach ( $excluded_terms as $excluded_term ) {
				$inverse_terms[] = $excluded_term * -1;
			}
			$excluded_terms = $inverse_terms;
		}

		$query_args['tax_query'] = array(
			array(
				'taxonomy' => $taxonomy,
				'terms'    => array_merge( $term_array, $excluded_terms ),
			),
		);
	}

	return get_posts( $query_args );
}

/**
 * Retrieves the previous post link that is adjacent to the current post.
 *
 * @since 3.7.0
 *
 * @param string       $format         Optional. Link anchor format. Default '&laquo; %link'.
 * @param string       $link           Optional. Link permalink format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return string The link URL of the previous post in relation to the current post.
 */
function get_previous_post_link( $format = '&laquo; %link', $link = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	return get_adjacent_post_link( $format, $link, $in_same_term, $excluded_terms, true, $taxonomy );
}

/**
 * Displays the previous post link that is adjacent to the current post.
 *
 * @since 1.5.0
 *
 * @see get_previous_post_link()
 *
 * @param string       $format         Optional. Link anchor format. Default '&laquo; %link'.
 * @param string       $link           Optional. Link permalink format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function previous_post_link( $format = '&laquo; %link', $link = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	echo get_previous_post_link( $format, $link, $in_same_term, $excluded_terms, $taxonomy );
}

/**
 * Retrieves the next post link that is adjacent to the current post.
 *
 * @since 3.7.0
 *
 * @param string       $format         Optional. Link anchor format. Default '&laquo; %link'.
 * @param string       $link           Optional. Link permalink format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return string The link URL of the next post in relation to the current post.
 */
function get_next_post_link( $format = '%link &raquo;', $link = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	return get_adjacent_post_link( $format, $link, $in_same_term, $excluded_terms, false, $taxonomy );
}

/**
 * Displays the next post link that is adjacent to the current post.
 *
 * @since 1.5.0
 *
 * @see get_next_post_link()
 *
 * @param string       $format         Optional. Link anchor format. Default '&laquo; %link'.
 * @param string       $link           Optional. Link permalink format. Default '%title'.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded term IDs.
 *                                     Default empty.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function next_post_link( $format = '%link &raquo;', $link = '%title', $in_same_term = false, $excluded_terms = '', $taxonomy = 'category' ) {
	echo get_next_post_link( $format, $link, $in_same_term, $excluded_terms, $taxonomy );
}

/**
 * Retrieves the adjacent post link.
 *
 * Can be either next post link or previous.
 *
 * @since 3.7.0
 *
 * @param string       $format         Link anchor format.
 * @param string       $link           Link permalink format.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded terms IDs.
 *                                     Default empty.
 * @param bool         $previous       Optional. Whether to display link to previous or next post.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 * @return string The link URL of the previous or next post in relation to the current post.
 */
function get_adjacent_post_link( $format, $link, $in_same_term = false, $excluded_terms = '', $previous = true, $taxonomy = 'category' ) {
	if ( $previous && is_attachment() ) {
		$post = get_post( get_post()->post_parent );
	} else {
		$post = get_adjacent_post( $in_same_term, $excluded_terms, $previous, $taxonomy );
	}

	if ( ! $post ) {
		$output = '';
	} else {
		$title = $post->post_title;

		if ( empty( $post->post_title ) ) {
			$title = $previous ? __( 'Previous Post' ) : __( 'Next Post' );
		}

		/** This filter is documented in wp-includes/post-template.php */
		$title = apply_filters( 'the_title', $title, $post->ID );

		$date = mysql2date( get_option( 'date_format' ), $post->post_date );
		$rel  = $previous ? 'prev' : 'next';

		$string = '<a href="' . get_permalink( $post ) . '" rel="' . $rel . '">';
		$inlink = str_replace( '%title', $title, $link );
		$inlink = str_replace( '%date', $date, $inlink );
		$inlink = $string . $inlink . '</a>';

		$output = str_replace( '%link', $inlink, $format );
	}

	$adjacent = $previous ? 'previous' : 'next';

	/**
	 * Filters the adjacent post link.
	 *
	 * The dynamic portion of the hook name, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * Possible hook names include:
	 *
	 *  - `next_post_link`
	 *  - `previous_post_link`
	 *
	 * @since 2.6.0
	 * @since 4.2.0 Added the `$adjacent` parameter.
	 *
	 * @param string         $output   The adjacent post link.
	 * @param string         $format   Link anchor format.
	 * @param string         $link     Link permalink format.
	 * @param WP_Post|string $post     The adjacent post. Empty string if no corresponding post exists.
	 * @param string         $adjacent Whether the post is previous or next.
	 */
	return apply_filters( "{$adjacent}_post_link", $output, $format, $link, $post, $adjacent );
}

/**
 * Displays the adjacent post link.
 *
 * Can be either next post link or previous.
 *
 * @since 2.5.0
 *
 * @param string       $format         Link anchor format.
 * @param string       $link           Link permalink format.
 * @param bool         $in_same_term   Optional. Whether link should be in the same taxonomy term.
 *                                     Default false.
 * @param int[]|string $excluded_terms Optional. Array or comma-separated list of excluded category IDs.
 *                                     Default empty.
 * @param bool         $previous       Optional. Whether to display link to previous or next post.
 *                                     Default true.
 * @param string       $taxonomy       Optional. Taxonomy, if `$in_same_term` is true. Default 'category'.
 */
function adjacent_post_link( $format, $link, $in_same_term = false, $excluded_terms = '', $previous = true, $taxonomy = 'category' ) {
	echo get_adjacent_post_link( $format, $link, $in_same_term, $excluded_terms, $previous, $taxonomy );
}

/**
 * Retrieves the link for a page number.
 *
 * @since 1.5.0
 *
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 *
 * @param int  $pagenum Optional. Page number. Default 1.
 * @param bool $escape  Optional. Whether to escape the URL for display, with esc_url().
 *                      If set to false, prepares the URL with sanitize_url(). Default true.
 * @return string The link URL for the given page number.
 */
function get_pagenum_link( $pagenum = 1, $escape = true ) {
	global $wp_rewrite;

	$pagenum = (int) $pagenum;

	$request = remove_query_arg( 'paged' );

	$home_root = parse_url( home_url() );
	$home_root = ( isset( $home_root['path'] ) ) ? $home_root['path'] : '';
	$home_root = preg_quote( $home_root, '|' );

	$request = preg_replace( '|^' . $home_root . '|i', '', $request );
	$request = preg_replace( '|^/+|', '', $request );

	if ( ! $wp_rewrite->using_permalinks() || is_admin() ) {
		$base = trailingslashit( get_bloginfo( 'url' ) );

		if ( $pagenum > 1 ) {
			$result = add_query_arg( 'paged', $pagenum, $base . $request );
		} else {
			$result = $base . $request;
		}
	} else {
		$qs_regex = '|\?.*?$|';
		preg_match( $qs_regex, $request, $qs_match );

		$parts   = array();
		$parts[] = untrailingslashit( get_bloginfo( 'url' ) );

		if ( ! empty( $qs_match[0] ) ) {
			$query_string = $qs_match[0];
			$request      = preg_replace( $qs_regex, '', $request );
		} else {
			$query_string = '';
		}

		$request = preg_replace( "|$wp_rewrite->pagination_base/\d+/?$|", '', $request );
		$request = preg_replace( '|^' . preg_quote( $wp_rewrite->index, '|' ) . '|i', '', $request );
		$request = ltrim( $request, '/' );

		if ( $wp_rewrite->using_index_permalinks() && ( $pagenum > 1 || '' !== $request ) ) {
			$parts[] = $wp_rewrite->index;
		}

		$parts[] = untrailingslashit( $request );

		if ( $pagenum > 1 ) {
			$parts[] = $wp_rewrite->pagination_base;
			$parts[] = $pagenum;
		}

		$result = user_trailingslashit( implode( '/', array_filter( $parts ) ), 'paged' );
		if ( ! empty( $query_string ) ) {
			$result .= $query_string;
		}
	}

	/**
	 * Filters the page number link for the current request.
	 *
	 * @since 2.5.0
	 * @since 5.2.0 Added the `$pagenum` argument.
	 *
	 * @param string $result  The page number link.
	 * @param int    $pagenum The page number.
	 */
	$result = apply_filters( 'get_pagenum_link', $result, $pagenum );

	if ( $escape ) {
		return esc_url( $result );
	} else {
		return sanitize_url( $result );
	}
}

/**
 * Retrieves the next posts page link.
 *
 * Backported from 2.1.3 to 2.0.10.
 *
 * @since 2.0.10
 *
 * @global int $paged
 *
 * @param int $max_page Optional. Max pages. Default 0.
 * @return string|void The link URL for next posts page.
 */
function get_next_posts_page_link( $max_page = 0 ) {
	global $paged;

	if ( ! is_single() ) {
		if ( ! $paged ) {
			$paged = 1;
		}

		$next_page = (int) $paged + 1;

		if ( ! $max_page || $max_page >= $next_page ) {
			return get_pagenum_link( $next_page );
		}
	}
}

/**
 * Displays or retrieves the next posts page link.
 *
 * @since 0.71
 *
 * @param int  $max_page Optional. Max pages. Default 0.
 * @param bool $display  Optional. Whether to echo the link. Default true.
 * @return string|void The link URL for next posts page if `$display = false`.
 */
function next_posts( $max_page = 0, $display = true ) {
	$link   = get_next_posts_page_link( $max_page );
	$output = $link ? esc_url( $link ) : '';

	if ( $display ) {
		echo $output;
	} else {
		return $output;
	}
}

/**
 * Retrieves the next posts page link.
 *
 * @since 2.7.0
 *
 * @global int      $paged
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string $label    Content for link text.
 * @param int    $max_page Optional. Max pages. Default 0.
 * @return string|void HTML-formatted next posts page link.
 */
function get_next_posts_link( $label = null, $max_page = 0 ) {
	global $paged, $wp_query;

	if ( ! $max_page ) {
		$max_page = $wp_query->max_num_pages;
	}

	if ( ! $paged ) {
		$paged = 1;
	}

	$next_page = (int) $paged + 1;

	if ( null === $label ) {
		$label = __( 'Next Page &raquo;' );
	}

	if ( ! is_single() && ( $next_page <= $max_page ) ) {
		/**
		 * Filters the anchor tag attributes for the next posts page link.
		 *
		 * @since 2.7.0
		 *
		 * @param string $attributes Attributes for the anchor tag.
		 */
		$attr = apply_filters( 'next_posts_link_attributes', '' );

		return sprintf(
			'<a href="%1$s" %2$s>%3$s</a>',
			next_posts( $max_page, false ),
			$attr,
			preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label )
		);
	}
}

/**
 * Displays the next posts page link.
 *
 * @since 0.71
 *
 * @param string $label    Content for link text.
 * @param int    $max_page Optional. Max pages. Default 0.
 */
function next_posts_link( $label = null, $max_page = 0 ) {
	echo get_next_posts_link( $label, $max_page );
}

/**
 * Retrieves the previous posts page link.
 *
 * Will only return string, if not on a single page or post.
 *
 * Backported to 2.0.10 from 2.1.3.
 *
 * @since 2.0.10
 *
 * @global int $paged
 *
 * @return string|void The link for the previous posts page.
 */
function get_previous_posts_page_link() {
	global $paged;

	if ( ! is_single() ) {
		$previous_page = (int) $paged - 1;

		if ( $previous_page < 1 ) {
			$previous_page = 1;
		}

		return get_pagenum_link( $previous_page );
	}
}

/**
 * Displays or retrieves the previous posts page link.
 *
 * @since 0.71
 *
 * @param bool $display Optional. Whether to echo the link. Default true.
 * @return string|void The previous posts page link if `$display = false`.
 */
function previous_posts( $display = true ) {
	$output = esc_url( get_previous_posts_page_link() );

	if ( $display ) {
		echo $output;
	} else {
		return $output;
	}
}

/**
 * Retrieves the previous posts page link.
 *
 * @since 2.7.0
 *
 * @global int $paged
 *
 * @param string $label Optional. Previous page link text.
 * @return string|void HTML-formatted previous page link.
 */
function get_previous_posts_link( $label = null ) {
	global $paged;

	if ( null === $label ) {
		$label = __( '&laquo; Previous Page' );
	}

	if ( ! is_single() && $paged > 1 ) {
		/**
		 * Filters the anchor tag attributes for the previous posts page link.
		 *
		 * @since 2.7.0
		 *
		 * @param string $attributes Attributes for the anchor tag.
		 */
		$attr = apply_filters( 'previous_posts_link_attributes', '' );

		return sprintf(
			'<a href="%1$s" %2$s>%3$s</a>',
			previous_posts( false ),
			$attr,
			preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label )
		);
	}
}

/**
 * Displays the previous posts page link.
 *
 * @since 0.71
 *
 * @param string $label Optional. Previous page link text.
 */
function previous_posts_link( $label = null ) {
	echo get_previous_posts_link( $label );
}

/**
 * Retrieves the post pages link navigation for previous and next pages.
 *
 * @since 2.8.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string|array $args {
 *     Optional. Arguments to build the post pages link navigation.
 *
 *     @type string $sep      Separator character. Default '&#8212;'.
 *     @type string $prelabel Link text to display for the previous page link.
 *                            Default '&laquo; Previous Page'.
 *     @type string $nxtlabel Link text to display for the next page link.
 *                            Default 'Next Page &raquo;'.
 * }
 * @return string The posts link navigation.
 */
function get_posts_nav_link( $args = array() ) {
	global $wp_query;

	$return = '';

	if ( ! is_singular() ) {
		$defaults = array(
			'sep'      => ' &#8212; ',
			'prelabel' => __( '&laquo; Previous Page' ),
			'nxtlabel' => __( 'Next Page &raquo;' ),
		);
		$args     = wp_parse_args( $args, $defaults );

		$max_num_pages = $wp_query->max_num_pages;
		$paged         = get_query_var( 'paged' );

		// Only have sep if there's both prev and next results.
		if ( $paged < 2 || $paged >= $max_num_pages ) {
			$args['sep'] = '';
		}

		if ( $max_num_pages > 1 ) {
			$return  = get_previous_posts_link( $args['prelabel'] );
			$return .= preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $args['sep'] );
			$return .= get_next_posts_link( $args['nxtlabel'] );
		}
	}
	return $return;
}

/**
 * Displays the post pages link navigation for previous and next pages.
 *
 * @since 0.71
 *
 * @param string $sep      Optional. Separator for posts navigation links. Default empty.
 * @param string $prelabel Optional. Label for previous pages. Default empty.
 * @param string $nxtlabel Optional Label for next pages. Default empty.
 */
function posts_nav_link( $sep = '', $prelabel = '', $nxtlabel = '' ) {
	$args = array_filter( compact( 'sep', 'prelabel', 'nxtlabel' ) );
	echo get_posts_nav_link( $args );
}

/**
 * Retrieves the navigation to next/previous post, when applicable.
 *
 * @since 4.1.0
 * @since 4.4.0 Introduced the `in_same_term`, `excluded_terms`, and `taxonomy` arguments.
 * @since 5.3.0 Added the `aria_label` parameter.
 * @since 5.5.0 Added the `class` parameter.
 *
 * @param array $args {
 *     Optional. Default post navigation arguments. Default empty array.
 *
 *     @type string       $prev_text          Anchor text to display in the previous post link.
 *                                            Default '%title'.
 *     @type string       $next_text          Anchor text to display in the next post link.
 *                                            Default '%title'.
 *     @type bool         $in_same_term       Whether link should be in the same taxonomy term.
 *                                            Default false.
 *     @type int[]|string $excluded_terms     Array or comma-separated list of excluded term IDs.
 *                                            Default empty.
 *     @type string       $taxonomy           Taxonomy, if `$in_same_term` is true. Default 'category'.
 *     @type string       $screen_reader_text Screen reader text for the nav element.
 *                                            Default 'Post navigation'.
 *     @type string       $aria_label         ARIA label text for the nav element. Default 'Posts'.
 *     @type string       $class              Custom class for the nav element. Default 'post-navigation'.
 * }
 * @return string Markup for post links.
 */
function get_the_post_navigation( $args = array() ) {
	// Make sure the nav element has an aria-label attribute: fallback to the screen reader text.
	if ( ! empty( $args['screen_reader_text'] ) && empty( $args['aria_label'] ) ) {
		$args['aria_label'] = $args['screen_reader_text'];
	}

	$args = wp_parse_args(
		$args,
		array(
			'prev_text'          => '%title',
			'next_text'          => '%title',
			'in_same_term'       => false,
			'excluded_terms'     => '',
			'taxonomy'           => 'category',
			'screen_reader_text' => __( 'Post navigation' ),
			'aria_label'         => __( 'Posts' ),
			'class'              => 'post-navigation',
		)
	);

	$navigation = '';

	$previous = get_previous_post_link(
		'<div class="nav-previous">%link</div>',
		$args['prev_text'],
		$args['in_same_term'],
		$args['excluded_terms'],
		$args['taxonomy']
	);

	$next = get_next_post_link(
		'<div class="nav-next">%link</div>',
		$args['next_text'],
		$args['in_same_term'],
		$args['excluded_terms'],
		$args['taxonomy']
	);

	// Only add markup if there's somewhere to navigate to.
	if ( $previous || $next ) {
		$navigation = _navigation_markup( $previous . $next, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
	}

	return $navigation;
}

/**
 * Displays the navigation to next/previous post, when applicable.
 *
 * @since 4.1.0
 *
 * @param array $args Optional. See get_the_post_navigation() for available arguments.
 *                    Default empty array.
 */
function the_post_navigation( $args = array() ) {
	echo get_the_post_navigation( $args );
}

/**
 * Returns the navigation to next/previous set of posts, when applicable.
 *
 * @since 4.1.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @since 5.5.0 Added the `class` parameter.
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param array $args {
 *     Optional. Default posts navigation arguments. Default empty array.
 *
 *     @type string $prev_text          Anchor text to display in the previous posts link.
 *                                      Default 'Older posts'.
 *     @type string $next_text          Anchor text to display in the next posts link.
 *                                      Default 'Newer posts'.
 *     @type string $screen_reader_text Screen reader text for the nav element.
 *                                      Default 'Posts navigation'.
 *     @type string $aria_label         ARIA label text for the nav element. Default 'Posts'.
 *     @type string $class              Custom class for the nav element. Default 'posts-navigation'.
 * }
 * @return string Markup for posts links.
 */
function get_the_posts_navigation( $args = array() ) {
	global $wp_query;

	$navigation = '';

	// Don't print empty markup if there's only one page.
	if ( $wp_query->max_num_pages > 1 ) {
		// Make sure the nav element has an aria-label attribute: fallback to the screen reader text.
		if ( ! empty( $args['screen_reader_text'] ) && empty( $args['aria_label'] ) ) {
			$args['aria_label'] = $args['screen_reader_text'];
		}

		$args = wp_parse_args(
			$args,
			array(
				'prev_text'          => __( 'Older posts' ),
				'next_text'          => __( 'Newer posts' ),
				'screen_reader_text' => __( 'Posts navigation' ),
				'aria_label'         => __( 'Posts' ),
				'class'              => 'posts-navigation',
			)
		);

		$next_link = get_previous_posts_link( $args['next_text'] );
		$prev_link = get_next_posts_link( $args['prev_text'] );

		if ( $prev_link ) {
			$navigation .= '<div class="nav-previous">' . $prev_link . '</div>';
		}

		if ( $next_link ) {
			$navigation .= '<div class="nav-next">' . $next_link . '</div>';
		}

		$navigation = _navigation_markup( $navigation, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
	}

	return $navigation;
}

/**
 * Displays the navigation to next/previous set of posts, when applicable.
 *
 * @since 4.1.0
 *
 * @param array $args Optional. See get_the_posts_navigation() for available arguments.
 *                    Default empty array.
 */
function the_posts_navigation( $args = array() ) {
	echo get_the_posts_navigation( $args );
}

/**
 * Retrieves a paginated navigation to next/previous set of posts, when applicable.
 *
 * @since 4.1.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @since 5.5.0 Added the `class` parameter.
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param array $args {
 *     Optional. Default pagination arguments, see paginate_links().
 *
 *     @type string $screen_reader_text Screen reader text for navigation element.
 *                                      Default 'Posts navigation'.
 *     @type string $aria_label         ARIA label text for the nav element. Default 'Posts'.
 *     @type string $class              Custom class for the nav element. Default 'pagination'.
 * }
 * @return string Markup for pagination links.
 */
function get_the_posts_pagination( $args = array() ) {
	global $wp_query;

	$navigation = '';

	// Don't print empty markup if there's only one page.
	if ( $wp_query->max_num_pages > 1 ) {
		// Make sure the nav element has an aria-label attribute: fallback to the screen reader text.
		if ( ! empty( $args['screen_reader_text'] ) && empty( $args['aria_label'] ) ) {
			$args['aria_label'] = $args['screen_reader_text'];
		}

		$args = wp_parse_args(
			$args,
			array(
				'mid_size'           => 1,
				'prev_text'          => _x( 'Previous', 'previous set of posts' ),
				'next_text'          => _x( 'Next', 'next set of posts' ),
				'screen_reader_text' => __( 'Posts navigation' ),
				'aria_label'         => __( 'Posts' ),
				'class'              => 'pagination',
			)
		);

		/**
		 * Filters the arguments for posts pagination links.
		 *
		 * @since 6.1.0
		 *
		 * @param array $args {
		 *     Optional. Default pagination arguments, see paginate_links().
		 *
		 *     @type string $screen_reader_text Screen reader text for navigation element.
		 *                                      Default 'Posts navigation'.
		 *     @type string $aria_label         ARIA label text for the nav element. Default 'Posts'.
		 *     @type string $class              Custom class for the nav element. Default 'pagination'.
		 * }
		 */
		$args = apply_filters( 'the_posts_pagination_args', $args );

		// Make sure we get a string back. Plain is the next best thing.
		if ( isset( $args['type'] ) && 'array' === $args['type'] ) {
			$args['type'] = 'plain';
		}

		// Set up paginated links.
		$links = paginate_links( $args );

		if ( $links ) {
			$navigation = _navigation_markup( $links, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
		}
	}

	return $navigation;
}

/**
 * Displays a paginated navigation to next/previous set of posts, when applicable.
 *
 * @since 4.1.0
 *
 * @param array $args Optional. See get_the_posts_pagination() for available arguments.
 *                    Default empty array.
 */
function the_posts_pagination( $args = array() ) {
	echo get_the_posts_pagination( $args );
}

/**
 * Wraps passed links in navigational markup.
 *
 * @since 4.1.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @access private
 *
 * @param string $links              Navigational links.
 * @param string $css_class          Optional. Custom class for the nav element.
 *                                   Default 'posts-navigation'.
 * @param string $screen_reader_text Optional. Screen reader text for the nav element.
 *                                   Default 'Posts navigation'.
 * @param string $aria_label         Optional. ARIA label for the nav element.
 *                                   Defaults to the value of `$screen_reader_text`.
 * @return string Navigation template tag.
 */
function _navigation_markup( $links, $css_class = 'posts-navigation', $screen_reader_text = '', $aria_label = '' ) {
	if ( empty( $screen_reader_text ) ) {
		$screen_reader_text = /* translators: Hidden accessibility text. */ __( 'Posts navigation' );
	}
	if ( empty( $aria_label ) ) {
		$aria_label = $screen_reader_text;
	}

	$template = '
	<nav class="navigation %1$s" aria-label="%4$s">
		<h2 class="screen-reader-text">%2$s</h2>
		<div class="nav-links">%3$s</div>
	</nav>';

	/**
	 * Filters the navigation markup template.
	 *
	 * Note: The filtered template HTML must contain specifiers for the navigation
	 * class (%1$s), the screen-reader-text value (%2$s), placement of the navigation
	 * links (%3$s), and ARIA label text if screen-reader-text does not fit that (%4$s):
	 *
	 *     <nav class="navigation %1$s" aria-label="%4$s">
	 *         <h2 class="screen-reader-text">%2$s</h2>
	 *         <div class="nav-links">%3$s</div>
	 *     </nav>
	 *
	 * @since 4.4.0
	 *
	 * @param string $template  The default template.
	 * @param string $css_class The class passed by the calling function.
	 * @return string Navigation template.
	 */
	$template = apply_filters( 'navigation_markup_template', $template, $css_class );

	return sprintf( $template, sanitize_html_class( $css_class ), esc_html( $screen_reader_text ), $links, esc_attr( $aria_label ) );
}

/**
 * Retrieves the comments page number link.
 *
 * @since 2.7.0
 *
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 *
 * @param int $pagenum  Optional. Page number. Default 1.
 * @param int $max_page Optional. The maximum number of comment pages. Default 0.
 * @return string The comments page number link URL.
 */
function get_comments_pagenum_link( $pagenum = 1, $max_page = 0 ) {
	global $wp_rewrite;

	$pagenum = (int) $pagenum;

	$result = get_permalink();

	if ( 'newest' === get_option( 'default_comments_page' ) ) {
		if ( $pagenum != $max_page ) {
			if ( $wp_rewrite->using_permalinks() ) {
				$result = user_trailingslashit( trailingslashit( $result ) . $wp_rewrite->comments_pagination_base . '-' . $pagenum, 'commentpaged' );
			} else {
				$result = add_query_arg( 'cpage', $pagenum, $result );
			}
		}
	} elseif ( $pagenum > 1 ) {
		if ( $wp_rewrite->using_permalinks() ) {
			$result = user_trailingslashit( trailingslashit( $result ) . $wp_rewrite->comments_pagination_base . '-' . $pagenum, 'commentpaged' );
		} else {
			$result = add_query_arg( 'cpage', $pagenum, $result );
		}
	}

	$result .= '#comments';

	/**
	 * Filters the comments page number link for the current request.
	 *
	 * @since 2.7.0
	 *
	 * @param string $result The comments page number link.
	 */
	return apply_filters( 'get_comments_pagenum_link', $result );
}

/**
 * Retrieves the link to the next comments page.
 *
 * @since 2.7.1
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string $label    Optional. Label for link text. Default empty.
 * @param int    $max_page Optional. Max page. Default 0.
 * @return string|void HTML-formatted link for the next page of comments.
 */
function get_next_comments_link( $label = '', $max_page = 0 ) {
	global $wp_query;

	if ( ! is_singular() ) {
		return;
	}

	$page = get_query_var( 'cpage' );

	if ( ! $page ) {
		$page = 1;
	}

	$next_page = (int) $page + 1;

	if ( empty( $max_page ) ) {
		$max_page = $wp_query->max_num_comment_pages;
	}

	if ( empty( $max_page ) ) {
		$max_page = get_comment_pages_count();
	}

	if ( $next_page > $max_page ) {
		return;
	}

	if ( empty( $label ) ) {
		$label = __( 'Newer Comments &raquo;' );
	}

	/**
	 * Filters the anchor tag attributes for the next comments page link.
	 *
	 * @since 2.7.0
	 *
	 * @param string $attributes Attributes for the anchor tag.
	 */
	$attr = apply_filters( 'next_comments_link_attributes', '' );

	return sprintf(
		'<a href="%1$s" %2$s>%3$s</a>',
		esc_url( get_comments_pagenum_link( $next_page, $max_page ) ),
		$attr,
		preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label )
	);
}

/**
 * Displays the link to the next comments page.
 *
 * @since 2.7.0
 *
 * @param string $label    Optional. Label for link text. Default empty.
 * @param int    $max_page Optional. Max page. Default 0.
 */
function next_comments_link( $label = '', $max_page = 0 ) {
	echo get_next_comments_link( $label, $max_page );
}

/**
 * Retrieves the link to the previous comments page.
 *
 * @since 2.7.1
 *
 * @param string $label Optional. Label for comments link text. Default empty.
 * @return string|void HTML-formatted link for the previous page of comments.
 */
function get_previous_comments_link( $label = '' ) {
	if ( ! is_singular() ) {
		return;
	}

	$page = get_query_var( 'cpage' );

	if ( (int) $page <= 1 ) {
		return;
	}

	$previous_page = (int) $page - 1;

	if ( empty( $label ) ) {
		$label = __( '&laquo; Older Comments' );
	}

	/**
	 * Filters the anchor tag attributes for the previous comments page link.
	 *
	 * @since 2.7.0
	 *
	 * @param string $attributes Attributes for the anchor tag.
	 */
	$attr = apply_filters( 'previous_comments_link_attributes', '' );

	return sprintf(
		'<a href="%1$s" %2$s>%3$s</a>',
		esc_url( get_comments_pagenum_link( $previous_page ) ),
		$attr,
		preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label )
	);
}

/**
 * Displays the link to the previous comments page.
 *
 * @since 2.7.0
 *
 * @param string $label Optional. Label for comments link text. Default empty.
 */
function previous_comments_link( $label = '' ) {
	echo get_previous_comments_link( $label );
}

/**
 * Displays or retrieves pagination links for the comments on the current post.
 *
 * @see paginate_links()
 * @since 2.7.0
 *
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 *
 * @param string|array $args Optional args. See paginate_links(). Default empty array.
 * @return void|string|array Void if 'echo' argument is true and 'type' is not an array,
 *                           or if the query is not for an existing single post of any post type.
 *                           Otherwise, markup for comment page links or array of comment page links,
 *                           depending on 'type' argument.
 */
function paginate_comments_links( $args = array() ) {
	global $wp_rewrite;

	if ( ! is_singular() ) {
		return;
	}

	$page = get_query_var( 'cpage' );
	if ( ! $page ) {
		$page = 1;
	}
	$max_page = get_comment_pages_count();
	$defaults = array(
		'base'         => add_query_arg( 'cpage', '%#%' ),
		'format'       => '',
		'total'        => $max_page,
		'current'      => $page,
		'echo'         => true,
		'type'         => 'plain',
		'add_fragment' => '#comments',
	);
	if ( $wp_rewrite->using_permalinks() ) {
		$defaults['base'] = user_trailingslashit( trailingslashit( get_permalink() ) . $wp_rewrite->comments_pagination_base . '-%#%', 'commentpaged' );
	}

	$args       = wp_parse_args( $args, $defaults );
	$page_links = paginate_links( $args );

	if ( $args['echo'] && 'array' !== $args['type'] ) {
		echo $page_links;
	} else {
		return $page_links;
	}
}

/**
 * Retrieves navigation to next/previous set of comments, when applicable.
 *
 * @since 4.4.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @since 5.5.0 Added the `class` parameter.
 *
 * @param array $args {
 *     Optional. Default comments navigation arguments.
 *
 *     @type string $prev_text          Anchor text to display in the previous comments link.
 *                                      Default 'Older comments'.
 *     @type string $next_text          Anchor text to display in the next comments link.
 *                                      Default 'Newer comments'.
 *     @type string $screen_reader_text Screen reader text for the nav element. Default 'Comments navigation'.
 *     @type string $aria_label         ARIA label text for the nav element. Default 'Comments'.
 *     @type string $class              Custom class for the nav element. Default 'comment-navigation'.
 * }
 * @return string Markup for comments links.
 */
function get_the_comments_navigation( $args = array() ) {
	$navigation = '';

	// Are there comments to navigate through?
	if ( get_comment_pages_count() > 1 ) {
		// Make sure the nav element has an aria-label attribute: fallback to the screen reader text.
		if ( ! empty( $args['screen_reader_text'] ) && empty( $args['aria_label'] ) ) {
			$args['aria_label'] = $args['screen_reader_text'];
		}

		$args = wp_parse_args(
			$args,
			array(
				'prev_text'          => __( 'Older comments' ),
				'next_text'          => __( 'Newer comments' ),
				'screen_reader_text' => __( 'Comments navigation' ),
				'aria_label'         => __( 'Comments' ),
				'class'              => 'comment-navigation',
			)
		);

		$prev_link = get_previous_comments_link( $args['prev_text'] );
		$next_link = get_next_comments_link( $args['next_text'] );

		if ( $prev_link ) {
			$navigation .= '<div class="nav-previous">' . $prev_link . '</div>';
		}

		if ( $next_link ) {
			$navigation .= '<div class="nav-next">' . $next_link . '</div>';
		}

		$navigation = _navigation_markup( $navigation, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
	}

	return $navigation;
}

/**
 * Displays navigation to next/previous set of comments, when applicable.
 *
 * @since 4.4.0
 *
 * @param array $args See get_the_comments_navigation() for available arguments. Default empty array.
 */
function the_comments_navigation( $args = array() ) {
	echo get_the_comments_navigation( $args );
}

/**
 * Retrieves a paginated navigation to next/previous set of comments, when applicable.
 *
 * @since 4.4.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @since 5.5.0 Added the `class` parameter.
 *
 * @see paginate_comments_links()
 *
 * @param array $args {
 *     Optional. Default pagination arguments.
 *
 *     @type string $screen_reader_text Screen reader text for the nav element. Default 'Comments navigation'.
 *     @type string $aria_label         ARIA label text for the nav element. Default 'Comments'.
 *     @type string $class              Custom class for the nav element. Default 'comments-pagination'.
 * }
 * @return string Markup for pagination links.
 */
function get_the_comments_pagination( $args = array() ) {
	$navigation = '';

	// Make sure the nav element has an aria-label attribute: fallback to the screen reader text.
	if ( ! empty( $args['screen_reader_text'] ) && empty( $args['aria_label'] ) ) {
		$args['aria_label'] = $args['screen_reader_text'];
	}

	$args         = wp_parse_args(
		$args,
		array(
			'screen_reader_text' => __( 'Comments navigation' ),
			'aria_label'         => __( 'Comments' ),
			'class'              => 'comments-pagination',
		)
	);
	$args['echo'] = false;

	// Make sure we get a string back. Plain is the next best thing.
	if ( isset( $args['type'] ) && 'array' === $args['type'] ) {
		$args['type'] = 'plain';
	}

	$links = paginate_comments_links( $args );

	if ( $links ) {
		$navigation = _navigation_markup( $links, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
	}

	return $navigation;
}

/**
 * Displays a paginated navigation to next/previous set of comments, when applicable.
 *
 * @since 4.4.0
 *
 * @param array $args See get_the_comments_pagination() for available arguments. Default empty array.
 */
function the_comments_pagination( $args = array() ) {
	echo get_the_comments_pagination( $args );
}

/**
 * Retrieves the URL for the current site where the front end is accessible.
 *
 * Returns the 'home' option with the appropriate protocol. The protocol will be 'https'
 * if is_ssl() evaluates to true; otherwise, it will be the same as the 'home' option.
 * If `$scheme` is 'http' or 'https', is_ssl() is overridden.
 *
 * @since 3.0.0
 *
 * @param string      $path   Optional. Path relative to the home URL. Default empty.
 * @param string|null $scheme Optional. Scheme to give the home URL context. Accepts
 *                            'http', 'https', 'relative', 'rest', or null. Default null.
 * @return string Home URL link with optional path appended.
 */
function home_url( $path = '', $scheme = null ) {
	return get_home_url( null, $path, $scheme );
}

/**
 * Retrieves the URL for a given site where the front end is accessible.
 *
 * Returns the 'home' option with the appropriate protocol. The protocol will be 'https'
 * if is_ssl() evaluates to true; otherwise, it will be the same as the 'home' option.
 * If `$scheme` is 'http' or 'https', is_ssl() is overridden.
 *
 * @since 3.0.0
 *
 * @param int|null    $blog_id Optional. Site ID. Default null (current site).
 * @param string      $path    Optional. Path relative to the home URL. Default empty.
 * @param string|null $scheme  Optional. Scheme to give the home URL context. Accepts
 *                             'http', 'https', 'relative', 'rest', or null. Default null.
 * @return string Home URL link with optional path appended.
 */
function get_home_url( $blog_id = null, $path = '', $scheme = null ) {
	$orig_scheme = $scheme;

	if ( empty( $blog_id ) || ! is_multisite() ) {
		$url = get_option( 'home' );
	} else {
		switch_to_blog( $blog_id );
		$url = get_option( 'home' );
		restore_current_blog();
	}

	if ( ! in_array( $scheme, array( 'http', 'https', 'relative' ), true ) ) {
		if ( is_ssl() ) {
			$scheme = 'https';
		} else {
			$scheme = parse_url( $url, PHP_URL_SCHEME );
		}
	}

	$url = set_url_scheme( $url, $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= '/' . ltrim( $path, '/' );
	}

	/**
	 * Filters the home URL.
	 *
	 * @since 3.0.0
	 *
	 * @param string      $url         The complete home URL including scheme and path.
	 * @param string      $path        Path relative to the home URL. Blank string if no path is specified.
	 * @param string|null $orig_scheme Scheme to give the home URL context. Accepts 'http', 'https',
	 *                                 'relative', 'rest', or null.
	 * @param int|null    $blog_id     Site ID, or null for the current site.
	 */
	return apply_filters( 'home_url', $url, $path, $orig_scheme, $blog_id );
}

/**
 * Retrieves the URL for the current site where WordPress application files
 * (e.g. wp-blog-header.php or the wp-admin/ folder) are accessible.
 *
 * Returns the 'site_url' option with the appropriate protocol, 'https' if
 * is_ssl() and 'http' otherwise. If $scheme is 'http' or 'https', is_ssl() is
 * overridden.
 *
 * @since 3.0.0
 *
 * @param string      $path   Optional. Path relative to the site URL. Default empty.
 * @param string|null $scheme Optional. Scheme to give the site URL context. See set_url_scheme().
 * @return string Site URL link with optional path appended.
 */
function site_url( $path = '', $scheme = null ) {
	return get_site_url( null, $path, $scheme );
}

/**
 * Retrieves the URL for a given site where WordPress application files
 * (e.g. wp-blog-header.php or the wp-admin/ folder) are accessible.
 *
 * Returns the 'site_url' option with the appropriate protocol, 'https' if
 * is_ssl() and 'http' otherwise. If `$scheme` is 'http' or 'https',
 * `is_ssl()` is overridden.
 *
 * @since 3.0.0
 *
 * @param int|null    $blog_id Optional. Site ID. Default null (current site).
 * @param string      $path    Optional. Path relative to the site URL. Default empty.
 * @param string|null $scheme  Optional. Scheme to give the site URL context. Accepts
 *                             'http', 'https', 'login', 'login_post', 'admin', or
 *                             'relative'. Default null.
 * @return string Site URL link with optional path appended.
 */
function get_site_url( $blog_id = null, $path = '', $scheme = null ) {
	if ( empty( $blog_id ) || ! is_multisite() ) {
		$url = get_option( 'siteurl' );
	} else {
		switch_to_blog( $blog_id );
		$url = get_option( 'siteurl' );
		restore_current_blog();
	}

	$url = set_url_scheme( $url, $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= '/' . ltrim( $path, '/' );
	}

	/**
	 * Filters the site URL.
	 *
	 * @since 2.7.0
	 *
	 * @param string      $url     The complete site URL including scheme and path.
	 * @param string      $path    Path relative to the site URL. Blank string if no path is specified.
	 * @param string|null $scheme  Scheme to give the site URL context. Accepts 'http', 'https', 'login',
	 *                             'login_post', 'admin', 'relative' or null.
	 * @param int|null    $blog_id Site ID, or null for the current site.
	 */
	return apply_filters( 'site_url', $url, $path, $scheme, $blog_id );
}

/**
 * Retrieves the URL to the admin area for the current site.
 *
 * @since 2.6.0
 *
 * @param string $path   Optional. Path relative to the admin URL. Default empty.
 * @param string $scheme The scheme to use. Default is 'admin', which obeys force_ssl_admin() and is_ssl().
 *                       'http' or 'https' can be passed to force those schemes.
 * @return string Admin URL link with optional path appended.
 */
function admin_url( $path = '', $scheme = 'admin' ) {
	return get_admin_url( null, $path, $scheme );
}

/**
 * Retrieves the URL to the admin area for a given site.
 *
 * @since 3.0.0
 *
 * @param int|null $blog_id Optional. Site ID. Default null (current site).
 * @param string   $path    Optional. Path relative to the admin URL. Default empty.
 * @param string   $scheme  Optional. The scheme to use. Accepts 'http' or 'https',
 *                          to force those schemes. Default 'admin', which obeys
 *                          force_ssl_admin() and is_ssl().
 * @return string Admin URL link with optional path appended.
 */
function get_admin_url( $blog_id = null, $path = '', $scheme = 'admin' ) {
	$url = get_site_url( $blog_id, 'wp-admin/', $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the admin area URL.
	 *
	 * @since 2.8.0
	 * @since 5.8.0 The `$scheme` parameter was added.
	 *
	 * @param string      $url     The complete admin area URL including scheme and path.
	 * @param string      $path    Path relative to the admin area URL. Blank string if no path is specified.
	 * @param int|null    $blog_id Site ID, or null for the current site.
	 * @param string|null $scheme  The scheme to use. Accepts 'http', 'https',
	 *                             'admin', or null. Default 'admin', which obeys force_ssl_admin() and is_ssl().
	 */
	return apply_filters( 'admin_url', $url, $path, $blog_id, $scheme );
}

/**
 * Retrieves the URL to the includes directory.
 *
 * @since 2.6.0
 *
 * @param string      $path   Optional. Path relative to the includes URL. Default empty.
 * @param string|null $scheme Optional. Scheme to give the includes URL context. Accepts
 *                            'http', 'https', or 'relative'. Default null.
 * @return string Includes URL link with optional path appended.
 */
function includes_url( $path = '', $scheme = null ) {
	$url = site_url( '/' . WPINC . '/', $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the URL to the includes directory.
	 *
	 * @since 2.8.0
	 * @since 5.8.0 The `$scheme` parameter was added.
	 *
	 * @param string      $url    The complete URL to the includes directory including scheme and path.
	 * @param string      $path   Path relative to the URL to the wp-includes directory. Blank string
	 *                            if no path is specified.
	 * @param string|null $scheme Scheme to give the includes URL context. Accepts
	 *                            'http', 'https', 'relative', or null. Default null.
	 */
	return apply_filters( 'includes_url', $url, $path, $scheme );
}

/**
 * Retrieves the URL to the content directory.
 *
 * @since 2.6.0
 *
 * @param string $path Optional. Path relative to the content URL. Default empty.
 * @return string Content URL link with optional path appended.
 */
function content_url( $path = '' ) {
	$url = set_url_scheme( WP_CONTENT_URL );

	if ( $path && is_string( $path ) ) {
		$url .= '/' . ltrim( $path, '/' );
	}

	/**
	 * Filters the URL to the content directory.
	 *
	 * @since 2.8.0
	 *
	 * @param string $url  The complete URL to the content directory including scheme and path.
	 * @param string $path Path relative to the URL to the content directory. Blank string
	 *                     if no path is specified.
	 */
	return apply_filters( 'content_url', $url, $path );
}

/**
 * Retrieves a URL within the plugins or mu-plugins directory.
 *
 * Defaults to the plugins directory URL if no arguments are supplied.
 *
 * @since 2.6.0
 *
 * @param string $path   Optional. Extra path appended to the end of the URL, including
 *                       the relative directory if $plugin is supplied. Default empty.
 * @param string $plugin Optional. A full path to a file inside a plugin or mu-plugin.
 *                       The URL will be relative to its directory. Default empty.
 *                       Typically this is done by passing `__FILE__` as the argument.
 * @return string Plugins URL link with optional paths appended.
 */
function plugins_url( $path = '', $plugin = '' ) {

	$path          = wp_normalize_path( $path );
	$plugin        = wp_normalize_path( $plugin );
	$mu_plugin_dir = wp_normalize_path( WPMU_PLUGIN_DIR );

	if ( ! empty( $plugin ) && str_starts_with( $plugin, $mu_plugin_dir ) ) {
		$url = WPMU_PLUGIN_URL;
	} else {
		$url = WP_PLUGIN_URL;
	}

	$url = set_url_scheme( $url );

	if ( ! empty( $plugin ) && is_string( $plugin ) ) {
		$folder = dirname( plugin_basename( $plugin ) );
		if ( '.' !== $folder ) {
			$url .= '/' . ltrim( $folder, '/' );
		}
	}

	if ( $path && is_string( $path ) ) {
		$url .= '/' . ltrim( $path, '/' );
	}

	/**
	 * Filters the URL to the plugins directory.
	 *
	 * @since 2.8.0
	 *
	 * @param string $url    The complete URL to the plugins directory including scheme and path.
	 * @param string $path   Path relative to the URL to the plugins directory. Blank string
	 *                       if no path is specified.
	 * @param string $plugin The plugin file path to be relative to. Blank string if no plugin
	 *                       is specified.
	 */
	return apply_filters( 'plugins_url', $url, $path, $plugin );
}

/**
 * Retrieves the site URL for the current network.
 *
 * Returns the site URL with the appropriate protocol, 'https' if
 * is_ssl() and 'http' otherwise. If $scheme is 'http' or 'https', is_ssl() is
 * overridden.
 *
 * @since 3.0.0
 *
 * @see set_url_scheme()
 *
 * @param string      $path   Optional. Path relative to the site URL. Default empty.
 * @param string|null $scheme Optional. Scheme to give the site URL context. Accepts
 *                            'http', 'https', or 'relative'. Default null.
 * @return string Site URL link with optional path appended.
 */
function network_site_url( $path = '', $scheme = null ) {
	if ( ! is_multisite() ) {
		return site_url( $path, $scheme );
	}

	$current_network = get_network();

	if ( 'relative' === $scheme ) {
		$url = $current_network->path;
	} else {
		$url = set_url_scheme( 'http://' . $current_network->domain . $current_network->path, $scheme );
	}

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the network site URL.
	 *
	 * @since 3.0.0
	 *
	 * @param string      $url    The complete network site URL including scheme and path.
	 * @param string      $path   Path relative to the network site URL. Blank string if
	 *                            no path is specified.
	 * @param string|null $scheme Scheme to give the URL context. Accepts 'http', 'https',
	 *                            'relative' or null.
	 */
	return apply_filters( 'network_site_url', $url, $path, $scheme );
}

/**
 * Retrieves the home URL for the current network.
 *
 * Returns the home URL with the appropriate protocol, 'https' is_ssl()
 * and 'http' otherwise. If `$scheme` is 'http' or 'https', `is_ssl()` is
 * overridden.
 *
 * @since 3.0.0
 *
 * @param string      $path   Optional. Path relative to the home URL. Default empty.
 * @param string|null $scheme Optional. Scheme to give the home URL context. Accepts
 *                            'http', 'https', or 'relative'. Default null.
 * @return string Home URL link with optional path appended.
 */
function network_home_url( $path = '', $scheme = null ) {
	if ( ! is_multisite() ) {
		return home_url( $path, $scheme );
	}

	$current_network = get_network();
	$orig_scheme     = $scheme;

	if ( ! in_array( $scheme, array( 'http', 'https', 'relative' ), true ) ) {
		$scheme = is_ssl() ? 'https' : 'http';
	}

	if ( 'relative' === $scheme ) {
		$url = $current_network->path;
	} else {
		$url = set_url_scheme( 'http://' . $current_network->domain . $current_network->path, $scheme );
	}

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the network home URL.
	 *
	 * @since 3.0.0
	 *
	 * @param string      $url         The complete network home URL including scheme and path.
	 * @param string      $path        Path relative to the network home URL. Blank string
	 *                                 if no path is specified.
	 * @param string|null $orig_scheme Scheme to give the URL context. Accepts 'http', 'https',
	 *                                 'relative' or null.
	 */
	return apply_filters( 'network_home_url', $url, $path, $orig_scheme );
}

/**
 * Retrieves the URL to the admin area for the network.
 *
 * @since 3.0.0
 *
 * @param string $path   Optional path relative to the admin URL. Default empty.
 * @param string $scheme Optional. The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                       and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Admin URL link with optional path appended.
 */
function network_admin_url( $path = '', $scheme = 'admin' ) {
	if ( ! is_multisite() ) {
		return admin_url( $path, $scheme );
	}

	$url = network_site_url( 'wp-admin/network/', $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the network admin URL.
	 *
	 * @since 3.0.0
	 * @since 5.8.0 The `$scheme` parameter was added.
	 *
	 * @param string      $url    The complete network admin URL including scheme and path.
	 * @param string      $path   Path relative to the network admin URL. Blank string if
	 *                            no path is specified.
	 * @param string|null $scheme The scheme to use. Accepts 'http', 'https',
	 *                            'admin', or null. Default is 'admin', which obeys force_ssl_admin() and is_ssl().
	 */
	return apply_filters( 'network_admin_url', $url, $path, $scheme );
}

/**
 * Retrieves the URL to the admin area for the current user.
 *
 * @since 3.0.0
 *
 * @param string $path   Optional. Path relative to the admin URL. Default empty.
 * @param string $scheme Optional. The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                       and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Admin URL link with optional path appended.
 */
function user_admin_url( $path = '', $scheme = 'admin' ) {
	$url = network_site_url( 'wp-admin/user/', $scheme );

	if ( $path && is_string( $path ) ) {
		$url .= ltrim( $path, '/' );
	}

	/**
	 * Filters the user admin URL for the current user.
	 *
	 * @since 3.1.0
	 * @since 5.8.0 The `$scheme` parameter was added.
	 *
	 * @param string      $url    The complete URL including scheme and path.
	 * @param string      $path   Path relative to the URL. Blank string if
	 *                            no path is specified.
	 * @param string|null $scheme The scheme to use. Accepts 'http', 'https',
	 *                            'admin', or null. Default is 'admin', which obeys force_ssl_admin() and is_ssl().
	 */
	return apply_filters( 'user_admin_url', $url, $path, $scheme );
}

/**
 * Retrieves the URL to the admin area for either the current site or the network depending on context.
 *
 * @since 3.1.0
 *
 * @param string $path   Optional. Path relative to the admin URL. Default empty.
 * @param string $scheme Optional. The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                       and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Admin URL link with optional path appended.
 */
function self_admin_url( $path = '', $scheme = 'admin' ) {
	if ( is_network_admin() ) {
		$url = network_admin_url( $path, $scheme );
	} elseif ( is_user_admin() ) {
		$url = user_admin_url( $path, $scheme );
	} else {
		$url = admin_url( $path, $scheme );
	}

	/**
	 * Filters the admin URL for the current site or network depending on context.
	 *
	 * @since 4.9.0
	 *
	 * @param string $url    The complete URL including scheme and path.
	 * @param string $path   Path relative to the URL. Blank string if no path is specified.
	 * @param string $scheme The scheme to use.
	 */
	return apply_filters( 'self_admin_url', $url, $path, $scheme );
}

/**
 * Sets the scheme for a URL.
 *
 * @since 3.4.0
 * @since 4.4.0 The 'rest' scheme was added.
 *
 * @param string      $url    Absolute URL that includes a scheme
 * @param string|null $scheme Optional. Scheme to give $url. Currently 'http', 'https', 'login',
 *                            'login_post', 'admin', 'relative', 'rest', 'rpc', or null. Default null.
 * @return string URL with chosen scheme.
 */
function set_url_scheme( $url, $scheme = null ) {
	$orig_scheme = $scheme;

	if ( ! $scheme ) {
		$scheme = is_ssl() ? 'https' : 'http';
	} elseif ( 'admin' === $scheme || 'login' === $scheme || 'login_post' === $scheme || 'rpc' === $scheme ) {
		$scheme = is_ssl() || force_ssl_admin() ? 'https' : 'http';
	} elseif ( 'http' !== $scheme && 'https' !== $scheme && 'relative' !== $scheme ) {
		$scheme = is_ssl() ? 'https' : 'http';
	}

	$url = trim( $url );
	if ( str_starts_with( $url, '//' ) ) {
		$url = 'http:' . $url;
	}

	if ( 'relative' === $scheme ) {
		$url = ltrim( preg_replace( '#^\w+://[^/]*#', '', $url ) );
		if ( '' !== $url && '/' === $url[0] ) {
			$url = '/' . ltrim( $url, "/ \t\n\r\0\x0B" );
		}
	} else {
		$url = preg_replace( '#^\w+://#', $scheme . '://', $url );
	}

	/**
	 * Filters the resulting URL after setting the scheme.
	 *
	 * @since 3.4.0
	 *
	 * @param string      $url         The complete URL including scheme and path.
	 * @param string      $scheme      Scheme applied to the URL. One of 'http', 'https', or 'relative'.
	 * @param string|null $orig_scheme Scheme requested for the URL. One of 'http', 'https', 'login',
	 *                                 'login_post', 'admin', 'relative', 'rest', 'rpc', or null.
	 */
	return apply_filters( 'set_url_scheme', $url, $scheme, $orig_scheme );
}

/**
 * Retrieves the URL to the user's dashboard.
 *
 * If a user does not belong to any site, the global user dashboard is used. If the user
 * belongs to the current site, the dashboard for the current site is returned. If the user
 * cannot edit the current site, the dashboard to the user's primary site is returned.
 *
 * @since 3.1.0
 *
 * @param int    $user_id Optional. User ID. Defaults to current user.
 * @param string $path    Optional path relative to the dashboard. Use only paths known to
 *                        both site and user admins. Default empty.
 * @param string $scheme  The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                        and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Dashboard URL link with optional path appended.
 */
function get_dashboard_url( $user_id = 0, $path = '', $scheme = 'admin' ) {
	$user_id = $user_id ? (int) $user_id : get_current_user_id();

	$blogs = get_blogs_of_user( $user_id );

	if ( is_multisite() && ! user_can( $user_id, 'manage_network' ) && empty( $blogs ) ) {
		$url = user_admin_url( $path, $scheme );
	} elseif ( ! is_multisite() ) {
		$url = admin_url( $path, $scheme );
	} else {
		$current_blog = get_current_blog_id();

		if ( $current_blog && ( user_can( $user_id, 'manage_network' ) || in_array( $current_blog, array_keys( $blogs ), true ) ) ) {
			$url = admin_url( $path, $scheme );
		} else {
			$active = get_active_blog_for_user( $user_id );
			if ( $active ) {
				$url = get_admin_url( $active->blog_id, $path, $scheme );
			} else {
				$url = user_admin_url( $path, $scheme );
			}
		}
	}

	/**
	 * Filters the dashboard URL for a user.
	 *
	 * @since 3.1.0
	 *
	 * @param string $url     The complete URL including scheme and path.
	 * @param int    $user_id The user ID.
	 * @param string $path    Path relative to the URL. Blank string if no path is specified.
	 * @param string $scheme  Scheme to give the URL context. Accepts 'http', 'https', 'login',
	 *                        'login_post', 'admin', 'relative' or null.
	 */
	return apply_filters( 'user_dashboard_url', $url, $user_id, $path, $scheme );
}

/**
 * Retrieves the URL to the user's profile editor.
 *
 * @since 3.1.0
 *
 * @param int    $user_id Optional. User ID. Defaults to current user.
 * @param string $scheme  Optional. The scheme to use. Default is 'admin', which obeys force_ssl_admin()
 *                        and is_ssl(). 'http' or 'https' can be passed to force those schemes.
 * @return string Dashboard URL link with optional path appended.
 */
function get_edit_profile_url( $user_id = 0, $scheme = 'admin' ) {
	$user_id = $user_id ? (int) $user_id : get_current_user_id();

	if ( is_user_admin() ) {
		$url = user_admin_url( 'profile.php', $scheme );
	} elseif ( is_network_admin() ) {
		$url = network_admin_url( 'profile.php', $scheme );
	} else {
		$url = get_dashboard_url( $user_id, 'profile.php', $scheme );
	}

	/**
	 * Filters the URL for a user's profile editor.
	 *
	 * @since 3.1.0
	 *
	 * @param string $url     The complete URL including scheme and path.
	 * @param int    $user_id The user ID.
	 * @param string $scheme  Scheme to give the URL context. Accepts 'http', 'https', 'login',
	 *                        'login_post', 'admin', 'relative' or null.
	 */
	return apply_filters( 'edit_profile_url', $url, $user_id, $scheme );
}

/**
 * Returns the canonical URL for a post.
 *
 * When the post is the same as the current requested page the function will handle the
 * pagination arguments too.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or object. Default is global `$post`.
 * @return string|false The canonical URL. False if the post does not exist
 *                      or has not been published yet.
 */
function wp_get_canonical_url( $post = null ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return false;
	}

	if ( 'publish' !== $post->post_status ) {
		return false;
	}

	$canonical_url = get_permalink( $post );

	// If a canonical is being generated for the current page, make sure it has pagination if needed.
	if ( get_queried_object_id() === $post->ID ) {
		$page = get_query_var( 'page', 0 );
		if ( $page >= 2 ) {
			if ( ! get_option( 'permalink_structure' ) ) {
				$canonical_url = add_query_arg( 'page', $page, $canonical_url );
			} else {
				$canonical_url = trailingslashit( $canonical_url ) . user_trailingslashit( $page, 'single_paged' );
			}
		}

		$cpage = get_query_var( 'cpage', 0 );
		if ( $cpage ) {
			$canonical_url = get_comments_pagenum_link( $cpage );
		}
	}

	/**
	 * Filters the canonical URL for a post.
	 *
	 * @since 4.6.0
	 *
	 * @param string  $canonical_url The post's canonical URL.
	 * @param WP_Post $post          Post object.
	 */
	return apply_filters( 'get_canonical_url', $canonical_url, $post );
}

/**
 * Outputs rel=canonical for singular queries.
 *
 * @since 2.9.0
 * @since 4.6.0 Adjusted to use `wp_get_canonical_url()`.
 */
function rel_canonical() {
	if ( ! is_singular() ) {
		return;
	}

	$id = get_queried_object_id();

	if ( 0 === $id ) {
		return;
	}

	$url = wp_get_canonical_url( $id );

	if ( ! empty( $url ) ) {
		echo '<link rel="canonical" href="' . esc_url( $url ) . '" />' . "\n";
	}
}

/**
 * Returns a shortlink for a post, page, attachment, or site.
 *
 * This function exists to provide a shortlink tag that all themes and plugins can target.
 * A plugin must hook in to provide the actual shortlinks. Default shortlink support is
 * limited to providing ?p= style links for posts. Plugins can short-circuit this function
 * via the {@see 'pre_get_shortlink'} filter or filter the output via the {@see 'get_shortlink'}
 * filter.
 *
 * @since 3.0.0
 *
 * @param int    $id          Optional. A post or site ID. Default is 0, which means the current post or site.
 * @param string $context     Optional. Whether the ID is a 'site' ID, 'post' ID, or 'media' ID. If 'post',
 *                            the post_type of the post is consulted. If 'query', the current query is consulted
 *                            to determine the ID and context. Default 'post'.
 * @param bool   $allow_slugs Optional. Whether to allow post slugs in the shortlink. It is up to the plugin how
 *                            and whether to honor this. Default true.
 * @return string A shortlink or an empty string if no shortlink exists for the requested resource or if shortlinks
 *                are not enabled.
 */
function wp_get_shortlink( $id = 0, $context = 'post', $allow_slugs = true ) {
	/**
	 * Filters whether to preempt generating a shortlink for the given post.
	 *
	 * Returning a value other than false from the filter will short-circuit
	 * the shortlink generation process, returning that value instead.
	 *
	 * @since 3.0.0
	 *
	 * @param false|string $return      Short-circuit return value. Either false or a URL string.
	 * @param int          $id          Post ID, or 0 for the current post.
	 * @param string       $context     The context for the link. One of 'post' or 'query',
	 * @param bool         $allow_slugs Whether to allow post slugs in the shortlink.
	 */
	$shortlink = apply_filters( 'pre_get_shortlink', false, $id, $context, $allow_slugs );

	if ( false !== $shortlink ) {
		return $shortlink;
	}

	$post_id = 0;
	if ( 'query' === $context && is_singular() ) {
		$post_id = get_queried_object_id();
		$post    = get_post( $post_id );
	} elseif ( 'post' === $context ) {
		$post = get_post( $id );
		if ( ! empty( $post->ID ) ) {
			$post_id = $post->ID;
		}
	}

	$shortlink = '';

	// Return `?p=` link for all public post types.
	if ( ! empty( $post_id ) ) {
		$post_type = get_post_type_object( $post->post_type );

		if ( 'page' === $post->post_type && get_option( 'page_on_front' ) == $post->ID && 'page' === get_option( 'show_on_front' ) ) {
			$shortlink = home_url( '/' );
		} elseif ( $post_type && $post_type->public ) {
			$shortlink = home_url( '?p=' . $post_id );
		}
	}

	/**
	 * Filters the shortlink for a post.
	 *
	 * @since 3.0.0
	 *
	 * @param string $shortlink   Shortlink URL.
	 * @param int    $id          Post ID, or 0 for the current post.
	 * @param string $context     The context for the link. One of 'post' or 'query',
	 * @param bool   $allow_slugs Whether to allow post slugs in the shortlink. Not used by default.
	 */
	return apply_filters( 'get_shortlink', $shortlink, $id, $context, $allow_slugs );
}

/**
 * Injects rel=shortlink into the head if a shortlink is defined for the current page.
 *
 * Attached to the {@see 'wp_head'} action.
 *
 * @since 3.0.0
 */
function wp_shortlink_wp_head() {
	$shortlink = wp_get_shortlink( 0, 'query' );

	if ( empty( $shortlink ) ) {
		return;
	}

	echo "<link rel='shortlink' href='" . esc_url( $shortlink ) . "' />\n";
}

/**
 * Sends a Link: rel=shortlink header if a shortlink is defined for the current page.
 *
 * Attached to the {@see 'wp'} action.
 *
 * @since 3.0.0
 */
function wp_shortlink_header() {
	if ( headers_sent() ) {
		return;
	}

	$shortlink = wp_get_shortlink( 0, 'query' );

	if ( empty( $shortlink ) ) {
		return;
	}

	header( 'Link: <' . $shortlink . '>; rel=shortlink', false );
}

/**
 * Displays the shortlink for a post.
 *
 * Must be called from inside "The Loop"
 *
 * Call like the_shortlink( __( 'Shortlinkage FTW' ) )
 *
 * @since 3.0.0
 *
 * @param string $text   Optional The link text or HTML to be displayed. Defaults to 'This is the short link.'
 * @param string $title  Optional The tooltip for the link. Must be sanitized. Defaults to the sanitized post title.
 * @param string $before Optional HTML to display before the link. Default empty.
 * @param string $after  Optional HTML to display after the link. Default empty.
 */
function the_shortlink( $text = '', $title = '', $before = '', $after = '' ) {
	$post = get_post();

	if ( empty( $text ) ) {
		$text = __( 'This is the short link.' );
	}

	if ( empty( $title ) ) {
		$title = the_title_attribute( array( 'echo' => false ) );
	}

	$shortlink = wp_get_shortlink( $post->ID );

	if ( ! empty( $shortlink ) ) {
		$link = '<a rel="shortlink" href="' . esc_url( $shortlink ) . '" title="' . $title . '">' . $text . '</a>';

		/**
		 * Filters the short link anchor tag for a post.
		 *
		 * @since 3.0.0
		 *
		 * @param string $link      Shortlink anchor tag.
		 * @param string $shortlink Shortlink URL.
		 * @param string $text      Shortlink's text.
		 * @param string $title     Shortlink's title attribute.
		 */
		$link = apply_filters( 'the_shortlink', $link, $shortlink, $text, $title );
		echo $before, $link, $after;
	}
}

/**
 * Retrieves the avatar URL.
 *
 * @since 4.2.0
 *
 * @param mixed $id_or_email The avatar to retrieve a URL for. Accepts a user ID, Gravatar MD5 hash,
 *                           user email, WP_User object, WP_Post object, or WP_Comment object.
 * @param array $args {
 *     Optional. Arguments to use instead of the default arguments.
 *
 *     @type int    $size           Height and width of the avatar in pixels. Default 96.
 *     @type string $default        URL for the default image or a default type. Accepts:
 *                                  - '404' (return a 404 instead of a default image)
 *                                  - 'retro' (a 8-bit arcade-style pixelated face)
 *                                  - 'robohash' (a robot)
 *                                  - 'monsterid' (a monster)
 *                                  - 'wavatar' (a cartoon face)
 *                                  - 'identicon' (the "quilt", a geometric pattern)
 *                                  - 'mystery', 'mm', or 'mysteryman' (The Oyster Man)
 *                                  - 'blank' (transparent GIF)
 *                                  - 'gravatar_default' (the Gravatar logo)
 *                                  Default is the value of the 'avatar_default' option,
 *                                  with a fallback of 'mystery'.
 *     @type bool   $force_default  Whether to always show the default image, never the Gravatar.
 *                                  Default false.
 *     @type string $rating         What rating to display avatars up to. Accepts:
 *                                  - 'G' (suitable for all audiences)
 *                                  - 'PG' (possibly offensive, usually for audiences 13 and above)
 *                                  - 'R' (intended for adult audiences above 17)
 *                                  - 'X' (even more mature than above)
 *                                  Default is the value of the 'avatar_rating' option.
 *     @type string $scheme         URL scheme to use. See set_url_scheme() for accepted values.
 *                                  Default null.
 *     @type array  $processed_args When the function returns, the value will be the processed/sanitized $args
 *                                  plus a "found_avatar" guess. Pass as a reference. Default null.
 * }
 * @return string|false The URL of the avatar on success, false on failure.
 */
function get_avatar_url( $id_or_email, $args = null ) {
	$args = get_avatar_data( $id_or_email, $args );
	return $args['url'];
}

/**
 * Check if this comment type allows avatars to be retrieved.
 *
 * @since 5.1.0
 *
 * @param string $comment_type Comment type to check.
 * @return bool Whether the comment type is allowed for retrieving avatars.
 */
function is_avatar_comment_type( $comment_type ) {
	/**
	 * Filters the list of allowed comment types for retrieving avatars.
	 *
	 * @since 3.0.0
	 *
	 * @param array $types An array of content types. Default only contains 'comment'.
	 */
	$allowed_comment_types = apply_filters( 'get_avatar_comment_types', array( 'comment' ) );

	return in_array( $comment_type, (array) $allowed_comment_types, true );
}

/**
 * Retrieves default data about the avatar.
 *
 * @since 4.2.0
 *
 * @param mixed $id_or_email The avatar to retrieve. Accepts a user ID, Gravatar MD5 hash,
 *                           user email, WP_User object, WP_Post object, or WP_Comment object.
 * @param array $args {
 *     Optional. Arguments to use instead of the default arguments.
 *
 *     @type int    $size           Height and width of the avatar in pixels. Default 96.
 *     @type int    $height         Display height of the avatar in pixels. Defaults to $size.
 *     @type int    $width          Display width of the avatar in pixels. Defaults to $size.
 *     @type string $default        URL for the default image or a default type. Accepts:
 *                                  - '404' (return a 404 instead of a default image)
 *                                  - 'retro' (a 8-bit arcade-style pixelated face)
 *                                  - 'robohash' (a robot)
 *                                  - 'monsterid' (a monster)
 *                                  - 'wavatar' (a cartoon face)
 *                                  - 'identicon' (the "quilt", a geometric pattern)
 *                                  - 'mystery', 'mm', or 'mysteryman' (The Oyster Man)
 *                                  - 'blank' (transparent GIF)
 *                                  - 'gravatar_default' (the Gravatar logo)
 *                                  Default is the value of the 'avatar_default' option,
 *                                  with a fallback of 'mystery'.
 *     @type bool   $force_default  Whether to always show the default image, never the Gravatar.
 *                                  Default false.
 *     @type string $rating         What rating to display avatars up to. Accepts:
 *                                  - 'G' (suitable for all audiences)
 *                                  - 'PG' (possibly offensive, usually for audiences 13 and above)
 *                                  - 'R' (intended for adult audiences above 17)
 *                                  - 'X' (even more mature than above)
 *                                  Default is the value of the 'avatar_rating' option.
 *     @type string $scheme         URL scheme to use. See set_url_scheme() for accepted values.
 *                                  Default null.
 *     @type array  $processed_args When the function returns, the value will be the processed/sanitized $args
 *                                  plus a "found_avatar" guess. Pass as a reference. Default null.
 *     @type string $extra_attr     HTML attributes to insert in the IMG element. Is not sanitized.
 *                                  Default empty.
 * }
 * @return array {
 *     Along with the arguments passed in `$args`, this will contain a couple of extra arguments.
 *
 *     @type bool         $found_avatar True if an avatar was found for this user,
 *                                      false or not set if none was found.
 *     @type string|false $url          The URL of the avatar that was found, or false.
 * }
 */
function get_avatar_data( $id_or_email, $args = null ) {
	$args = wp_parse_args(
		$args,
		array(
			'size'           => 96,
			'height'         => null,
			'width'          => null,
			'default'        => get_option( 'avatar_default', 'mystery' ),
			'force_default'  => false,
			'rating'         => get_option( 'avatar_rating' ),
			'scheme'         => null,
			'processed_args' => null, // If used, should be a reference.
			'extra_attr'     => '',
		)
	);

	if ( is_numeric( $args['size'] ) ) {
		$args['size'] = absint( $args['size'] );
		if ( ! $args['size'] ) {
			$args['size'] = 96;
		}
	} else {
		$args['size'] = 96;
	}

	if ( is_numeric( $args['height'] ) ) {
		$args['height'] = absint( $args['height'] );
		if ( ! $args['height'] ) {
			$args['height'] = $args['size'];
		}
	} else {
		$args['height'] = $args['size'];
	}

	if ( is_numeric( $args['width'] ) ) {
		$args['width'] = absint( $args['width'] );
		if ( ! $args['width'] ) {
			$args['width'] = $args['size'];
		}
	} else {
		$args['width'] = $args['size'];
	}

	if ( empty( $args['default'] ) ) {
		$args['default'] = get_option( 'avatar_default', 'mystery' );
	}

	switch ( $args['default'] ) {
		case 'mm':
		case 'mystery':
		case 'mysteryman':
			$args['default'] = 'mm';
			break;
		case 'gravatar_default':
			$args['default'] = false;
			break;
	}

	$args['force_default'] = (bool) $args['force_default'];

	$args['rating'] = strtolower( $args['rating'] );

	$args['found_avatar'] = false;

	/**
	 * Filters whether to retrieve the avatar URL early.
	 *
	 * Passing a non-null value in the 'url' member of the return array will
	 * effectively short circuit get_avatar_data(), passing the value through
	 * the {@see 'get_avatar_data'} filter and returning early.
	 *
	 * @since 4.2.0
	 *
	 * @param array $args        Arguments passed to get_avatar_data(), after processing.
	 * @param mixed $id_or_email The avatar to retrieve. Accepts a user ID, Gravatar MD5 hash,
	 *                           user email, WP_User object, WP_Post object, or WP_Comment object.
	 */
	$args = apply_filters( 'pre_get_avatar_data', $args, $id_or_email );

	if ( isset( $args['url'] ) ) {
		/** This filter is documented in wp-includes/link-template.php */
		return apply_filters( 'get_avatar_data', $args, $id_or_email );
	}

	$email_hash = '';
	$user       = false;
	$email      = false;

	if ( is_object( $id_or_email ) && isset( $id_or_email->comment_ID ) ) {
		$id_or_email = get_comment( $id_or_email );
	}

	// Process the user identifier.
	if ( is_numeric( $id_or_email ) ) {
		$user = get_user_by( 'id', absint( $id_or_email ) );
	} elseif ( is_string( $id_or_email ) ) {
		if ( str_contains( $id_or_email, '@md5.gravatar.com' ) ) {
			// MD5 hash.
			list( $email_hash ) = explode( '@', $id_or_email );
		} else {
			// Email address.
			$email = $id_or_email;
		}
	} elseif ( $id_or_email instanceof WP_User ) {
		// User object.
		$user = $id_or_email;
	} elseif ( $id_or_email instanceof WP_Post ) {
		// Post object.
		$user = get_user_by( 'id', (int) $id_or_email->post_author );
	} elseif ( $id_or_email instanceof WP_Comment ) {
		if ( ! is_avatar_comment_type( get_comment_type( $id_or_email ) ) ) {
			$args['url'] = false;
			/** This filter is documented in wp-includes/link-template.php */
			return apply_filters( 'get_avatar_data', $args, $id_or_email );
		}

		if ( ! empty( $id_or_email->user_id ) ) {
			$user = get_user_by( 'id', (int) $id_or_email->user_id );
		}
		if ( ( ! $user || is_wp_error( $user ) ) && ! empty( $id_or_email->comment_author_email ) ) {
			$email = $id_or_email->comment_author_email;
		}
	}

	if ( ! $email_hash ) {
		if ( $user ) {
			$email = $user->user_email;
		}

		if ( $email ) {
			$email_hash = md5( strtolower( trim( $email ) ) );
		}
	}

	if ( $email_hash ) {
		$args['found_avatar'] = true;
		$gravatar_server      = hexdec( $email_hash[0] ) % 3;
	} else {
		$gravatar_server = rand( 0, 2 );
	}

	$url_args = array(
		's' => $args['size'],
		'd' => $args['default'],
		'f' => $args['force_default'] ? 'y' : false,
		'r' => $args['rating'],
	);

	if ( is_ssl() ) {
		$url = 'https://secure.gravatar.com/avatar/' . $email_hash;
	} else {
		$url = sprintf( 'http://%d.gravatar.com/avatar/%s', $gravatar_server, $email_hash );
	}

	$url = add_query_arg(
		rawurlencode_deep( array_filter( $url_args ) ),
		set_url_scheme( $url, $args['scheme'] )
	);

	/**
	 * Filters the avatar URL.
	 *
	 * @since 4.2.0
	 *
	 * @param string $url         The URL of the avatar.
	 * @param mixed  $id_or_email The avatar to retrieve. Accepts a user ID, Gravatar MD5 hash,
	 *                            user email, WP_User object, WP_Post object, or WP_Comment object.
	 * @param array  $args        Arguments passed to get_avatar_data(), after processing.
	 */
	$args['url'] = apply_filters( 'get_avatar_url', $url, $id_or_email, $args );

	/**
	 * Filters the avatar data.
	 *
	 * @since 4.2.0
	 *
	 * @param array $args        Arguments passed to get_avatar_data(), after processing.
	 * @param mixed $id_or_email The avatar to retrieve. Accepts a user ID, Gravatar MD5 hash,
	 *                           user email, WP_User object, WP_Post object, or WP_Comment object.
	 */
	return apply_filters( 'get_avatar_data', $args, $id_or_email );
}

/**
 * Retrieves the URL of a file in the theme.
 *
 * Searches in the stylesheet directory before the template directory so themes
 * which inherit from a parent theme can just override one file.
 *
 * @since 4.7.0
 *
 * @param string $file Optional. File to search for in the stylesheet directory.
 * @return string The URL of the file.
 */
function get_theme_file_uri( $file = '' ) {
	$file = ltrim( $file, '/' );

	$stylesheet_directory = get_stylesheet_directory();

	if ( empty( $file ) ) {
		$url = get_stylesheet_directory_uri();
	} elseif ( get_template_directory() !== $stylesheet_directory && file_exists( $stylesheet_directory . '/' . $file ) ) {
		$url = get_stylesheet_directory_uri() . '/' . $file;
	} else {
		$url = get_template_directory_uri() . '/' . $file;
	}

	/**
	 * Filters the URL to a file in the theme.
	 *
	 * @since 4.7.0
	 *
	 * @param string $url  The file URL.
	 * @param string $file The requested file to search for.
	 */
	return apply_filters( 'theme_file_uri', $url, $file );
}

/**
 * Retrieves the URL of a file in the parent theme.
 *
 * @since 4.7.0
 *
 * @param string $file Optional. File to return the URL for in the template directory.
 * @return string The URL of the file.
 */
function get_parent_theme_file_uri( $file = '' ) {
	$file = ltrim( $file, '/' );

	if ( empty( $file ) ) {
		$url = get_template_directory_uri();
	} else {
		$url = get_template_directory_uri() . '/' . $file;
	}

	/**
	 * Filters the URL to a file in the parent theme.
	 *
	 * @since 4.7.0
	 *
	 * @param string $url  The file URL.
	 * @param string $file The requested file to search for.
	 */
	return apply_filters( 'parent_theme_file_uri', $url, $file );
}

/**
 * Retrieves the path of a file in the theme.
 *
 * Searches in the stylesheet directory before the template directory so themes
 * which inherit from a parent theme can just override one file.
 *
 * @since 4.7.0
 *
 * @param string $file Optional. File to search for in the stylesheet directory.
 * @return string The path of the file.
 */
function get_theme_file_path( $file = '' ) {
	$file = ltrim( $file, '/' );

	$stylesheet_directory = get_stylesheet_directory();
	$template_directory   = get_template_directory();

	if ( empty( $file ) ) {
		$path = $stylesheet_directory;
	} elseif ( $stylesheet_directory !== $template_directory && file_exists( $stylesheet_directory . '/' . $file ) ) {
		$path = $stylesheet_directory . '/' . $file;
	} else {
		$path = $template_directory . '/' . $file;
	}

	/**
	 * Filters the path to a file in the theme.
	 *
	 * @since 4.7.0
	 *
	 * @param string $path The file path.
	 * @param string $file The requested file to search for.
	 */
	return apply_filters( 'theme_file_path', $path, $file );
}

/**
 * Retrieves the path of a file in the parent theme.
 *
 * @since 4.7.0
 *
 * @param string $file Optional. File to return the path for in the template directory.
 * @return string The path of the file.
 */
function get_parent_theme_file_path( $file = '' ) {
	$file = ltrim( $file, '/' );

	if ( empty( $file ) ) {
		$path = get_template_directory();
	} else {
		$path = get_template_directory() . '/' . $file;
	}

	/**
	 * Filters the path to a file in the parent theme.
	 *
	 * @since 4.7.0
	 *
	 * @param string $path The file path.
	 * @param string $file The requested file to search for.
	 */
	return apply_filters( 'parent_theme_file_path', $path, $file );
}

/**
 * Retrieves the URL to the privacy policy page.
 *
 * @since 4.9.6
 *
 * @return string The URL to the privacy policy page. Empty string if it doesn't exist.
 */
function get_privacy_policy_url() {
	$url            = '';
	$policy_page_id = (int) get_option( 'wp_page_for_privacy_policy' );

	if ( ! empty( $policy_page_id ) && get_post_status( $policy_page_id ) === 'publish' ) {
		$url = (string) get_permalink( $policy_page_id );
	}

	/**
	 * Filters the URL of the privacy policy page.
	 *
	 * @since 4.9.6
	 *
	 * @param string $url            The URL to the privacy policy page. Empty string
	 *                               if it doesn't exist.
	 * @param int    $policy_page_id The ID of privacy policy page.
	 */
	return apply_filters( 'privacy_policy_url', $url, $policy_page_id );
}

/**
 * Displays the privacy policy link with formatting, when applicable.
 *
 * @since 4.9.6
 *
 * @param string $before Optional. Display before privacy policy link. Default empty.
 * @param string $after  Optional. Display after privacy policy link. Default empty.
 */
function the_privacy_policy_link( $before = '', $after = '' ) {
	echo get_the_privacy_policy_link( $before, $after );
}

/**
 * Returns the privacy policy link with formatting, when applicable.
 *
 * @since 4.9.6
 * @since 6.2.0 Added 'privacy-policy' rel attribute.
 *
 * @param string $before Optional. Display before privacy policy link. Default empty.
 * @param string $after  Optional. Display after privacy policy link. Default empty.
 * @return string Markup for the link and surrounding elements. Empty string if it
 *                doesn't exist.
 */
function get_the_privacy_policy_link( $before = '', $after = '' ) {
	$link               = '';
	$privacy_policy_url = get_privacy_policy_url();
	$policy_page_id     = (int) get_option( 'wp_page_for_privacy_policy' );
	$page_title         = ( $policy_page_id ) ? get_the_title( $policy_page_id ) : '';

	if ( $privacy_policy_url && $page_title ) {
		$link = sprintf(
			'<a class="privacy-policy-link" href="%s" rel="privacy-policy">%s</a>',
			esc_url( $privacy_policy_url ),
			esc_html( $page_title )
		);
	}

	/**
	 * Filters the privacy policy link.
	 *
	 * @since 4.9.6
	 *
	 * @param string $link               The privacy policy link. Empty string if it
	 *                                   doesn't exist.
	 * @param string $privacy_policy_url The URL of the privacy policy. Empty string
	 *                                   if it doesn't exist.
	 */
	$link = apply_filters( 'the_privacy_policy_link', $link, $privacy_policy_url );

	if ( $link ) {
		return $before . $link . $after;
	}

	return '';
}

/**
 * Returns an array of URL hosts which are considered to be internal hosts.
 *
 * By default the list of internal hosts is comprised of the host name of
 * the site's home_url() (as parsed by wp_parse_url()).
 *
 * This list is used when determining if a specificed URL is a link to a page on
 * the site itself or a link offsite (to an external host). This is used, for
 * example, when determining if the "nofollow" attribute should be applied to a
 * link.
 *
 * @see wp_is_internal_link
 *
 * @since 6.2.0
 *
 * @return string[] An array of URL hosts.
 */
function wp_internal_hosts() {
	static $internal_hosts;

	if ( empty( $internal_hosts ) ) {
		/**
		 * Filters the array of URL hosts which are considered internal.
		 *
		 * @since 6.2.0
		 *
		 * @param string[] $internal_hosts An array of internal URL hostnames.
		 */
		$internal_hosts = apply_filters(
			'wp_internal_hosts',
			array(
				wp_parse_url( home_url(), PHP_URL_HOST ),
			)
		);
		$internal_hosts = array_unique(
			array_map( 'strtolower', (array) $internal_hosts )
		);
	}

	return $internal_hosts;
}

/**
 * Determines whether or not the specified URL is of a host included in the internal hosts list.
 *
 * @see wp_internal_hosts()
 *
 * @since 6.2.0
 *
 * @param string $link The URL to test.
 * @return bool Returns true for internal URLs and false for all other URLs.
 */
function wp_is_internal_link( $link ) {
	$link = strtolower( $link );
	if ( in_array( wp_parse_url( $link, PHP_URL_SCHEME ), wp_allowed_protocols(), true ) ) {
		return in_array( wp_parse_url( $link, PHP_URL_HOST ), wp_internal_hosts(), true );
	}
	return false;
}
' ) ) {
					// @TODO: Indicate a parse error once it's possible. This error does not impact the logic here.
					$this->generate_implied_end_tags();
					$this->state->stack_of_open_elements->pop_until( 'BUTTON' );
				}

				$this->reconstruct_active_formatting_elements();
				$this->insert_html_element( $this->state->current_token );
				$this->state->frameset_ok = false;

				return true;

			/*
			 * > A start tag whose tag name is one of: "address", "article", "aside",
			 * > "blockquote", "center", "details", "dialog", "dir", "div", "dl",
			 * > "fieldset", "figcaption", "figure", "footer", "header", "hgroup",
			 * > "main", "menu", "nav", "ol", "p", "search", "section", "summary", "ul"
			 */
			case '+BLOCKQUOTE':
			case '+DIV':
			case '+FIGCAPTION':
			case '+FIGURE':
			case '+P':
				if ( $this->state->stack_of_open_elements->has_p_in_button_scope() ) {
					$this->close_a_p_element();
				}

				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > An end tag whose tag name is one of: "address", "article", "aside", "blockquote",
			 * > "button", "center", "details", "dialog", "dir", "div", "dl", "fieldset",
			 * > "figcaption", "figure", "footer", "header", "hgroup", "listing", "main",
			 * > "menu", "nav", "ol", "pre", "search", "section", "summary", "ul"
			 */
			case '-BLOCKQUOTE':
			case '-BUTTON':
			case '-DIV':
			case '-FIGCAPTION':
			case '-FIGURE':
				if ( ! $this->state->stack_of_open_elements->has_element_in_scope( $tag_name ) ) {
					// @TODO: Report parse error.
					// Ignore the token.
					return $this->step();
				}

				$this->generate_implied_end_tags();
				if ( $this->state->stack_of_open_elements->current_node()->node_name !== $tag_name ) {
					// @TODO: Record parse error: this error doesn't impact parsing.
				}
				$this->state->stack_of_open_elements->pop_until( $tag_name );
				return true;

			/*
			 * > An end tag whose tag name is "p"
			 */
			case '-P':
				if ( ! $this->state->stack_of_open_elements->has_p_in_button_scope() ) {
					$this->insert_html_element( $this->state->current_token );
				}

				$this->close_a_p_element();
				return true;

			// > A start tag whose tag name is "a"
			case '+A':
				foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {
					switch ( $item->node_name ) {
						case 'marker':
							break;

						case 'A':
							$this->run_adoption_agency_algorithm();
							$this->state->active_formatting_elements->remove_node( $item );
							$this->state->stack_of_open_elements->remove_node( $item );
							break;
					}
				}

				$this->reconstruct_active_formatting_elements();
				$this->insert_html_element( $this->state->current_token );
				$this->state->active_formatting_elements->push( $this->state->current_token );
				return true;

			/*
			 * > A start tag whose tag name is one of: "b", "big", "code", "em", "font", "i",
			 * > "s", "small", "strike", "strong", "tt", "u"
			 */
			case '+B':
			case '+BIG':
			case '+CODE':
			case '+EM':
			case '+FONT':
			case '+I':
			case '+S':
			case '+SMALL':
			case '+STRIKE':
			case '+STRONG':
			case '+TT':
			case '+U':
				$this->reconstruct_active_formatting_elements();
				$this->insert_html_element( $this->state->current_token );
				$this->state->active_formatting_elements->push( $this->state->current_token );
				return true;

			/*
			 * > An end tag whose tag name is one of: "a", "b", "big", "code", "em", "font", "i",
			 * > "nobr", "s", "small", "strike", "strong", "tt", "u"
			 */
			case '-A':
			case '-B':
			case '-BIG':
			case '-CODE':
			case '-EM':
			case '-FONT':
			case '-I':
			case '-S':
			case '-SMALL':
			case '-STRIKE':
			case '-STRONG':
			case '-TT':
			case '-U':
				$this->run_adoption_agency_algorithm();
				return true;

			/*
			 * > A start tag whose tag name is one of: "area", "br", "embed", "img", "keygen", "wbr"
			 */
			case '+IMG':
				$this->reconstruct_active_formatting_elements();
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > Any other start tag
			 */
			case '+SPAN':
				$this->reconstruct_active_formatting_elements();
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * Any other end tag
			 */
			case '-SPAN':
				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
					// > If node is an HTML element with the same tag name as the token, then:
					if ( $item->node_name === $tag_name ) {
						$this->generate_implied_end_tags( $tag_name );

						// > If node is not the current node, then this is a parse error.

						$this->state->stack_of_open_elements->pop_until( $tag_name );
						return true;
					}

					// > Otherwise, if node is in the special category, then this is a parse error; ignore the token, and return.
					if ( self::is_special( $item->node_name ) ) {
						return $this->step();
					}
				}
				// Execution should not reach here; if it does then something went wrong.
				return false;

			default:
				$this->last_error = self::ERROR_UNSUPPORTED;
				throw new WP_HTML_Unsupported_Exception( "Cannot process {$tag_name} element." );
		}
	}

	/*
	 * Internal helpers
	 */

	/**
	 * Creates a new bookmark for the currently-matched tag and returns the generated name.
	 *
	 * @since 6.4.0
	 *
	 * @throws Exception When unable to allocate requested bookmark.
	 *
	 * @return string|false Name of created bookmark, or false if unable to create.
	 */
	private function bookmark_tag() {
		if ( ! $this->get_tag() ) {
			return false;
		}

		if ( ! parent::set_bookmark( ++$this->bookmark_counter ) ) {
			$this->last_error = self::ERROR_EXCEEDED_MAX_BOOKMARKS;
			throw new Exception( 'could not allocate bookmark' );
		}

		return "{$this->bookmark_counter}";
	}

	/*
	 * HTML semantic overrides for Tag Processor
	 */

	/**
	 * Returns the uppercase name of the matched tag.
	 *
	 * The semantic rules for HTML specify that certain tags be reprocessed
	 * with a different tag name. Because of this, the tag name presented
	 * by the HTML Processor may differ from the one reported by the HTML
	 * Tag Processor, which doesn't apply these semantic rules.
	 *
	 * Example:
	 *
	 *     $processor = new WP_HTML_Tag_Processor( '<div class="test">Test</div>' );
	 *     $processor->next_tag() === true;
	 *     $processor->get_tag() === 'DIV';
	 *
	 *     $processor->next_tag() === false;
	 *     $processor->get_tag() === null;
	 *
	 * @since 6.4.0
	 *
	 * @return string|null Name of currently matched tag in input HTML, or `null` if none found.
	 */
	public function get_tag() {
		if ( null !== $this->last_error ) {
			return null;
		}

		$tag_name = parent::get_tag();

		switch ( $tag_name ) {
			case 'IMAGE':
				/*
				 * > A start tag whose tag name is "image"
				 * > Change the token's tag name to "img" and reprocess it. (Don't ask.)
				 */
				return 'IMG';

			default:
				return $tag_name;
		}
	}

	/**
	 * Removes a bookmark that is no longer needed.
	 *
	 * Releasing a bookmark frees up the small
	 * performance overhead it requires.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Name of the bookmark to remove.
	 * @return bool Whether the bookmark already existed before removal.
	 */
	public function release_bookmark( $bookmark_name ) {
		return parent::release_bookmark( "_{$bookmark_name}" );
	}

	/**
	 * Moves the internal cursor in the HTML Processor to a given bookmark's location.
	 *
	 * In order to prevent accidental infinite loops, there's a
	 * maximum limit on the number of times seek() can be called.
	 *
	 * @throws Exception When unable to allocate a bookmark for the next token in the input HTML document.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Jump to the place in the document identified by this bookmark name.
	 * @return bool Whether the internal cursor was successfully moved to the bookmark's location.
	 */
	public function seek( $bookmark_name ) {
		$actual_bookmark_name = "_{$bookmark_name}";
		$processor_started_at = $this->state->current_token
			? $this->bookmarks[ $this->state->current_token->bookmark_name ]->start
			: 0;
		$bookmark_starts_at   = $this->bookmarks[ $actual_bookmark_name ]->start;
		$direction            = $bookmark_starts_at > $processor_started_at ? 'forward' : 'backward';

		switch ( $direction ) {
			case 'forward':
				// When moving forwards, re-parse the document until reaching the same location as the original bookmark.
				while ( $this->step() ) {
					if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
						return true;
					}
				}

				return false;

			case 'backward':
				/*
				 * When moving backwards, clear out all existing stack entries which appear after the destination
				 * bookmark. These could be stored for later retrieval, but doing so would require additional
				 * memory overhead and also demand that references and bookmarks are updated as the document
				 * changes. In time this could be a valuable optimization, but it's okay to give up that
				 * optimization in exchange for more CPU time to recompute the stack, to re-parse the
				 * document that may have already been parsed once.
				 */
				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
					if ( $bookmark_starts_at >= $this->bookmarks[ $item->bookmark_name ]->start ) {
						break;
					}

					$this->state->stack_of_open_elements->remove_node( $item );
				}

				foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {
					if ( $bookmark_starts_at >= $this->bookmarks[ $item->bookmark_name ]->start ) {
						break;
					}

					$this->state->active_formatting_elements->remove_node( $item );
				}

				return parent::seek( $actual_bookmark_name );
		}
	}

	/**
	 * Sets a bookmark in the HTML document.
	 *
	 * Bookmarks represent specific places or tokens in the HTML
	 * document, such as a tag opener or closer. When applying
	 * edits to a document, such as setting an attribute, the
	 * text offsets of that token may shift; the bookmark is
	 * kept updated with those shifts and remains stable unless
	 * the entire span of text in which the token sits is removed.
	 *
	 * Release bookmarks when they are no longer needed.
	 *
	 * Example:
	 *
	 *     <main><h2>Surprising fact you may not know!</h2></main>
	 *           ^  ^
	 *            \-|-- this `H2` opener bookmark tracks the token
	 *
	 *     <main class="clickbait"><h2>Surprising fact you may no…
	 *                             ^  ^
	 *                              \-|-- it shifts with edits
	 *
	 * Bookmarks provide the ability to seek to a previously-scanned
	 * place in the HTML document. This avoids the need to re-scan
	 * the entire document.
	 *
	 * Example:
	 *
	 *     <ul><li>One</li><li>Two</li><li>Three</li></ul>
	 *                                 ^^^^
	 *                                 want to note this last item
	 *
	 *     $p = new WP_HTML_Tag_Processor( $html );
	 *     $in_list = false;
	 *     while ( $p->next_tag( array( 'tag_closers' => $in_list ? 'visit' : 'skip' ) ) ) {
	 *         if ( 'UL' === $p->get_tag() ) {
	 *             if ( $p->is_tag_closer() ) {
	 *                 $in_list = false;
	 *                 $p->set_bookmark( 'resume' );
	 *                 if ( $p->seek( 'last-li' ) ) {
	 *                     $p->add_class( 'last-li' );
	 *                 }
	 *                 $p->seek( 'resume' );
	 *                 $p->release_bookmark( 'last-li' );
	 *                 $p->release_bookmark( 'resume' );
	 *             } else {
	 *                 $in_list = true;
	 *             }
	 *         }
	 *
	 *         if ( 'LI' === $p->get_tag() ) {
	 *             $p->set_bookmark( 'last-li' );
	 *         }
	 *     }
	 *
	 * Bookmarks intentionally hide the internal string offsets
	 * to which they refer. They are maintained internally as
	 * updates are applied to the HTML document and therefore
	 * retain their "position" - the location to which they
	 * originally pointed. The inability to use bookmarks with
	 * functions like `substr` is therefore intentional to guard
	 * against accidentally breaking the HTML.
	 *
	 * Because bookmarks allocate memory and require processing
	 * for every applied update, they are limited and require
	 * a name. They should not be created with programmatically-made
	 * names, such as "li_{$index}" with some loop. As a general
	 * rule they should only be created with string-literal names
	 * like "start-of-section" or "last-paragraph".
	 *
	 * Bookmarks are a powerful tool to enable complicated behavior.
	 * Consider double-checking that you need this tool if you are
	 * reaching for it, as inappropriate use could lead to broken
	 * HTML structure or unwanted processing overhead.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Identifies this particular bookmark.
	 * @return bool Whether the bookmark was successfully created.
	 */
	public function set_bookmark( $bookmark_name ) {
		return parent::set_bookmark( "_{$bookmark_name}" );
	}

	/*
	 * HTML Parsing Algorithms
	 */

	/**
	 * Closes a P element.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#close-a-p-element
	 */
	private function close_a_p_element() {
		$this->generate_implied_end_tags( 'P' );
		$this->state->stack_of_open_elements->pop_until( 'P' );
	}

	/**
	 * Closes elements that have implied end tags.
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
	 *
	 * @param string|null $except_for_this_element Perform as if this element doesn't exist in the stack of open elements.
	 */
	private function generate_implied_end_tags( $except_for_this_element = null ) {
		$elements_with_implied_end_tags = array(
			'P',
		);

		$current_node = $this->state->stack_of_open_elements->current_node();
		while (
			$current_node && $current_node->node_name !== $except_for_this_element &&
			in_array( $this->state->stack_of_open_elements->current_node(), $elements_with_implied_end_tags, true )
		) {
			$this->state->stack_of_open_elements->pop();
		}
	}

	/**
	 * Closes elements that have implied end tags, thoroughly.
	 *
	 * See the HTML specification for an explanation why this is
	 * different from generating end tags in the normal sense.
	 *
	 * @since 6.4.0
	 *
	 * @see WP_HTML_Processor::generate_implied_end_tags
	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
	 */
	private function generate_implied_end_tags_thoroughly() {
		$elements_with_implied_end_tags = array(
			'P',
		);

		while ( in_array( $this->state->stack_of_open_elements->current_node(), $elements_with_implied_end_tags, true ) ) {
			$this->state->stack_of_open_elements->pop();
		}
	}

	/**
	 * Reconstructs the active formatting elements.
	 *
	 * > This has the effect of reopening all the formatting elements that were opened
	 * > in the current body, cell, or caption (whichever is youngest) that haven't
	 * > been explicitly closed.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#reconstruct-the-active-formatting-elements
	 *
	 * @return bool Whether any formatting elements needed to be reconstructed.
	 */
	private function reconstruct_active_formatting_elements() {
		/*
		 * > If there are no entries in the list of active formatting elements, then there is nothing
		 * > to reconstruct; stop this algorithm.
		 */
		if ( 0 === $this->state->active_formatting_elements->count() ) {
			return false;
		}

		$last_entry = $this->state->active_formatting_elements->current_node();
		if (

			/*
			 * > If the last (most recently added) entry in the list of active formatting elements is a marker;
			 * > stop this algorithm.
			 */
			'marker' === $last_entry->node_name ||

			/*
			 * > If the last (most recently added) entry in the list of active formatting elements is an
			 * > element that is in the stack of open elements, then there is nothing to reconstruct;
			 * > stop this algorithm.
			 */
			$this->state->stack_of_open_elements->contains_node( $last_entry )
		) {
			return false;
		}

		$this->last_error = self::ERROR_UNSUPPORTED;
		throw new WP_HTML_Unsupported_Exception( 'Cannot reconstruct active formatting elements when advancing and rewinding is required.' );
	}

	/**
	 * Runs the adoption agency algorithm.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#adoption-agency-algorithm
	 */
	private function run_adoption_agency_algorithm() {
		$budget       = 1000;
		$subject      = $this->get_tag();
		$current_node = $this->state->stack_of_open_elements->current_node();

		if (
			// > If the current node is an HTML element whose tag name is subject
			$current_node && $subject === $current_node->node_name &&
			// > the current node is not in the list of active formatting elements
			! $this->state->active_formatting_elements->contains_node( $current_node )
		) {
			$this->state->stack_of_open_elements->pop();
			return;
		}

		$outer_loop_counter = 0;
		while ( $budget-- > 0 ) {
			if ( $outer_loop_counter++ >= 8 ) {
				return;
			}

			/*
			 * > Let formatting element be the last element in the list of active formatting elements that:
			 * >   - is between the end of the list and the last marker in the list,
			 * >     if any, or the start of the list otherwise,
			 * >   - and has the tag name subject.
			 */
			$formatting_element = null;
			foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {
				if ( 'marker' === $item->node_name ) {
					break;
				}

				if ( $subject === $item->node_name ) {
					$formatting_element = $item;
					break;
				}
			}

			// > If there is no such element, then return and instead act as described in the "any other end tag" entry above.
			if ( null === $formatting_element ) {
				$this->last_error = self::ERROR_UNSUPPORTED;
				throw new WP_HTML_Unsupported_Exception( 'Cannot run adoption agency when "any other end tag" is required.' );
			}

			// > If formatting element is not in the stack of open elements, then this is a parse error; remove the element from the list, and return.
			if ( ! $this->state->stack_of_open_elements->contains_node( $formatting_element ) ) {
				$this->state->active_formatting_elements->remove_node( $formatting_element->bookmark_name );
				return;
			}

			// > If formatting element is in the stack of open elements, but the element is not in scope, then this is a parse error; return.
			if ( ! $this->state->stack_of_open_elements->has_element_in_scope( $formatting_element->node_name ) ) {
				return;
			}

			/*
			 * > Let furthest block be the topmost node in the stack of open elements that is lower in the stack
			 * > than formatting element, and is an element in the special category. There might not be one.
			 */
			$is_above_formatting_element = true;
			$furthest_block              = null;
			foreach ( $this->state->stack_of_open_elements->walk_down() as $item ) {
				if ( $is_above_formatting_element && $formatting_element->bookmark_name !== $item->bookmark_name ) {
					continue;
				}

				if ( $is_above_formatting_element ) {
					$is_above_formatting_element = false;
					continue;
				}

				if ( self::is_special( $item->node_name ) ) {
					$furthest_block = $item;
					break;
				}
			}

			/*
			 * > If there is no furthest block, then the UA must first pop all the nodes from the bottom of the
			 * > stack of open elements, from the current node up to and including formatting element, then
			 * > remove formatting element from the list of active formatting elements, and finally return.
			 */
			if ( null === $furthest_block ) {
				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
					$this->state->stack_of_open_elements->pop();

					if ( $formatting_element->bookmark_name === $item->bookmark_name ) {
						$this->state->active_formatting_elements->remove_node( $formatting_element );
						return;
					}
				}
			}

			$this->last_error = self::ERROR_UNSUPPORTED;
			throw new WP_HTML_Unsupported_Exception( 'Cannot extract common ancestor in adoption agency algorithm.' );
		}

		$this->last_error = self::ERROR_UNSUPPORTED;
		throw new WP_HTML_Unsupported_Exception( 'Cannot run adoption agency when looping required.' );
	}

	/**
	 * Inserts an HTML element on the stack of open elements.
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#insert-a-foreign-element
	 *
	 * @param WP_HTML_Token $token Name of bookmark pointing to element in original input HTML.
	 */
	private function insert_html_element( $token ) {
		$this->state->stack_of_open_elements->push( $token );
	}

	/*
	 * HTML Specification Helpers
	 */

	/**
	 * Returns whether an element of a given name is in the HTML special category.
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#special
	 *
	 * @param string $tag_name Name of element to check.
	 * @return bool Whether the element of the given name is in the special category.
	 */
	public static function is_special( $tag_name ) {
		$tag_name = strtoupper( $tag_name );

		return (
			'ADDRESS' === $tag_name ||
			'APPLET' === $tag_name ||
			'AREA' === $tag_name ||
			'ARTICLE' === $tag_name ||
			'ASIDE' === $tag_name ||
			'BASE' === $tag_name ||
			'BASEFONT' === $tag_name ||
			'BGSOUND' === $tag_name ||
			'BLOCKQUOTE' === $tag_name ||
			'BODY' === $tag_name ||
			'BR' === $tag_name ||
			'BUTTON' === $tag_name ||
			'CAPTION' === $tag_name ||
			'CENTER' === $tag_name ||
			'COL' === $tag_name ||
			'COLGROUP' === $tag_name ||
			'DD' === $tag_name ||
			'DETAILS' === $tag_name ||
			'DIR' === $tag_name ||
			'DIV' === $tag_name ||
			'DL' === $tag_name ||
			'DT' === $tag_name ||
			'EMBED' === $tag_name ||
			'FIELDSET' === $tag_name ||
			'FIGCAPTION' === $tag_name ||
			'FIGURE' === $tag_name ||
			'FOOTER' === $tag_name ||
			'FORM' === $tag_name ||
			'FRAME' === $tag_name ||
			'FRAMESET' === $tag_name ||
			'H1' === $tag_name ||
			'H2' === $tag_name ||
			'H3' === $tag_name ||
			'H4' === $tag_name ||
			'H5' === $tag_name ||
			'H6' === $tag_name ||
			'HEAD' === $tag_name ||
			'HEADER' === $tag_name ||
			'HGROUP' === $tag_name ||
			'HR' === $tag_name ||
			'HTML' === $tag_name ||
			'IFRAME' === $tag_name ||
			'IMG' === $tag_name ||
			'INPUT' === $tag_name ||
			'KEYGEN' === $tag_name ||
			'LI' === $tag_name ||
			'LINK' === $tag_name ||
			'LISTING' === $tag_name ||
			'MAIN' === $tag_name ||
			'MARQUEE' === $tag_name ||
			'MENU' === $tag_name ||
			'META' === $tag_name ||
			'NAV' === $tag_name ||
			'NOEMBED' === $tag_name ||
			'NOFRAMES' === $tag_name ||
			'NOSCRIPT' === $tag_name ||
			'OBJECT' === $tag_name ||
			'OL' === $tag_name ||
			'P' === $tag_name ||
			'PARAM' === $tag_name ||
			'PLAINTEXT' === $tag_name ||
			'PRE' === $tag_name ||
			'SCRIPT' === $tag_name ||
			'SEARCH' === $tag_name ||
			'SECTION' === $tag_name ||
			'SELECT' === $tag_name ||
			'SOURCE' === $tag_name ||
			'STYLE' === $tag_name ||
			'SUMMARY' === $tag_name ||
			'TABLE' === $tag_name ||
			'TBODY' === $tag_name ||
			'TD' === $tag_name ||
			'TEMPLATE' === $tag_name ||
			'TEXTAREA' === $tag_name ||
			'TFOOT' === $tag_name ||
			'TH' === $tag_name ||
			'THEAD' === $tag_name ||
			'TITLE' === $tag_name ||
			'TR' === $tag_name ||
			'TRACK' === $tag_name ||
			'UL' === $tag_name ||
			'WBR' === $tag_name ||
			'XMP' === $tag_name ||

			// MathML.
			'MI' === $tag_name ||
			'MO' === $tag_name ||
			'MN' === $tag_name ||
			'MS' === $tag_name ||
			'MTEXT' === $tag_name ||
			'ANNOTATION-XML' === $tag_name ||

			// SVG.
			'FOREIGNOBJECT' === $tag_name ||
			'DESC' === $tag_name ||
			'TITLE' === $tag_name
		);
	}

	/**
	 * Returns whether a given element is an HTML Void Element
	 *
	 * > area, base, br, col, embed, hr, img, input, link, meta, source, track, wbr
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#void-elements
	 *
	 * @param string $tag_name Name of HTML tag to check.
	 * @return bool Whether the given tag is an HTML Void Element.
	 */
	public static function is_void( $tag_name ) {
		$tag_name = strtoupper( $tag_name );

		return (
			'AREA' === $tag_name ||
			'BASE' === $tag_name ||
			'BR' === $tag_name ||
			'COL' === $tag_name ||
			'EMBED' === $tag_name ||
			'HR' === $tag_name ||
			'IMG' === $tag_name ||
			'INPUT' === $tag_name ||
			'LINK' === $tag_name ||
			'META' === $tag_name ||
			'SOURCE' === $tag_name ||
			'TRACK' === $tag_name ||
			'WBR' === $tag_name
		);
	}

	/*
	 * Constants that would pollute the top of the class if they were found there.
	 */

	/**
	 * Indicates that the next HTML token should be parsed and processed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const PROCESS_NEXT_NODE = 'process-next-node';

	/**
	 * Indicates that the current HTML token should be reprocessed in the newly-selected insertion mode.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const REPROCESS_CURRENT_NODE = 'reprocess-current-node';

	/**
	 * Indicates that the parser encountered unsupported markup and has bailed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const ERROR_UNSUPPORTED = 'unsupported';

	/**
	 * Indicates that the parser encountered more HTML tokens than it
	 * was able to process and has bailed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const ERROR_EXCEEDED_MAX_BOOKMARKS = 'exceeded-max-bookmarks';

	/**
	 * Unlock code that must be passed into the constructor to create this class.
	 *
	 * This class extends the WP_HTML_Tag_Processor, which has a public class
	 * constructor. Therefore, it's not possible to have a private constructor here.
	 *
	 * This unlock code is used to ensure that anyone calling the constructor is
	 * doing so with a full understanding that it's intended to be a private API.
	 *
	 * @access private
	 */
	const CONSTRUCTOR_UNLOCK_CODE = 'Use WP_HTML_Processor::create_fragment() instead of calling the class constructor directly.';
}