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 ( false !== strpos( $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'.
	 *
	 * @since 4.4.0
	 *
	 * @param array|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 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 ( (array) $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, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
	 *
	 * @param string  $join           The JOIN clause in the SQL.
	 * @param bool    $in_same_term   Whether post should be in a same taxonomy term.
	 * @param array   $excluded_terms Array of excluded term IDs.
	 * @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, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
	 *
	 * @param string  $where          The `WHERE` clause in the SQL.
	 * @param bool    $in_same_term   Whether post should be in a same taxonomy term.
	 * @param array   $excluded_terms Array of excluded term IDs.
	 * @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, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * @since 2.5.0
	 * @since 4.4.0 Added the `$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";
	$query_key = 'adjacent_post_' . md5( $query );
	$result    = wp_cache_get( $query_key, 'counts' );
	if ( false !== $result ) {
		if ( $result ) {
			$result = get_post( $result );
		}
		return $result;
	}

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

	wp_cache_set( $query_key, $result, 'counts' );

	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 a 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'.
	 *
	 * @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 a 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 a 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 a 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 a 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 null|array 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 a 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 a 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 a 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 a 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 a 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, `$adjacent`, refers to the type
	 * of adjacency, 'next' or 'previous'.
	 *
	 * @since 2.6.0
	 * @since 4.2.0 Added the `$adjacent` parameter.
	 *
	 * @param string  $output   The adjacent post link.
	 * @param string  $format   Link anchor format.
	 * @param string  $link     Link permalink format.
	 * @param WP_Post $post     The adjacent post.
	 * @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 a 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(). Defaults to true.
 *                      Otherwise, prepares the URL with esc_url_raw().
 * @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 );

		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, '/' );

		$base = trailingslashit( get_bloginfo( 'url' ) );

		if ( $wp_rewrite->using_index_permalinks() && ( $pagenum > 1 || '' !== $request ) ) {
			$base .= $wp_rewrite->index . '/';
		}

		if ( $pagenum > 1 ) {
			$request = ( ( ! empty( $request ) ) ? trailingslashit( $request ) : $request ) . user_trailingslashit( $wp_rewrite->pagination_base . '/' . $pagenum, 'paged' );
		}

		$result = $base . $request . $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 esc_url_raw( $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;
		}
		$nextpage = (int) $paged + 1;
		if ( ! $max_page || $max_page >= $nextpage ) {
			return get_pagenum_link( $nextpage );
		}
	}
}

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

	if ( $echo ) {
		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;
	}

	$nextpage = (int) $paged + 1;

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

	if ( ! is_single() && ( $nextpage <= $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 '<a href="' . next_posts( $max_page, false ) . "\" $attr>" . preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label ) . '</a>';
	}
}

/**
 * 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() ) {
		$nextpage = (int) $paged - 1;
		if ( $nextpage < 1 ) {
			$nextpage = 1;
		}
		return get_pagenum_link( $nextpage );
	}
}

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

	if ( $echo ) {
		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 '<a href="' . previous_posts( false ) . "\" $attr>" . preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label ) . '</a>';
	}
}

/**
 * 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 a 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() ) {
	$navigation = '';

	// Don't print empty markup if there's only one page.
	if ( $GLOBALS['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.
 *
 * @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() ) {
	$navigation = '';

	// Don't print empty markup if there's only one page.
	if ( $GLOBALS['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',
			)
		);

		// 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 $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, $class = 'posts-navigation', $screen_reader_text = '', $aria_label = '' ) {
	if ( empty( $screen_reader_text ) ) {
		$screen_reader_text = __( 'Posts navigation' );
	}
	if ( empty( $aria_label ) ) {
		$aria_label = $screen_reader_text;
	}

	$template = '
	<nav class="navigation %1$s" role="navigation" 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$s" role="navigation" aria-label="%4$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 $class    The class passed by the calling function.
	 * @return string Navigation template.
	 */
	$template = apply_filters( 'navigation_markup_template', $template, $class );

	return sprintf( $template, sanitize_html_class( $class ), esc_html( $screen_reader_text ), $links, esc_html( $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;
	}

	$nextpage = (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 ( $nextpage > $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.
	 */
	return '<a href="' . esc_url( get_comments_pagenum_link( $nextpage, $max_page ) ) . '" ' . apply_filters( 'next_comments_link_attributes', '' ) . '>' . preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label ) . '</a>';
}

/**
 * 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;
	}

	$prevpage = (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.
	 */
	return '<a href="' . esc_url( get_comments_pagenum_link( $prevpage ) ) . '" ' . apply_filters( 'previous_comments_link_attributes', '' ) . '>' . preg_replace( '/&([^#])(?![a-z]{1,8};)/i', '&#038;$1', $label ) . '</a>';
}

/**
 * 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 'admin'.
 * @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
	 *
	 * @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.
	 */
	return apply_filters( 'admin_url', $url, $path, $blog_id );
}

/**
 * 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
	 *
	 * @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.
	 */
	return apply_filters( 'includes_url', $url, $path );
}

/**
 * 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 ) && 0 === strpos( $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
	 *
	 * @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.
	 */
	return apply_filters( 'network_admin_url', $url, $path );
}

/**
 * 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
	 *
	 * @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.
	 */
	return apply_filters( 'user_admin_url', $url, $path );
}

/**
 * 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 ( substr( $url, 0, 2 ) === '//' ) {
		$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, or 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 truthy value from the filter will effectively 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 Gravatar 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 return 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' (8bit), 'monsterid' (monster),
 *                                  'wavatar' (cartoon face), 'indenticon' (the "quilt"), 'mystery', 'mm',
 *                                  or 'mysteryman' (The Oyster Man), 'blank' (transparent GIF), or
 *                                  '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', 'PG', 'R', 'X', and are
 *                                  judged in that order. 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 Gravatar 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 return instead of the default arguments.
 *
 *     @type int    $size           Height and width of the avatar image file 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' (8bit), 'monsterid' (monster),
 *                                  'wavatar' (cartoon face), 'indenticon' (the "quilt"), 'mystery', 'mm',
 *                                  or 'mysteryman' (The Oyster Man), 'blank' (transparent GIF), or
 *                                  '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', 'PG', 'R', 'X', and are
 *                                  judged in that order. 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 we were able to find an avatar for this user,
 *                                false or not set if we couldn't.
 *     @type string $url          The URL of the avatar we found.
 * }
 */
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 Gravatar 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 ( strpos( $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 Gravatar 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 Gravatar 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, '/' );

	if ( empty( $file ) ) {
		$url = get_stylesheet_directory_uri();
	} elseif ( file_exists( get_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, '/' );

	if ( empty( $file ) ) {
		$path = get_stylesheet_directory();
	} elseif ( file_exists( get_stylesheet_directory() . '/' . $file ) ) {
		$path = get_stylesheet_directory() . '/' . $file;
	} else {
		$path = get_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
 *
 * @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">%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 '';
}