t null.
 *     @type string       $post_type    Post type to query for. Default 'page'.
 *     @type string|array $post_status  Comma-separated list or array of post statuses to include. Default 'publish'.
 *     @type string       $show_date    Whether to display the page publish or modified date for each page. Accepts
 *                                      'modified' or any other value. An empty value hides the date. Default empty.
 *     @type string       $sort_column  Comma-separated list of column names to sort the pages by. Accepts 'post_author',
 *                                      'post_date', 'post_title', 'post_name', 'post_modified', 'post_modified_gmt',
 *                                      'menu_order', 'post_parent', 'ID', 'rand', or 'comment_count'. Default 'post_title'.
 *     @type string       $title_li     List heading. Passing a null or empty value will result in no heading, and the list
 *                                      will not be wrapped with unordered list `<ul>` tags. Default 'Pages'.
 *     @type string       $item_spacing Whether to preserve whitespace within the menu's HTML. Accepts 'preserve' or 'discard'.
 *                                      Default 'preserve'.
 *     @type Walker       $walker       Walker instance to use for listing pages. Default empty which results in a
 *                                      Walker_Page instance being used.
 * }
 * @return void|string Void if 'echo' argument is true, HTML list of pages if 'echo' is false.
 */
function wp_list_pages( $args = '' ) {
	$defaults = array(
		'depth'        => 0,
		'show_date'    => '',
		'date_format'  => get_option( 'date_format' ),
		'child_of'     => 0,
		'exclude'      => '',
		'title_li'     => __( 'Pages' ),
		'echo'         => 1,
		'authors'      => '',
		'sort_column'  => 'menu_order, post_title',
		'link_before'  => '',
		'link_after'   => '',
		'item_spacing' => 'preserve',
		'walker'       => '',
	);

	$parsed_args = wp_parse_args( $args, $defaults );

	if ( ! in_array( $parsed_args['item_spacing'], array( 'preserve', 'discard' ), true ) ) {
		// Invalid value, fall back to default.
		$parsed_args['item_spacing'] = $defaults['item_spacing'];
	}

	$output       = '';
	$current_page = 0;

	// Sanitize, mostly to keep spaces out.
	$parsed_args['exclude'] = preg_replace( '/[^0-9,]/', '', $parsed_args['exclude'] );

	// Allow plugins to filter an array of excluded pages (but don't put a nullstring into the array).
	$exclude_array = ( $parsed_args['exclude'] ) ? explode( ',', $parsed_args['exclude'] ) : array();

	/**
	 * Filters the array of pages to exclude from the pages list.
	 *
	 * @since 2.1.0
	 *
	 * @param string[] $exclude_array An array of page IDs to exclude.
	 */
	$parsed_args['exclude'] = implode( ',', apply_filters( 'wp_list_pages_excludes', $exclude_array ) );

	$parsed_args['hierarchical'] = 0;

	// Query pages.
	$pages = get_pages( $parsed_args );

	if ( ! empty( $pages ) ) {
		if ( $parsed_args['title_li'] ) {
			$output .= '<li class="pagenav">' . $parsed_args['title_li'] . '<ul>';
		}
		global $wp_query;
		if ( is_page() || is_attachment() || $wp_query->is_posts_page ) {
			$current_page = get_queried_object_id();
		} elseif ( is_singular() ) {
			$queried_object = get_queried_object();
			if ( is_post_type_hierarchical( $queried_object->post_type ) ) {
				$current_page = $queried_object->ID;
			}
		}

		$output .= walk_page_tree( $pages, $parsed_args['depth'], $current_page, $parsed_args );

		if ( $parsed_args['title_li'] ) {
			$output .= '</ul></li>';
		}
	}

	/**
	 * Filters the HTML output of the pages to list.
	 *
	 * @since 1.5.1
	 * @since 4.4.0 `$pages` added as arguments.
	 *
	 * @see wp_list_pages()
	 *
	 * @param string    $output      HTML output of the pages list.
	 * @param array     $parsed_args An array of page-listing arguments. See wp_list_pages()
	 *                               for information on accepted arguments.
	 * @param WP_Post[] $pages       Array of the page objects.
	 */
	$html = apply_filters( 'wp_list_pages', $output, $parsed_args, $pages );

	if ( $parsed_args['echo'] ) {
		echo $html;
	} else {
		return $html;
	}
}

/**
 * Displays or retrieves a list of pages with an optional home link.
 *
 * The arguments are listed below and part of the arguments are for wp_list_pages() function.
 * Check that function for more info on those arguments.
 *
 * @since 2.7.0
 * @since 4.4.0 Added `menu_id`, `container`, `before`, `after`, and `walker` arguments.
 * @since 4.7.0 Added the `item_spacing` argument.
 *
 * @param array|string $args {
 *     Optional. Array or string of arguments to generate a page menu. See wp_list_pages() for additional arguments.
 *
 *     @type string          $sort_column  How to sort the list of pages. Accepts post column names.
 *                                         Default 'menu_order, post_title'.
 *     @type string          $menu_id      ID for the div containing the page list. Default is empty string.
 *     @type string          $menu_class   Class to use for the element containing the page list. Default 'menu'.
 *     @type string          $container    Element to use for the element containing the page list. Default 'div'.
 *     @type bool            $echo         Whether to echo the list or return it. Accepts true (echo) or false (return).
 *                                         Default true.
 *     @type int|bool|string $show_home    Whether to display the link to the home page. Can just enter the text
 *                                         you'd like shown for the home link. 1|true defaults to 'Home'.
 *     @type string          $link_before  The HTML or text to prepend to $show_home text. Default empty.
 *     @type string          $link_after   The HTML or text to append to $show_home text. Default empty.
 *     @type string          $before       The HTML or text to prepend to the menu. Default is '<ul>'.
 *     @type string          $after        The HTML or text to append to the menu. Default is '</ul>'.
 *     @type string          $item_spacing Whether to preserve whitespace within the menu's HTML. Accepts 'preserve'
 *                                         or 'discard'. Default 'discard'.
 *     @type Walker          $walker       Walker instance to use for listing pages. Default empty which results in a
 *                                         Walker_Page instance being used.
 * }
 * @return void|string Void if 'echo' argument is true, HTML menu if 'echo' is false.
 */
function wp_page_menu( $args = array() ) {
	$defaults = array(
		'sort_column'  => 'menu_order, post_title',
		'menu_id'      => '',
		'menu_class'   => 'menu',
		'container'    => 'div',
		'echo'         => true,
		'link_before'  => '',
		'link_after'   => '',
		'before'       => '<ul>',
		'after'        => '</ul>',
		'item_spacing' => 'discard',
		'walker'       => '',
	);
	$args     = wp_parse_args( $args, $defaults );

	if ( ! in_array( $args['item_spacing'], array( 'preserve', 'discard' ), true ) ) {
		// Invalid value, fall back to default.
		$args['item_spacing'] = $defaults['item_spacing'];
	}

	if ( 'preserve' === $args['item_spacing'] ) {
		$t = "\t";
		$n = "\n";
	} else {
		$t = '';
		$n = '';
	}

	/**
	 * Filters the arguments used to generate a page-based menu.
	 *
	 * @since 2.7.0
	 *
	 * @see wp_page_menu()
	 *
	 * @param array $args An array of page menu arguments. See wp_page_menu()
	 *                    for information on accepted arguments.
	 */
	$args = apply_filters( 'wp_page_menu_args', $args );

	$menu = '';

	$list_args = $args;

	// Show Home in the menu.
	if ( ! empty( $args['show_home'] ) ) {
		if ( true === $args['show_home'] || '1' === $args['show_home'] || 1 === $args['show_home'] ) {
			$text = __( 'Home' );
		} else {
			$text = $args['show_home'];
		}
		$class = '';
		if ( is_front_page() && ! is_paged() ) {
			$class = 'class="current_page_item"';
		}
		$menu .= '<li ' . $class . '><a href="' . esc_url( home_url( '/' ) ) . '">' . $args['link_before'] . $text . $args['link_after'] . '</a></li>';
		// If the front page is a page, add it to the exclude list.
		if ( 'page' === get_option( 'show_on_front' ) ) {
			if ( ! empty( $list_args['exclude'] ) ) {
				$list_args['exclude'] .= ',';
			} else {
				$list_args['exclude'] = '';
			}
			$list_args['exclude'] .= get_option( 'page_on_front' );
		}
	}

	$list_args['echo']     = false;
	$list_args['title_li'] = '';
	$menu                 .= wp_list_pages( $list_args );

	$container = sanitize_text_field( $args['container'] );

	// Fallback in case `wp_nav_menu()` was called without a container.
	if ( empty( $container ) ) {
		$container = 'div';
	}

	if ( $menu ) {

		// wp_nav_menu() doesn't set before and after.
		if ( isset( $args['fallback_cb'] ) &&
			'wp_page_menu' === $args['fallback_cb'] &&
			'ul' !== $container ) {
			$args['before'] = "<ul>{$n}";
			$args['after']  = '</ul>';
		}

		$menu = $args['before'] . $menu . $args['after'];
	}

	$attrs = '';
	if ( ! empty( $args['menu_id'] ) ) {
		$attrs .= ' id="' . esc_attr( $args['menu_id'] ) . '"';
	}

	if ( ! empty( $args['menu_class'] ) ) {
		$attrs .= ' class="' . esc_attr( $args['menu_class'] ) . '"';
	}

	$menu = "<{$container}{$attrs}>" . $menu . "</{$container}>{$n}";

	/**
	 * Filters the HTML output of a page-based menu.
	 *
	 * @since 2.7.0
	 *
	 * @see wp_page_menu()
	 *
	 * @param string $menu The HTML output.
	 * @param array  $args An array of arguments. See wp_page_menu()
	 *                     for information on accepted arguments.
	 */
	$menu = apply_filters( 'wp_page_menu', $menu, $args );

	if ( $args['echo'] ) {
		echo $menu;
	} else {
		return $menu;
	}
}

//
// Page helpers.
//

/**
 * Retrieves HTML list content for page list.
 *
 * @uses Walker_Page to create HTML list content.
 * @since 2.1.0
 *
 * @param array $pages
 * @param int   $depth
 * @param int   $current_page
 * @param array $args
 * @return string
 */
function walk_page_tree( $pages, $depth, $current_page, $args ) {
	if ( empty( $args['walker'] ) ) {
		$walker = new Walker_Page();
	} else {
		/**
		 * @var Walker $walker
		 */
		$walker = $args['walker'];
	}

	foreach ( (array) $pages as $page ) {
		if ( $page->post_parent ) {
			$args['pages_with_children'][ $page->post_parent ] = true;
		}
	}

	return $walker->walk( $pages, $depth, $args, $current_page );
}

/**
 * Retrieves HTML dropdown (select) content for page list.
 *
 * @since 2.1.0
 * @since 5.3.0 Formalized the existing `...$args` parameter by adding it
 *              to the function signature.
 *
 * @uses Walker_PageDropdown to create HTML dropdown content.
 * @see Walker_PageDropdown::walk() for parameters and return description.
 *
 * @param mixed ...$args Elements array, maximum hierarchical depth and optional additional arguments.
 * @return string
 */
function walk_page_dropdown_tree( ...$args ) {
	if ( empty( $args[2]['walker'] ) ) { // The user's options are the third parameter.
		$walker = new Walker_PageDropdown();
	} else {
		/**
		 * @var Walker $walker
		 */
		$walker = $args[2]['walker'];
	}

	return $walker->walk( ...$args );
}

//
// Attachments.
//

/**
 * Displays an attachment page link using an image or icon.
 *
 * @since 2.0.0
 *
 * @param int|WP_Post $post       Optional. Post ID or post object.
 * @param bool        $fullsize   Optional. Whether to use full size. Default false.
 * @param bool        $deprecated Deprecated. Not used.
 * @param bool        $permalink Optional. Whether to include permalink. Default false.
 */
function the_attachment_link( $post = 0, $fullsize = false, $deprecated = false, $permalink = false ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.5.0' );
	}

	if ( $fullsize ) {
		echo wp_get_attachment_link( $post, 'full', $permalink );
	} else {
		echo wp_get_attachment_link( $post, 'thumbnail', $permalink );
	}
}

/**
 * Retrieves an attachment page link using an image or icon, if possible.
 *
 * @since 2.5.0
 * @since 4.4.0 The `$post` parameter can now accept either a post ID or `WP_Post` object.
 *
 * @param int|WP_Post  $post      Optional. Post ID or post object.
 * @param string|int[] $size      Optional. Image size. Accepts any registered image size name, or an array
 *                                of width and height values in pixels (in that order). Default 'thumbnail'.
 * @param bool         $permalink Optional. Whether to add permalink to image. Default false.
 * @param bool         $icon      Optional. Whether the attachment is an icon. Default false.
 * @param string|false $text      Optional. Link text to use. Activated by passing a string, false otherwise.
 *                                Default false.
 * @param array|string $attr      Optional. Array or string of attributes. Default empty.
 * @return string HTML content.
 */
function wp_get_attachment_link( $post = 0, $size = 'thumbnail', $permalink = false, $icon = false, $text = false, $attr = '' ) {
	$_post = get_post( $post );

	if ( empty( $_post ) || ( 'attachment' !== $_post->post_type ) || ! wp_get_attachment_url( $_post->ID ) ) {
		return __( 'Missing Attachment' );
	}

	$url = wp_get_attachment_url( $_post->ID );

	if ( $permalink ) {
		$url = get_attachment_link( $_post->ID );
	}

	if ( $text ) {
		$link_text = $text;
	} elseif ( $size && 'none' !== $size ) {
		$link_text = wp_get_attachment_image( $_post->ID, $size, $icon, $attr );
	} else {
		$link_text = '';
	}

	if ( '' === trim( $link_text ) ) {
		$link_text = $_post->post_title;
	}

	if ( '' === trim( $link_text ) ) {
		$link_text = esc_html( pathinfo( get_attached_file( $_post->ID ), PATHINFO_FILENAME ) );
	}

	/**
	 * Filters the list of attachment link attributes.
	 *
	 * @since 6.2.0
	 *
	 * @param array $attributes An array of attributes for the link markup,
	 *                          keyed on the attribute name.
	 * @param int   $id         Post ID.
	 */
	$attributes = apply_filters( 'wp_get_attachment_link_attributes', array( 'href' => $url ), $_post->ID );

	$link_attributes = '';
	foreach ( $attributes as $name => $value ) {
		$value            = 'href' === $name ? esc_url( $value ) : esc_attr( $value );
		$link_attributes .= ' ' . esc_attr( $name ) . "='" . $value . "'";
	}

	$link_html = "<a$link_attributes>$link_text</a>";

	/**
	 * Filters a retrieved attachment page link.
	 *
	 * @since 2.7.0
	 * @since 5.1.0 Added the `$attr` parameter.
	 *
	 * @param string       $link_html The page link HTML output.
	 * @param int|WP_Post  $post      Post ID or object. Can be 0 for the current global post.
	 * @param string|int[] $size      Requested image size. Can be any registered image size name, or
	 *                                an array of width and height values in pixels (in that order).
	 * @param bool         $permalink Whether to add permalink to image. Default false.
	 * @param bool         $icon      Whether to include an icon.
	 * @param string|false $text      If string, will be link text.
	 * @param array|string $attr      Array or string of attributes.
	 */
	return apply_filters( 'wp_get_attachment_link', $link_html, $post, $size, $permalink, $icon, $text, $attr );
}

/**
 * Wraps attachment in paragraph tag before content.
 *
 * @since 2.0.0
 *
 * @param string $content
 * @return string
 */
function prepend_attachment( $content ) {
	$post = get_post();

	if ( empty( $post->post_type ) || 'attachment' !== $post->post_type ) {
		return $content;
	}

	if ( wp_attachment_is( 'video', $post ) ) {
		$meta = wp_get_attachment_metadata( get_the_ID() );
		$atts = array( 'src' => wp_get_attachment_url() );
		if ( ! empty( $meta['width'] ) && ! empty( $meta['height'] ) ) {
			$atts['width']  = (int) $meta['width'];
			$atts['height'] = (int) $meta['height'];
		}
		if ( has_post_thumbnail() ) {
			$atts['poster'] = wp_get_attachment_url( get_post_thumbnail_id() );
		}
		$p = wp_video_shortcode( $atts );
	} elseif ( wp_attachment_is( 'audio', $post ) ) {
		$p = wp_audio_shortcode( array( 'src' => wp_get_attachment_url() ) );
	} else {
		$p = '<p class="attachment">';
		// Show the medium sized image representation of the attachment if available, and link to the raw file.
		$p .= wp_get_attachment_link( 0, 'medium', false );
		$p .= '</p>';
	}

	/**
	 * Filters the attachment markup to be prepended to the post content.
	 *
	 * @since 2.0.0
	 *
	 * @see prepend_attachment()
	 *
	 * @param string $p The attachment HTML output.
	 */
	$p = apply_filters( 'prepend_attachment', $p );

	return "$p\n$content";
}

//
// Misc.
//

/**
 * Retrieves protected post password form content.
 *
 * @since 1.0.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
 * @return string HTML content for password form for password protected post.
 */
function get_the_password_form( $post = 0 ) {
	$post   = get_post( $post );
	$label  = 'pwbox-' . ( empty( $post->ID ) ? rand() : $post->ID );
	$output = '<form action="' . esc_url( site_url( 'wp-login.php?action=postpass', 'login_post' ) ) . '" class="post-password-form" method="post">
	<p>' . __( 'This content is password protected. To view it please enter your password below:' ) . '</p>
	<p><label for="' . $label . '">' . __( 'Password:' ) . ' <input name="post_password" id="' . $label . '" type="password" spellcheck="false" size="20" /></label> <input type="submit" name="Submit" value="' . esc_attr_x( 'Enter', 'post password form' ) . '" /></p></form>
	';

	/**
	 * Filters the HTML output for the protected post password form.
	 *
	 * If modifying the password field, please note that the core database schema
	 * limits the password field to 20 characters regardless of the value of the
	 * size attribute in the form input.
	 *
	 * @since 2.7.0
	 * @since 5.8.0 Added the `$post` parameter.
	 *
	 * @param string  $output The password form HTML output.
	 * @param WP_Post $post   Post object.
	 */
	return apply_filters( 'the_password_form', $output, $post );
}

/**
 * Determines whether the current post uses a page template.
 *
 * This template tag allows you to determine if you are in a page template.
 * You can optionally provide a template filename or array of template filenames
 * and then the check will be specific to that template.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.5.0
 * @since 4.2.0 The `$template` parameter was changed to also accept an array of page templates.
 * @since 4.7.0 Now works with any post type, not just pages.
 *
 * @param string|string[] $template The specific template filename or array of templates to match.
 * @return bool True on success, false on failure.
 */
function is_page_template( $template = '' ) {
	if ( ! is_singular() ) {
		return false;
	}

	$page_template = get_page_template_slug( get_queried_object_id() );

	if ( empty( $template ) ) {
		return (bool) $page_template;
	}

	if ( $template == $page_template ) {
		return true;
	}

	if ( is_array( $template ) ) {
		if ( ( in_array( 'default', $template, true ) && ! $page_template )
			|| in_array( $page_template, $template, true )
		) {
			return true;
		}
	}

	return ( 'default' === $template && ! $page_template );
}

/**
 * Gets the specific template filename for a given post.
 *
 * @since 3.4.0
 * @since 4.7.0 Now works with any post type, not just pages.
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
 * @return string|false Page template filename. Returns an empty string when the default page template
 *                      is in use. Returns false if the post does not exist.
 */
function get_page_template_slug( $post = null ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return false;
	}

	$template = get_post_meta( $post->ID, '_wp_page_template', true );

	if ( ! $template || 'default' === $template ) {
		return '';
	}

	return $template;
}

/**
 * Retrieves formatted date timestamp of a revision (linked to that revisions's page).
 *
 * @since 2.6.0
 *
 * @param int|object $revision Revision ID or revision object.
 * @param bool       $link     Optional. Whether to link to revision's page. Default true.
 * @return string|false i18n formatted datetimestamp or localized 'Current Revision'.
 */
function wp_post_revision_title( $revision, $link = true ) {
	$revision = get_post( $revision );

	if ( ! $revision ) {
		return $revision;
	}

	if ( ! in_array( $revision->post_type, array( 'post', 'page', 'revision' ), true ) ) {
		return false;
	}

	/* translators: Revision date format, see https://www.php.net/manual/datetime.format.php */
	$datef = _x( 'F j, Y @ H:i:s', 'revision date format' );
	/* translators: %s: Revision date. */
	$autosavef = __( '%s [Autosave]' );
	/* translators: %s: Revision date. */
	$currentf = __( '%s [Current Revision]' );

	$date      = date_i18n( $datef, strtotime( $revision->post_modified ) );
	$edit_link = get_edit_post_link( $revision->ID );
	if ( $link && current_user_can( 'edit_post', $revision->ID ) && $edit_link ) {
		$date = "<a href='$edit_link'>$date</a>";
	}

	if ( ! wp_is_post_revision( $revision ) ) {
		$date = sprintf( $currentf, $date );
	} elseif ( wp_is_post_autosave( $revision ) ) {
		$date = sprintf( $autosavef, $date );
	}

	return $date;
}

/**
 * Retrieves formatted date timestamp of a revision (linked to that revisions's page).
 *
 * @since 3.6.0
 *
 * @param int|object $revision Revision ID or revision object.
 * @param bool       $link     Optional. Whether to link to revision's page. Default true.
 * @return string|false gravatar, user, i18n formatted datetimestamp or localized 'Current Revision'.
 */
function wp_post_revision_title_expanded( $revision, $link = true ) {
	$revision = get_post( $revision );

	if ( ! $revision ) {
		return $revision;
	}

	if ( ! in_array( $revision->post_type, array( 'post', 'page', 'revision' ), true ) ) {
		return false;
	}

	$author = get_the_author_meta( 'display_name', $revision->post_author );
	/* translators: Revision date format, see https://www.php.net/manual/datetime.format.php */
	$datef = _x( 'F j, Y @ H:i:s', 'revision date format' );

	$gravatar = get_avatar( $revision->post_author, 24 );

	$date      = date_i18n( $datef, strtotime( $revision->post_modified ) );
	$edit_link = get_edit_post_link( $revision->ID );
	if ( $link && current_user_can( 'edit_post', $revision->ID ) && $edit_link ) {
		$date = "<a href='$edit_link'>$date</a>";
	}

	$revision_date_author = sprintf(
		/* translators: Post revision title. 1: Author avatar, 2: Author name, 3: Time ago, 4: Date. */
		__( '%1$s %2$s, %3$s ago (%4$s)' ),
		$gravatar,
		$author,
		human_time_diff( strtotime( $revision->post_modified_gmt ) ),
		$date
	);

	/* translators: %s: Revision date with author avatar. */
	$autosavef = __( '%s [Autosave]' );
	/* translators: %s: Revision date with author avatar. */
	$currentf = __( '%s [Current Revision]' );

	if ( ! wp_is_post_revision( $revision ) ) {
		$revision_date_author = sprintf( $currentf, $revision_date_author );
	} elseif ( wp_is_post_autosave( $revision ) ) {
		$revision_date_author = sprintf( $autosavef, $revision_date_author );
	}

	/**
	 * Filters the formatted author and date for a revision.
	 *
	 * @since 4.4.0
	 *
	 * @param string  $revision_date_author The formatted string.
	 * @param WP_Post $revision             The revision object.
	 * @param bool    $link                 Whether to link to the revisions page, as passed into
	 *                                      wp_post_revision_title_expanded().
	 */
	return apply_filters( 'wp_post_revision_title_expanded', $revision_date_author, $revision, $link );
}

/**
 * Displays a list of a post's revisions.
 *
 * Can output either a UL with edit links or a TABLE with diff interface, and
 * restore action links.
 *
 * @since 2.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
 * @param string      $type 'all' (default), 'revision' or 'autosave'
 */
function wp_list_post_revisions( $post = 0, $type = 'all' ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return;
	}

	// $args array with (parent, format, right, left, type) deprecated since 3.6.
	if ( is_array( $type ) ) {
		$type = ! empty( $type['type'] ) ? $type['type'] : $type;
		_deprecated_argument( __FUNCTION__, '3.6.0' );
	}

	$revisions = wp_get_post_revisions( $post->ID );

	if ( ! $revisions ) {
		return;
	}

	$rows = '';
	foreach ( $revisions as $revision ) {
		if ( ! current_user_can( 'read_post', $revision->ID ) ) {
			continue;
		}

		$is_autosave = wp_is_post_autosave( $revision );
		if ( ( 'revision' === $type && $is_autosave ) || ( 'autosave' === $type && ! $is_autosave ) ) {
			continue;
		}

		$rows .= "\t<li>" . wp_post_revision_title_expanded( $revision ) . "</li>\n";
	}

	echo "<div class='hide-if-js'><p>" . __( 'JavaScript must be enabled to use this feature.' ) . "</p></div>\n";

	echo "<ul class='post-revisions hide-if-no-js'>\n";
	echo $rows;
	echo '</ul>';
}

/**
 * Retrieves the parent post object for the given post.
 *
 * @since 5.7.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global $post.
 * @return WP_Post|null Parent post object, or null if there isn't one.
 */
function get_post_parent( $post = null ) {
	$wp_post = get_post( $post );
	return ! empty( $wp_post->post_parent ) ? get_post( $wp_post->post_parent ) : null;
}

/**
 * Returns whether the given post has a parent post.
 *
 * @since 5.7.0
 *
 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global $post.
 * @return bool Whether the post has a parent post.
 */
function has_post_parent( $post = null ) {
	return (bool) get_post_parent( $post );
}
ts 'ids' for comment IDs
	 *                                                      only or empty for all fields. Default empty.
	 *     @type array           $include_unapproved        Array of IDs or email addresses of users whose unapproved
	 *                                                      comments will be returned by the query regardless of
	 *                                                      `$status`. Default empty.
	 *     @type int             $karma                     Karma score to retrieve matching comments for.
	 *                                                      Default empty.
	 *     @type string|string[] $meta_key                  Meta key or keys to filter by.
	 *     @type string|string[] $meta_value                Meta value or values to filter by.
	 *     @type string          $meta_compare              MySQL operator used for comparing the meta value.
	 *                                                      See WP_Meta_Query::__construct() for accepted values and default value.
	 *     @type string          $meta_compare_key          MySQL operator used for comparing the meta key.
	 *                                                      See WP_Meta_Query::__construct() for accepted values and default value.
	 *     @type string          $meta_type                 MySQL data type that the meta_value column will be CAST to for comparisons.
	 *                                                      See WP_Meta_Query::__construct() for accepted values and default value.
	 *     @type string          $meta_type_key             MySQL data type that the meta_key column will be CAST to for comparisons.
	 *                                                      See WP_Meta_Query::__construct() for accepted values and default value.
	 *     @type array           $meta_query                An associative array of WP_Meta_Query arguments.
	 *                                                      See WP_Meta_Query::__construct() for accepted values.
	 *     @type int             $number                    Maximum number of comments to retrieve.
	 *                                                      Default empty (no limit).
	 *     @type int             $paged                     When used with `$number`, defines the page of results to return.
	 *                                                      When used with `$offset`, `$offset` takes precedence. Default 1.
	 *     @type int             $offset                    Number of comments to offset the query. Used to build
	 *                                                      LIMIT clause. Default 0.
	 *     @type bool            $no_found_rows             Whether to disable the `SQL_CALC_FOUND_ROWS` query.
	 *                                                      Default: true.
	 *     @type string|array    $orderby                   Comment status or array of statuses. To use 'meta_value'
	 *                                                      or 'meta_value_num', `$meta_key` must also be defined.
	 *                                                      To sort by a specific `$meta_query` clause, use that
	 *                                                      clause's array key. Accepts:
	 *                                                      - 'comment_agent'
	 *                                                      - 'comment_approved'
	 *                                                      - 'comment_author'
	 *                                                      - 'comment_author_email'
	 *                                                      - 'comment_author_IP'
	 *                                                      - 'comment_author_url'
	 *                                                      - 'comment_content'
	 *                                                      - 'comment_date'
	 *                                                      - 'comment_date_gmt'
	 *                                                      - 'comment_ID'
	 *                                                      - 'comment_karma'
	 *                                                      - 'comment_parent'
	 *                                                      - 'comment_post_ID'
	 *                                                      - 'comment_type'
	 *                                                      - 'user_id'
	 *                                                      - 'comment__in'
	 *                                                      - 'meta_value'
	 *                                                      - 'meta_value_num'
	 *                                                      - The value of `$meta_key`
	 *                                                      - The array keys of `$meta_query`
	 *                                                      - false, an empty array, or 'none' to disable `ORDER BY` clause.
	 *                                                      Default: 'comment_date_gmt'.
	 *     @type string          $order                     How to order retrieved comments. Accepts 'ASC', 'DESC'.
	 *                                                      Default: 'DESC'.
	 *     @type int             $parent                    Parent ID of comment to retrieve children of.
	 *                                                      Default empty.
	 *     @type int[]           $parent__in                Array of parent IDs of comments to retrieve children for.
	 *                                                      Default empty.
	 *     @type int[]           $parent__not_in            Array of parent IDs of comments *not* to retrieve
	 *                                                      children for. Default empty.
	 *     @type int[]           $post_author__in           Array of author IDs to retrieve comments for.
	 *                                                      Default empty.
	 *     @type int[]           $post_author__not_in       Array of author IDs *not* to retrieve comments for.
	 *                                                      Default empty.
	 *     @type int             $post_id                   Limit results to those affiliated with a given post ID.
	 *                                                      Default 0.
	 *     @type int[]           $post__in                  Array of post IDs to include affiliated comments for.
	 *                                                      Default empty.
	 *     @type int[]           $post__not_in              Array of post IDs to exclude affiliated comments for.
	 *                                                      Default empty.
	 *     @type int             $post_author               Post author ID to limit results by. Default empty.
	 *     @type string|string[] $post_status               Post status or array of post statuses to retrieve
	 *                                                      affiliated comments for. Pass 'any' to match any value.
	 *                                                      Default empty.
	 *     @type string|string[] $post_type                 Post type or array of post types to retrieve affiliated
	 *                                                      comments for. Pass 'any' to match any value. Default empty.
	 *     @type string          $post_name                 Post name to retrieve affiliated comments for.
	 *                                                      Default empty.
	 *     @type int             $post_parent               Post parent ID to retrieve affiliated comments for.
	 *                                                      Default empty.
	 *     @type string          $search                    Search term(s) to retrieve matching comments for.
	 *                                                      Default empty.
	 *     @type string|array    $status                    Comment statuses to limit results by. Accepts an array
	 *                                                      or space/comma-separated list of 'hold' (`comment_status=0`),
	 *                                                      'approve' (`comment_status=1`), 'all', or a custom
	 *                                                      comment status. Default 'all'.
	 *     @type string|string[] $type                      Include comments of a given type, or array of types.
	 *                                                      Accepts 'comment', 'pings' (includes 'pingback' and
	 *                                                      'trackback'), or any custom type string. Default empty.
	 *     @type string[]        $type__in                  Include comments from a given array of comment types.
	 *                                                      Default empty.
	 *     @type string[]        $type__not_in              Exclude comments from a given array of comment types.
	 *                                                      Default empty.
	 *     @type int             $user_id                   Include comments for a specific user ID. Default empty.
	 *     @type bool|string     $hierarchical              Whether to include comment descendants in the results.
	 *                                                      - 'threaded' returns a tree, with each comment's children
	 *                                                        stored in a `children` property on the `WP_Comment` object.
	 *                                                      - 'flat' returns a flat array of found comments plus
	 *                                                        their children.
	 *                                                      - Boolean `false` leaves out descendants.
	 *                                                      The parameter is ignored (forced to `false`) when
	 *                                                      `$fields` is 'ids' or 'counts'. Accepts 'threaded',
	 *                                                      'flat', or false. Default: false.
	 *     @type string          $cache_domain              Unique cache key to be produced when this query is stored in
	 *                                                      an object cache. Default is 'core'.
	 *     @type bool            $update_comment_meta_cache Whether to prime the metadata cache for found comments.
	 *                                                      Default true.
	 *     @type bool            $update_comment_post_cache Whether to prime the cache for comment posts.
	 *                                                      Default false.
	 * }
	 */
	public function __construct( $query = '' ) {
		$this->query_var_defaults = array(
			'author_email'              => '',
			'author_url'                => '',
			'author__in'                => '',
			'author__not_in'            => '',
			'include_unapproved'        => '',
			'fields'                    => '',
			'ID'                        => '',
			'comment__in'               => '',
			'comment__not_in'           => '',
			'karma'                     => '',
			'number'                    => '',
			'offset'                    => '',
			'no_found_rows'             => true,
			'orderby'                   => '',
			'order'                     => 'DESC',
			'paged'                     => 1,
			'parent'                    => '',
			'parent__in'                => '',
			'parent__not_in'            => '',
			'post_author__in'           => '',
			'post_author__not_in'       => '',
			'post_ID'                   => '',
			'post_id'                   => 0,
			'post__in'                  => '',
			'post__not_in'              => '',
			'post_author'               => '',
			'post_name'                 => '',
			'post_parent'               => '',
			'post_status'               => '',
			'post_type'                 => '',
			'status'                    => 'all',
			'type'                      => '',
			'type__in'                  => '',
			'type__not_in'              => '',
			'user_id'                   => '',
			'search'                    => '',
			'count'                     => false,
			'meta_key'                  => '',
			'meta_value'                => '',
			'meta_query'                => '',
			'date_query'                => null, // See WP_Date_Query.
			'hierarchical'              => false,
			'cache_domain'              => 'core',
			'update_comment_meta_cache' => true,
			'update_comment_post_cache' => false,
		);

		if ( ! empty( $query ) ) {
			$this->query( $query );
		}
	}

	/**
	 * Parse arguments passed to the comment query with default query parameters.
	 *
	 * @since 4.2.0 Extracted from WP_Comment_Query::query().
	 *
	 * @param string|array $query WP_Comment_Query arguments. See WP_Comment_Query::__construct()
	 */
	public function parse_query( $query = '' ) {
		if ( empty( $query ) ) {
			$query = $this->query_vars;
		}

		$this->query_vars = wp_parse_args( $query, $this->query_var_defaults );

		/**
		 * Fires after the comment query vars have been parsed.
		 *
		 * @since 4.2.0
		 *
		 * @param WP_Comment_Query $query The WP_Comment_Query instance (passed by reference).
		 */
		do_action_ref_array( 'parse_comment_query', array( &$this ) );
	}

	/**
	 * Sets up the WordPress query for retrieving comments.
	 *
	 * @since 3.1.0
	 * @since 4.1.0 Introduced 'comment__in', 'comment__not_in', 'post_author__in',
	 *              'post_author__not_in', 'author__in', 'author__not_in', 'post__in',
	 *              'post__not_in', 'include_unapproved', 'type__in', and 'type__not_in'
	 *              arguments to $query_vars.
	 * @since 4.2.0 Moved parsing to WP_Comment_Query::parse_query().
	 *
	 * @param string|array $query Array or URL query string of parameters.
	 * @return array|int List of comments, or number of comments when 'count' is passed as a query var.
	 */
	public function query( $query ) {
		$this->query_vars = wp_parse_args( $query );
		return $this->get_comments();
	}

	/**
	 * Get a list of comments matching the query vars.
	 *
	 * @since 4.2.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @return int|int[]|WP_Comment[] List of comments or number of found comments if `$count` argument is true.
	 */
	public function get_comments() {
		global $wpdb;

		$this->parse_query();

		// Parse meta query.
		$this->meta_query = new WP_Meta_Query();
		$this->meta_query->parse_query_vars( $this->query_vars );

		/**
		 * Fires before comments are retrieved.
		 *
		 * @since 3.1.0
		 *
		 * @param WP_Comment_Query $query Current instance of WP_Comment_Query (passed by reference).
		 */
		do_action_ref_array( 'pre_get_comments', array( &$this ) );

		// Reparse query vars, in case they were modified in a 'pre_get_comments' callback.
		$this->meta_query->parse_query_vars( $this->query_vars );
		if ( ! empty( $this->meta_query->queries ) ) {
			$this->meta_query_clauses = $this->meta_query->get_sql( 'comment', $wpdb->comments, 'comment_ID', $this );
		}

		$comment_data = null;

		/**
		 * Filters the comments data before the query takes place.
		 *
		 * Return a non-null value to bypass WordPress' default comment queries.
		 *
		 * The expected return type from this filter depends on the value passed
		 * in the request query vars:
		 * - When `$this->query_vars['count']` is set, the filter should return
		 *   the comment count as an integer.
		 * - When `'ids' === $this->query_vars['fields']`, the filter should return
		 *   an array of comment IDs.
		 * - Otherwise the filter should return an array of WP_Comment objects.
		 *
		 * Note that if the filter returns an array of comment data, it will be assigned
		 * to the `comments` property of the current WP_Comment_Query instance.
		 *
		 * Filtering functions that require pagination information are encouraged to set
		 * the `found_comments` and `max_num_pages` properties of the WP_Comment_Query object,
		 * passed to the filter by reference. If WP_Comment_Query does not perform a database
		 * query, it will not have enough information to generate these values itself.
		 *
		 * @since 5.3.0
		 * @since 5.6.0 The returned array of comment data is assigned to the `comments` property
		 *              of the current WP_Comment_Query instance.
		 *
		 * @param array|int|null   $comment_data Return an array of comment data to short-circuit WP's comment query,
		 *                                       the comment count as an integer if `$this->query_vars['count']` is set,
		 *                                       or null to allow WP to run its normal queries.
		 * @param WP_Comment_Query $query        The WP_Comment_Query instance, passed by reference.
		 */
		$comment_data = apply_filters_ref_array( 'comments_pre_query', array( $comment_data, &$this ) );

		if ( null !== $comment_data ) {
			if ( is_array( $comment_data ) && ! $this->query_vars['count'] ) {
				$this->comments = $comment_data;
			}

			return $comment_data;
		}

		/*
		 * Only use the args defined in the query_var_defaults to compute the key,
		 * but ignore 'fields', 'update_comment_meta_cache', 'update_comment_post_cache' which does not affect query results.
		 */
		$_args = wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) );
		unset( $_args['fields'], $_args['update_comment_meta_cache'], $_args['update_comment_post_cache'] );

		$key          = md5( serialize( $_args ) );
		$last_changed = wp_cache_get_last_changed( 'comment' );

		$cache_key   = "get_comments:$key:$last_changed";
		$cache_value = wp_cache_get( $cache_key, 'comment-queries' );
		if ( false === $cache_value ) {
			$comment_ids = $this->get_comment_ids();
			if ( $comment_ids ) {
				$this->set_found_comments();
			}

			$cache_value = array(
				'comment_ids'    => $comment_ids,
				'found_comments' => $this->found_comments,
			);
			wp_cache_add( $cache_key, $cache_value, 'comment-queries' );
		} else {
			$comment_ids          = $cache_value['comment_ids'];
			$this->found_comments = $cache_value['found_comments'];
		}

		if ( $this->found_comments && $this->query_vars['number'] ) {
			$this->max_num_pages = ceil( $this->found_comments / $this->query_vars['number'] );
		}

		// If querying for a count only, there's nothing more to do.
		if ( $this->query_vars['count'] ) {
			// $comment_ids is actually a count in this case.
			return (int) $comment_ids;
		}

		$comment_ids = array_map( 'intval', $comment_ids );

		if ( $this->query_vars['update_comment_meta_cache'] ) {
			wp_lazyload_comment_meta( $comment_ids );
		}

		if ( 'ids' === $this->query_vars['fields'] ) {
			$this->comments = $comment_ids;
			return $this->comments;
		}

		_prime_comment_caches( $comment_ids, false );

		// Fetch full comment objects from the primed cache.
		$_comments = array();
		foreach ( $comment_ids as $comment_id ) {
			$_comment = get_comment( $comment_id );
			if ( $_comment ) {
				$_comments[] = $_comment;
			}
		}

		// Prime comment post caches.
		if ( $this->query_vars['update_comment_post_cache'] ) {
			$comment_post_ids = array();
			foreach ( $_comments as $_comment ) {
				$comment_post_ids[] = $_comment->comment_post_ID;
			}

			_prime_post_caches( $comment_post_ids, false, false );
		}

		/**
		 * Filters the comment query results.
		 *
		 * @since 3.1.0
		 *
		 * @param WP_Comment[]     $_comments An array of comments.
		 * @param WP_Comment_Query $query     Current instance of WP_Comment_Query (passed by reference).
		 */
		$_comments = apply_filters_ref_array( 'the_comments', array( $_comments, &$this ) );

		// Convert to WP_Comment instances.
		$comments = array_map( 'get_comment', $_comments );

		if ( $this->query_vars['hierarchical'] ) {
			$comments = $this->fill_descendants( $comments );
		}

		$this->comments = $comments;
		return $this->comments;
	}

	/**
	 * Used internally to get a list of comment IDs matching the query vars.
	 *
	 * @since 4.4.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @return int|array A single count of comment IDs if a count query. An array of comment IDs if a full query.
	 */
	protected function get_comment_ids() {
		global $wpdb;

		// Assemble clauses related to 'comment_approved'.
		$approved_clauses = array();

		// 'status' accepts an array or a comma-separated string.
		$status_clauses = array();
		$statuses       = wp_parse_list( $this->query_vars['status'] );

		// Empty 'status' should be interpreted as 'all'.
		if ( empty( $statuses ) ) {
			$statuses = array( 'all' );
		}

		// 'any' overrides other statuses.
		if ( ! in_array( 'any', $statuses, true ) ) {
			foreach ( $statuses as $status ) {
				switch ( $status ) {
					case 'hold':
						$status_clauses[] = "comment_approved = '0'";
						break;

					case 'approve':
						$status_clauses[] = "comment_approved = '1'";
						break;

					case 'all':
					case '':
						$status_clauses[] = "( comment_approved = '0' OR comment_approved = '1' )";
						break;

					default:
						$status_clauses[] = $wpdb->prepare( 'comment_approved = %s', $status );
						break;
				}
			}

			if ( ! empty( $status_clauses ) ) {
				$approved_clauses[] = '( ' . implode( ' OR ', $status_clauses ) . ' )';
			}
		}

		// User IDs or emails whose unapproved comments are included, regardless of $status.
		if ( ! empty( $this->query_vars['include_unapproved'] ) ) {
			$include_unapproved = wp_parse_list( $this->query_vars['include_unapproved'] );

			foreach ( $include_unapproved as $unapproved_identifier ) {
				// Numeric values are assumed to be user IDs.
				if ( is_numeric( $unapproved_identifier ) ) {
					$approved_clauses[] = $wpdb->prepare( "( user_id = %d AND comment_approved = '0' )", $unapproved_identifier );
				} else {
					// Otherwise we match against email addresses.
					if ( ! empty( $_GET['unapproved'] ) && ! empty( $_GET['moderation-hash'] ) ) {
						// Only include requested comment.
						$approved_clauses[] = $wpdb->prepare( "( comment_author_email = %s AND comment_approved = '0' AND {$wpdb->comments}.comment_ID = %d )", $unapproved_identifier, (int) $_GET['unapproved'] );
					} else {
						// Include all of the author's unapproved comments.
						$approved_clauses[] = $wpdb->prepare( "( comment_author_email = %s AND comment_approved = '0' )", $unapproved_identifier );
					}
				}
			}
		}

		// Collapse comment_approved clauses into a single OR-separated clause.
		if ( ! empty( $approved_clauses ) ) {
			if ( 1 === count( $approved_clauses ) ) {
				$this->sql_clauses['where']['approved'] = $approved_clauses[0];
			} else {
				$this->sql_clauses['where']['approved'] = '( ' . implode( ' OR ', $approved_clauses ) . ' )';
			}
		}

		$order = ( 'ASC' === strtoupper( $this->query_vars['order'] ) ) ? 'ASC' : 'DESC';

		// Disable ORDER BY with 'none', an empty array, or boolean false.
		if ( in_array( $this->query_vars['orderby'], array( 'none', array(), false ), true ) ) {
			$orderby = '';
		} elseif ( ! empty( $this->query_vars['orderby'] ) ) {
			$ordersby = is_array( $this->query_vars['orderby'] ) ?
				$this->query_vars['orderby'] :
				preg_split( '/[,\s]/', $this->query_vars['orderby'] );

			$orderby_array            = array();
			$found_orderby_comment_id = false;
			foreach ( $ordersby as $_key => $_value ) {
				if ( ! $_value ) {
					continue;
				}

				if ( is_int( $_key ) ) {
					$_orderby = $_value;
					$_order   = $order;
				} else {
					$_orderby = $_key;
					$_order   = $_value;
				}

				if ( ! $found_orderby_comment_id && in_array( $_orderby, array( 'comment_ID', 'comment__in' ), true ) ) {
					$found_orderby_comment_id = true;
				}

				$parsed = $this->parse_orderby( $_orderby );

				if ( ! $parsed ) {
					continue;
				}

				if ( 'comment__in' === $_orderby ) {
					$orderby_array[] = $parsed;
					continue;
				}

				$orderby_array[] = $parsed . ' ' . $this->parse_order( $_order );
			}

			// If no valid clauses were found, order by comment_date_gmt.
			if ( empty( $orderby_array ) ) {
				$orderby_array[] = "$wpdb->comments.comment_date_gmt $order";
			}

			// To ensure determinate sorting, always include a comment_ID clause.
			if ( ! $found_orderby_comment_id ) {
				$comment_id_order = '';

				// Inherit order from comment_date or comment_date_gmt, if available.
				foreach ( $orderby_array as $orderby_clause ) {
					if ( preg_match( '/comment_date(?:_gmt)*\ (ASC|DESC)/', $orderby_clause, $match ) ) {
						$comment_id_order = $match[1];
						break;
					}
				}

				// If no date-related order is available, use the date from the first available clause.
				if ( ! $comment_id_order ) {
					foreach ( $orderby_array as $orderby_clause ) {
						if ( str_contains( 'ASC', $orderby_clause ) ) {
							$comment_id_order = 'ASC';
						} else {
							$comment_id_order = 'DESC';
						}

						break;
					}
				}

				// Default to DESC.
				if ( ! $comment_id_order ) {
					$comment_id_order = 'DESC';
				}

				$orderby_array[] = "$wpdb->comments.comment_ID $comment_id_order";
			}

			$orderby = implode( ', ', $orderby_array );
		} else {
			$orderby = "$wpdb->comments.comment_date_gmt $order";
		}

		$number = absint( $this->query_vars['number'] );
		$offset = absint( $this->query_vars['offset'] );
		$paged  = absint( $this->query_vars['paged'] );
		$limits = '';

		if ( ! empty( $number ) ) {
			if ( $offset ) {
				$limits = 'LIMIT ' . $offset . ',' . $number;
			} else {
				$limits = 'LIMIT ' . ( $number * ( $paged - 1 ) ) . ',' . $number;
			}
		}

		if ( $this->query_vars['count'] ) {
			$fields = 'COUNT(*)';
		} else {
			$fields = "$wpdb->comments.comment_ID";
		}

		$post_id = absint( $this->query_vars['post_id'] );
		if ( ! empty( $post_id ) ) {
			$this->sql_clauses['where']['post_id'] = $wpdb->prepare( 'comment_post_ID = %d', $post_id );
		}

		// Parse comment IDs for an IN clause.
		if ( ! empty( $this->query_vars['comment__in'] ) ) {
			$this->sql_clauses['where']['comment__in'] = "$wpdb->comments.comment_ID IN ( " . implode( ',', wp_parse_id_list( $this->query_vars['comment__in'] ) ) . ' )';
		}

		// Parse comment IDs for a NOT IN clause.
		if ( ! empty( $this->query_vars['comment__not_in'] ) ) {
			$this->sql_clauses['where']['comment__not_in'] = "$wpdb->comments.comment_ID NOT IN ( " . implode( ',', wp_parse_id_list( $this->query_vars['comment__not_in'] ) ) . ' )';
		}

		// Parse comment parent IDs for an IN clause.
		if ( ! empty( $this->query_vars['parent__in'] ) ) {
			$this->sql_clauses['where']['parent__in'] = 'comment_parent IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['parent__in'] ) ) . ' )';
		}

		// Parse comment parent IDs for a NOT IN clause.
		if ( ! empty( $this->query_vars['parent__not_in'] ) ) {
			$this->sql_clauses['where']['parent__not_in'] = 'comment_parent NOT IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['parent__not_in'] ) ) . ' )';
		}

		// Parse comment post IDs for an IN clause.
		if ( ! empty( $this->query_vars['post__in'] ) ) {
			$this->sql_clauses['where']['post__in'] = 'comment_post_ID IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['post__in'] ) ) . ' )';
		}

		// Parse comment post IDs for a NOT IN clause.
		if ( ! empty( $this->query_vars['post__not_in'] ) ) {
			$this->sql_clauses['where']['post__not_in'] = 'comment_post_ID NOT IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['post__not_in'] ) ) . ' )';
		}

		if ( '' !== $this->query_vars['author_email'] ) {
			$this->sql_clauses['where']['author_email'] = $wpdb->prepare( 'comment_author_email = %s', $this->query_vars['author_email'] );
		}

		if ( '' !== $this->query_vars['author_url'] ) {
			$this->sql_clauses['where']['author_url'] = $wpdb->prepare( 'comment_author_url = %s', $this->query_vars['author_url'] );
		}

		if ( '' !== $this->query_vars['karma'] ) {
			$this->sql_clauses['where']['karma'] = $wpdb->prepare( 'comment_karma = %d', $this->query_vars['karma'] );
		}

		// Filtering by comment_type: 'type', 'type__in', 'type__not_in'.
		$raw_types = array(
			'IN'     => array_merge( (array) $this->query_vars['type'], (array) $this->query_vars['type__in'] ),
			'NOT IN' => (array) $this->query_vars['type__not_in'],
		);

		$comment_types = array();
		foreach ( $raw_types as $operator => $_raw_types ) {
			$_raw_types = array_unique( $_raw_types );

			foreach ( $_raw_types as $type ) {
				switch ( $type ) {
					// An empty translates to 'all', for backward compatibility.
					case '':
					case 'all':
						break;

					case 'comment':
					case 'comments':
						$comment_types[ $operator ][] = "''";
						$comment_types[ $operator ][] = "'comment'";
						break;

					case 'pings':
						$comment_types[ $operator ][] = "'pingback'";
						$comment_types[ $operator ][] = "'trackback'";
						break;

					default:
						$comment_types[ $operator ][] = $wpdb->prepare( '%s', $type );
						break;
				}
			}

			if ( ! empty( $comment_types[ $operator ] ) ) {
				$types_sql = implode( ', ', $comment_types[ $operator ] );
				$this->sql_clauses['where'][ 'comment_type__' . strtolower( str_replace( ' ', '_', $operator ) ) ] = "comment_type $operator ($types_sql)";
			}
		}

		$parent = $this->query_vars['parent'];
		if ( $this->query_vars['hierarchical'] && ! $parent ) {
			$parent = 0;
		}

		if ( '' !== $parent ) {
			$this->sql_clauses['where']['parent'] = $wpdb->prepare( 'comment_parent = %d', $parent );
		}

		if ( is_array( $this->query_vars['user_id'] ) ) {
			$this->sql_clauses['where']['user_id'] = 'user_id IN (' . implode( ',', array_map( 'absint', $this->query_vars['user_id'] ) ) . ')';
		} elseif ( '' !== $this->query_vars['user_id'] ) {
			$this->sql_clauses['where']['user_id'] = $wpdb->prepare( 'user_id = %d', $this->query_vars['user_id'] );
		}

		// Falsey search strings are ignored.
		if ( isset( $this->query_vars['search'] ) && strlen( $this->query_vars['search'] ) ) {
			$search_sql = $this->get_search_sql(
				$this->query_vars['search'],
				array( 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_author_IP', 'comment_content' )
			);

			// Strip leading 'AND'.
			$this->sql_clauses['where']['search'] = preg_replace( '/^\s*AND\s*/', '', $search_sql );
		}

		// If any post-related query vars are passed, join the posts table.
		$join_posts_table = false;
		$plucked          = wp_array_slice_assoc( $this->query_vars, array( 'post_author', 'post_name', 'post_parent' ) );
		$post_fields      = array_filter( $plucked );

		if ( ! empty( $post_fields ) ) {
			$join_posts_table = true;
			foreach ( $post_fields as $field_name => $field_value ) {
				// $field_value may be an array.
				$esses = array_fill( 0, count( (array) $field_value ), '%s' );

				// phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare
				$this->sql_clauses['where'][ $field_name ] = $wpdb->prepare( " {$wpdb->posts}.{$field_name} IN (" . implode( ',', $esses ) . ')', $field_value );
			}
		}

		// 'post_status' and 'post_type' are handled separately, due to the specialized behavior of 'any'.
		foreach ( array( 'post_status', 'post_type' ) as $field_name ) {
			$q_values = array();
			if ( ! empty( $this->query_vars[ $field_name ] ) ) {
				$q_values = $this->query_vars[ $field_name ];
				if ( ! is_array( $q_values ) ) {
					$q_values = explode( ',', $q_values );
				}

				// 'any' will cause the query var to be ignored.
				if ( in_array( 'any', $q_values, true ) || empty( $q_values ) ) {
					continue;
				}

				$join_posts_table = true;

				$esses = array_fill( 0, count( $q_values ), '%s' );

				// phpcs:ignore WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare
				$this->sql_clauses['where'][ $field_name ] = $wpdb->prepare( " {$wpdb->posts}.{$field_name} IN (" . implode( ',', $esses ) . ')', $q_values );
			}
		}

		// Comment author IDs for an IN clause.
		if ( ! empty( $this->query_vars['author__in'] ) ) {
			$this->sql_clauses['where']['author__in'] = 'user_id IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['author__in'] ) ) . ' )';
		}

		// Comment author IDs for a NOT IN clause.
		if ( ! empty( $this->query_vars['author__not_in'] ) ) {
			$this->sql_clauses['where']['author__not_in'] = 'user_id NOT IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['author__not_in'] ) ) . ' )';
		}

		// Post author IDs for an IN clause.
		if ( ! empty( $this->query_vars['post_author__in'] ) ) {
			$join_posts_table                              = true;
			$this->sql_clauses['where']['post_author__in'] = 'post_author IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['post_author__in'] ) ) . ' )';
		}

		// Post author IDs for a NOT IN clause.
		if ( ! empty( $this->query_vars['post_author__not_in'] ) ) {
			$join_posts_table                                  = true;
			$this->sql_clauses['where']['post_author__not_in'] = 'post_author NOT IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['post_author__not_in'] ) ) . ' )';
		}

		$join    = '';
		$groupby = '';

		if ( $join_posts_table ) {
			$join .= "JOIN $wpdb->posts ON $wpdb->posts.ID = $wpdb->comments.comment_post_ID";
		}

		if ( ! empty( $this->meta_query_clauses ) ) {
			$join .= $this->meta_query_clauses['join'];

			// Strip leading 'AND'.
			$this->sql_clauses['where']['meta_query'] = preg_replace( '/^\s*AND\s*/', '', $this->meta_query_clauses['where'] );

			if ( ! $this->query_vars['count'] ) {
				$groupby = "{$wpdb->comments}.comment_ID";
			}
		}

		if ( ! empty( $this->query_vars['date_query'] ) && is_array( $this->query_vars['date_query'] ) ) {
			$this->date_query = new WP_Date_Query( $this->query_vars['date_query'], 'comment_date' );

			// Strip leading 'AND'.
			$this->sql_clauses['where']['date_query'] = preg_replace( '/^\s*AND\s*/', '', $this->date_query->get_sql() );
		}

		$where = implode( ' AND ', $this->sql_clauses['where'] );

		$pieces = array( 'fields', 'join', 'where', 'orderby', 'limits', 'groupby' );

		/**
		 * Filters the comment query clauses.
		 *
		 * @since 3.1.0
		 *
		 * @param string[]         $clauses An associative array of comment query clauses.
		 * @param WP_Comment_Query $query   Current instance of WP_Comment_Query (passed by reference).
		 */
		$clauses = apply_filters_ref_array( 'comments_clauses', array( compact( $pieces ), &$this ) );

		$fields  = isset( $clauses['fields'] ) ? $clauses['fields'] : '';
		$join    = isset( $clauses['join'] ) ? $clauses['join'] : '';
		$where   = isset( $clauses['where'] ) ? $clauses['where'] : '';
		$orderby = isset( $clauses['orderby'] ) ? $clauses['orderby'] : '';
		$limits  = isset( $clauses['limits'] ) ? $clauses['limits'] : '';
		$groupby = isset( $clauses['groupby'] ) ? $clauses['groupby'] : '';

		$this->filtered_where_clause = $where;

		if ( $where ) {
			$where = 'WHERE ' . $where;
		}

		if ( $groupby ) {
			$groupby = 'GROUP BY ' . $groupby;
		}

		if ( $orderby ) {
			$orderby = "ORDER BY $orderby";
		}

		$found_rows = '';
		if ( ! $this->query_vars['no_found_rows'] ) {
			$found_rows = 'SQL_CALC_FOUND_ROWS';
		}

		$this->sql_clauses['select']  = "SELECT $found_rows $fields";
		$this->sql_clauses['from']    = "FROM $wpdb->comments $join";
		$this->sql_clauses['groupby'] = $groupby;
		$this->sql_clauses['orderby'] = $orderby;
		$this->sql_clauses['limits']  = $limits;

		$this->request = "
			{$this->sql_clauses['select']}
			{$this->sql_clauses['from']}
			{$where}
			{$this->sql_clauses['groupby']}
			{$this->sql_clauses['orderby']}
			{$this->sql_clauses['limits']}
		";

		if ( $this->query_vars['count'] ) {
			return (int) $wpdb->get_var( $this->request );
		} else {
			$comment_ids = $wpdb->get_col( $this->request );
			return array_map( 'intval', $comment_ids );
		}
	}

	/**
	 * Populates found_comments and max_num_pages properties for the current
	 * query if the limit clause was used.
	 *
	 * @since 4.6.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 */
	private function set_found_comments() {
		global $wpdb;

		if ( $this->query_vars['number'] && ! $this->query_vars['no_found_rows'] ) {
			/**
			 * Filters the query used to retrieve found comment count.
			 *
			 * @since 4.4.0
			 *
			 * @param string           $found_comments_query SQL query. Default 'SELECT FOUND_ROWS()'.
			 * @param WP_Comment_Query $comment_query        The `WP_Comment_Query` instance.
			 */
			$found_comments_query = apply_filters( 'found_comments_query', 'SELECT FOUND_ROWS()', $this );

			$this->found_comments = (int) $wpdb->get_var( $found_comments_query );
		}
	}

	/**
	 * Fetch descendants for located comments.
	 *
	 * Instead of calling `get_children()` separately on each child comment, we do a single set of queries to fetch
	 * the descendant trees for all matched top-level comments.
	 *
	 * @since 4.4.0
	 *
	 * @param WP_Comment[] $comments Array of top-level comments whose descendants should be filled in.
	 * @return array
	 */
	protected function fill_descendants( $comments ) {
		$levels = array(
			0 => wp_list_pluck( $comments, 'comment_ID' ),
		);

		$key          = md5( serialize( wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) ) ) );
		$last_changed = wp_cache_get_last_changed( 'comment' );

		// Fetch an entire level of the descendant tree at a time.
		$level        = 0;
		$exclude_keys = array( 'parent', 'parent__in', 'parent__not_in' );
		do {
			// Parent-child relationships may be cached. Only query for those that are not.
			$child_ids           = array();
			$uncached_parent_ids = array();
			$_parent_ids         = $levels[ $level ];
			if ( $_parent_ids ) {
				$cache_keys = array();
				foreach ( $_parent_ids as $parent_id ) {
					$cache_keys[ $parent_id ] = "get_comment_child_ids:$parent_id:$key:$last_changed";
				}
				$cache_data = wp_cache_get_multiple( array_values( $cache_keys ), 'comment-queries' );
				foreach ( $_parent_ids as $parent_id ) {
					$parent_child_ids = $cache_data[ $cache_keys[ $parent_id ] ];
					if ( false !== $parent_child_ids ) {
						$child_ids = array_merge( $child_ids, $parent_child_ids );
					} else {
						$uncached_parent_ids[] = $parent_id;
					}
				}
			}

			if ( $uncached_parent_ids ) {
				// Fetch this level of comments.
				$parent_query_args = $this->query_vars;
				foreach ( $exclude_keys as $exclude_key ) {
					$parent_query_args[ $exclude_key ] = '';
				}
				$parent_query_args['parent__in']    = $uncached_parent_ids;
				$parent_query_args['no_found_rows'] = true;
				$parent_query_args['hierarchical']  = false;
				$parent_query_args['offset']        = 0;
				$parent_query_args['number']        = 0;

				$level_comments = get_comments( $parent_query_args );

				// Cache parent-child relationships.
				$parent_map = array_fill_keys( $uncached_parent_ids, array() );
				foreach ( $level_comments as $level_comment ) {
					$parent_map[ $level_comment->comment_parent ][] = $level_comment->comment_ID;
					$child_ids[]                                    = $level_comment->comment_ID;
				}

				$data = array();
				foreach ( $parent_map as $parent_id => $children ) {
					$cache_key          = "get_comment_child_ids:$parent_id:$key:$last_changed";
					$data[ $cache_key ] = $children;
				}
				wp_cache_set_multiple( $data, 'comment-queries' );
			}

			++$level;
			$levels[ $level ] = $child_ids;
		} while ( $child_ids );

		// Prime comment caches for non-top-level comments.
		$descendant_ids = array();
		for ( $i = 1, $c = count( $levels ); $i < $c; $i++ ) {
			$descendant_ids = array_merge( $descendant_ids, $levels[ $i ] );
		}

		_prime_comment_caches( $descendant_ids, $this->query_vars['update_comment_meta_cache'] );

		// Assemble a flat array of all comments + descendants.
		$all_comments = $comments;
		foreach ( $descendant_ids as $descendant_id ) {
			$all_comments[] = get_comment( $descendant_id );
		}

		// If a threaded representation was requested, build the tree.
		if ( 'threaded' === $this->query_vars['hierarchical'] ) {
			$threaded_comments = array();
			$ref               = array();
			foreach ( $all_comments as $k => $c ) {
				$_c = get_comment( $c->comment_ID );

				// If the comment isn't in the reference array, it goes in the top level of the thread.
				if ( ! isset( $ref[ $c->comment_parent ] ) ) {
					$threaded_comments[ $_c->comment_ID ] = $_c;
					$ref[ $_c->comment_ID ]               = $threaded_comments[ $_c->comment_ID ];

					// Otherwise, set it as a child of its parent.
				} else {

					$ref[ $_c->comment_parent ]->add_child( $_c );
					$ref[ $_c->comment_ID ] = $ref[ $_c->comment_parent ]->get_child( $_c->comment_ID );
				}
			}

			// Set the 'populated_children' flag, to ensure additional database queries aren't run.
			foreach ( $ref as $_ref ) {
				$_ref->populated_children( true );
			}

			$comments = $threaded_comments;
		} else {
			$comments = $all_comments;
		}

		return $comments;
	}

	/**
	 * Used internally to generate an SQL string for searching across multiple columns.
	 *
	 * @since 3.1.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param string   $search  Search string.
	 * @param string[] $columns Array of columns to search.
	 * @return string Search SQL.
	 */
	protected function get_search_sql( $search, $columns ) {
		global $wpdb;

		$like = '%' . $wpdb->esc_like( $search ) . '%';

		$searches = array();
		foreach ( $columns as $column ) {
			$searches[] = $wpdb->prepare( "$column LIKE %s", $like );
		}

		return ' AND (' . implode( ' OR ', $searches ) . ')';
	}

	/**
	 * Parse and sanitize 'orderby' keys passed to the comment query.
	 *
	 * @since 4.2.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param string $orderby Alias for the field to order by.
	 * @return string|false Value to used in the ORDER clause. False otherwise.
	 */
	protected function parse_orderby( $orderby ) {
		global $wpdb;

		$allowed_keys = array(
			'comment_agent',
			'comment_approved',
			'comment_author',
			'comment_author_email',
			'comment_author_IP',
			'comment_author_url',
			'comment_content',
			'comment_date',
			'comment_date_gmt',
			'comment_ID',
			'comment_karma',
			'comment_parent',
			'comment_post_ID',
			'comment_type',
			'user_id',
		);

		if ( ! empty( $this->query_vars['meta_key'] ) ) {
			$allowed_keys[] = $this->query_vars['meta_key'];
			$allowed_keys[] = 'meta_value';
			$allowed_keys[] = 'meta_value_num';
		}

		$meta_query_clauses = $this->meta_query->get_clauses();
		if ( $meta_query_clauses ) {
			$allowed_keys = array_merge( $allowed_keys, array_keys( $meta_query_clauses ) );
		}

		$parsed = false;
		if ( $this->query_vars['meta_key'] === $orderby || 'meta_value' === $orderby ) {
			$parsed = "$wpdb->commentmeta.meta_value";
		} elseif ( 'meta_value_num' === $orderby ) {
			$parsed = "$wpdb->commentmeta.meta_value+0";
		} elseif ( 'comment__in' === $orderby ) {
			$comment__in = implode( ',', array_map( 'absint', $this->query_vars['comment__in'] ) );
			$parsed      = "FIELD( {$wpdb->comments}.comment_ID, $comment__in )";
		} elseif ( in_array( $orderby, $allowed_keys, true ) ) {

			if ( isset( $meta_query_clauses[ $orderby ] ) ) {
				$meta_clause = $meta_query_clauses[ $orderby ];
				$parsed      = sprintf( 'CAST(%s.meta_value AS %s)', esc_sql( $meta_clause['alias'] ), esc_sql( $meta_clause['cast'] ) );
			} else {
				$parsed = "$wpdb->comments.$orderby";
			}
		}

		return $parsed;
	}

	/**
	 * Parse an 'order' query variable and cast it to ASC or DESC as necessary.
	 *
	 * @since 4.2.0
	 *
	 * @param string $order The 'order' query variable.
	 * @return string The sanitized 'order' query variable.
	 */
	protected function parse_order( $order ) {
		if ( ! is_string( $order ) || empty( $order ) ) {
			return 'DESC';
		}

		if ( 'ASC' === strtoupper( $order ) ) {
			return 'ASC';
		} else {
			return 'DESC';
		}
	}
}