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	 * WordPress environment.
	 *
	 * @since 2.0.0
	 *
	 * @global WP_Query     $wp_query     WordPress Query object.
	 * @global string       $query_string Query string for the loop.
	 * @global array        $posts        The found posts.
	 * @global WP_Post|null $post         The current post, if available.
	 * @global string       $request      The SQL statement for the request.
	 * @global int          $more         Only set, if single page or post.
	 * @global int          $single       If single page or post. Only set, if single page or post.
	 * @global WP_User      $authordata   Only set, if author archive.
	 */
	public function register_globals() {
		global $wp_query;

		// Extract updated query vars back into global namespace.
		foreach ( (array) $wp_query->query_vars as $key => $value ) {
			$GLOBALS[ $key ] = $value;
		}

		$GLOBALS['query_string'] = $this->query_string;
		$GLOBALS['posts']        = & $wp_query->posts;
		$GLOBALS['post']         = isset( $wp_query->post ) ? $wp_query->post : null;
		$GLOBALS['request']      = $wp_query->request;

		if ( $wp_query->is_single() || $wp_query->is_page() ) {
			$GLOBALS['more']   = 1;
			$GLOBALS['single'] = 1;
		}

		if ( $wp_query->is_author() ) {
			$GLOBALS['authordata'] = get_userdata( get_queried_object_id() );
		}
	}

	/**
	 * Set up the current user.
	 *
	 * @since 2.0.0
	 */
	public function init() {
		wp_get_current_user();
	}

	/**
	 * Set up the Loop based on the query variables.
	 *
	 * @since 2.0.0
	 *
	 * @global WP_Query $wp_the_query WordPress Query object.
	 */
	public function query_posts() {
		global $wp_the_query;
		$this->build_query_string();
		$wp_the_query->query( $this->query_vars );
	}

	/**
	 * Set the Headers for 404, if nothing is found for requested URL.
	 *
	 * Issue a 404 if a request doesn't match any posts and doesn't match any object
	 * (e.g. an existing-but-empty category, tag, author) and a 404 was not already issued,
	 * and if the request was not a search or the homepage.
	 *
	 * Otherwise, issue a 200.
	 *
	 * This sets headers after posts have been queried. handle_404() really means "handle status".
	 * By inspecting the result of querying posts, seemingly successful requests can be switched to
	 * a 404 so that canonical redirection logic can kick in.
	 *
	 * @since 2.0.0
	 *
	 * @global WP_Query $wp_query WordPress Query object.
	 */
	public function handle_404() {
		global $wp_query;

		/**
		 * Filters whether to short-circuit default header status handling.
		 *
		 * Returning a non-false value from the filter will short-circuit the handling
		 * and return early.
		 *
		 * @since 4.5.0
		 *
		 * @param bool     $preempt  Whether to short-circuit default header status handling. Default false.
		 * @param WP_Query $wp_query WordPress Query object.
		 */
		if ( false !== apply_filters( 'pre_handle_404', false, $wp_query ) ) {
			return;
		}

		// If we've already issued a 404, bail.
		if ( is_404() ) {
			return;
		}

		$set_404 = true;

		// Never 404 for the admin, robots, or favicon.
		if ( is_admin() || is_robots() || is_favicon() ) {
			$set_404 = false;

			// If posts were found, check for paged content.
		} elseif ( $wp_query->posts ) {
			$content_found = true;

			if ( is_singular() ) {
				$post = isset( $wp_query->post ) ? $wp_query->post : null;
				$next = '<!--nextpage-->';

				// Check for paged content that exceeds the max number of pages.
				if ( $post && ! empty( $this->query_vars['page'] ) ) {
					// Check if content is actually intended to be paged.
					if ( str_contains( $post->post_content, $next ) ) {
						$page          = trim( $this->query_vars['page'], '/' );
						$content_found = (int) $page <= ( substr_count( $post->post_content, $next ) + 1 );
					} else {
						$content_found = false;
					}
				}
			}

			// The posts page does not support the <!--nextpage--> pagination.
			if ( $wp_query->is_posts_page && ! empty( $this->query_vars['page'] ) ) {
				$content_found = false;
			}

			if ( $content_found ) {
				$set_404 = false;
			}

			// We will 404 for paged queries, as no posts were found.
		} elseif ( ! is_paged() ) {
			$author = get_query_var( 'author' );

			// Don't 404 for authors without posts as long as they matched an author on this site.
			if ( is_author() && is_numeric( $author ) && $author > 0 && is_user_member_of_blog( $author )
				// Don't 404 for these queries if they matched an object.
				|| ( is_tag() || is_category() || is_tax() || is_post_type_archive() ) && get_queried_object()
				// Don't 404 for these queries either.
				|| is_home() || is_search() || is_feed()
			) {
				$set_404 = false;
			}
		}

		if ( $set_404 ) {
			// Guess it's time to 404.
			$wp_query->set_404();
			status_header( 404 );
			nocache_headers();
		} else {
			status_header( 200 );
		}
	}

	/**
	 * Sets up all of the variables required by the WordPress environment.
	 *
	 * The action {@see 'wp'} has one parameter that references the WP object. It
	 * allows for accessing the properties and methods to further manipulate the
	 * object.
	 *
	 * @since 2.0.0
	 *
	 * @param string|array $query_args Passed to parse_request().
	 */
	public function main( $query_args = '' ) {
		$this->init();

		$parsed = $this->parse_request( $query_args );

		if ( $parsed ) {
			$this->query_posts();
			$this->handle_404();
			$this->register_globals();
		}

		$this->send_headers();

		/**
		 * Fires once the WordPress environment has been set up.
		 *
		 * @since 2.1.0
		 *
		 * @param WP $wp Current WordPress environment instance (passed by reference).
		 */
		do_action_ref_array( 'wp', array( &$this ) );
	}
}