}
	}

	/**
	 * Reset all options for a specific multisite blog to their default values based upon a
	 * specified default blog if one was chosen on the network page or the plugin defaults if it was not.
	 *
	 * @param int|string $blog_id Blog id of the blog for which to reset the options.
	 *
	 * @return void
	 */
	public static function reset_ms_blog( $blog_id ) {
		if ( is_multisite() ) {
			$options      = get_site_option( 'wpseo_ms' );
			$option_names = static::get_option_names();

			if ( is_array( $option_names ) && $option_names !== [] ) {
				$base_blog_id = $blog_id;
				if ( $options['defaultblog'] !== '' && $options['defaultblog'] !== 0 ) {
					$base_blog_id = $options['defaultblog'];
				}

				foreach ( $option_names as $option_name ) {
					delete_blog_option( $blog_id, $option_name );

					$new_option = get_blog_option( $base_blog_id, $option_name );

					/* Remove sensitive, theme dependent and site dependent info. */
					if ( isset( static::$option_instances[ $option_name ] ) && static::$option_instances[ $option_name ]->ms_exclude !== [] ) {
						foreach ( static::$option_instances[ $option_name ]->ms_exclude as $key ) {
							unset( $new_option[ $key ] );
						}
					}

					if ( $option_name === 'wpseo' ) {
						$new_option['ms_defaults_set'] = true;
					}

					update_blog_option( $blog_id, $option_name, $new_option );
				}
			}
		}
	}

	/**
	 * Saves the option to the database.
	 *
	 * @param string $wpseo_options_group_name The name for the wpseo option group in the database.
	 * @param string $option_name              The name for the option to set.
	 * @param mixed  $option_value             The value for the option.
	 *
	 * @return bool Returns true if the option is successfully saved in the database.
	 */
	public static function save_option( $wpseo_options_group_name, $option_name, $option_value ) {
		$options                 = static::get_option( $wpseo_options_group_name );
		$options[ $option_name ] = $option_value;

		if ( isset( static::$option_instances[ $wpseo_options_group_name ] ) && static::$option_instances[ $wpseo_options_group_name ]->multisite_only === true ) {
			static::update_site_option( $wpseo_options_group_name, $options );
		}
		else {
			update_option( $wpseo_options_group_name, $options );
		}

		// Check if everything got saved properly.
		$saved_option = static::get_option( $wpseo_options_group_name );

		// Clear our cache.
		static::clear_cache();

		return $saved_option[ $option_name ] === $options[ $option_name ];
	}

	/**
	 * Adds the multisite options to the option stack if relevant.
	 *
	 * @param array $option The currently present options settings.
	 *
	 * @return array Options possibly including multisite.
	 */
	protected static function add_ms_option( $option ) {
		if ( ! is_multisite() ) {
			return $option;
		}

		$ms_option = static::get_option( 'wpseo_ms' );
		if ( $ms_option === null ) {
			return $option;
		}

		return array_merge( $option, $ms_option );
	}

	/**
	 * Checks if installation is multisite.
	 *
	 * @return bool True when is multisite.
	 */
	protected static function is_multisite() {
		static $is_multisite;

		if ( $is_multisite === null ) {
			$is_multisite = is_multisite();
		}

		return $is_multisite;
	}

	/**
	 * Retrieves a lookup table to find in which option_group a key is stored.
	 *
	 * @return array The lookup table.
	 */
	private static function get_lookup_table() {
		$lookup_table = [];


		foreach ( array_keys( static::$options ) as $option_name ) {
			$full_option = static::get_option( $option_name );
			foreach ( $full_option as $key => $value ) {
				$lookup_table[ $key ] = $option_name;
			}
		}

		return $lookup_table;
	}

	/**
	 * Retrieves a lookup table to find in which option_group a key is stored.
	 *
	 * @return array The lookup table.
	 */
	private static function get_pattern_table() {
		$pattern_table = [];
		foreach ( static::$options as $option_name => $option_class ) {
			$instance = call_user_func( [ $option_class, 'get_instance' ] );
			foreach ( $instance->get_patterns() as $key ) {
				$pattern_table[ $key ] = $option_name;
			}
		}

		return $pattern_table;
	}
}