public function widget( $args, $instance ) {
		// abort if we don't have an address to show.
		if ( empty( $instance['location_slug'] ) ) {
			return;
		}

		// abort if we do not have a mapbox.com API token.
		$settings = INVP::settings();
		if ( empty( $settings['mapbox_public_token'] ) ) {
			return;
		}

		$location_terms = get_terms(
			array(
				'hide_empty' => false,
				'slug'       => $instance['location_slug'],
				'taxonomy'   => 'location',
			)
		);
		if ( ! $location_terms ) {
			// there are no dealership addresses stored in this site, abort.
			return;
		}

		if ( empty( $args['widget_id'] ) ) {
			// Sometimes the widget ID is unavailable in stuff like Elementor.
			$args['widget_id'] = '9999';
		}

		/**
		 * Create an array that contains the data needed to create the markers
		 * and popups: location names, addresses, and lat lon coords
		 */
		$popups         = array();
		$location_count = count( $location_terms );
		for ( $t = 0; $t < $location_count; $t++ ) {
			$popup = new stdClass();
			/**
			 * Store the widget ID in case there are two instances of this
			 * widget on the same page.
			 */
			$popup->widget_id = $args['widget_id'];
			// Location title/dealership name - escape to prevent XSS.
			$popup->name = esc_html( $location_terms[ $t ]->name );
			// Address - allow <br /> tags but escape other HTML to prevent XSS.
			$popup->address = wp_kses_post( str_replace( "\r", '', str_replace( PHP_EOL, '<br />', $location_terms[ $t ]->description ) ) );
			// Get the latitude and longitude coordinates for this address.
			$location = INVP::fetch_latitude_and_longitude( $location_terms[ $t ]->term_id );
			if ( false !== $location ) {
				$popup->coords      = new stdClass();
				$popup->coords->lat = $location->lat;
				$popup->coords->lon = $location->lon;
				$popups[]           = $popup;
			}
		}

		if ( empty( $popups ) ) {
			/**
			 * We didn't find any latitude & longitude coordinates using the
			 * addresses on openstreetmap.org. It is likely that the addresses
			 * need to be added to the buildings for this dealer's locations.
			 */
			return;
		}

		// Enqueue leaflet.js scripts and styles.
		if ( ! wp_script_is( self::SCRIPT_HANDLE_LEAFLET ) ) {
			wp_enqueue_script( self::SCRIPT_HANDLE_LEAFLET );
			wp_enqueue_style( self::SCRIPT_HANDLE_LEAFLET );
			wp_enqueue_style( self::ID_BASE );
		}

		// Include the JavaScript file that powers the map.
		$handle = 'invp-maps';
		/**
		 * If there are two Map widgets on the same page, we need to avoid the
		 * second one redefining the same invp_maps constant because that will
		 * produce a JavaScript error.
		 */
		if ( ! wp_script_is( $handle ) ) {
			// First instance of this widget on the page.
			wp_enqueue_script( $handle );
			// Localize an API key and the popups array for JavaScript.
			wp_add_inline_script(
				$handle,
				'const invp_maps = ' . wp_json_encode(
					array(
						'mapbox_public_token' => $settings['mapbox_public_token'],
						'popups'              => $popups,
					)
				),
				'before'
			);
		} else {
			// There is another Map widget on this page already.
			foreach ( $popups as $popup ) {
				wp_add_inline_script( $handle, 'invp_maps.popups.push( ' . wp_json_encode( $popup ) . ' );', 'before' );
			}
		}

		// before and after widget arguments are defined by themes.
		echo wp_kses_post( $args['before_widget'] );

		$title = apply_filters( 'widget_title', $instance['title'] );
		if ( ! empty( $title ) ) {
			echo wp_kses_post( $args['before_title'] ) . esc_html( $title ) . wp_kses_post( $args['after_title'] );
		}

		printf( '<div class="invp-map %1$s" id="%1$s-inner"></div>', esc_attr( $args['widget_id'] ) );
		echo wp_kses_post( $args['after_widget'] );
	}