Noptin_Post_Types::display_form_columns( string $column, int $post_id )

	public function display_form_columns( $column, $post_id ) {

		switch ( $column ) {
			case 'subscriptions':
				$views = (int) get_post_meta( $post_id, '_noptin_subscribers_count', true );
				if ( empty( $views ) ) {

					// Ensure that there is always a subscriber count for sorting to count.
					update_post_meta( $post_id, '_noptin_subscribers_count', 0 );

				} else {

					// Link to the list of subscribers who signed up using this specific form.
					$url   = get_noptin_subscribers_overview_url();
					$url   = esc_url( add_query_arg( '_subscriber_via', $post_id, $url ) );
					$title = esc_attr__( 'View the list of subscribers who signed up using this form.', 'newsletter-optin-box' );
					$views = "<a href='$url' title='$title'>$views</a>";

				}

				echo $views;

				break;

			case 'type':
				$types = array(
					'sidebar'  => _x( 'Widget', 'Subscription forms that are meant to appear in a widget area', 'newsletter-optin-box' ),
					'inpost'   => _x( 'Shortcode', 'Subscription forms that are embedded in posts using shortcodes', 'newsletter-optin-box' ),
					'popup'    => _x( 'Popup', 'Subscription forms that appear in a popup', 'newsletter-optin-box' ),
					'slide_in' => _x( 'Sliding', 'Subscription forms that slide into view', 'newsletter-optin-box' ),
				);
				$type  = get_post_meta( $post_id, '_noptin_optin_type', true );

				if ( empty( $types[ $type ] ) ) {
					echo '<strong>' . noptin_clean( $type ) . '</strong>';
				} else {
					echo '<strong>' . esc_html( $types[ $type ] ) . '</strong>';
				}

				if ( 'inpost' === $type ) {
					$title = esc_attr__( 'Use this shortcode to display the form on your website', 'newsletter-optin-box' );
					echo "<br><input title='$title' style='color: #607D8B;' onClick='this.select();' type='text' value='[noptin-form id=$post_id]' disabled />";
				}
				break;

			case 'impressions':
				$impressions = (int) get_post_meta( $post_id, '_noptin_form_views', true );
				if ( empty( $impressions ) ) {
					update_post_meta( $post_id, '_noptin_form_views', 0 );
				}

				echo $impressions;

				break;

			case 'conversion':
				$subscriptions = (int) get_post_meta( $post_id, '_noptin_subscribers_count', true );
				$impressions   = (int) get_post_meta( $post_id, '_noptin_form_views', true );
				$conversion    = ( $subscriptions && $impressions ) ? ( $subscriptions * 100 / $impressions ) : 0;
				$conversion    = empty( $conversion ) ? 0 : round( $conversion, 2 ) . '%';
				echo $conversion;
				break;

			case 'shortcode':
				$form_type = get_post_meta( $post_id, '_noptin_optin_type', true );

				if ( 'inpost' === $form_type ) {
					echo "[noptin-form id=$post_id]";
				} else {
					echo '__';
				}

				break;
		}

	}