Noptin_Post_Types::custom_filters( string $post_type )

	public function custom_filters( $post_type ) {

		// Make sure this is our post type.
		if ( 'noptin-form' !== $post_type ) {
			return;
		}

		// Filter by form type.
		$form_types = array(
			'sidebar'  => __( 'Widget Forms', 'newsletter-optin-box' ),
			'inpost'   => __( 'Shortcode Forms', 'newsletter-optin-box' ),
			'popup'    => __( 'Popup Forms', 'newsletter-optin-box' ),
			'slide_in' => __( 'Sliding Forms', 'newsletter-optin-box' ),
		);

		$form_type = 'all';

		if ( isset( $_REQUEST['form_type'] ) && ! empty( $form_types[ $_REQUEST['form_type'] ] ) ) {
			$form_type = $_REQUEST['form_type'];
		}

		// build a custom dropdown list of values to filter by.
		echo '<select id="noptin-form-type" name="form_type">';
		echo '<option value="all">' . __( 'All Forms', 'newsletter-optin-box' ) . ' </option>';

		foreach ( $form_types as $key => $title ) {
			$key      = esc_attr( $key );
			$title    = esc_html( $title );
			$selected = selected( $key, $form_type, false );
			echo "<option value='$key' $selected>$title</option>";
		}

		echo '</select>';
	}