Add get_pdf_filename() to API

api.php

@@ -351,6 +351,48 @@ public static function delete_pdf( $form_id, $pdf_id ) {
 		return $options->delete_pdf( $form_id, $pdf_id );
 	}
 
+	/**
+	 * Retrieve the filename of the PDF document
+	 * The .pdf extension is not returned by default (pass true to the 3rd param)
+	 *
+	 * See https://docs.gravitypdf.com/v6/developers/api/get_pdf_filename/ for more information about this method
+	 *
+	 * @param int    $entry_id          The Gravity Form entry ID
+	 * @param string $pdf_id            The Gravity PDF ID number (the pid number in the URL when viewing a setting in the admin area)
+	 * @param bool   $include_extension Whether to include the .pdf extension in the filename
+	 *
+	 * @return string|WP_Error   Return the filename of the PDF, or a WP_Error on failure
+	 *
+	 * @return string|WP_Error
+	 *
+	 * @since 6.12
+	 */
+	public static function get_pdf_filename( $entry_id, $pdf_id, bool $include_extension ) {
+		$form_class = static::get_form_class();
+
+		/* Get our entry */
+		$entry = $form_class->get_entry( $entry_id );
+		if ( is_wp_error( $entry ) ) {
+			return new WP_Error( 'invalid_entry', esc_html__( 'Make sure to pass in a valid Gravity Forms Entry ID', 'gravity-forms-pdf-extended' ) );
+		}
+
+		/* Get our settings */
+		$setting = static::get_pdf( $entry['form_id'], $pdf_id );
+		if ( is_wp_error( $setting ) ) {
+			return new WP_Error( 'invalid_pdf_setting', esc_html__( 'Could not located the PDF Settings. Ensure you pass in a valid PDF ID.', 'gravity-forms-pdf-extended' ) );
+		}
+
+		/** @var \GFPDF\Model\Model_PDF $pdf */
+		$pdf = static::get_mvc_class( 'Model_PDF' );
+
+		$filename = $pdf->get_pdf_name( $setting, $entry );
+		if ( $include_extension ) {
+			$filename .= '.pdf';
+		}
+
+		return $filename;
+	}
+
 	/**
 	 * Retrieve an array of the global Gravity PDF settings (this doesn't include individual form configuration details - see GPDFAPI::get_form_pdfs)
 	 *