Retroactively Populate Unique IDs

<?php
/**
 * Gravity Perks // GP Unique ID // Retroactively Populate Unique IDs
 * https://gravitywiz.com/documentation/gp-unique-id/
 *
 * 1. Install snippet using instructions at https://gravitywiz.com/documentation/how-do-i-install-a-snippet/
 * 2. Go to your home page and add the following parameters to the query string:
 *
 *     gpui_retro_pop=1
 *     form_id=123
 *
 *     Make sure you replace "123" with the ID of your form. Full URL should look like this:
 *
 *     http://mysite.com/?gpui_retro_pop=1&form_id=123
 *
 * 3. Submit the updated URL. If everything is correct, you will be greeted with a success message and updated entry count.
 * 4. Important! Remove snippet after verifying that unique IDs have been generated for previous entries.
 *
 * NOTE: This snippet has a hard-coded limit of 999 entries.
 */
add_action( 'init', function() {
	if ( isset( $_GET['gpui_retro_pop'] ) && class_exists( 'GFAPI' ) ) {

		$form_id = rgget( 'form_id' );
		$form    = GFAPI::get_form( $form_id );
		if ( ! $form ) {
			echo 'Please provide a valid form ID.';
			exit;
		}

		$unique_id_fields = GFCommon::get_fields_by_type( $form, array( 'uid' ) );
		if ( empty( $unique_id_fields ) ) {
			echo 'There are no Unique ID fields on this form.';
			exit;
		}

		$filters = array();
		foreach ( $unique_id_fields as $unique_id_field ) {
			$filters[] = array(
				'key'   => $unique_id_field->id,
				'value' => null,
			);
		}
		$filters['mode'] = 'any';

		$entries = GFAPI::get_entries(
			$form['id'],
			array(
				'field_filters' => $filters,
			),
			null,
			array(
				'offset'    => 0,
				'page_size' => 999,
			)
		);

		if ( empty( $entries ) ) {
			echo 'There are no entries requiring retroactive population.';
			exit;
		}

		$count = 0;

		foreach ( $entries as $entry ) {

			$has_update = false;

			foreach ( $unique_id_fields as $unique_id_field ) {
				if ( empty( $entry[ $unique_id_field->id ] ) ) {
					$entry[ $unique_id_field->id ] = gp_unique_id()->get_unique( $form['id'], $unique_id_field );
					$has_update                    = true;
				}
			}

			if ( $has_update ) {
				GFAPI::update_entry( $entry );
				$count ++;
			}
		}

		printf( '%d entries updated.', $count );

		exit;
	}
} );