<?php
/**
 * Personal data exporter.
 *
 * @package Consentfold
 */

declare(strict_types=1);

namespace Consentfold\Privacy;

use Consentfold\Consent\LogRepository;
use Consentfold\Consent\UserConsentIds;

/**
 * Adds the consent log records of a user to the export of Tools > Export Personal Data. The log holds no personal
 * data itself; the records are found through the consent IDs kept in the user's meta (docs/subsystems.md §5.5).
 */
final class Exporter {

	public const GROUP = 'consentfold-consents';

	/**
	 * Prefix of the transients that carry the last row id sent from one page of an export to the next, one per user
	 * and page, so a retried page or two exports of one user read the same cursor.
	 */
	private const MARKER = 'consentfold_export_';

	/**
	 * Log storage.
	 *
	 * @var LogRepository
	 */
	private LogRepository $log;

	/**
	 * Constructor.
	 *
	 * @param LogRepository $log Log storage.
	 */
	public function __construct( LogRepository $log ) {
		$this->log = $log;
	}

	/**
	 * Hook the exporter.
	 */
	public function register(): void {
		add_filter( 'wp_privacy_personal_data_exporters', array( $this, 'add' ) );
	}

	/**
	 * Add the exporter to core's list.
	 *
	 * @param mixed $exporters Registered exporters.
	 * @return array<mixed>
	 */
	public function add( $exporters ): array {
		$exporters   = is_array( $exporters ) ? $exporters : array();
		$exporters[] = array(
			'exporter_friendly_name' => __( 'Consent log', 'consentfold' ),
			'callback'               => array( $this, 'export' ),
		);

		return $exporters;
	}

	/**
	 * Export the records of the user with an email address.
	 *
	 * @param string $email Email address.
	 * @param int    $page  Page of the export, from 1; core asks again until `done`. Page 1 starts fresh; later pages
	 *                      continue after the last row id the previous page kept for an hour; a lost cursor falls back to
	 *                      skipping `(page - 1) * PRIVACY_PAGE` records, so the export always ends.
	 * @return array{data: list<array<string, mixed>>, done: bool}
	 */
	public function export( string $email, int $page = 1 ): array {
		$user = get_user_by( 'email', $email );
		$data = array();
		$done = true;

		if ( $user instanceof \WP_User ) {
			$marker = self::MARKER . $user->ID . '_';
			$after  = $page > 1 ? (int) get_transient( $marker . $page ) : 0;
			$offset = $page > 1 && 0 === $after ? ( $page - 1 ) * LogRepository::PRIVACY_PAGE : 0;
			$result = $this->log->history_page( UserConsentIds::get( $user->ID ), $after, $offset );
			$done   = $result['done'];

			if ( $page > 1 ) {
				delete_transient( $marker . $page );
			}
			if ( ! $done && array() !== $result['records'] ) {
				set_transient( $marker . ( $page + 1 ), end( $result['records'] )['id'], HOUR_IN_SECONDS );
			}

			foreach ( $result['records'] as $record ) {
				$data[] = array(
					'group_id'    => self::GROUP,
					'group_label' => __( 'Consent log', 'consentfold' ),
					'item_id'     => 'consentfold-' . $record['id'],
					'data'        => array(
						array(
							'name'  => __( 'Consent ID', 'consentfold' ),
							'value' => $record['consent_id'],
						),
						array(
							'name'  => __( 'Date (UTC)', 'consentfold' ),
							'value' => $record['recorded_at'],
						),
						array(
							'name'  => __( 'Categories', 'consentfold' ),
							'value' => implode( ', ', $record['categories'] ),
						),
						array(
							'name'  => __( 'Method', 'consentfold' ),
							'value' => $record['method'],
						),
						array(
							'name'  => __( 'Region', 'consentfold' ),
							'value' => (string) $record['region'],
						),
						array(
							'name'  => __( 'Language', 'consentfold' ),
							'value' => (string) $record['lang'],
						),
					),
				);
			}
		}

		return array(
			'data' => $data,
			'done' => $done,
		);
	}
}