<?php
/**
 * Live progress for a running sync.
 *
 * @package SharelyAI
 */

namespace SharelyAI;

defined( 'ABSPATH' ) || exit;

/**
 * What a sync is doing right now, as JSON, for the status screen to poll.
 *
 * The screen used to reload itself every five seconds while a run was in
 * progress. That technically worked and read as broken: the page blinked, the
 * scroll position went, and between blinks nothing moved — so an administrator
 * watching it could not tell a slow sync from a stuck one.
 *
 * Polling a small endpoint instead lets the numbers tick up in place. There is
 * a second effect that matters more than it looks on a site without Action
 * Scheduler: each poll is a request to WordPress, and a request to WordPress is
 * what makes WP-Cron run the next batch. Watching the page helps it along.
 *
 * The screen is still rendered by PHP and still correct without JavaScript.
 * This only updates what is already on it, and reloads once at the end so the
 * finished state — the summary, the failures, the log, the cards — comes from
 * the server rather than being rebuilt here in two places.
 */
final class Progress {

	/**
	 * The admin-ajax action, which is also the nonce's name.
	 */
	public const ACTION = 'sharelyai_progress';

	/**
	 * Constructor.
	 *
	 * @param Connection $connection The connection being reported on.
	 */
	public function __construct( private Connection $connection ) {}

	/**
	 * Hooks the endpoint up.
	 *
	 * Only the logged-in variant: there is nothing here for a visitor, and
	 * `wp_ajax_nopriv_` would be an unauthenticated read of how much of this
	 * site has been sent where.
	 */
	public function register(): void {
		add_action( 'wp_ajax_' . self::ACTION, array( $this, 'handle' ) );
	}

	/**
	 * Answers one poll.
	 */
	public function handle(): void {
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( array( 'message' => __( 'You are not allowed to do that.', 'sharelyai' ) ), 403 );
		}
		check_ajax_referer( self::ACTION );
		wp_send_json_success( $this->state() );
	}

	/**
	 * Everything the screen shows that can change while a sync runs.
	 *
	 * Formatted here rather than in JavaScript: `number_format_i18n()` knows
	 * the site's locale and the browser does not know the site's locale.
	 *
	 * @return array<string, mixed>
	 */
	public function state(): array {
		if ( ! $this->connection->is_connected() ) {
			return array(
				'connected' => false,
				'running'   => false,
			);
		}

		$sync    = new Sync( $this->connection );
		$run     = $sync->run();
		$stats   = $sync->stats();
		$total   = (int) ( $run['total'] ?? 0 );
		$done    = (int) ( $run['done'] ?? 0 );
		$running = $sync->is_running();

		return array(
			'connected' => true,
			'running'   => $running,
			'run'       => array(
				'total'   => $total,
				'done'    => $done,
				'percent' => $total > 0 ? min( 100, (int) round( ( $done / $total ) * 100 ) ) : 0,
				'text'    => sprintf(
					/* translators: 1: entries done, 2: entries in total. */
					__( '%1$s of %2$s done.', 'sharelyai' ),
					number_format_i18n( $done ),
					number_format_i18n( $total )
				),
			),
			'scope'     => array(
				'in_scope' => number_format_i18n( $stats['in_scope'] ),
				'synced'   => number_format_i18n( $stats['synced'] ),
				'percent'  => $stats['in_scope'] > 0
					? min( 100, (int) round( ( $stats['synced'] / $stats['in_scope'] ) * 100 ) )
					: 0,
				'waiting'  => sprintf(
					/* translators: 1: entries waiting, 2: entries that failed. */
					__( '%1$s waiting · %2$s failed', 'sharelyai' ),
					number_format_i18n( $stats['queued'] ),
					number_format_i18n( $stats['failed'] )
				),
			),
			'recent'    => $this->recent( $sync ),
		);
	}

	/**
	 * The last few entries, newest first — the part that shows it is moving.
	 *
	 * @param Sync $sync The sync service.
	 *
	 * @return array<int, array{title:string, outcome:string, failed:bool}>
	 */
	private function recent( Sync $sync ): array {
		$recent = array();
		foreach ( array_slice( $sync->log(), 0, 5 ) as $event ) {
			$title    = (string) $event['title'];
			$recent[] = array(
				'title'   => '' !== $title ? $title : '#' . (int) $event['post_id'],
				'outcome' => Status::outcome_label( (string) $event['outcome'] ),
				'failed'  => 'failed' === $event['outcome'],
			);
		}
		return $recent;
	}
}