<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Auth;

use Unsupervised\Schedular\Val;

/**
 * Pure helper for splitting a student's dated rows into upcoming and past.
 */
class StudentSchedule {

	/**
	 * Partition rows (each with a `start_dt` string in `Y-m-d H:i:s`) relative to
	 * `$now`. Upcoming rows are sorted ascending, past rows descending. Rows
	 * without a usable `start_dt` fall into `past`.
	 *
	 * @param list<array<string, mixed>> $rows
	 * @return array{upcoming: list<array<string, mixed>>, past: list<array<string, mixed>>}
	 */
	public static function partition( array $rows, string $now ): array {
		$upcoming = [];
		$past     = [];

		foreach ( $rows as $row ) {
			$start = Val::string( $row['start_dt'] ?? '' );
			if ( '' !== $start && $start >= $now ) {
				$upcoming[] = $row;
			} else {
				$past[] = $row;
			}
		}

		usort( $upcoming, static fn( array $a, array $b ): int => strcmp( Val::string( $a['start_dt'] ?? '' ), Val::string( $b['start_dt'] ?? '' ) ) );
		usort( $past, static fn( array $a, array $b ): int => strcmp( Val::string( $b['start_dt'] ?? '' ), Val::string( $a['start_dt'] ?? '' ) ) );

		return [
			'upcoming' => $upcoming,
			'past'     => $past,
		];
	}
}