<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Auth;

use Unsupervised\Schedular\Val;

/**
 * Admin page (Students → Pending Students) for reviewing self-signup accounts:
 * approve a confirmed applicant into a full student, or reject (delete) them.
 * Only relevant while open registration is enabled.
 */
class RegistrationApprovalController {

	public const PAGE_SLUG    = 'us-pending-students';
	public const NONCE_ACTION = 'usc_registration_approval';

	public function __construct( private RegistrationMailer $mailer ) {}

	public function renderPage(): void {
		if ( ! current_user_can( RoleManager::CAP_MANAGE_STUDENTS ) ) {
			wp_die( esc_html__( 'You do not have permission to manage student registrations.', 'unsupervised-schedular' ) );
		}

		if ( isset( $_POST['usc_action'] ) && check_admin_referer( self::NONCE_ACTION ) ) {
			$this->handleAction();
		}

		$awaitingApproval     = [];
		$awaitingConfirmation = [];
		foreach ( $this->pendingUsers() as $user ) {
			if ( RegistrationStatus::emailConfirmed( (int) $user->ID ) ) {
				$awaitingApproval[] = $user;
			} else {
				$awaitingConfirmation[] = $user;
			}
		}

		include USC_PLUGIN_DIR . 'templates/admin/registrations.php';
	}

	/**
	 * Approve or reject the posted user. Approval clears the pending flags and
	 * emails the student; rejection emails them, then hard-deletes the account so
	 * the email is freed to re-apply.
	 */
	private function handleAction(): void {
		// Nonce is verified by the caller (renderPage) before this method runs.
		// phpcs:disable WordPress.Security.NonceVerification.Missing
		$action = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ?? '' ) ) );
		$userId = absint( Val::int( $_POST['user_id'] ?? 0 ) );
		// phpcs:enable WordPress.Security.NonceVerification.Missing

		if ( $userId <= 0 || ! RegistrationStatus::isAwaitingApproval( $userId ) ) {
			return;
		}

		if ( 'approve' === $action ) {
			RegistrationStatus::approve( $userId );
			$user = get_user_by( 'id', $userId );
			if ( $user instanceof \WP_User ) {
				$this->mailer->sendApproved( $user );
			}
			return;
		}

		if ( 'reject' === $action ) {
			$user  = get_user_by( 'id', $userId );
			$email = $user instanceof \WP_User ? (string) $user->user_email : '';
			if ( '' !== $email ) {
				$this->mailer->sendRejected( $email );
			}

			if ( ! function_exists( 'wp_delete_user' ) ) {
				require_once ABSPATH . 'wp-admin/includes/user.php';
			}
			wp_delete_user( $userId );
		}
	}

	/**
	 * Every account still awaiting approval (confirmed or not).
	 *
	 * @return list<\WP_User>
	 */
	private function pendingUsers(): array {
		return array_values(
			array_filter(
				get_users(
					[
						'meta_key' => RegistrationStatus::META_AWAITING_APPROVAL, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
					'meta_value'   => '1', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value
					'number'       => 500,
					'orderby'      => 'user_registered',
					'order'        => 'ASC',
					]
				),
				static fn( mixed $user ): bool => $user instanceof \WP_User
			)
		);
	}
}