<?php
/**
 * Atomic, blog-local Connector V2 enrollment lock.
 */

if (!defined('ABSPATH')) {
    exit;
}

class Akkedli_Enrollment_Lock
{
    const OPTION = 'akkedli_connector_v2_enrollment_lock';
    const TTL = 60;

    public static function acquire()
    {
        try {
            $owner = Akkedli_V2_Crypto::base64url_encode(random_bytes(24));
        } catch (Throwable $error) {
            unset($error);
            return false;
        }

        $lock = array('owner' => $owner, 'expires' => time() + self::TTL);
        if (add_option(self::OPTION, $lock, '', 'no')) {
            return $owner;
        }

        $current = get_option(self::OPTION, null);
        if (!is_array($current) || !isset($current['owner'], $current['expires']) || (int) $current['expires'] <= time()) {
            if (self::compare_and_delete($current) && add_option(self::OPTION, $lock, '', 'no')) {
                return $owner;
            }
        }

        unset($owner, $lock, $current);
        return false;
    }

    public static function release($owner)
    {
        $current = get_option(self::OPTION, null);
        if (!is_array($current) || !isset($current['owner']) || !is_string($current['owner'])
            || !is_string($owner) || !hash_equals($current['owner'], $owner)) {
            return false;
        }
        return self::compare_and_delete($current);
    }

    private static function compare_and_delete($expected)
    {
        global $wpdb;

        $serialized = maybe_serialize($expected);
        $deleted = $wpdb->query(
            $wpdb->prepare(
                "DELETE FROM {$wpdb->options} WHERE option_name = %s AND option_value = %s",
                self::OPTION,
                $serialized
            )
        );
        if (1 === $deleted) {
            wp_cache_delete(self::OPTION, 'options');
            return true;
        }
        return false;
    }
}