<?php

namespace classes;

use objects\logs_o;
use objects\passkeys_o;
use objects\subusers_o;
use objects\users_o;
use Throwable;
use traits\boolean_normalization_t;

require_once __DIR__ . '/../traits/boolean_normalization_t.php';

class account_deletion_service
{
    use boolean_normalization_t;

    public const CONFIRMATION_PHRASE = 'SLET MIN KONTO';
    public const POLICY_VERSION = '2026-07-20';
    public const MAX_RETRIES = 5;
    public const PROCESSING_LEASE_SECONDS = 900;
    public const LEGACY_SESSION_CUTOFF = '2026-07-20 14:45:20';
    private const MAX_CREDENTIAL_ATTEMPTS = 4;

    /** @var array<string, bool> */
    private static array $tableExistsCache = [];
    /** @var array<string, array<int, string>> */
    private static array $columnsCache = [];

    public function __construct()
    {
        $schema = account_deletion_schema_bootstrap::check();
        if (!$schema['ready']) {
            throw new \RuntimeException('Account deletion schema is not ready; run the explicit schema CLI.');
        }
        self::$tableExistsCache['account_deletion_requests'] = true;
        unset(self::$columnsCache['users'], self::$columnsCache['subusers']);
    }

    public static function apiEnabled(): bool
    {
        return self::featureEnabled('api_enabled');
    }

    public static function workerEnabled(): bool
    {
        return self::featureEnabled('worker_enabled');
    }

    private static function featureEnabled(string $variable): bool
    {
        global $db;
        if (!isset($db) || !is_object($db) || !method_exists($db, 'query')) return false;
        try {
            $module = $db->escape_string('account_deletion');
            $variable = $db->escape_string($variable);
            $result = $db->query("SELECT value FROM module_config WHERE module = '$module' AND variable = '$variable' LIMIT 1");
            if ($result === false || $result->num_rows === 0) return false;
            $row = $result->fetch_assoc();
            return self::normalizeBoolean((string)($row['value'] ?? ''));
        } catch (Throwable) {
            return false;
        }
    }

    public function passkeyChallenge(array $principal): array
    {
        if ($this->principalHasPassword($principal)) {
            throw new account_deletion_http_exception('Passkey reauthentication is only required for passwordless accounts', 400);
        }
        global $db;
        $id = (int)$principal['id'];
        $isSubuser = $principal['type'] === 'subuser' ? 1 : 0;
        $result = $db->query("SELECT credential_id, transports FROM passkeys WHERE user_id = $id AND is_subuser = $isSubuser AND deleted_at IS NULL");
        if ($result === false) throw new \RuntimeException('Unable to load deletion passkeys.');
        $rows = $db->fetch_all($result);
        if ($rows === []) throw new account_deletion_http_exception('No active passkey is available', 403);
        $token = bin2hex(random_bytes(32));
        $this->execute("INSERT INTO tokens (user_id, token, type) VALUES ($id, " . self::sql($token) . ", 'ACCOUNT_DELETION_PASSKEY_CHALLENGE')", 'Unable to persist deletion passkey challenge.');
        $originHost = parse_url((string)($_SERVER['HTTP_ORIGIN'] ?? ''), PHP_URL_HOST);
        $httpHost = isset($_SERVER['HTTP_HOST']) ? explode(':', (string)$_SERVER['HTTP_HOST'])[0] : null;
        $challenge = rtrim(strtr(base64_encode((string)hex2bin($token)), '+/', '-_'), '=');
        return ['challenge_token' => $token, 'publicKey' => [
            'challenge' => $challenge,
            'rpId' => $originHost ?: $httpHost ?: ($_SERVER['SERVER_NAME'] ?? 'truckwash.io'),
            'timeout' => 60000, 'userVerification' => 'required',
            'allowCredentials' => array_map(static function (array $row): array {
                $transports = json_decode((string)($row['transports'] ?? '[]'), true);
                return ['type' => 'public-key', 'id' => (string)$row['credential_id'], 'transports' => is_array($transports) ? $transports : []];
            }, $rows),
        ]];
    }

    /**
     * Authentication hot-path guard. Missing pre-deployment schema is treated as no block;
     * once the deletion schema exists, either an active request or deleted_at blocks access.
     */
    public static function principalIsBlocked(string $principalType, int $principalId): bool
    {
        if (!in_array($principalType, ['customer', 'subuser'], true) || $principalId <= 0) {
            return true;
        }

        global $db;
        if (!isset($db) || !is_object($db) || !method_exists($db, 'query')) {
            return false;
        }

        if (self::tableExists('account_deletion_requests')) {
            $key = self::sql($principalType . ':' . $principalId);
            $result = $db->query(
                "SELECT id FROM account_deletion_requests
                 WHERE active_principal_key = $key
                   AND status IN ('requested', 'processing', 'failed', 'manual_review')
                 LIMIT 1"
            );
            if ($result === false) {
                throw new \RuntimeException('Unable to inspect active account deletion requests.');
            }
            if ($result->num_rows > 0) {
                return true;
            }
        }

        $table = $principalType === 'customer' ? 'users' : 'subusers';
        if (!self::tableExists($table) || !in_array('deleted_at', self::columns($table), true)) {
            return false;
        }

        $result = $db->query("SELECT deleted_at FROM `$table` WHERE id = $principalId LIMIT 1");
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect principal deletion state.');
        }
        if ($result->num_rows === 0) {
            return false;
        }

        $row = $result->fetch_assoc();
        return ($row['deleted_at'] ?? null) !== null;
    }

    /** @return array{type:string,id:int,customer_number:?int,object:users_o|subusers_o,token:string,email:?string,name:string} */
    public function currentPrincipal(): array
    {
        $authentication = new authentication();
        $user = $authentication->get_user();
        if ($user !== false) {
            $bearerToken = $this->bearerToken();
            $this->rejectImpersonationToken($bearerToken);
            $customerNumber = (int)$user->customer_number->value();
            if ($customerNumber <= 0) {
                throw new account_deletion_http_exception(
                    'Account deletion is only available to customer accounts',
                    403
                );
            }
            return [
                'type' => 'customer',
                'id' => (int)$user->id,
                'customer_number' => $customerNumber,
                'object' => $user,
                'token' => $bearerToken,
                'email' => $this->nullableString($user->email->value()),
                'name' => $this->nullableString($user->display_name->value()) ?? 'Kunde',
            ];
        }

        $subuser = $authentication->get_subuser();
        if ($subuser !== false) {
            return [
                'type' => 'subuser',
                'id' => (int)$subuser->id,
                'customer_number' => null,
                'object' => $subuser,
                'token' => $this->bearerToken(),
                'email' => $this->nullableString($subuser->email->value()),
                'name' => $this->nullableString($subuser->name->value()) ?? 'Chauffør',
            ];
        }

        throw new account_deletion_http_exception('Unauthorized', 401);
    }

    public function state(array $principal): array
    {
        $row = $this->activeRequest((string)$principal['type'], (int)$principal['id']);
        return $this->statePayload($principal, $row);
    }

    public function request(array $principal, array $input, ?string $ip, ?string $userAgent): array
    {
        $this->validateConfirmation($input);
        $throttleKey = $this->recordCredentialAttempt($principal, $ip);
        $this->verifyCredentials($principal, $input);
        $this->clearCredentialAttempts($throttleKey);

        $existing = $this->activeRequest((string)$principal['type'], (int)$principal['id']);
        if ($existing !== null) {
            return $this->acceptedPayload($existing);
        }

        global $db;
        $connection = $db->conn();
        $connection->begin_transaction();
        try {
            $existing = $this->activeRequest((string)$principal['type'], (int)$principal['id'], true);
            if ($existing !== null) {
                $connection->commit();
                return $this->acceptedPayload($existing);
            }

            $requestId = self::uuidV4();
            $principalType = (string)$principal['type'];
            $principalId = (int)$principal['id'];
            $customerNumber = $principal['customer_number'] !== null ? (int)$principal['customer_number'] : null;
            $retained = json_encode($this->retainedDataCategories($principalType), JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
            if (!is_string($retained)) {
                throw new \RuntimeException('Could not encode retained-data categories.');
            }
            $now = date('Y-m-d H:i:s');
            $activeKey = $principalType . ':' . $principalId;

            $sql = "INSERT INTO account_deletion_requests
                    (request_id, principal_type, principal_id, customer_number_snapshot,
                     active_principal_key, status, policy_version, retained_data_json,
                     request_ip, request_user_agent, requested_at, next_attempt_at)
                    VALUES ("
                . self::sql($requestId) . ', '
                . self::sql($principalType) . ', '
                . $principalId . ', '
                . ($customerNumber !== null ? (string)$customerNumber : 'NULL') . ', '
                . self::sql($activeKey) . ", 'requested', "
                . self::sql(self::POLICY_VERSION) . ', '
                . self::sql($retained) . ', '
                . ($ip !== null ? self::sql(substr($ip, 0, 45)) : 'NULL') . ', '
                . ($userAgent !== null ? self::sql(substr($userAgent, 0, 512)) : 'NULL') . ', '
                . self::sql($now) . ', '
                . self::sql($now) . ')';
            $this->execute($sql, 'Unable to create account deletion request.');

            $this->blockPrincipalImmediately($principalType, $principalId, $customerNumber, $now);
            $this->enqueueOutbox($requestId, 'requested', ['principal_type' => $principalType, 'principal_id' => $principalId]);
            $connection->commit();
        } catch (Throwable $throwable) {
            $connection->rollback();
            $existing = $this->activeRequest((string)$principal['type'], (int)$principal['id']);
            if ($existing !== null) {
                return $this->acceptedPayload($existing);
            }
            throw $throwable;
        }

        $this->revokeCaches($principal);
        $this->sendRequestedNotification($principal, $requestId);

        $created = $this->requestByPublicId($requestId);
        if ($created === null) {
            throw new \RuntimeException('Account deletion request was not persisted.');
        }
        return $this->acceptedPayload($created);
    }

    /** @return array{processed:int,completed:int,failed:int} */
    public function processPending(int $limit = 25): array
    {
        $limit = max(1, min(100, $limit));
        global $db;
        $now = self::sql(date('Y-m-d H:i:s'));
        $staleBefore = self::sql(date('Y-m-d H:i:s', time() - self::PROCESSING_LEASE_SECONDS));
        $result = $db->query(
            "SELECT * FROM account_deletion_requests
             WHERE (
                 (status IN ('requested', 'failed')
                  AND retry_count < " . self::MAX_RETRIES . "
                  AND (next_attempt_at IS NULL OR next_attempt_at <= $now))
                 OR
                 (status = 'processing' AND (processing_at IS NULL OR processing_at <= $staleBefore))
             )
             ORDER BY requested_at ASC, id ASC
             LIMIT $limit"
        );
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect queued account deletion requests.');
        }
        $rows = $db->fetch_all($result);
        $summary = ['processed' => 0, 'completed' => 0, 'failed' => 0];

        foreach ($rows as $row) {
            $id = (int)($row['id'] ?? 0);
            if ($id <= 0 || !$this->claim($id)) {
                continue;
            }
            $summary['processed']++;
            try {
                $this->complete($row);
                $summary['completed']++;
            } catch (Throwable $throwable) {
                $this->recordFailure($id, (int)($row['retry_count'] ?? 0), $throwable);
                $summary['failed']++;
            }
        }

        $this->dispatchOutbox(50);
        return $summary;
    }

    private function dispatchOutbox(int $limit): void
    {
        global $db;
        $limit = max(1, min(100, $limit));
        $result = $db->query("SELECT * FROM account_deletion_outbox WHERE (status = 'pending' AND available_at <= NOW()) OR (status = 'processing' AND processing_at <= DATE_SUB(NOW(), INTERVAL 15 MINUTE)) ORDER BY id ASC LIMIT $limit");
        if ($result === false) throw new \RuntimeException('Unable to inspect account deletion outbox.');
        foreach ($db->fetch_all($result) as $event) {
            $id = (int)($event['id'] ?? 0);
            if ($id <= 0) continue;
            $this->execute("UPDATE account_deletion_outbox SET status = 'processing', processing_at = NOW() WHERE id = $id AND (status = 'pending' OR (status = 'processing' AND processing_at <= DATE_SUB(NOW(), INTERVAL 15 MINUTE)))", 'Unable to claim deletion outbox event.');
            if ((int)$db->conn()->affected_rows !== 1) continue;
            $connection = $db->conn();
            $connection->begin_transaction();
            try {
                $payload = json_decode((string)$event['payload_json'], true);
                $actor = is_array($payload) ? (int)($payload['principal_id'] ?? 0) : 0;
                $action = 'ACCOUNT_DELETION_' . strtoupper((string)$event['event_type']);
                $this->execute(
                    "INSERT INTO logs (module, department, type, user_id, action, message, created_at, updated_at) VALUES "
                    . "('account_deletion', 'global', 1, $actor, " . self::sql($action) . ', '
                    . self::sql('request:' . (string)$event['request_id']) . ', NOW(), NOW())',
                    'Unable to persist account deletion audit event.'
                );
                $this->execute("UPDATE account_deletion_outbox SET status = 'delivered', processing_at = NULL, delivered_at = NOW(), last_error = NULL WHERE id = $id AND status = 'processing'", 'Unable to acknowledge deletion outbox event.');
                $connection->commit();
            } catch (Throwable $throwable) {
                $connection->rollback();
                $error = substr((new \ReflectionClass($throwable))->getShortName(), 0, 191);
                $this->execute("UPDATE account_deletion_outbox SET status = 'pending', processing_at = NULL, attempts = attempts + 1, available_at = DATE_ADD(NOW(), INTERVAL 5 MINUTE), last_error = " . self::sql($error) . " WHERE id = $id", 'Unable to reschedule deletion outbox event.');
            }
        }
    }

    private function validateConfirmation(array $input): void
    {
        if (($input['confirmation'] ?? null) !== self::CONFIRMATION_PHRASE) {
            throw new account_deletion_http_exception('Confirmation phrase does not match', 400);
        }
        if (($input['acknowledge_legal_retention'] ?? null) !== true) {
            throw new account_deletion_http_exception('Legal retention acknowledgement is required', 400);
        }
    }

    private function verifyCredentials(array $principal, array $input): void
    {
        $object = $principal['object'];
        $password = $input['password'] ?? null;
        $passwordMatches = false;
        if ($object instanceof users_o) {
            $hash = $object->getPassword();
            if (is_string($hash) && $hash !== '') {
                if (!is_string($password) || $password === '') {
                    throw new account_deletion_http_exception('Password is required', 400);
                }
                try {
                    $passwordMatches = $object->passwordMatches($password);
                } catch (Throwable) {
                    $passwordMatches = false;
                }
            } else {
                $passwordMatches = $this->verifyDeletionPasskey($principal, $input);
            }
        } elseif ($object instanceof subusers_o) {
            $hash = $object->password->value();
            if (is_string($hash) && $hash !== '') {
                if (!is_string($password) || $password === '') {
                    throw new account_deletion_http_exception('Password is required', 400);
                }
                $passwordMatches = password_verify($password, $hash);
            } else {
                $passwordMatches = $this->verifyDeletionPasskey($principal, $input);
            }
        }

        if (!$passwordMatches) {
            throw new account_deletion_http_exception('Invalid credentials', 401);
        }

        if ($object->isTwoFactorEnabled()) {
            $code = $input['two_factor_code'] ?? null;
            if (!is_string($code) || trim($code) === '') {
                throw new account_deletion_http_exception('Two-factor code is required', 400);
            }
            if (!(new authentication())->verify_2fa_code($object, $code)) {
                throw new account_deletion_http_exception('Invalid two-factor code', 401);
            }
        }
    }

    private function verifyDeletionPasskey(array $principal, array $input): bool
    {
        global $db;
        $challenge = $input['passkey_challenge_token'] ?? null;
        $credential = $input['passkey_credential'] ?? null;
        if (!is_string($challenge) || strlen($challenge) !== 64 || $credential === null) {
            throw new account_deletion_http_exception('A fresh deletion passkey assertion is required', 400);
        }
        $credentialJson = is_string($credential) ? $credential : json_encode($credential, JSON_UNESCAPED_SLASHES);
        $credentialArray = is_array($credential) ? $credential : json_decode((string)$credentialJson, true);
        $credentialId = is_array($credentialArray) ? ($credentialArray['id'] ?? $credentialArray['rawId'] ?? null) : null;
        $id = (int)$principal['id'];
        $challengeSql = self::sql($challenge);
        $result = $db->query("SELECT id FROM tokens WHERE token = $challengeSql AND user_id = $id AND type = 'ACCOUNT_DELETION_PASSKEY_CHALLENGE' AND created_at >= DATE_SUB(NOW(), INTERVAL 5 MINUTE) LIMIT 1");
        if ($result === false) throw new \RuntimeException('Unable to inspect deletion passkey challenge.');
        $this->execute("DELETE FROM tokens WHERE token = $challengeSql AND type = 'ACCOUNT_DELETION_PASSKEY_CHALLENGE'", 'Unable to consume deletion passkey challenge.');
        if ($result->num_rows === 0 || (int)$db->conn()->affected_rows !== 1 || !is_string($credentialId) || !is_string($credentialJson)) return false;
        $passkey = (new passkeys_o())->findByCredentialId($credentialId, $id);
        if ($passkey === null || (bool)$passkey->is_subuser->value() !== ($principal['type'] === 'subuser')) return false;
        $host = parse_url((string)($_SERVER['HTTP_ORIGIN'] ?? ''), PHP_URL_HOST) ?: ($_SERVER['SERVER_NAME'] ?? 'localhost');
        return (new webauthn())->verifyAssertion($credentialJson, $challenge, $passkey, $host);
    }

    private function recordCredentialAttempt(array $principal, ?string $ip): string
    {
        $key = hash(
            'sha256',
            (string)$principal['type'] . ':' . (int)$principal['id'] . ':' . trim((string)$ip)
        );
        $keySql = self::sql($key);
        $maximumAttempts = self::MAX_CREDENTIAL_ATTEMPTS;
        $this->execute(
            "INSERT INTO account_deletion_credential_attempts (throttle_key, attempt_count, window_started_at)
             VALUES ($keySql, 1, NOW()) ON DUPLICATE KEY UPDATE
             blocked_until = IF(
                 window_started_at < DATE_SUB(NOW(), INTERVAL 15 MINUTE),
                 NULL,
                 IF(attempt_count + 1 >= $maximumAttempts, DATE_ADD(NOW(), INTERVAL 15 MINUTE), blocked_until)
             ),
             attempt_count = IF(window_started_at < DATE_SUB(NOW(), INTERVAL 15 MINUTE), 1, attempt_count + 1),
             window_started_at = IF(window_started_at < DATE_SUB(NOW(), INTERVAL 15 MINUTE), NOW(), window_started_at)",
            'Unable to record deletion credential attempt.'
        );
        global $db;
        $result = $db->query("SELECT attempt_count, blocked_until FROM account_deletion_credential_attempts WHERE throttle_key = $keySql LIMIT 1");
        if ($result === false || $result->num_rows !== 1) throw new \RuntimeException('Unable to enforce deletion credential throttle.');
        $row = $result->fetch_assoc();
        if ((int)$row['attempt_count'] >= self::MAX_CREDENTIAL_ATTEMPTS || (($row['blocked_until'] ?? null) !== null && strtotime((string)$row['blocked_until']) > time())) {
            throw new account_deletion_http_exception('Too many deletion confirmation attempts', 429);
        }
        return $key;
    }

    private function clearCredentialAttempts(string $key): void
    {
        $this->execute('DELETE FROM account_deletion_credential_attempts WHERE throttle_key = ' . self::sql($key), 'Unable to clear deletion credential attempts.');
    }

    private function blockPrincipalImmediately(string $type, int $id, ?int $customerNumber, string $now): void
    {
        global $db;
        if ($type === 'customer') {
            if (self::tableExists('limited_backoffice_employees')) {
                $employeeLock = $db->query(
                    "SELECT user_id FROM limited_backoffice_employees
                     WHERE user_id = $id LIMIT 1 FOR UPDATE"
                );
                if ($employeeLock === false) {
                    throw new \RuntimeException('Unable to lock deleted employee.');
                }
            }
            $this->updateExistingColumns('users', $id, ['deleted_at' => $now]);
            if (self::tableExists('limited_backoffice_login_grants')) {
                $this->execute(
                    "UPDATE limited_backoffice_login_grants
                     SET revoked_at = COALESCE(revoked_at, " . self::sql($now) . ")
                     WHERE (target_user_id = $id OR actor_user_id = $id)
                       AND consumed_at IS NULL",
                    'Unable to revoke deleted principal login grants.'
                );
            }
            $this->deleteTokensForPrincipal('customer', $id);
        } else {
            $this->updateExistingColumns('subusers', $id, ['suspended_at' => $now, 'deleted_at' => $now]);
            $this->execute(
                "UPDATE subuser_grants
                 SET enabled = 0, deleted_at = COALESCE(deleted_at, " . self::sql($now) . "), note = NULL
                 WHERE subuser = $id", 'Unable to revoke deleted subuser grants.'
            );
            $this->deleteTokensForPrincipal('subuser', $id);
        }

        if (self::tableExists('passkeys')) {
            $this->execute(
                "UPDATE passkeys SET deleted_at = COALESCE(deleted_at, " . self::sql($now) . ")
                 WHERE user_id = $id AND is_subuser = " . ($type === 'subuser' ? '1' : '0'),
                'Unable to revoke deleted principal passkeys.'
            );
        }
    }

    private function deleteTokensForPrincipal(string $type, int $id): void
    {
        global $db;
        $types = $type === 'customer'
            ? "'AUTH_TOKEN', '2FA_VERIFICATION_USER', 'PASSKEY_CHALLENGE'"
            : "'AUTH_TOKEN_SUBUSER', '2FA_VERIFICATION_SUBUSER', 'PASSKEY_CHALLENGE'";
        $typeWhere = "type IN ($types)";
        if ($type === 'customer') {
            $typeWhere = "($typeWhere OR LEFT(type, 25) = 'AUTH_TOKEN_IMPERSONATION:')";
        }
        $result = $db->query("SELECT token FROM tokens WHERE user_id = $id AND $typeWhere");
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect principal credentials.');
        }
        $tokens = $db->fetch_all($result);
        $this->execute("DELETE FROM tokens WHERE user_id = $id AND $typeWhere", 'Unable to revoke deleted principal tokens.');
        if (!defined('redis')) {
            return;
        }
        foreach ($tokens as $tokenRow) {
            $token = (string)($tokenRow['token'] ?? '');
            if ($token === '') {
                continue;
            }
            try {
                constant('redis')->clear_token($token)->clear_auth_session($token);
                constant('redis')->delete('passkey_challenge_principal:' . $token);
            } catch (Throwable) {
            }
        }
    }

    private function revokeCaches(array $principal): void
    {
        if (!defined('redis')) {
            return;
        }

        $redis = constant('redis');
        $id = (int)$principal['id'];
        $token = (string)($principal['token'] ?? '');
        try {
            if ($token !== '') {
                $redis->clear_token($token)->clear_auth_session($token);
                (new subusers_o())->invalidateSessionToken($token);
            }
            if ($principal['type'] === 'customer') {
                $customerNumber = (int)($principal['customer_number'] ?? 0);
                if ($customerNumber > 0) {
                    $redis->clear_user_id_from_customer_number($customerNumber);
                }
                $redis->clear_customer_number_from_user_id($id);
            } else {
                foreach ($redis->get_keys('*subuser_sessions_session_token:*') as $key) {
                    if ((int)$redis->get((string)$key) === $id) {
                        $redis->delete((string)$key);
                    }
                }
                foreach ($redis->get_keys('*subuser_setup_token*') as $key) {
                    $key = (string)$key;
                    if (str_ends_with($key, ':' . $id) || (int)$redis->get($key) === $id) {
                        $redis->delete($key);
                    }
                }
            }
            foreach ($redis->get_keys('obj_prop:' . ($principal['type'] === 'customer' ? 'users' : 'subusers') . ':' . $id . ':*') as $key) {
                $redis->delete((string)$key);
            }
        } catch (Throwable) {
            // Database token deletion and auth guards remain authoritative.
        }
    }

    private function claim(int $id): bool
    {
        global $db;
        $now = self::sql(date('Y-m-d H:i:s'));
        $staleBefore = self::sql(date('Y-m-d H:i:s', time() - self::PROCESSING_LEASE_SECONDS));
        $this->execute(
            "UPDATE account_deletion_requests
             SET status = 'processing', processing_at = $now, failure_code = NULL
             WHERE id = $id AND (
                 status IN ('requested', 'failed')
                 OR (status = 'processing' AND (processing_at IS NULL OR processing_at <= $staleBefore))
             )", 'Unable to claim account deletion request.'
        );
        return (int)$db->conn()->affected_rows === 1;
    }

    private function complete(array $row): void
    {
        global $db;
        $id = (int)$row['id'];
        $principalType = (string)$row['principal_type'];
        $principalId = (int)$row['principal_id'];
        $email = $this->principalEmail($principalType, $principalId);
        $name = $this->principalName($principalType, $principalId);

        $connection = $db->conn();
        $connection->begin_transaction();
        try {
            $now = date('Y-m-d H:i:s');
            if ($principalType === 'customer') {
                $this->updateExistingColumns('users', $principalId, [
                    'display_name' => 'Slettet konto',
                    'email' => null,
                    'phone_country_code' => null,
                    'phone' => null,
                    'password' => null,
                    'xlvask_customer_id' => null,
                    'sms_notifications_enabled' => 0,
                    'email_notifications_enabled' => 0,
                    'wash_certificate_email' => null,
                    'two_factor_secret' => null,
                    'two_factor_enabled' => 0,
                    'deleted_at' => $now,
                ]);
                $this->deleteIfColumnsExist('user_key_value_pairs', ['user_id' => $principalId]);
                $this->deleteIfColumnsExist('customer_attributes', ['user_id' => $principalId]);
            } else {
                $this->updateExistingColumns('subusers', $principalId, [
                    'username' => null,
                    'password' => null,
                    'name' => 'Slettet chauffør',
                    'email' => null,
                    'email_verified_at' => null,
                    'phone_country_code' => null,
                    'phone' => null,
                    'phone_verified_at' => null,
                    'two_factor_secret' => null,
                    'two_factor_enabled' => 0,
                    'suspended_at' => $now,
                    'deleted_at' => $now,
                ]);
            }

            $this->softDeleteAttachments($principalType, $principalId, $now);
            $this->deleteSessionActivity($principalType, $principalId);
            $this->execute(
                "UPDATE account_deletion_requests
                 SET status = 'completed', active_principal_key = NULL,
                     completed_at = " . self::sql($now) . ", next_attempt_at = NULL, failure_code = NULL
                 WHERE id = $id AND status = 'processing'", 'Unable to complete account deletion request.'
            );
            if ((int)$db->conn()->affected_rows !== 1) throw new \RuntimeException('Account deletion completion lease was lost.');
            $this->enqueueOutbox((string)$row['request_id'], 'completed', ['principal_type' => $principalType, 'principal_id' => $principalId]);
            $connection->commit();
        } catch (Throwable $throwable) {
            $connection->rollback();
            throw $throwable;
        }

        $principal = [
            'type' => $principalType,
            'id' => $principalId,
            'customer_number' => $row['customer_number_snapshot'] !== null ? (int)$row['customer_number_snapshot'] : null,
            'token' => '',
        ];
        $this->revokeCaches($principal);
        $this->sendCompletedNotification($email, $name, (string)$row['request_id']);
    }

    private function recordFailure(int $id, int $previousRetries, Throwable $throwable): void
    {
        global $db;
        $retryCount = $previousRetries + 1;
        $delay = min(86400, 300 * (2 ** max(0, $retryCount - 1)));
        $nextAttempt = $retryCount >= self::MAX_RETRIES ? null : date('Y-m-d H:i:s', time() + $delay);
        $failureCode = substr((new \ReflectionClass($throwable))->getShortName(), 0, 191);
        $nextAttemptSql = $nextAttempt !== null ? self::sql($nextAttempt) : 'NULL';
        $terminal = $retryCount >= self::MAX_RETRIES;
        $status = $terminal ? 'manual_review' : 'failed';
        $connection = $db->conn();
        $connection->begin_transaction();
        try {
            $this->execute(
                "UPDATE account_deletion_requests SET status = " . self::sql($status) . ", retry_count = $retryCount,
                 failure_code = " . self::sql($failureCode) . ", next_attempt_at = $nextAttemptSql,
                 manual_review_required_at = " . ($terminal ? 'NOW()' : 'NULL') . " WHERE id = $id",
                'Unable to persist account deletion failure.'
            );
            if ($terminal) {
                $result = $db->query("SELECT request_id FROM account_deletion_requests WHERE id = $id LIMIT 1");
                if ($result === false || $result->num_rows !== 1) throw new \RuntimeException('Unable to identify terminal deletion failure.');
                $failureRow = $result->fetch_assoc();
                $this->enqueueOutbox((string)$failureRow['request_id'], 'manual_review_required', ['failure_code' => $failureCode]);
            }
            $connection->commit();
        } catch (Throwable $failure) {
            $connection->rollback();
            throw $failure;
        }
        $this->auditRaw('ACCOUNT_DELETION_FAILED', 0, 'request_row:' . $id . ';failure:' . $failureCode);
        if ($terminal) {
            $message = 'request_row:' . $id . ';failure:' . $failureCode . ';action:manual_support_review';
            $this->auditRaw('ACCOUNT_DELETION_REQUIRES_SUPPORT', 0, $message);
            error_log('[account-deletion] Terminal failure requires support review: ' . $message);
        }
    }

    private function activeRequest(string $type, int $id, bool $forUpdate = false): ?array
    {
        global $db;
        $key = self::sql($type . ':' . $id);
        $result = $db->query(
            "SELECT * FROM account_deletion_requests
             WHERE active_principal_key = $key
             LIMIT 1" . ($forUpdate ? ' FOR UPDATE' : '')
        );
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect active account deletion requests.');
        }
        if ($result->num_rows === 0) {
            return null;
        }
        return $result->fetch_assoc() ?: null;
    }

    private function requestByPublicId(string $requestId): ?array
    {
        global $db;
        $result = $db->query(
            'SELECT * FROM account_deletion_requests WHERE request_id = ' . self::sql($requestId) . ' LIMIT 1'
        );
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect account deletion request state.');
        }
        if ($result->num_rows === 0) {
            return null;
        }
        return $result->fetch_assoc() ?: null;
    }

    private function statePayload(array $principal, ?array $row): array
    {
        $status = $row !== null ? (string)$row['status'] : 'available';
        return [
            'principal_type' => $principal['type'],
            'status' => $status,
            'confirmation_phrase' => self::CONFIRMATION_PHRASE,
            'password_required' => $this->principalHasPassword($principal),
            'two_factor_required' => (bool)$principal['object']->isTwoFactorEnabled(),
            'access_effect' => $principal['type'] === 'customer'
                ? 'Din loginidentitet lukkes straks. Andre loginidentiteter og virksomhedens historiske data bevares.'
                : 'Din chaufførkonto lukkes straks, og alle dine virksomhedsadgange deaktiveres.',
            'retained_data_categories' => $this->retainedDataCategories((string)$principal['type']),
            'privacy_policy_version' => self::POLICY_VERSION,
            'request_id' => $row['request_id'] ?? null,
            'requested_at' => $row['requested_at'] ?? null,
        ];
    }

    private function principalHasPassword(array $principal): bool
    {
        $object = $principal['object'];
        if ($object instanceof users_o) {
            return $object->hasPassword();
        }
        $password = $object->password->value();
        return is_string($password) && trim($password) !== '';
    }

    private function acceptedPayload(array $row): array
    {
        $retained = json_decode((string)($row['retained_data_json'] ?? '[]'), true);
        return [
            'request_id' => (string)$row['request_id'],
            'status' => (string)$row['status'],
            'requested_at' => (string)$row['requested_at'],
            'access_revoked' => true,
            'retained_data_categories' => is_array($retained) ? array_values($retained) : [],
        ];
    }

    /** @return array<int, string> */
    private function retainedDataCategories(string $principalType): array
    {
        $categories = [
            'invoices_payments_accounting',
            'orders_wash_history',
            'security_audit_logs',
            'legal_obligations',
        ];
        if ($principalType === 'customer') {
            $categories[] = 'customer_reference';
        } else {
            $categories[] = 'driver_reference';
        }
        return $categories;
    }

    private function updateExistingColumns(string $table, int $id, array $updates): void
    {
        global $db;
        $columns = self::columns($table);
        $set = [];
        foreach ($updates as $column => $value) {
            if (!in_array($column, $columns, true)) {
                continue;
            }
            $set[] = '`' . $column . '` = ' . self::valueSql($value);
        }
        if ($set !== []) {
            $this->execute("UPDATE `$table` SET " . implode(', ', $set) . " WHERE id = $id", "Unable to update deletion principal in $table.");
        }
    }

    private function deleteIfColumnsExist(string $table, array $conditions): void
    {
        if (!self::tableExists($table)) {
            return;
        }
        $columns = self::columns($table);
        foreach (array_keys($conditions) as $column) {
            if (!in_array($column, $columns, true)) {
                return;
            }
        }
        global $db;
        $where = [];
        foreach ($conditions as $column => $value) {
            $where[] = '`' . $column . '` = ' . self::valueSql($value);
        }
        $this->execute("DELETE FROM `$table` WHERE " . implode(' AND ', $where), "Unable to delete identity-owned data from $table.");
    }

    private function softDeleteAttachments(string $principalType, int $principalId, string $now): void
    {
        if (!self::tableExists('object_attachments')) {
            return;
        }
        $columns = self::columns('object_attachments');
        if (!array_diff(['object_type', 'object_id', 'content', 'deleted_at'], $columns)) {
            global $db;
            $objectType = $principalType === 'customer' ? 'users' : 'subusers';
            $this->execute(
                "UPDATE object_attachments SET deleted_at = COALESCE(deleted_at, " . self::sql($now) . '), content = NULL'
                . ' WHERE object_type = ' . self::sql($objectType) . " AND object_id = $principalId", 'Unable to delete identity attachments.'
            );
        }
    }

    private function deleteSessionActivity(string $principalType, int $principalId): void
    {
        if (!self::tableExists('system_session_activity')) {
            return;
        }
        $columns = self::columns('system_session_activity');
        if (!array_diff(['session_kind', 'principal_id'], $columns)) {
            global $db;
            $sessionKind = $principalType === 'customer' ? 'user' : 'subuser';
            $this->execute(
                'DELETE FROM system_session_activity WHERE session_kind = ' . self::sql($sessionKind)
                . " AND principal_id = $principalId", 'Unable to delete identity session activity.'
            );
        }
    }

    private function principalEmail(string $type, int $id): ?string
    {
        return $this->principalField($type, $id, 'email');
    }

    private function principalName(string $type, int $id): string
    {
        $field = $type === 'customer' ? 'display_name' : 'name';
        return $this->principalField($type, $id, $field) ?? ($type === 'customer' ? 'Kunde' : 'Chauffør');
    }

    private function principalField(string $type, int $id, string $field): ?string
    {
        $table = $type === 'customer' ? 'users' : 'subusers';
        if (!in_array($field, self::columns($table), true)) {
            return null;
        }
        global $db;
        $result = $db->query("SELECT `$field` FROM `$table` WHERE id = $id LIMIT 1");
        if ($result === false || $result->num_rows === 0) {
            return null;
        }
        $row = $result->fetch_assoc();
        return $this->nullableString($row[$field] ?? null);
    }

    private function sendRequestedNotification(array $principal, string $requestId): void
    {
        $email = $principal['email'] ?? null;
        if (!is_string($email) || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
            return;
        }
        try {
            (new email())->sendEmail(
                $email,
                (string)$principal['name'],
                'Vi har modtaget din anmodning om kontosletning',
                '<p>Din adgang er nu lukket, og anmodningen behandles.</p><p>Reference: '
                    . htmlspecialchars($requestId, ENT_QUOTES, 'UTF-8') . '</p>'
            );
        } catch (Throwable $throwable) {
            $this->auditRaw('ACCOUNT_DELETION_NOTIFICATION_FAILED', (int)$principal['id'], 'requested');
        }
    }

    private function sendCompletedNotification(?string $email, string $name, string $requestId): void
    {
        if ($email === null || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
            return;
        }
        try {
            (new email())->sendEmail(
                $email,
                $name,
                'Din kontosletning er gennemført',
                '<p>Dine personlige kontooplysninger er anonymiseret. Lovpligtige historiske data opbevares som beskrevet i privatlivspolitikken.</p><p>Reference: '
                    . htmlspecialchars($requestId, ENT_QUOTES, 'UTF-8') . '</p>'
            );
        } catch (Throwable) {
            $this->auditRaw('ACCOUNT_DELETION_NOTIFICATION_FAILED', 0, 'completed');
        }
    }

    private function auditRaw(string $action, int $actorId, string $message): void
    {
        try {
            (new logs_o())->add('account_deletion', 'global', 1, $actorId, $action, $message);
        } catch (Throwable) {
        }
    }

    private function enqueueOutbox(string $requestId, string $eventType, array $payload): void
    {
        $json = json_encode($payload, JSON_UNESCAPED_SLASHES);
        if (!is_string($json)) throw new \RuntimeException('Unable to encode deletion outbox event.');
        $this->execute(
            'INSERT INTO account_deletion_outbox (request_id, event_type, payload_json, available_at) VALUES ('
            . self::sql($requestId) . ', ' . self::sql($eventType) . ', ' . self::sql($json) . ', NOW()) '
            . 'ON DUPLICATE KEY UPDATE payload_json = VALUES(payload_json), available_at = LEAST(available_at, VALUES(available_at))',
            'Unable to persist account deletion outbox event.'
        );
    }

    private function bearerToken(): string
    {
        $headers = function_exists('getallheaders') ? getallheaders() : [];
        $value = (string)($headers['Authorization'] ?? $_SERVER['HTTP_AUTHORIZATION'] ?? '');
        return trim(str_replace('Bearer ', '', $value));
    }

    private function rejectImpersonationToken(string $token): void
    {
        if ($token === '') {
            return;
        }
        global $db;
        $result = $db->query(
            'SELECT type, created_at FROM tokens WHERE token = ' . self::sql($token) . ' LIMIT 1'
        );
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect account deletion session provenance.');
        }
        $row = $result->fetch_assoc();
        if (str_starts_with((string)($row['type'] ?? ''), 'AUTH_TOKEN_IMPERSONATION:')) {
            throw new account_deletion_http_exception(
                'Account deletion is unavailable during support impersonation',
                403
            );
        }
        if (($row['type'] ?? '') === 'AUTH_TOKEN' && strtotime((string)($row['created_at'] ?? '')) < strtotime(self::LEGACY_SESSION_CUTOFF)) {
            throw new account_deletion_http_exception('A fresh login is required before account deletion', 403);
        }
    }

    private function nullableString(mixed $value): ?string
    {
        if (!is_scalar($value)) {
            return null;
        }
        $value = trim((string)$value);
        return $value !== '' ? $value : null;
    }

    private static function tableExists(string $table): bool
    {
        if (array_key_exists($table, self::$tableExistsCache)) {
            return self::$tableExistsCache[$table];
        }
        global $db;
        $tableSql = $db->escape_string($table);
        $result = $db->query("SHOW TABLES LIKE '$tableSql'");
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect database table availability.');
        }
        return self::$tableExistsCache[$table] = $result->num_rows > 0;
    }

    /** @return array<int, string> */
    private static function columns(string $table): array
    {
        if (isset(self::$columnsCache[$table])) {
            return self::$columnsCache[$table];
        }
        if (!self::tableExists($table)) {
            return self::$columnsCache[$table] = [];
        }
        global $db;
        $result = $db->query('SHOW COLUMNS FROM `' . preg_replace('/[^a-zA-Z0-9_]/', '', $table) . '`');
        if ($result === false) {
            throw new \RuntimeException('Unable to inspect database column availability.');
        }
        $rows = $db->fetch_all($result);
        return self::$columnsCache[$table] = array_values(array_map('strval', array_column($rows, 'Field')));
    }

    private static function valueSql(mixed $value): string
    {
        if ($value === null) {
            return 'NULL';
        }
        if (is_bool($value)) {
            return $value ? '1' : '0';
        }
        if (is_int($value) || is_float($value)) {
            return (string)$value;
        }
        return self::sql((string)$value);
    }

    private function execute(string $sql, string $message): void
    {
        global $db;
        if ($db->query($sql) === false) throw new \RuntimeException($message);
    }

    private static function sql(string $value): string
    {
        global $db;
        return "'" . $db->escape_string($value) . "'";
    }

    private static function uuidV4(): string
    {
        $bytes = random_bytes(16);
        $bytes[6] = chr((ord($bytes[6]) & 0x0f) | 0x40);
        $bytes[8] = chr((ord($bytes[8]) & 0x3f) | 0x80);
        $hex = bin2hex($bytes);
        return substr($hex, 0, 8) . '-' . substr($hex, 8, 4) . '-' . substr($hex, 12, 4)
            . '-' . substr($hex, 16, 4) . '-' . substr($hex, 20);
    }
}