<?php
/** Approved code-free session transition into existing encrypted binding state. */
if (!defined('ABSPATH')) {
    exit;
}
class Akkedli_V2_Session_Exchange
{
    public static function advance(array $session, array $status, $transport, $readiness = null)
    {
        if ('success' !== $status['kind']) {
            if ('rejected' === $status['kind']) return self::fail();
            return 'retry' === $status['kind'] ? 'session_retry' : 'session_pending';
        }
        if (!isset($status['expected_store_url']) || !hash_equals(
            $session['expected_store_url'], $status['expected_store_url']
        )) return 'session_pending';
        if ('expired' === $status['state']) return self::cleanup_terminal('session_expired');
        if ('failed_terminal' === $status['state']) return self::fail();
        if (!in_array($status['state'], array('proof_verified', 'exchanged'), true)) {
            return 'failed_retryable' === $status['state']
                ? 'session_retry' : 'session_pending';
        }
        $result = $transport->exchange($session);
        if ('success' !== $result['kind']) {
            if ('rejected' === $result['kind']) return self::fail();
            return 'retry' === $result['kind'] ? 'session_retry' : 'session_pending';
        }
        unset($result['kind']);
        $validated = Akkedli_V2_Credential_Response::validate($result, $session['callback_url']);
        unset($result);
        if (!is_array($validated)
            || !Akkedli_V2_Outbox_Readiness::check($readiness, true)) return 'session_error';
        $expected = Akkedli_Connector_State::load();
        if (!is_array($expected) || 'migration_pending' !== $expected['mode'])
            return 'session_error';
        $pending = Akkedli_V2_Binding_State::pending(
            $validated, $expected['legacy_backup'], time());
        unset($validated);
        if (!Akkedli_Connector_State::replace($pending, $expected)) return 'session_error';
        if ('verifying' !== self::clear_session('verifying')) return 'session_error';
        Akkedli_V2_Binding_Poller::schedule_current();
        return 'verifying';
    }
    public static function cleanup_terminal($notice) {
        if (!in_array($notice, array('session_failed', 'session_expired'), true)
            || !Akkedli_Connector_State::delete_pending()
            || 'absent' !== Akkedli_Connector_State::status()) return 'session_error';
        return self::clear_session($notice);
    }
    public static function clear_session($notice) {
        if (!in_array($notice, array('verifying', 'session_failed',
            'session_expired', 'session_error'), true)) return 'session_error';
        return Akkedli_V2_Session_State::delete()
            && !Akkedli_V2_Session_State::exists() ? $notice : 'session_error';
    }
    private static function fail() { return self::cleanup_terminal('session_failed'); }
}