<?php
/** Exact-snapshot CAS transitions for callback binding. */
if (!defined('ABSPATH')) {
    exit;
}
class Akkedli_V2_Binding_Transition
{
    const OFFSETS = array(45, 90, 150, 240, 360, 480, 600, 720);
    public static function apply(array $expected, array $result, $automatic, $now, $readiness = null)
    {
        if ('status' === $result['kind'] && 'verified' === $result['status']) {
            if (Akkedli_V2_Outbox_Readiness::check($readiness)) {
                $replaced = Akkedli_Connector_State::replace(
                    Akkedli_V2_Binding_State::verified($expected), $expected);
                return $replaced && Akkedli_V2_Outbox_Recovery::authority_recovered();
            }
            $result = array('kind' => 'retry');
        }
        if ('status' === $result['kind'] && 'failed' === $result['status']) {
            return Akkedli_Connector_State::replace(
                Akkedli_V2_Binding_State::failed($expected), $expected);
        }
        if ('terminal' === $result['kind']) {
            return Akkedli_Connector_State::replace(Akkedli_V2_Binding_State::failed($expected), $expected);
        }
        if ('paused' === $result['kind']) return self::stop($expected);
        if ('manual' === $result['kind']) {
            $next = $expected;
            $next['automatic_stopped'] = true;
            $next['next_attempt_at'] = 0;
            return Akkedli_Connector_State::replace($next, $expected);
        }
        if (!$automatic) return true;
        $next = $expected;
        // attempt_count is the number of consumed offsets, including skipped overdue slots.
        while ($next['attempt_count'] < count(self::OFFSETS)
            && $next['poll_started_at'] + self::OFFSETS[$next['attempt_count']] <= $now) {
            $next['attempt_count']++;
        }
        $expired = $next['attempt_count'] >= count(self::OFFSETS)
            || $now - $next['poll_started_at'] >= 900;
        $next['automatic_stopped'] = $expired;
        $next['next_attempt_at'] = $expired ? 0
            : $next['poll_started_at'] + self::OFFSETS[$next['attempt_count']];
        if (!$expired && isset($result['retry_after']) && is_int($result['retry_after']))
            $next['next_attempt_at'] = min($next['poll_started_at'] + 900,
                max($next['next_attempt_at'], $now + $result['retry_after']));
        return Akkedli_Connector_State::replace($next, $expected);
    }
    public static function stop(array $expected)
    {
        $next = $expected;
        $next['automatic_stopped'] = true;
        $next['next_attempt_at'] = 0;
        return Akkedli_Connector_State::replace($next, $expected);
    }
}