<?php
namespace AAP\Modules\Schedule;

use AAP\Core\Options;
use AAP\Core\Registry;
use AAP\Modules\Logs\Logger;
use AAP\Modules\Pipeline\PipelineModule;
use AAP\Modules\Pipeline\RunState;

defined('ABSPATH') || exit;

/**
 * Own scheduler (no WP-Cron): stores the next run timestamp and spawns the
 * pipeline when the time comes.
 */
final class Scheduler {

    public static function interval_seconds(): int {
        $value = max(1, Options::int('aap_auto_interval_value'));
        $unit  = (string) Options::get('aap_auto_interval_unit', 'hours');

        return match ($unit) {
            'minutes' => $value * MINUTE_IN_SECONDS,
            'days'    => $value * DAY_IN_SECONDS,
            default   => $value * HOUR_IN_SECONDS,
        };
    }

    public function start(string $mode, int $user_id, int $first_run_at = 0): void {
        update_option('aap_auto_enabled', true);
        update_option('aap_auto_user_id', $user_id);

        $label = Options::int('aap_auto_interval_value') . ' ' . Options::get('aap_auto_interval_unit', 'hours');

        if ($mode === 'now') {
            update_option('aap_next_auto_run', time() + self::interval_seconds());
            Logger::info("Automatic generation enabled (user {$user_id}, interval {$label}). Running now.", 'schedule');
            $this->spawn($user_id);
            return;
        }

        $first = ($first_run_at > 0 && $first_run_at > time())
            ? $first_run_at
            : time() + self::interval_seconds();

        update_option('aap_next_auto_run', $first);
        Logger::info(
            "Automatic generation enabled (user {$user_id}, interval {$label}). First run: " . wp_date('d/m/Y H:i', $first) . '.',
            'schedule'
        );
    }

    public function stop(): void {
        update_option('aap_auto_enabled', false);
        delete_option('aap_next_auto_run');
        delete_transient('aap_auto_spawn_lock');
        wp_clear_scheduled_hook('aap_auto_run');

        Logger::info('Automatic generation paused.', 'schedule');
    }

    public function reschedule(): void {
        if (!Options::bool('aap_auto_enabled')) {
            return;
        }

        update_option('aap_next_auto_run', time() + self::interval_seconds());
        Logger::info('Interval changed; next run rescheduled.', 'schedule');
    }

    /** Called on every web request (shutdown) and by the system cron. */
    public function tick(): void {
        if (!Options::bool('aap_auto_enabled')) {
            return;
        }

        if (RunState::is_running() && !RunState::is_stale()) {
            return;
        }

        $next = (int) get_option('aap_next_auto_run', 0);
        if ($next === 0 || time() < $next) {
            return;
        }

        // Atomic-ish lock: avoid double spawn in concurrent requests.
        if (get_transient('aap_auto_spawn_lock')) {
            return;
        }
        set_transient('aap_auto_spawn_lock', 1, 60);

        $next_ts = time() + self::interval_seconds();
        update_option('aap_next_auto_run', $next_ts);

        $author = (int) get_option('aap_auto_user_id', 0);
        Logger::info('Automatic run triggered by the scheduler. Next: ' . wp_date('d/m/Y H:i', $next_ts) . '.', 'schedule');

        $this->spawn($author);
    }

    private function spawn(int $user_id): bool {
        $pipeline = Registry::get('pipeline');

        if (!$pipeline instanceof PipelineModule) {
            Logger::error('Pipeline module unavailable; cannot start a run.', 'schedule');
            return false;
        }

        return $pipeline->spawn($user_id);
    }
}