<?php

namespace App\Jobs;

use App\Models\Calendar;
use App\Models\CalendarInstance;
use App\Models\Event;
use App\Models\EventMeta;
use App\Models\Subscription;
use Carbon\Carbon;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Foundation\Bus\Dispatchable;
use Illuminate\Http\Client\ConnectionException;
use Illuminate\Queue\InteractsWithQueue;
use Illuminate\Queue\SerializesModels;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Str;
use Sabre\VObject\Reader;

/**
 * Mirrors a remote iCalendar (ICS) feed into the local Sabre tables.
 *
 * • Runs in the background (ShouldQueue).
 * • Ensures a hidden “mirror” calendar exists once per subscription.
 * • Upserts every VEVENT into calendarobjects + event_meta.
 */
class SyncSubscription implements ShouldQueue
{
    use Dispatchable, Queueable, InteractsWithQueue, SerializesModels;

    /** @var \App\Models\Subscription */
    public Subscription $subscription;

    /**
     * @param  Subscription  $subscription  The feed to sync.
     */
    public function __construct(Subscription $subscription)
    {
        $this->subscription = $subscription;
    }

    /**
     * Main entry-point executed by the queue worker.
     */
    public function handle(): void
    {
        /**
         * download the remote .ics file with retry and a long timeout */
        try {
            $ics = Http::retry(3, 5000)->timeout(30)
                ->withHeaders(['User-Agent' => 'Kithkin CalDAV Bot'])
                ->get($this->subscription->source)
                ->throw() // throws if not 2xx
                ->body();
        } catch (ConnectionException | \Throwable $e) {
            Log::warning('Feed fetch failed', [
                'sub' => $this->subscription->id,
                'msg' => $e->getMessage(),
            ]);

            /* mark the job as failed and let Horizon / queue retry logic handle it */
            $this->fail($e);
            return;
        }

        /**
         * get the mirror calendar, or lazy create it */
        $meta = $this->subscription->meta ?? $this->subscription->meta()->create();

        if (! $meta->calendar_id) {
            $meta->calendar_id = $this->createMirrorCalendar($meta);
            $meta->save();
        }

        $calendarId = $meta->calendar_id;

        /**
         * parse and upsert vevents */
        $vcalendar = Reader::read($ics);

        Log::info('Syncing subscription '.$this->subscription->id);

        foreach ($vcalendar->VEVENT as $vevent) {

            $uid  = (string) $vevent->UID;
            $now  = now()->timestamp;
            $blob = (string) $vevent->serialize();

            /** @var Event $object */
            $object = Event::updateOrCreate(
                ['uid' => $uid, 'calendarid' => $calendarId],
                [
                    'uri'           => Str::uuid().'.ics',
                    'lastmodified'  => $now,
                    'etag'          => md5($blob),
                    'size'          => strlen($blob),
                    'componenttype' => 'VEVENT',
                    'calendardata'  => $blob,
                ]
            );

            $startUtc = Carbon::parse($vevent->DTSTART->getDateTime());
            $endUtc   = isset($vevent->DTEND)
                      ? Carbon::parse($vevent->DTEND->getDateTime())
                      : $startUtc;

            EventMeta::upsertForEvent($object->id, [
                'title'       => (string) ($vevent->SUMMARY ?? 'Untitled'),
                'description' => (string) ($vevent->DESCRIPTION ?? ''),
                'location'    => (string) ($vevent->LOCATION ?? ''),
                'all_day'     => $vevent->DTSTART->isFloating(),
                'start_at'    => $startUtc->utc(),
                'end_at'      => $endUtc->utc(),
            ]);
        }

        Log::info('Syncing subscription post foreach '.$this->subscription->id);
    }

    /**
     * Lazily builds the shadow calendar + instance when missing
     * (for legacy subscriptions added before we moved creation to the controller).
     */
    private function createMirrorCalendar($meta): int
    {
        // check if controller created one already and return it if so
        if ($meta->calendar_id) {
            return $meta->calendar_id;
        }

        // check if a mirror calendar already exists, and return that if so
        $existing = CalendarInstance::where('principaluri', $this->subscription->principaluri)
            ->where('description', 'Remote feed: '.$this->subscription->source)
            ->first();
        if ($existing) {
            return $existing->calendarid;
        }

        // otherwise create the new master calendar in `calendars`
        $calendar = Calendar::create([
            'synctoken'  => 1,
            'components' => 'VEVENT',
        ]);

        // attach an instance for this user
        CalendarInstance::create([
            'calendarid'    => $calendar->id,
            'principaluri'  => $this->subscription->principaluri,
            'uri'           => Str::uuid(),
            'displayname'   => $this->subscription->displayname,
            'description'   => 'Remote feed: '.$this->subscription->source,
            'calendarcolor' => $meta->color ?? '#1a1a1a',
            'timezone'      => config('app.timezone', 'UTC'),
        ]);

        return $calendar->id;
    }
}