<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Str;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use App\Models\Calendar;
use App\Models\Event;
use App\Models\EventMeta;

class EventController extends Controller
{
    /**
     * create a new event page
     */
    public function create(Calendar $calendar)
    {
        $this->authorize('update', $calendar);

        $instance = $calendar->instanceForUser();
        $event = new Event;
        $event->meta = (object) [
            'title' => '',
            'description' => '',
            'location' => '',
            'start_at' => null,
            'end_at' => null,
            'all_day' => false,
            'category' => '',
        ];
        $start = $event->start_at;
        $end = $event->end_at;

        return view('event.form', compact('calendar', 'instance', 'event', 'start', 'end'));
    }

    /**
     * edit event page
     */
    public function edit(Calendar $calendar, Event $event)
    {
        $this->authorize('update', $calendar);

        $instance = $calendar->instanceForUser();
        $timezone = $instance?->timezone ?? 'UTC';

        $start = optional($event->meta?->start_at)
            ?->timezone($timezone)
            ?->format('Y-m-d\TH:i');

        $end = optional($event->meta?->end_at)
            ?->timezone($timezone)
            ?->format('Y-m-d\TH:i');

        return view('event.form', compact('calendar', 'instance', 'event', 'start', 'end'));
    }

    /**
     * single event view handling
     *
     * URL: /calendar/{uuid}/event/{event_id}
     */
    public function show(Request $request, Calendar $calendar, Event $event)
    {
        // ensure the event really belongs to the parent calendar
        if ((int) $event->calendarid !== (int) $calendar->id) {
            abort(Response::HTTP_NOT_FOUND);
        }

        // authorize
        $this->authorize('view', $event);

        // eager-load meta so the view has everything
        $event->load('meta');

        // check for HTML; it sends `HX-Request: true` on every AJAX call
        $isHtmx = $request->header('HX-Request') === 'true';

        // convert Sabre timestamps if meta is missing
        $start = $event->meta->start_at
              ?? Carbon::createFromTimestamp($event->firstoccurence);
        $end   = $event->meta->end_at
              ?? ($event->lastoccurence
                  ? Carbon::createFromTimestamp($event->lastoccurence)
                  : $start);

        $data = compact('calendar', 'event', 'start', 'end');

        return $isHtmx
            ? view('event.partials.details', $data) // tiny fragment for the modal
            : view('event.show', $data);           // full-page fallback
    }


    /**
     * BACKEND METHODS
     *
     */

    /**
     * insert vevent into sabre’s calendarobjects + meta row
     */
    public function store(Request $req, Calendar $calendar)
    {
        $this->authorize('update', $calendar);

        $data = $req->validate([
            'title'       => 'required|string|max:200',
            'start_at'    => 'required|date',
            'end_at'      => 'required|date|after:start_at',
            'description' => 'nullable|string',
            'location'    => 'nullable|string',
            'all_day'     => 'sometimes|boolean',
            'category'    => 'nullable|string|max:50',
        ]);

        // prepare payload
        $uid   = Str::uuid() . '@' . parse_url(config('app.url'), PHP_URL_HOST);

        // store events as UTC in the database; convert to calendar time in the view
        $client_timezone = $calendar->timezone ?? 'UTC';
        $start = Carbon::createFromFormat('Y-m-d\TH:i', $data['start_at'], $client_timezone)
            ->setTimezone('UTC');
        $end = Carbon::createFromFormat('Y-m-d\TH:i', $data['end_at'], $client_timezone)
            ->setTimezone('UTC');

        // prepare strings
        $description = $data['description'] ?? '';
        $location    = $data['location']    ?? '';
        $description = str_replace("\n", '\\n', $description);
        $location    = str_replace("\n", '\\n', $location);

        /* build minimal iCalendar payload */
        $ical = <<<ICS
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Kithkin//Laravel CalDAV//EN
BEGIN:VEVENT
UID:$uid
DTSTAMP:{$start->utc()->format('Ymd\\THis\\Z')}
DTSTART:{$start->format('Ymd\\THis')}
DTEND:{$end->format('Ymd\\THis')}
SUMMARY:{$data['title']}
DESCRIPTION:$description
LOCATION:$location
END:VEVENT
END:VCALENDAR

ICS;

        $event = Event::create([
            'calendarid'    => $calendar->id,
            'uri'           => Str::uuid() . '.ics',
            'lastmodified'  => time(),
            'etag'          => md5($ical),
            'size'          => strlen($ical),
            'componenttype' => 'VEVENT',
            'uid'           => $uid,
            'calendardata'  => $ical,
        ]);

        $event->meta()->create([
            'title'       => $data['title'],
            'description' => $data['description'] ?? null,
            'location'    => $data['location'] ?? null,
            'all_day'     => $data['all_day'] ?? false,
            'category'    => $data['category'] ?? null,
            'start_at'    => $start,
            'end_at'      => $end,
        ]);

        return redirect()->route('calendar.show', $calendar);
    }

    /**
     * update vevent + meta
     */
    public function update(Request $req, Calendar $calendar, Event $event)
    {
        $this->authorize('update', $calendar);

        $data = $req->validate([
            'title'       => 'required|string|max:200',
            'start_at'    => 'required|date',
            'end_at'      => 'required|date|after:start_at',
            'description' => 'nullable|string',
            'location'    => 'nullable|string',
            'category'    => 'nullable|string|max:50',
        ]);

        // rebuild the icalendar payload
        $calendar_timezone = $calendar->timezone ?? 'UTC';
        $start = Carbon::createFromFormat('Y-m-d\TH:i', $data['start_at'], $calendar_timezone)->setTimezone($calendar_timezone);
        $end = Carbon::createFromFormat('Y-m-d\TH:i', $data['end_at'], $calendar_timezone)->setTimezone($calendar_timezone);

        // prepare strings
        $description = $data['description'] ?? '';
        $location    = $data['location']    ?? '';
        $description = str_replace("\n", '\\n', $description);
        $location    = str_replace("\n", '\\n', $location);

        // note: keep the UID stable (CalDAV relies on it!)
        $uid    = $event->uid;

        $ical   = <<<ICS
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Kithkin//Laravel CalDAV//EN
BEGIN:VEVENT
UID:$uid
DTSTAMP:{$start->utc()->format('Ymd\\THis\\Z')}
DTSTART;TZID={$calendar_timezone}:{$start->format('Ymd\\THis')}
DTEND;TZID={$calendar_timezone}:{$end->format('Ymd\\THis')}
SUMMARY:{$data['title']}
DESCRIPTION:$description
LOCATION:$location
END:VEVENT
END:VCALENDAR

ICS;

        // persist changes
        $event->update([
            'calendardata' => $ical,
            'etag'         => md5($ical),
            'lastmodified' => time(),
        ]);

        $event->meta()->updateOrCreate([], [
            'title'       => $data['title'],
            'description' => $data['description'] ?? null,
            'location'    => $data['location'] ?? null,
            'all_day'     => $data['all_day'] ?? false,
            'category'    => $data['category'] ?? null,
            'start_at'    => $start,
            'end_at'      => $end,
        ]);

        return redirect()->route('calendar.show', $calendar);
    }
}