<?php

declare(strict_types=1);

namespace App\Http\Controllers\Api\V1;

use App\Http\Controllers\Controller;
use App\Http\Requests\Api\V1\StoreEventRequest;
use App\Http\Requests\Api\V1\UpdateEventRequest;
use App\Http\Requests\Api\V1\UploadEventImageRequest;
use App\Http\Resources\Api\V1\EventResource;
use App\Models\Event;
use App\Models\Organisation;
use App\Models\PersonIdentityMatch;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Http\Resources\Json\AnonymousResourceCollection;
use Illuminate\Support\Facades\Gate;
use Illuminate\Support\Facades\Storage;

final class EventController extends Controller
{
    public function index(Request $request, Organisation $organisation): AnonymousResourceCollection
    {
        Gate::authorize('viewAny', [Event::class, $organisation]);

        $query = $organisation->events()
            ->topLevel()
            ->latest('start_date');

        if ($request->query('type')) {
            $query->where('event_type', $request->query('type'));
        }

        if ($request->boolean('include_children')) {
            $query->with('children');
        }

        return EventResource::collection($query->paginate());
    }

    public function show(Organisation $organisation, Event $event): JsonResponse
    {
        Gate::authorize('view', [$event, $organisation]);

        $event->load(['organisation', 'children', 'parent'])
            ->loadCount('children');

        return $this->success(new EventResource($event));
    }

    public function store(StoreEventRequest $request, Organisation $organisation): JsonResponse
    {
        Gate::authorize('create', [Event::class, $organisation]);

        $data = $request->validated();

        if (!empty($data['parent_event_id'])) {
            $parentEvent = Event::where('id', $data['parent_event_id'])
                ->where('organisation_id', $organisation->id)
                ->first();

            if (!$parentEvent) {
                return $this->error('Parent event does not belong to this organisation.', 422);
            }
        }

        if (!isset($data['event_type'])) {
            $data['event_type'] = 'event';
        }

        $event = $organisation->events()->create($data);

        return $this->created(new EventResource($event));
    }

    public function update(UpdateEventRequest $request, Organisation $organisation, Event $event): JsonResponse
    {
        Gate::authorize('update', [$event, $organisation]);

        $event->update($request->validated());

        return $this->success(new EventResource($event->fresh()));
    }

    public function destroy(Organisation $organisation, Event $event): JsonResponse
    {
        Gate::authorize('delete', [$event, $organisation]);

        $event->delete();

        return $this->success(null, 'Event deleted');
    }

    public function transition(Request $request, Organisation $organisation, Event $event): JsonResponse
    {
        Gate::authorize('update', [$event, $organisation]);

        $request->validate(['status' => 'required|string']);
        $newStatus = $request->status;

        $result = $event->canTransitionToWithPrerequisites($newStatus);

        if (! empty($result['errors'])) {
            return response()->json([
                'message' => 'Status transition not possible.',
                'errors' => $result['errors'],
                'current_status' => $event->status,
                'requested_status' => $newStatus,
                'allowed_transitions' => Event::STATUS_TRANSITIONS[$event->status] ?? [],
            ], 422);
        }

        $event->transitionTo($newStatus);

        return $this->success(new EventResource($event->fresh()));
    }

    public function children(Organisation $organisation, Event $event): AnonymousResourceCollection
    {
        Gate::authorize('view', [$event, $organisation]);

        $children = $event->children()
            ->orderBy('start_date')
            ->orderBy('name')
            ->paginate();

        return EventResource::collection($children);
    }

    public function uploadImage(UploadEventImageRequest $request, Organisation $organisation, Event $event): JsonResponse
    {
        Gate::authorize('update', [$event, $organisation]);

        $path = $request->file('image')->store(
            "events/{$event->id}",
            'public'
        );

        $field = $request->type === 'banner'
            ? 'registration_banner_url'
            : 'registration_logo_url';

        $event->update([$field => Storage::disk('public')->url($path)]);

        return response()->json(['url' => $event->fresh()->{$field}]);
    }

    public function stats(Event $event): JsonResponse
    {
        Gate::authorize('view', $event);

        $personCounts = $event->persons()
            ->selectRaw("
                COUNT(*) as total,
                SUM(CASE WHEN status = 'approved' THEN 1 ELSE 0 END) as approved,
                SUM(CASE WHEN status IN ('pending', 'applied') THEN 1 ELSE 0 END) as pending,
                SUM(CASE WHEN status = 'rejected' THEN 1 ELSE 0 END) as rejected
            ")
            ->first();

        $approvedWithoutShift = $event->persons()
            ->where('status', 'approved')
            ->whereDoesntHave('shiftAssignments')
            ->count();

        $pendingMatches = PersonIdentityMatch::pending()
            ->whereHas('person', fn ($q) => $q->where('event_id', $event->id))
            ->count();

        $shifts = $event->festivalSections()
            ->with(['shifts' => fn ($q) => $q->withCount([
                'shiftAssignments' => fn ($q) => $q->where('status', 'approved'),
            ])])
            ->get()
            ->flatMap->shifts;

        $shiftsTotal = $shifts->count();
        $shiftsFilled = $shifts->filter(
            fn ($s) => $s->shift_assignments_count >= $s->slots_total
        )->count();

        $total = (int) $personCounts->total;
        $approved = (int) $personCounts->approved;
        $pending = (int) $personCounts->pending;
        $rejected = (int) $personCounts->rejected;

        return response()->json(['data' => [
            'persons_total' => $total,
            'persons_approved' => $approved,
            'persons_pending' => $pending,
            'persons_rejected' => $rejected,
            'persons_other' => $total - $approved - $pending - $rejected,
            'persons_approved_without_shift' => $approvedWithoutShift,
            'pending_identity_matches' => $pendingMatches,
            'shifts_total' => $shiftsTotal,
            'shifts_filled' => $shiftsFilled,
            'shifts_understaffed' => $shiftsTotal - $shiftsFilled,
        ]]);
    }
}