<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\EventPackage;
use App\Models\TenantPackage;
use App\Support\ApiError;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Symfony\Component\HttpFoundation\Response;

class TenantPackageController extends Controller
{
    public function index(Request $request): JsonResponse
    {
        $tenant = $request->attributes->get('tenant');

        if (! $tenant) {
            return ApiError::response(
                'tenant_not_found',
                'Tenant Not Found',
                'The authenticated tenant context could not be resolved.',
                Response::HTTP_NOT_FOUND
            );
        }

        $packages = TenantPackage::where('tenant_id', $tenant->id)
            ->with('package')
            ->orderBy('created_at', 'desc')
            ->get();

        $usageEventPackage = $this->resolveUsageEventPackage($tenant->id);
        $linkedEventPackages = $this->resolveLinkedEventPackages($tenant->id, $packages->pluck('id')->all());

        $packages->each(function (TenantPackage $package) use ($usageEventPackage, $linkedEventPackages): void {
            $eventPackage = $package->active ? $usageEventPackage : null;
            $this->hydratePackageSnapshot($package, $eventPackage);
            $this->attachUsageEvents($package, $linkedEventPackages);
        });

        $activePackage = $tenant->getActiveResellerPackage();

        if (! ($activePackage instanceof TenantPackage)) {
            $activePackage = $packages->firstWhere('active', true);
        } else {
            $this->hydratePackageSnapshot($activePackage, $usageEventPackage);
            $this->attachUsageEvents($activePackage, $linkedEventPackages);
        }

        return response()->json([
            'data' => $packages,
            'active_package' => $activePackage,
            'message' => 'Tenant packages loaded successfully.',
        ]);
    }

    /**
     * @param  array<int, int>  $tenantPackageIds
     * @return array<int, array{current: ?EventPackage, last: ?EventPackage, count: int}>
     */
    private function resolveLinkedEventPackages(int $tenantId, array $tenantPackageIds): array
    {
        if ($tenantPackageIds === []) {
            return [];
        }

        $eventPackages = EventPackage::query()
            ->whereIn('tenant_package_id', $tenantPackageIds)
            ->whereHas('event', fn ($query) => $query->where('tenant_id', $tenantId))
            ->with(['event:id,slug,name,date,status'])
            ->orderByDesc('purchased_at')
            ->orderByDesc('created_at')
            ->get()
            ->groupBy('tenant_package_id');

        $result = [];

        foreach ($eventPackages as $tenantPackageId => $groupedPackages) {
            $current = $groupedPackages
                ->first(function (EventPackage $eventPackage) {
                    return $eventPackage->gallery_expires_at && $eventPackage->gallery_expires_at->isFuture();
                });

            $result[(int) $tenantPackageId] = [
                'current' => $current,
                'last' => $groupedPackages->first(),
                'count' => $groupedPackages->count(),
            ];
        }

        return $result;
    }

    /**
     * @param  array<int, array{current: ?EventPackage, last: ?EventPackage, count: int}>  $linkedEventPackages
     */
    private function attachUsageEvents(TenantPackage $package, array $linkedEventPackages): void
    {
        $usage = $linkedEventPackages[$package->id] ?? null;

        if (! $usage) {
            $package->linked_events_count = 0;
            $package->current_event = null;
            $package->last_event = null;

            return;
        }

        $package->linked_events_count = $usage['count'];
        $package->current_event = $this->formatLinkedEvent($usage['current']);
        $package->last_event = $this->formatLinkedEvent($usage['last']);
    }

    private function formatLinkedEvent(?EventPackage $eventPackage): ?array
    {
        if (! $eventPackage || ! $eventPackage->event) {
            return null;
        }

        return [
            'id' => $eventPackage->event->id,
            'slug' => $eventPackage->event->slug,
            'name' => $eventPackage->event->name,
            'status' => $eventPackage->event->status,
            'event_date' => $eventPackage->event->date?->toIso8601String(),
            'linked_at' => $eventPackage->purchased_at?->toIso8601String(),
        ];
    }

    private function hydratePackageSnapshot(TenantPackage $package, ?EventPackage $eventPackage = null): void
    {
        $pkg = $package->package;

        $maxEvents = $pkg?->max_events_per_year;
        $package->remaining_events = $maxEvents === null ? null : max($maxEvents - $package->used_events, 0);
        $package->package_limits = array_merge(
            $pkg?->limits ?? [],
            $this->buildUsageSnapshot($eventPackage),
            [
                'included_package_slug' => $pkg?->included_package_slug,
                'branding_allowed' => $pkg?->branding_allowed,
                'watermark_allowed' => $pkg?->watermark_allowed,
                'features' => $pkg?->features ?? [],
            ]
        );
    }

    /**
     * @return Collection<int, EventPackage>
     */
    private function resolveUsageEventPackage(int $tenantId): ?EventPackage
    {
        $baseQuery = EventPackage::query()
            ->whereHas('event', fn ($query) => $query->where('tenant_id', $tenantId))
            ->with('package')
            ->orderByDesc('purchased_at')
            ->orderByDesc('created_at');

        $activeEventPackage = (clone $baseQuery)
            ->whereNotNull('gallery_expires_at')
            ->where('gallery_expires_at', '>=', now())
            ->first();

        return $activeEventPackage ?? $baseQuery->first();
    }

    private function buildUsageSnapshot(?EventPackage $eventPackage): array
    {
        if (! $eventPackage) {
            return [];
        }

        $limits = $eventPackage->effectiveLimits();
        $maxPhotos = $this->normalizeLimit($limits['max_photos'] ?? null);
        $maxGuests = $this->normalizeLimit($limits['max_guests'] ?? null);
        $galleryDays = $this->normalizeLimit($limits['gallery_days'] ?? null);

        $usedPhotos = (int) $eventPackage->used_photos;
        $usedGuests = (int) $eventPackage->used_guests;

        $remainingPhotos = $maxPhotos === null ? null : max(0, $maxPhotos - $usedPhotos);
        $remainingGuests = $maxGuests === null ? null : max(0, $maxGuests - $usedGuests);

        $remainingGalleryDays = null;
        $usedGalleryDays = null;
        if ($galleryDays !== null && $eventPackage->gallery_expires_at) {
            $remainingGalleryDays = max(0, now()->diffInDays($eventPackage->gallery_expires_at, false));
            $usedGalleryDays = max(0, $galleryDays - $remainingGalleryDays);
        }

        return array_filter([
            'used_photos' => $maxPhotos === null ? null : $usedPhotos,
            'remaining_photos' => $remainingPhotos,
            'used_guests' => $maxGuests === null ? null : $usedGuests,
            'remaining_guests' => $remainingGuests,
            'used_gallery_days' => $usedGalleryDays,
            'remaining_gallery_days' => $remainingGalleryDays,
        ], static fn ($value) => $value !== null);
    }

    private function normalizeLimit(?int $value): ?int
    {
        if ($value === null) {
            return null;
        }

        $value = (int) $value;

        if ($value <= 0) {
            return null;
        }

        return $value;
    }
}