<?php

namespace App\Services\Scan;

use App\Models\CollectionLog;
use App\Models\DropOffPoint;
use App\Models\QrCode;
use App\Models\Trip;
use App\Models\TripStop;
use App\Models\User;
use App\Services\Qr\QrAllocator;
use App\Services\Trip\TripExecutor;
use App\States\QrCode\Active;
use App\States\QrCode\Used;
use Illuminate\Support\Facades\DB;
use MatanYadaev\EloquentSpatial\Objects\Point;

class ScanService
{
    public const MAX_DISTANCE_METERS = 200;

    public function __construct(
        private readonly TripExecutor $tripExecutor,
        private readonly QrAllocator $qrAllocator,
    ) {}

    /**
     * Validate + record a scan. Returns ScanResult with status and optional
     * CollectionLog. Transitions code unassigned -> won't happen (rejected).
     * Active -> Used. Writes timeline event when trip context provided.
     */
    public function scan(
        string $serial,
        DropOffPoint $dropOff,
        User $scanner,
        float $lat,
        float $lng,
        ?Trip $trip = null,
        ?TripStop $tripStop = null,
        ?int $weightKg = null,
        ?string $wasteType = null,
        ?string $photoPath = null,
        ?string $notes = null,
        ?\DateTimeInterface $scannedAt = null,
    ): ScanResult {
        $code = QrCode::where('serial', $serial)->first();
        $when = $scannedAt ?? now();

        if (! $code) {
            return ScanResult::reject('not_found');
        }

        $statusName = (string) $code->status;
        if ($statusName === Used::$name) {
            return ScanResult::reject('duplicate', $code, CollectionLog::STATUS_DUPLICATE);
        }
        if ($statusName !== Active::$name) {
            return ScanResult::reject('invalid_state:'.$statusName, $code, CollectionLog::STATUS_INVALID);
        }

        if ($code->expires_at && $code->expires_at->isPast()) {
            return ScanResult::reject('expired', $code, CollectionLog::STATUS_EXPIRED);
        }

        // Geo proximity check
        if ($dropOff->coordinates) {
            $row = DB::selectOne(
                'SELECT ST_Distance_Sphere(coordinates, ST_SRID(POINT(?, ?), 4326)) AS m FROM drop_off_points WHERE id = ?',
                [$lng, $lat, $dropOff->id],
            );
            $distance = (float) ($row->m ?? 999999);
            if ($distance > self::MAX_DISTANCE_METERS) {
                return ScanResult::reject('out_of_range:'.(int) $distance.'m', $code, CollectionLog::STATUS_INVALID);
            }
        }

        return DB::transaction(function () use (
            $code, $dropOff, $scanner, $lat, $lng, $trip, $tripStop,
            $weightKg, $wasteType, $photoPath, $notes, $when,
        ) {
            $code->status->transitionTo(Used::class);
            $code->forceFill([
                'used_at' => $when,
                'used_at_drop_off_id' => $dropOff->id,
                'scanned_by_user_id' => $scanner->id,
            ])->save();

            $log = CollectionLog::create([
                'qr_code_id' => $code->id,
                'household_id' => $code->assigned_to_household_id,
                'drop_off_point_id' => $dropOff->id,
                'scanned_by_user_id' => $scanner->id,
                'trip_id' => $trip?->id,
                'trip_stop_id' => $tripStop?->id,
                'scanned_at' => $when,
                'coordinates_at_scan' => new Point($lat, $lng, 4326),
                'weight_kg' => $weightKg,
                'waste_type' => $wasteType,
                'photo_path' => $photoPath,
                'notes' => $notes,
                'verification_status' => CollectionLog::STATUS_VALID,
            ]);

            if ($tripStop) {
                $tripStop->increment('total_scans');
            }

            if ($trip) {
                $this->tripExecutor->log(
                    $trip,
                    \App\Models\TripTimelineEvent::TYPE_QR_SCANNED,
                    $scanner,
                    $lat, $lng,
                    relatedType: CollectionLog::class,
                    relatedId: $log->id,
                    metadata: ['serial' => $code->serial],
                );
            }

            // Notify if household balance is low after this scan
            if ($code->household) {
                $this->qrAllocator->notifyBalanceIfLow($code->household);
            }

            return ScanResult::accepted($code->fresh(), $log);
        });
    }
}