<?php

namespace App\Services;

use App\Enums\StatusSlug;
use App\Events\RequestAssigned;
use App\Events\RequestCreated;
use App\Events\RequestStatusChanged;
use App\Models\RequestType;
use App\Models\ServiceRequest;
use App\Models\Status;
use App\Models\User;
use Illuminate\Support\Carbon;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Arr;
use Illuminate\Support\Facades\DB;

class RequestService
{
    public function __construct(private readonly SettingsService $settingsService)
    {
    }

    public function create(array $data, User $actor): ServiceRequest
    {
        return DB::transaction(function () use ($data, $actor): ServiceRequest {
            $payload = $this->preparePayload($data);
            $payload['ticket_number'] = $this->generateTicketNumber();

            $request = ServiceRequest::query()->create($payload);

            $this->persistAttachments($request, Arr::get($data, 'attachments', []), $actor);

            event(new RequestCreated($request, $actor));

            if ($request->assigned_to) {
                event(new RequestAssigned($request, $actor));
            }

            return $request;
        });
    }

    public function update(ServiceRequest $request, array $data, User $actor): ServiceRequest
    {
        return DB::transaction(function () use ($request, $data, $actor): ServiceRequest {
            $oldAssignee = $request->assigned_to;
            $oldStatusId = $request->status_id;
            $payload = $this->preparePayload($data, $request);

            $request->fill($payload);
            $request->save();

            $this->persistAttachments($request, Arr::get($data, 'attachments', []), $actor);

            if ($oldStatusId !== $request->status_id) {
                event(new RequestStatusChanged($request->fresh('status'), $actor, $oldStatusId, $request->status_id));
            }

            if ($oldAssignee !== $request->assigned_to && $request->assigned_to) {
                event(new RequestAssigned($request->fresh(), $actor));
            }

            return $request->fresh(['type', 'priority', 'status', 'client', 'assignee', 'equipment']);
        });
    }

    public function changeStatus(ServiceRequest $request, Status $targetStatus, User $actor): ServiceRequest
    {
        $oldStatusId = $request->status_id;

        $request->status_id = $targetStatus->id;

        if ($targetStatus->slug === StatusSlug::IN_PROGRESS->value && !$request->started_at) {
            $request->started_at = now();
        }

        if (in_array($targetStatus->slug, [StatusSlug::RESOLVED->value, StatusSlug::CLOSED->value], true)) {
            $request->completed_at = now();
        }

        $request->save();

        event(new RequestStatusChanged($request->fresh('status'), $actor, $oldStatusId, $targetStatus->id));

        return $request;
    }

    public function allowedTransitions(ServiceRequest $request, User $user): array
    {
        $staffTransitions = [
            StatusSlug::NEW->value => [StatusSlug::IN_PROGRESS->value, StatusSlug::WAITING->value, StatusSlug::CANCELLED->value],
            StatusSlug::IN_PROGRESS->value => [StatusSlug::WAITING->value, StatusSlug::RESOLVED->value, StatusSlug::CANCELLED->value],
            StatusSlug::WAITING->value => [StatusSlug::IN_PROGRESS->value, StatusSlug::RESOLVED->value, StatusSlug::CANCELLED->value],
            StatusSlug::RESOLVED->value => [StatusSlug::CLOSED->value, StatusSlug::IN_PROGRESS->value],
            StatusSlug::CLOSED->value => [],
            StatusSlug::CANCELLED->value => [],
        ];

        $technicianTransitions = [
            StatusSlug::NEW->value => [StatusSlug::IN_PROGRESS->value, StatusSlug::WAITING->value],
            StatusSlug::IN_PROGRESS->value => [StatusSlug::WAITING->value, StatusSlug::RESOLVED->value],
            StatusSlug::WAITING->value => [StatusSlug::IN_PROGRESS->value, StatusSlug::RESOLVED->value],
            StatusSlug::RESOLVED->value => [StatusSlug::IN_PROGRESS->value],
            StatusSlug::CLOSED->value => [],
            StatusSlug::CANCELLED->value => [],
        ];

        $map = $user->isTechnician() ? $technicianTransitions : $staffTransitions;

        return $map[$request->status?->slug ?? StatusSlug::NEW->value] ?? [];
    }

    public function generateTicketNumber(): string
    {
        $maxId = ServiceRequest::withTrashed()->max('id') ?? 0;

        return sprintf('SRV-%04d', $maxId + 1);
    }

    private function preparePayload(array $data, ?ServiceRequest $request = null): array
    {
        $typeId = Arr::get($data, 'type_id', $request?->type_id);
        $type = $typeId ? RequestType::query()->find($typeId) : null;

        $deadlineAt = Arr::get($data, 'deadline_at');

        if (!$deadlineAt && $type) {
            $baseDate = Arr::get($data, 'planned_at') ?: now();
            $deadlineAt = Carbon::parse((string) $baseDate)->addHours($type->sla_hours)->toDateTimeString();
        }

        if (!$deadlineAt && !$type) {
            $fallbackHours = $this->settingsService->defaultSlaHours();
            $baseDate = Arr::get($data, 'planned_at') ?: now();
            $deadlineAt = Carbon::parse((string) $baseDate)->addHours($fallbackHours)->toDateTimeString();
        }

        return [
            'title' => Arr::get($data, 'title'),
            'description' => Arr::get($data, 'description'),
            'type_id' => $typeId,
            'priority_id' => Arr::get($data, 'priority_id'),
            'status_id' => Arr::get($data, 'status_id', $request?->status_id),
            'client_id' => Arr::get($data, 'client_id', $request?->client_id),
            'assigned_to' => Arr::get($data, 'assigned_to'),
            'equipment_id' => Arr::get($data, 'equipment_id'),
            'location' => Arr::get($data, 'location'),
            'planned_at' => Arr::get($data, 'planned_at'),
            'deadline_at' => $deadlineAt,
            'started_at' => Arr::get($data, 'started_at', $request?->started_at),
            'completed_at' => Arr::get($data, 'completed_at', $request?->completed_at),
            'resolution_notes' => Arr::get($data, 'resolution_notes'),
            'client_rating' => Arr::get($data, 'client_rating'),
            'client_comment' => Arr::get($data, 'client_comment'),
        ];
    }

    private function persistAttachments(ServiceRequest $request, array $attachments, User $actor): void
    {
        /** @var UploadedFile $attachment */
        foreach ($attachments as $attachment) {
            $path = $attachment->store('request-attachments/'.$request->id, 'local');

            $request->attachments()->create([
                'user_id' => $actor->id,
                'filename' => $attachment->getClientOriginalName(),
                'path' => $path,
                'size' => $attachment->getSize() ?: 0,
            ]);
        }
    }
}