<?php

namespace App\Domain\Approvals\Services;

use App\Domain\Approvals\Models\ApprovalAction;
use App\Domain\Audit\Models\AuditLog;
use App\Domain\Identity\Enums\RoleName;
use App\Domain\Inventory\Models\SnipeAsset;
use App\Domain\Reservations\Enums\ReservationItemStatus;
use App\Domain\Reservations\Enums\ReservationStatus;
use App\Domain\Reservations\Models\Reservation;
use App\Domain\Reservations\Models\ReservationItem;
use App\Domain\Reservations\Services\AvailabilityService;
use App\Models\User;
use App\Notifications\ReservationDecisionNotification;
use Illuminate\Auth\Access\AuthorizationException;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class ApprovalService
{
    public function __construct(private readonly AvailabilityService $availability) {}

    public function approve(Reservation $reservation, User $actor, ?string $comment = null): Reservation
    {
        $this->authorize($actor);

        $approved = DB::transaction(function () use ($reservation, $actor, $comment): Reservation {
            $locked = $this->lockPending($reservation);
            $items = $locked->items()->with('asset')->get();
            SnipeAsset::query()->whereKey($items->pluck('snipe_asset_id'))->orderBy('id')->lockForUpdate()->get();

            $unavailable = $items->filter(fn ($item): bool => ! $this->availability->isAvailable(
                $item->asset,
                $item->starts_at,
                $item->ends_at,
                $locked->id,
            ));
            if ($unavailable->isNotEmpty()) {
                throw ValidationException::withMessages([
                    'decision' => 'A disponibilidade mudou: '.$unavailable->pluck('asset.name')->join(', ').'.',
                ]);
            }

            $this->transition($locked, $actor, ReservationStatus::Approved, 'approved', $comment, [
                'approved_by' => $actor->id,
                'approved_at' => now(),
                'decision_reason' => $comment,
            ]);
            $locked->items()->where('status', ReservationItemStatus::Held)->update([
                'status' => ReservationItemStatus::Reserved,
            ]);

            return $locked->load('requester', 'items.asset');
        }, 3);

        $approved->requester->notify(new ReservationDecisionNotification($approved, 'approved', $comment));

        return $approved;
    }

    public function reject(Reservation $reservation, User $actor, string $reason): Reservation
    {
        $this->authorize($actor);

        $rejected = DB::transaction(function () use ($reservation, $actor, $reason): Reservation {
            $locked = $this->lockPending($reservation);
            $this->transition($locked, $actor, ReservationStatus::Rejected, 'rejected', $reason, [
                'rejected_by' => $actor->id,
                'rejected_at' => now(),
                'decision_reason' => $reason,
            ]);
            $locked->items()->whereIn('status', ReservationItemStatus::blockingValues())->update([
                'status' => ReservationItemStatus::Cancelled,
            ]);

            return $locked->load('requester', 'items.asset');
        }, 3);

        $rejected->requester->notify(new ReservationDecisionNotification($rejected, 'rejected', $reason));

        return $rejected;
    }

    public function requestInformation(Reservation $reservation, User $actor, string $comment): Reservation
    {
        $this->authorize($actor);

        $awaitingInformation = DB::transaction(function () use ($reservation, $actor, $comment): Reservation {
            $locked = $this->lockPending($reservation);
            $this->transition($locked, $actor, ReservationStatus::AwaitingInformation, 'information_requested', $comment, [
                'decision_reason' => $comment,
                'approval_deadline' => now()->addHours(48),
            ]);

            return $locked->load('requester', 'items.asset');
        }, 3);

        $awaitingInformation->requester->notify(
            new ReservationDecisionNotification($awaitingInformation, 'information_requested', $comment)
        );

        return $awaitingInformation;
    }

    public function substituteAsset(
        Reservation $reservation,
        ReservationItem $item,
        SnipeAsset $replacement,
        User $actor,
        string $reason,
    ): Reservation {
        $this->authorize($actor);

        $updated = DB::transaction(function () use ($reservation, $item, $replacement, $actor, $reason): Reservation {
            $locked = $this->lockPending($reservation);
            $lockedItem = ReservationItem::query()->whereKey($item->id)->lockForUpdate()->firstOrFail();
            if ($lockedItem->reservation_id !== $locked->id || $lockedItem->status !== ReservationItemStatus::Held) {
                throw ValidationException::withMessages(['replacement_asset_id' => 'O item já não pode ser substituído.']);
            }

            $assets = SnipeAsset::query()
                ->whereKey([$lockedItem->snipe_asset_id, $replacement->id])
                ->orderBy('id')
                ->lockForUpdate()
                ->get()
                ->keyBy('id');
            $original = $assets->get($lockedItem->snipe_asset_id);
            $newAsset = $assets->get($replacement->id);

            if ($original === null || $newAsset === null || ! $this->sameCategory($original, $newAsset)) {
                throw ValidationException::withMessages(['replacement_asset_id' => 'Selecione um equipamento da mesma categoria.']);
            }
            if ($locked->items()->where('snipe_asset_id', $newAsset->id)->exists()
                || ! $this->availability->isAvailable($newAsset, $lockedItem->starts_at, $lockedItem->ends_at)) {
                throw ValidationException::withMessages(['replacement_asset_id' => 'O equipamento substituto não está disponível.']);
            }

            $lockedItem->update(['status' => ReservationItemStatus::Cancelled]);
            $locked->items()->create([
                'snipe_asset_id' => $newAsset->id,
                'starts_at' => $lockedItem->starts_at,
                'ends_at' => $lockedItem->ends_at,
                'status' => ReservationItemStatus::Held,
                'notes' => "Substitui {$original->asset_tag}: {$reason}",
            ]);
            ApprovalAction::create([
                'reservation_id' => $locked->id,
                'actor_id' => $actor->id,
                'action' => 'asset_substituted',
                'previous_status' => $locked->status->value,
                'new_status' => $locked->status->value,
                'comment' => $reason,
            ]);
            AuditLog::create([
                'actor_id' => $actor->id,
                'event' => 'reservation.asset_substituted',
                'auditable_type' => $locked->getMorphClass(),
                'auditable_id' => $locked->id,
                'metadata' => [
                    'original_asset_id' => $original->id,
                    'replacement_asset_id' => $newAsset->id,
                    'reason' => $reason,
                ],
            ]);

            return $locked->load('requester', 'items.asset');
        }, 3);

        $updated->requester->notify(new ReservationDecisionNotification($updated, 'asset_substituted', $reason));

        return $updated;
    }

    private function authorize(User $actor): void
    {
        if (! $actor->active || (! $actor->hasRole(RoleName::Approver) && ! $actor->hasRole(RoleName::Administrator))) {
            throw new AuthorizationException('Não tem permissão para decidir requisições.');
        }
    }

    private function sameCategory(SnipeAsset $original, SnipeAsset $replacement): bool
    {
        if ($original->category_id !== null && $replacement->category_id !== null) {
            return $original->category_id === $replacement->category_id;
        }

        return filled($original->category_name) && $original->category_name === $replacement->category_name;
    }

    private function lockPending(Reservation $reservation): Reservation
    {
        $locked = Reservation::query()->whereKey($reservation->id)->lockForUpdate()->firstOrFail();
        if ($locked->status !== ReservationStatus::PendingApproval) {
            throw ValidationException::withMessages(['decision' => 'A requisição já não aguarda uma decisão.']);
        }

        return $locked;
    }

    /** @param array<string, mixed> $attributes */
    private function transition(Reservation $reservation, User $actor, ReservationStatus $next, string $action, ?string $comment, array $attributes): void
    {
        $previous = $reservation->status;
        if (! $previous->canTransitionTo($next)) {
            throw ValidationException::withMessages(['decision' => 'Transição de estado inválida.']);
        }

        $reservation->update(['status' => $next, ...$attributes]);
        ApprovalAction::create([
            'reservation_id' => $reservation->id,
            'actor_id' => $actor->id,
            'action' => $action,
            'previous_status' => $previous->value,
            'new_status' => $next->value,
            'comment' => $comment,
        ]);
        AuditLog::create([
            'actor_id' => $actor->id,
            'event' => "reservation.{$action}",
            'auditable_type' => $reservation->getMorphClass(),
            'auditable_id' => $reservation->id,
            'before' => ['status' => $previous->value],
            'after' => ['status' => $next->value, 'comment' => $comment],
        ]);
    }
}