<?php

namespace App\Traits\Models;

use App\Interfaces\OrderableInterface;
use Illuminate\Database\Eloquent\Model;

trait Orderable
{
    /**
     * @property int $priority_order
     */

    /**
     * Returns the grouping field used for ordering.
     * Returns null if the order is global
     *
     * @return string|null
     */
    public function getOrderGroupField(): ?string
    {
        return null;
    }

    /**
     * Returns the priority order value of the model.
     *
     * @return integer
     */
    public function getPriorityOrder(): int
    {
        return $this->priority_order ?? 0;
    }

    /**
     * shifts down by 1 all elements positioned after the delete.
     *
     * @param Model&OrderableInterface $model
     * @return void
     */
    public static function setOrder(OrderableInterface $model): void
    {
        $groupField = $model->getOrderGroupField();
        $query      = $model::query()->where('priority_order', '>', $model->getPriorityOrder());

        if ($groupField) {
            $query->where($groupField, $model->{$groupField});
        }

        $query->each(function (Model $item): void {
            /** @var Model&OrderableInterface $item */
            $item->setAttribute('priority_order', $item->getPriorityOrder() - 1);
            $item->saveOrFail();
        });
    }

    /**
     * Assigns the next order value on creation.
     *
     * @return void
     */
    public static function bootOrderable(): void
    {
        static::creating(function (Model $model): void {
            /** @var Model&OrderableInterface $model */
            if (!$model->getPriorityOrder()) {
                $groupField = $model->getOrderGroupField();
                $query      = static::query();

                if ($groupField) {
                    $query->where($groupField, $model->{$groupField});
                }

                $model->setAttribute('priority_order', ($query->max('priority_order') ?? 0) + 1);
            }
        });
    }
}