<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use EloquentFilter\Filterable;

class Keyword extends Model
{
    use HasFactory;
    use Filterable;

    protected $fillable = ['name', 'key', 'value', 'parent_id', 'parent_key', 'path', 'sort', 'lv'];
    
    protected function serializeDate(\DateTimeInterface $date)
    {
        return $date->format('Y-m-d H:i:s');
    }

    protected static function boot()
    {
        parent::boot();
        // 监听 Keyword 的创建事件，用于初始化 path 和 lv 字段值
        static::creating(function ($keyword) {
            // 如果创建的是一个根类目
            if (! $keyword->parent_id) {
                // 将层级设为 1
                $keyword->lv = 1;
                // 将 path 设为 -
                $keyword->path = '-';
            } else {
                // 将层级设为父类目的层级 + 1
                $keyword->lv = $keyword->parent->lv ++;
                $keyword->parent_key = $keyword->parent->key;
                // 将 path 值设为父类目的 path 追加父类目 ID 以及最后跟上一个 - 分隔符
                $keyword->path = $keyword->parent->path.$keyword->parent_id.'-';
            }
        });
    }

    public function parent()
    {
        return $this->belongsTo(static::class, 'parent_id');
    }

    public function children()
    {
        return $this->hasMany(static::class, 'parent_id');
    }
}