<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;

/**
 * 商品分类模型（蔬菜/水果/其他，多级分类自关联）
 */
class ProductCategoryModel extends Model
{
    /** 状态：停用 */
    public const int STATUS_DISABLED = 0;
    /** 状态：正常 */
    public const int STATUS_NORMAL = 1;

    protected $table = 'product_category';
    protected $primaryKey = 'id';

    protected $fillable = [
        'parent_id',
        'name',
        'sort',
        'status'
    ];

    protected $casts = [
        'parent_id' => 'integer',
        'sort' => 'integer',
        'status' => 'integer',
        'created_at' => 'datetime:Y-m-d H:i:s',
        'updated_at' => 'datetime:Y-m-d H:i:s',
    ];

    /**
     * 父分类
     */
    public function parent(): BelongsTo
    {
        return $this->belongsTo(self::class, 'parent_id', 'id');
    }

    /**
     * 子分类
     */
    public function children(): HasMany
    {
        return $this->hasMany(self::class, 'parent_id', 'id')->orderBy('sort');
    }

    /**
     * 分类下的商品
     */
    public function products(): HasMany
    {
        return $this->hasMany(ProductModel::class, 'category_id', 'id');
    }

    /**
     * 获取分类树（树表展示 / 级联下拉选项复用）
     *
     * @param bool $onlyEnabled 是否仅返回启用分类
     * @return array<int, array{id: int, name: string, parent_id: int, sort: int, status: int, children?: array}>
     */
    public static function getTreeData($columns = ['*'], bool $onlyEnabled = false): array
    {
        $query = static::query()->orderBy('sort')->orderBy('id');
        if ($onlyEnabled) {
            $query->where('status', self::STATUS_NORMAL);
        }

        return static::buildTree($query->get($columns)->toArray());
    }

    /**
     * 按树展示顺序（sort/id 深度优先）获取分类 ID 列表，供商品列表等按分类顺序排序
     *
     * @param bool $onlyEnabled 是否仅包含启用分类
     * @return array<int, int>
     */
    public static function getTreeOrderedIds(bool $onlyEnabled = false): array
    {
        return static::flattenTreeIds(static::getTreeData(['id', 'parent_id'], $onlyEnabled));
    }

    /**
     * 深度优先展开分类树为有序 ID 列表
     *
     * @param array<int, array<string, mixed>> $tree
     * @return array<int, int>
     */
    private static function flattenTreeIds(array $tree): array
    {
        $ids = [];
        foreach ($tree as $node) {
            $ids[] = (int) $node['id'];
            if (!empty($node['children'])) {
                $ids = [...$ids, ...static::flattenTreeIds($node['children'])];
            }
        }

        return $ids;
    }

    /**
     * 将扁平分类列表组装为树
     *
     * @param array<int, array<string, mixed>> $items
     * @param int $parentId
     * @return array<int, array<string, mixed>>
     */
    public static function buildTree(array $items, int $parentId = 0): array
    {
        $tree = [];
        foreach ($items as $item) {
            if ((int) $item['parent_id'] !== $parentId) {
                continue;
            }
            $children = static::buildTree($items, (int) $item['id']);
            if ($children !== []) {
                $item['children'] = $children;
            }
            $tree[] = $item;
        }

        return $tree;
    }
}