<?php

namespace App\Exports;

use App\Models\ProductCategoryModel;
use App\Models\ProductModel;
use App\Models\SupplierModel;
use Illuminate\Support\Collection;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\WithStrictNullComparison;
use Maatwebsite\Excel\Concerns\WithStyles;
use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;

/**
 * 商品档案导出：列格式与导入模板完全一致（首行即列头，导出文件修改后可直接重新导入）。
 * 分类列输出「父分类/子分类」完整路径；状态列输出中文。
 * template 模式仅输出列头 + 一行示例数据（首次导入前下载参考）。
 */
class ProductExport implements FromCollection, WithStrictNullComparison, WithStyles
{
    /** 列头（与 ProductImport 的解析顺序一一对应，改动需同步） */
    public const array HEADERS = ['品名', '分类', '供应商', '市场', '规格/包规', '单位', '成本价', '排序', '库存', '保质期', '状态', '备注'];

    private ?Collection $rows = null;

    /**
     * @param int $categoryId 末级分类筛选（0=全部商品）
     * @param bool $template 仅输出列头 + 示例行（导入模板）
     */
    public function __construct(
        private readonly int $categoryId = 0,
        private readonly bool $template = false,
    ) {
    }

    /**
     * 行结构：第 1 行列头，其后每行一件商品
     */
    public function collection(): Collection
    {
        if ($this->rows !== null) {
            return $this->rows;
        }

        $rows = [self::HEADERS];

        if ($this->template) {
            $rows[] = ['西红柿', '蔬菜/茄果类', '示例供应商', '新发地', '10斤/箱', '斤', 2.5, 0, 100, 3, '上架', '示例行，导入前请删除'];
            return $this->rows = collect($rows);
        }

        $products = ProductModel::query()
            ->when($this->categoryId > 0, fn ($query) => $query->where('category_id', $this->categoryId))
            ->orderBy('sort')
            ->orderBy('id')
            ->get()
            ->makeVisible('cost_price');

        $categoryPaths = $this->categoryPaths($products->pluck('category_id')->unique()->all());
        $supplierNames = SupplierModel::withTrashed()->pluck('name', 'id');

        foreach ($products as $product) {
            $rows[] = [
                $product->name,
                $categoryPaths[(int) $product->category_id] ?? '',
                $supplierNames[(int) $product->supplier_id] ?? '',
                $product->market,
                $product->spec,
                $product->unit,
                (float) $product->cost_price,
                (int) $product->sort,
                (int) $product->stock,
                (int) $product->shelf_life,
                (int) $product->status === ProductModel::STATUS_ON ? '上架' : '下架',
                $product->remark,
            ];
        }

        return $this->rows = collect($rows);
    }

    /**
     * 列头加粗、冻结首行、设置列宽
     */
    public function styles(Worksheet $sheet): array
    {
        $this->collection();

        $sheet->freezePane('A2');
        $widths = [20, 16, 14, 12, 14, 8, 10, 8, 8, 8, 8, 24];
        foreach ($widths as $index => $width) {
            $sheet->getColumnDimension(Coordinate::stringFromColumnIndex($index + 1))->setWidth($width);
        }

        return [
            1 => ['font' => ['bold' => true]],
        ];
    }

    /**
     * 分类ID => 「父分类/子分类」完整路径（沿 parent_id 上溯拼接）
     *
     * @param array<int, int> $categoryIds
     * @return array<int, string>
     */
    private function categoryPaths(array $categoryIds): array
    {
        $categories = ProductCategoryModel::all()->keyBy('id');
        $paths = [];
        foreach ($categoryIds as $categoryId) {
            $names = [];
            $cursor = (int) $categoryId;
            $guard = 0;
            while ($cursor > 0 && $guard++ < 20) {
                $category = $categories->get($cursor);
                if ($category === null) {
                    break;
                }
                array_unshift($names, $category->name);
                $cursor = (int) $category->parent_id;
            }
            $paths[(int) $categoryId] = implode('/', $names);
        }
        return $paths;
    }
}