<?php

namespace App\Exports;

use App\Models\ProductCategoryModel;
use App\Models\ProductModel;
use App\Models\PurchaseOrderModel;
use App\Models\SupplierModel;
use Illuminate\Support\Collection;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\WithHeadings;
use Maatwebsite\Excel\Concerns\WithMapping;
use Maatwebsite\Excel\Concerns\WithStyles;
use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;

/**
 * 采购单导出（C2 全品类按分类 sort 排序 / C3 仅蔬果分类）
 */
class PurchaseOrderExport implements FromCollection, WithHeadings, WithMapping, WithStyles
{
    /** @var array<int, string> 商品ID => 顶级分类名 */
    private array $categoryNames = [];

    /** @var array<int, string> 供应商ID => 名称 */
    private array $supplierNames = [];

    private ?Collection $items = null;

    /**
     * @param PurchaseOrderModel $purchase 采购单
     * @param string $type all 全品类 / category 仅蔬果分类
     */
    public function __construct(
        private readonly PurchaseOrderModel $purchase,
        private readonly string $type = 'all',
    ) {
    }

    /**
     * 导出行（按 sort 排序；蔬果分类时按顶级分类名过滤）
     */
    public function collection(): Collection
    {
        if ($this->items !== null) {
            return $this->items;
        }

        $items = $this->purchase->items()->orderBy('sort')->get();
        $this->loadLookups($items);

        if ($this->type === 'category') {
            $items = $items->filter(function ($item): bool {
                $rootName = $this->categoryNames[(int) $item->product_id] ?? '';
                return str_contains($rootName, '蔬菜') || str_contains($rootName, '水果');
            })->values();
        }

        return $this->items = $items;
    }

    public function headings(): array
    {
        return ['序号', '分类', '品名', '规格/包规', '单价', '数量', '实际称重', '金额', '供应商', '备注'];
    }

    public function map($item): array
    {
        return [
            $item->sort,
            $this->categoryNames[(int) $item->product_id] ?? '',
            $item->product_name,
            $item->product_spec,
            (float) $item->price,
            (float) $item->quantity,
            (float) $item->weight,
            (float) $item->amount,
            $this->supplierNames[(int) $item->supplier_id] ?? '',
            $item->remark,
        ];
    }

    /**
     * 表头加粗 + 冻结首行
     */
    public function styles(Worksheet $sheet): array
    {
        $sheet->freezePane('A2');

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

    /**
     * PDF 模板视图数据
     *
     * @return array{purchase: PurchaseOrderModel, items: Collection, categoryNames: array<int, string>, supplierNames: array<int, string>}
     */
    public function viewData(): array
    {
        return [
            'purchase' => $this->purchase,
            'items' => $this->collection(),
            'categoryNames' => $this->categoryNames,
            'supplierNames' => $this->supplierNames,
        ];
    }

    /**
     * 预加载供应商名与商品顶级分类名（商品/供应商均含软删除，保证历史单据可导出）
     */
    private function loadLookups(Collection $items): void
    {
        $this->supplierNames = SupplierModel::withTrashed()
            ->whereIn('id', $items->pluck('supplier_id')->unique())
            ->pluck('name', 'id')
            ->toArray();

        $productCategoryIds = ProductModel::withTrashed()
            ->whereIn('id', $items->pluck('product_id')->unique())
            ->pluck('category_id', 'id');

        $categories = ProductCategoryModel::all()->keyBy('id');
        $this->categoryNames = [];
        foreach ($productCategoryIds as $productId => $categoryId) {
            $rootName = '';
            $cursor = (int) $categoryId;
            $guard = 0;
            while ($cursor > 0 && $guard++ < 20) {
                $category = $categories->get($cursor);
                if ($category === null) {
                    break;
                }
                $rootName = $category->name;
                $cursor = (int) $category->parent_id;
            }
            $this->categoryNames[(int) $productId] = $rootName;
        }
    }
}