<?php

namespace App\Services;

use App\Models\BillModel;
use App\Models\ProductModel;
use App\Models\StoreOrderItemModel;
use Illuminate\Support\Collection;

/**
 * 账单详情数据组装（后台门店账单页与小程序账单详情共用）
 */
class BillDetailService
{
    /**
     * 合并后的商品明细：按商品聚合账单关联的全部订单明细
     * 单价为加权平均口径（Σ金额÷Σ数量），保证 单价×数量=金额；附商品首图
     *
     * @return array<int, array{product_id: int, product_name: string, product_spec: string, unit: string, price: string, quantity: int, weight: string, amount: string, image: string}>
     */
    public function mergedItems(BillModel $bill): array
    {
        $items = StoreOrderItemModel::query()
            ->where('bill_id', $bill->id)
            ->orderBy('id')
            ->get();

        return $this->aggregateItems($items);
    }

    /**
     * 合并后的商品明细（跨账单口径）：按商品聚合多张账单的全部订单明细
     * 用于账单合并导出，单价同为加权平均口径
     *
     * @param array<int, int> $billIds 账单ID列表
     * @return array<int, array{product_id: int, product_name: string, product_spec: string, unit: string, price: string, quantity: int, weight: string, amount: string, image: string}>
     */
    public function mergedItemsOfBills(array $billIds): array
    {
        $items = StoreOrderItemModel::query()
            ->whereIn('bill_id', $billIds)
            ->orderBy('id')
            ->get();

        return $this->aggregateItems($items);
    }

    /**
     * 按商品聚合订单明细：数量累加、重量/金额 bc 累加、单价加权平均，
     * 首图取明细快照 image_ids 批量解析，按「分类sort → 商品sort」排序
     *
     * @param Collection<int, StoreOrderItemModel> $items
     * @return array<int, array{product_id: int, product_name: string, product_spec: string, unit: string, price: string, quantity: int, weight: string, amount: string, image: string}>
     */
    private function aggregateItems(Collection $items): array
    {
        // 排序键：分类 sort → 商品 sort（与采购单明细矩阵同序）
        $products = ProductModel::withTrashed()
            ->with('category:id,sort')
            ->whereIn('id', $items->pluck('product_id')->unique())
            ->get()
            ->keyBy('id');

        $rows = [];
        foreach ($items->groupBy('product_id') as $productId => $group) {
            $product = $products->get((int) $productId);
            $first = $group->first();
            $quantity = 0;
            $weight = '0';
            $amount = '0';
            foreach ($group as $item) {
                $quantity += (int) $item->quantity;
                $weight = bcadd($weight, (string) $item->weight, 3);
                $amount = bcadd($amount, (string) $item->amount, 2);
            }

            $rows[] = [
                'product_id' => (int) $productId,
                'product_name' => $first->product_name,
                'product_spec' => $first->product_spec,
                'unit' => $first->unit,
                'price' => $quantity > 0
                    ? bcdiv($amount, (string) $quantity, 2)
                    : (string) $first->price,
                'quantity' => $quantity,
                'weight' => $weight,
                'amount' => $amount,
                'spec' => $product->spec,
                'price_unit' => $product->price_unit,
                'image_ids' => (array) $first->image_ids,
                'category_sort' => (int) ($product->category->sort ?? 9999),
                'product_sort' => (int) ($product->sort ?? 9999),
            ];
        }
        usort($rows, static fn (array $a, array $b): int =>
            [$a['category_sort'], $a['product_sort'], $a['product_id']]
            <=> [$b['category_sort'], $b['product_sort'], $b['product_id']]);

        // 首图批量解析（写入 image、移除 image_ids）
        app(ItemImageResolver::class)->resolve($rows);

        return array_map(static function (array $row): array {
            unset($row['category_sort'], $row['product_sort']);
            return $row;
        }, $rows);
    }
}