<?php

namespace App\Services;

use App\Exceptions\RepositoryException;
use App\Models\PurchaseOrderModel;
use App\Models\StoreOrderItemModel;
use App\Models\StoreOrderModel;
use Illuminate\Support\Facades\DB;
use Throwable;

/**
 * 订单汇总生成采购单
 */
readonly class PurchaseGenerateService
{
    public function __construct(private BillNumberService $billNumberService)
    {
    }

    /**
     * @param string $date 采购日期（Y-m-d）
     * @param int $operatorId 制单人（后台系统用户ID）
     * @param int[] $orderIds 指定合并的门店订单ID（空 = 全部已接单订单）
     * @return PurchaseOrderModel
     * @throws Throwable
     */
    public function generate(string $date, int $operatorId, array $orderIds = []): PurchaseOrderModel
    {
        return DB::transaction(function () use ($date, $operatorId, $orderIds) {
            // 1. 行锁已接单订单（并发防护）；指定订单时要求全部处于已接单，否则整批拒绝
            $query = StoreOrderModel::query()->lockForUpdate();
            if ($orderIds !== []) {
                $orders = $query->whereIn('id', $orderIds)->get();
                $invalid = $orders->where('status', '<>', StoreOrderModel::STATUS_SUMMARIZED);
                if ($orders->isEmpty() || $invalid->isNotEmpty()) {
                    throw new RepositoryException(
                        '所选订单包含非「已接单」状态，无法生成采购单：' . $invalid->pluck('order_no')->implode('、')
                    );
                }
            } else {
                $orders = $query->where('status', StoreOrderModel::STATUS_SUMMARIZED)->get();
            }

            if ($orders->isEmpty()) {
                throw new RepositoryException('无已接单订单，无法生成采购单');
            }

            $sourceOrderIds = $orders->pluck('id')->all();

            // 2. 订货明细汇总（采购单头数据）
            $items = StoreOrderItemModel::query()->whereIn('order_id', $sourceOrderIds)->get();
            if ($items->isEmpty()) {
                throw new RepositoryException('已接单订单均无明细，无法生成采购单');
            }

            $totalQuantity = $items->reduce(
                static fn (string $carry, $item): string => bcadd($carry, (string) $item->quantity, 2),
                '0'
            );
            // 预估成本
            $estimateAmount = $items->reduce(
                static fn (string $carry, $item): string => bcadd($carry, bcmul($item->quantity, $item->cost_price, 2), 2),
                '0'
            );
            // 参考总重量 = Σ 明细参考重量（下单时按订货量 × 规格预填）
            $totalWeight = $items->reduce(
                static fn (string $carry, $item): string => bcadd($carry, (string) $item->weight, 3),
                '0'
            );

            $purchase = PurchaseOrderModel::create([
                'purchase_no' => $this->billNumberService->make('PO'),
                'purchase_date' => $date,
                'status' => PurchaseOrderModel::STATUS_PENDING,
                'total_quantity' => $totalQuantity,
                'total_weight' => $totalWeight,
                'estimate_amount' => $estimateAmount,
                'actual_amount' => 0,
                'operator_id' => $operatorId,
            ]);

            // 3. 源订单回写「采购中」并关联采购单；订货明细同步回写 purchase_id
            StoreOrderModel::whereIn('id', $sourceOrderIds)
                ->update([
                    'status' => StoreOrderModel::STATUS_DELIVERING,
                    'purchase_id' => $purchase->id,
                ]);
            StoreOrderItemModel::whereIn('order_id', $sourceOrderIds)
                ->update(['purchase_id' => $purchase->id]);

            return $purchase;
        });
    }
}