<?php
namespace App\Services;

use App\Models\PurchaseOrder;
use App\Models\ReceivingOrder;
use App\Models\ReceivingOrderItem;
use App\Models\ErpSku;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;

class PurchaseService
{
    protected $stockService;

    public function __construct(StockService $stockService)
    {
        $this->stockService = $stockService;
    }

    /**
     * 生成采购单号
     */
    public function generatePoNo()
    {
        $prefix = 'PO';
        $date = date('Ymd');
        $last = PurchaseOrder::where('po_no', 'like', $prefix . $date . '%')
            ->orderBy('po_no', 'desc')
            ->first();
        if ($last) {
            $num = intval(substr($last->po_no, -4)) + 1;
        } else {
            $num = 1;
        }
        return $prefix . $date . str_pad($num, 4, '0', STR_PAD_LEFT);
    }

    /**
     * 生成收货单号
     */
    public function generateReceivingNo()
    {
        $prefix = 'RO';
        $date = date('Ymd');
        $last = ReceivingOrder::where('receiving_no', 'like', $prefix . $date . '%')
            ->orderBy('receiving_no', 'desc')
            ->first();
        if ($last) {
            $num = intval(substr($last->receiving_no, -4)) + 1;
        } else {
            $num = 1;
        }
        return $prefix . $date . str_pad($num, 4, '0', STR_PAD_LEFT);
    }

    /**
     * 审核采购单
     */
    public function approve(PurchaseOrder $order)
    {
        if ($order->status !== 'under_review') {
            throw new \Exception('采购单状态错误，无法审核');
        }

        DB::transaction(function () use ($order) {
            $order->status = 'approved';
            $order->save();

            // 自动生成收货单
            $receivingNo = $this->generateReceivingNo();
            $totalQty = $order->items->sum('quantity');

            $receivingOrder = ReceivingOrder::create([
                'receiving_no' => $receivingNo,
                'po_id' => $order->id,
                'warehouse_id' => $order->warehouse_id,
                'total_quantity' => $totalQty,
                'received_quantity' => 0,
                'status' => 'pending',
                'receiver' => null,
                'is_cloud_warehouse' => $order->cloud_system ? true : false,
            ]);

            foreach ($order->items as $item) {
                ReceivingOrderItem::create([
                    'receiving_order_id' => $receivingOrder->id,
                    'sku_code' => $item->sku_code,
                    'sku_name' => $item->sku_name,
                    'order_quantity' => $item->quantity,
                    'received_quantity' => 0,
                ]);
            }
        });

        return $order;
    }

    /**
     * 驳回采购单
     */
    public function reject(PurchaseOrder $order, $comment)
    {
        if ($order->status !== 'under_review') {
            throw new \Exception('采购单状态错误，无法驳回');
        }
        $order->status = 'rejected';
        $order->audit_comment = $comment;
        $order->save();
        return $order;
    }

    /**
     * 执行收货
     */
    public function receive(ReceivingOrder $receivingOrder, array $items, $receiver)
    {
        if ($receivingOrder->status === 'completed') {
            throw new \Exception('收货单已完成，无法再次收货');
        }

        DB::transaction(function () use ($receivingOrder, $items, $receiver) {
            $totalReceived = 0;
            $po = $receivingOrder->purchaseOrder;

            foreach ($receivingOrder->items as $orderItem) {
                $found = collect($items)->firstWhere('sku_code', $orderItem->sku_code);
                if ($found) {
                    $qty = min($found['received_quantity'], $orderItem->order_quantity - $orderItem->received_quantity);
                    if ($qty > 0) {
                        $orderItem->received_quantity += $qty;
                        $orderItem->save();

                        // 入库到库存
                        $this->stockService->inbound(
                            $orderItem->sku_code,
                            $receivingOrder->warehouse_id,
                            $qty,
                            $po->po_no,
                            '采购入库，采购单号：' . $po->po_no
                        );

                        $totalReceived += $qty;
                    }
                }
            }

            $receivingOrder->received_quantity += $totalReceived;
            $receivingOrder->receiver = $receiver;

            if ($receivingOrder->received_quantity >= $receivingOrder->total_quantity) {
                $receivingOrder->status = 'completed';
                $allCompleted = $po->receivingOrders()->where('status', '!=', 'completed')->count() == 0;
                if ($allCompleted && $po->status !== 'completed') {
                    $po->status = 'completed';
                    $po->save();
                }
            } else {
                $receivingOrder->status = 'partial';
            }
            $receivingOrder->save();
        });

        return $receivingOrder->fresh();
    }

    /**
     * 推送云仓（模拟）
     */
    public function pushToCloud(PurchaseOrder $order)
    {
        if ($order->pushed_to_cloud) {
            throw new \Exception('采购单已推送过云仓');
        }

        // 模拟推送逻辑，实际应调用对应云仓API
        try {
            $response = ['success' => true, 'message' => '推送成功', 'cloud_po_no' => 'CLOUD_' . $order->po_no];

            $order->pushed_to_cloud = true;
            $order->pushed_at = now();
            $order->cloud_response = json_encode($response);
            $order->save();

            return $response;
        } catch (\Exception $e) {
            throw new \Exception('推送云仓失败：' . $e->getMessage());
        }
    }
}