<?php

namespace App\Services;

use App\Exceptions\RepositoryException;
use App\Models\ProductCategoryModel;
use App\Models\ProductModel;
use App\Models\PurchaseAllocationModel;
use App\Models\PurchaseOrderItemModel;
use App\Models\PurchaseOrderModel;
use App\Models\ReconciliationItemModel;
use App\Models\ReconciliationModel;
use App\Models\StoreOrderItemModel;
use Illuminate\Support\Facades\DB;

/**
 * 对账明细构建（D1 品类 / D2 供应商筛选）
 *
 * 流程（事务内，可重复 build：先清后建）：
 * 1. 按周期 + 品类（含子孙分类）+ 供应商拉取 purchase_order_item
 * 2. 校验命中的采购明细均已完成 D3 分摊（分摊是门店/单品粒度的对账数据源）
 * 3. 每条分摊记录 → 一条对账明细：
 *    publish_amount = 订货金额（溯源 order_item.amount）
 *    actual_amount  = 分摊金额
 *    diff = publish − actual，冗余 product_name / store_id
 * 4. 汇总写回头的 publish/actual/diff_amount，status → 对账中
 */
class ReconciliationBuildService
{
    /**
     * @return int 生成的对账明细数
     */
    public function build(ReconciliationModel $recon): int
    {
        return DB::transaction(function () use ($recon) {
            // 1. 按周期 + 品类 + 供应商拉取采购明细
            $itemQuery = PurchaseOrderItemModel::query()
                ->join('purchase_order', 'purchase_order.id', '=', 'purchase_order_item.purchase_id')
                ->whereDate('purchase_order.purchase_date', '>=', $recon->period_start)
                ->whereDate('purchase_order.purchase_date', '<=', $recon->period_end)
                ->select('purchase_order_item.*');

            if ((int) $recon->supplier_id > 0) {
                $itemQuery->where('purchase_order_item.supplier_id', $recon->supplier_id);
            }
            if ((int) $recon->category_id > 0) {
                $productIds = ProductModel::withTrashed()
                    ->whereIn('category_id', $this->descendantCategoryIds((int) $recon->category_id))
                    ->pluck('id');
                $itemQuery->whereIn('purchase_order_item.product_id', $productIds);
            }

            $purchaseItems = $itemQuery->get();
            if ($purchaseItems->isEmpty()) {
                throw new RepositoryException('周期内无符合筛选条件的采购数据，无法生成对账明细');
            }

            // 2. 分摊记录（未完成分摊的采购单拒绝，保证对账数据到门店/单品粒度）
            $allocations = PurchaseAllocationModel::query()
                ->whereIn('purchase_item_id', $purchaseItems->pluck('id'))
                ->get()
                ->groupBy('purchase_item_id');

            $missing = $purchaseItems->filter(fn ($item) => ! $allocations->has($item->id));
            if ($missing->isNotEmpty()) {
                $purchaseNos = PurchaseOrderModel::query()
                    ->whereIn('id', $missing->pluck('purchase_id')->unique())
                    ->pluck('purchase_no')
                    ->implode('、');
                throw new RepositoryException('采购单 ' . $purchaseNos . ' 尚未完成金额分摊，请先执行分摊再生成对账明细');
            }

            // 3. 溯源订货金额（公布金额）
            $orderAmounts = StoreOrderItemModel::query()
                ->whereIn('id', $allocations->flatten()->pluck('order_item_id')->unique())
                ->pluck('amount', 'id');

            // 4. 先清后建（幂等）
            ReconciliationItemModel::where('recon_id', $recon->id)->delete();

            $publishTotal = '0';
            $actualTotal = '0';
            $rows = [];
            $sort = 1;
            $now = now();
            foreach ($allocations as $purchaseItemId => $group) {
                $purchaseItem = $purchaseItems->firstWhere('id', $purchaseItemId);
                foreach ($group as $allocation) {
                    $publish = (string) ($orderAmounts[$allocation->order_item_id] ?? '0');
                    $actual = (string) $allocation->amount;
                    $publishTotal = bcadd($publishTotal, $publish, 2);
                    $actualTotal = bcadd($actualTotal, $actual, 2);

                    $rows[] = [
                        'recon_id' => $recon->id,
                        'store_id' => $allocation->store_id,
                        'purchase_item_id' => $allocation->purchase_item_id,
                        'order_item_id' => $allocation->order_item_id,
                        'product_id' => $allocation->product_id,
                        'product_name' => $purchaseItem->product_name,
                        'quantity' => $allocation->quantity,
                        'weight' => $allocation->weight,
                        'publish_amount' => $publish,
                        'actual_amount' => $actual,
                        'diff_amount' => bcsub($publish, $actual, 2),
                        'is_reconciled' => ReconciliationItemModel::NOT_RECONCILED,
                        'store_remark' => '',
                        'sort' => $sort++,
                        'created_at' => $now,
                        'updated_at' => $now,
                    ];
                }
            }
            ReconciliationItemModel::insert($rows);

            // 5. 汇总写回头 + 状态流转
            $recon->publish_amount = $publishTotal;
            $recon->actual_amount = $actualTotal;
            $recon->diff_amount = bcsub($publishTotal, $actualTotal, 2);
            $recon->status = ReconciliationModel::STATUS_WORKING;
            $recon->save();

            return count($rows);
        });
    }

    /**
     * 分类自身 + 全部子孙分类ID（多级分类下按顶级分类筛选）
     *
     * @return array<int, int>
     */
    private function descendantCategoryIds(int $categoryId): array
    {
        $parentMap = ProductCategoryModel::pluck('parent_id', 'id');
        $ids = [$categoryId];
        $queue = [$categoryId];
        while ($queue !== []) {
            $current = array_shift($queue);
            foreach ($parentMap as $id => $parentId) {
                if ((int) $parentId === $current && ! in_array((int) $id, $ids, true)) {
                    $ids[] = (int) $id;
                    $queue[] = (int) $id;
                }
            }
        }

        return $ids;
    }
}