<?php

namespace App\Modules\Inventory\Services;

use App\Modules\Inventory\Models\GoodsReceipt;
use App\Modules\Inventory\Models\GoodsReceiptItem;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;

class DuplicateCheckService
{
    /**
     * 檢查疑似重複進貨
     * 
     * @param array $data
     * @return array
     */
    public function checkDuplicateReceipt(array $data): array
    {
        $warnings = [];
        $vendorId = isset($data['vendor_id']) && $data['vendor_id'] !== '' ? (int)$data['vendor_id'] : null;
        $poId = $data['purchase_order_id'] ?? null;
        $items = $data['items'] ?? [];
        $daysRange = 7; // 近期範圍天數

        // 1. 同 PO 重複檢查 (僅限標準採購)
        if ($data['type'] === 'standard' && $poId) {
            $existingReceipts = GoodsReceipt::where('purchase_order_id', $poId)
                ->where('status', '!=', 'cancelled')
                ->withCount('items')
                ->get();

            if ($existingReceipts->isNotEmpty()) {
                $warnings[] = [
                    'level' => 'high',
                    'type' => 'same_po',
                    'title' => '同一採購單已有進貨紀錄',
                    'message' => "此採購單已被引用於 {$existingReceipts->count()} 筆進貨單中，請確認是否為分批交貨。",
                    'related_receipts' => $existingReceipts->map(fn($r) => [
                        'id' => $r->id,
                        'code' => $r->code,
                        'received_date' => $r->received_date->format('Y-m-d'),
                        'status' => match($r->status) {
                            'completed' => '已完成',
                            'draft' => '草稿',
                            'pending_audit' => '待審核',
                            'rejected' => '已退回',
                            default => $r->status
                        },
                        'item_count' => $r->items_count,
                    ]),
                ];
            }
        }

        // 2. 近期同品項檢查 (針對每一個 item)
        $duplicatedItems = [];
        $recentDate = Carbon::now()->subDays($daysRange);

        foreach ($items as $item) {
            $productId = $item['product_id'];
            $qty = (float)$item['quantity_received'];

            // 尋找近期同供應商、同品項的進貨紀錄
            $recentHits = GoodsReceiptItem::whereHas('goodsReceipt', function($query) use ($vendorId, $recentDate) {
                    $query->where('vendor_id', $vendorId)
                        ->where('received_date', '>=', $recentDate)
                        ->where('status', '!=', 'cancelled');
                })
                ->where('product_id', $productId)
                ->with(['goodsReceipt:id,code,received_date'])
                ->get();

            foreach ($recentHits as $hit) {
                $hitQty = (float)$hit->quantity_received;
                
                // 如果數量完全相同，視為高風險
                $isExactMatch = abs($hitQty - $qty) < 0.001;
                
                $duplicatedItems[] = [
                    'product_id' => $productId,
                    'product_name' => $item['product_name'] ?? '未知商品',
                    'last_receipt_code' => $hit->goodsReceipt->code,
                    'last_receipt_date' => $hit->goodsReceipt->received_date->format('Y-m-d'),
                    'last_quantity' => $hitQty,
                    'current_quantity' => $qty,
                    'is_high_risk' => $isExactMatch
                ];
            }
        }

        if (!empty($duplicatedItems)) {
            // 按商品分組顯示
            $warnings[] = [
                'level' => collect($duplicatedItems)->contains('is_high_risk', true) ? 'high' : 'medium',
                'type' => 'recent_duplicate_product',
                'title' => '近期同供應商商品進貨紀錄',
                'message' => "偵測到以下商品在近 {$daysRange} 天內有過進貨紀錄，請確認是否重複收貨。",
                'duplicated_items' => $duplicatedItems,
            ];
        }

        // 3. 長期未調整單價檢查 (90 天內同供應商、同品項單價未變動)
        $stalePriceItems = $this->checkStalePrice($items, $vendorId);
        if (!empty($stalePriceItems)) {
            $warnings[] = [
                'level' => 'medium',
                'type' => 'stale_price',
                'title' => '長期未調整進貨單價',
                'message' => '以下商品的進貨單價在過去 90 天內未曾變動，建議確認是否需要重新議價。',
                'stale_items' => $stalePriceItems,
            ];
        }

        return [
            'has_warnings' => !empty($warnings),
            'warnings' => $warnings,
        ];
    }

    /**
     * 檢查長期未調整單價的品項
     *
     * 邏輯：針對每個品項，查詢同供應商在過去 90 天內的所有進貨單價。
     * 若所有紀錄的單價皆相同，且至少有 1 筆以上紀錄，則視為「未調整」。
     *
     * @param array $items 本次進貨的品項列表
     * @param mixed $vendorId 供應商 ID
     * @return array
     */
    private function checkStalePrice(array $items, $vendorId): array
    {
        // dump("Entering checkStalePrice", count($items), $vendorId);
        $staleDays = 90;
        $sinceDate = Carbon::now()->subDays($staleDays);
        $staleItems = [];

        foreach ($items as $item) {
            $productId = (int) $item['product_id'];
            $currentPrice = (float) ($item['unit_price'] ?? 0);

            // 查詢過去 90 天內的所有進貨單品項
            $query = GoodsReceiptItem::whereHas('goodsReceipt', function ($query) use ($vendorId, $sinceDate) {
                if ($vendorId) {
                    $query->where('vendor_id', $vendorId);
                }
                $query->where('received_date', '>=', $sinceDate->format('Y-m-d'))
                    ->where('status', '!=', 'cancelled');
            })
            ->where('product_id', $productId)
            ->with(['goodsReceipt:id,code,received_date'])
            ->orderBy('id', 'desc');

            $historicalPrices = $query->get();
            
            // dump("Prod $productId count: " . $historicalPrices->count());

            // 至少需要 1 筆歷史紀錄
            if ($historicalPrices->count() < 1) {
                continue;
            }

            // 檢查所有歷史單價是否完全相同 (排除 Decimal 物件比對問題)
            $prices = $historicalPrices->map(fn($h) => round((float)$h->unit_price, 2));
            $distinctPricesCount = $prices->unique()->count();

            if ($distinctPricesCount > 1) {
                continue; // 歷史上有變動過
            }

            $historicalPrice = $prices->first();

            // 本次單價也跟歷史相同 (容許小數差距)
            if (round($currentPrice, 2) === round($historicalPrice, 2)) {
                $oldestReceipt = $historicalPrices->last();
                $newestReceipt = $historicalPrices->first();

                $staleItems[] = [
                    'product_id' => $productId,
                    'product_name' => $item['product_name'] ?? '未知商品',
                    'unit_price' => $currentPrice,
                    'record_count' => $historicalPrices->count(),
                    'earliest_date' => $oldestReceipt->goodsReceipt->received_date->format('Y-m-d'),
                    'latest_date' => $newestReceipt->goodsReceipt->received_date->format('Y-m-d'),
                    'latest_code' => $newestReceipt->goodsReceipt->code,
                ];
            }
        }

        return $staleItems;
    }
}