<?php

namespace Modules\IndustrialEngineering\Services;

use App\Product;
use App\Variation;
use Illuminate\Support\Facades\DB;
use Modules\IndustrialEngineering\Models\ItemMaster;

/**
 * Links IE item masters to core ERP products/variations for stock, purchase, sales, costing.
 */
class ErpItemLinkService
{
    /**
     * Try to match item to ERP product by SKU or name.
     *
     * @return array{linked: bool, message: string, variation_id?: int}
     */
    public function autoMatchProduct(ItemMaster $item): array
    {
        if ($item->variation_id) {
            return ['linked' => true, 'message' => __('industrialengineering::lang.auto_erp_already_linked')];
        }

        $variation = Variation::query()
            ->whereHas('product', fn ($q) => $q->where('business_id', $item->business_id))
            ->where(function ($q) use ($item) {
                $q->where('sub_sku', $item->item_code)
                    ->orWhere('sub_sku', 'like', $item->item_code.'%');
            })
            ->with('product')
            ->first();

        if (! $variation) {
            $variation = Variation::query()
                ->whereHas('product', function ($q) use ($item) {
                    $q->where('business_id', $item->business_id)
                        ->where('name', 'like', '%'.$item->name.'%');
                })
                ->with('product')
                ->first();
        }

        if ($variation) {
            $this->linkItem($item, ['variation_id' => $variation->id]);

            return [
                'linked' => true,
                'message' => __('industrialengineering::lang.auto_erp_matched', ['name' => $this->variationLabel($variation)]),
                'variation_id' => $variation->id,
            ];
        }

        return [
            'linked' => false,
            'message' => __('industrialengineering::lang.auto_erp_not_found', ['code' => $item->item_code]),
        ];
    }
    public function linkItem(ItemMaster $item, array $data): ItemMaster
    {
        $updates = [];

        if (! empty($data['variation_id'])) {
            $variation = Variation::with('product')->find($data['variation_id']);
            if ($variation) {
                $updates['variation_id'] = $variation->id;
                $updates['product_id'] = $variation->product_id;
                if (empty($data['standard_cost']) && $variation->dpp_inc_tax) {
                    $updates['standard_cost'] = $variation->dpp_inc_tax;
                }
                if (empty($item->name) || $item->name === $item->item_code) {
                    $updates['name'] = $this->variationLabel($variation);
                }
            }
        } elseif (! empty($data['product_id'])) {
            $product = Product::find($data['product_id']);
            if ($product) {
                $updates['product_id'] = $product->id;
                $variation = $product->variations()->first();
                if ($variation) {
                    $updates['variation_id'] = $variation->id;
                }
            }
        }

        if ($updates) {
            $item->update($updates);
        }

        return $item->fresh(['product', 'variation']);
    }

    public function erpLabel(?ItemMaster $item): ?string
    {
        if (! $item) {
            return null;
        }

        if ($item->variation_id) {
            $variation = $item->variation ?? Variation::with('product')->find($item->variation_id);
            if ($variation) {
                return $this->variationLabel($variation);
            }
        }

        if ($item->product_id && ($product = $item->product ?? Product::find($item->product_id))) {
            return $product->name;
        }

        return null;
    }

    public function variationLabel(?Variation $variation): string
    {
        if (! $variation) {
            return '';
        }

        $variation->loadMissing('product');
        $label = $variation->product->name ?? 'محصول';
        if (($variation->product->type ?? '') === 'variable') {
            $label .= ' — '.$variation->name;
        }

        return $label;
    }

    public function stockSummary(ItemMaster $item): array
    {
        if (! $item->variation_id) {
            return ['linked' => false, 'qty' => 0];
        }

        $qty = \DB::table('variation_location_details')
            ->where('variation_id', $item->variation_id)
            ->sum('qty_available');

        return ['linked' => true, 'qty' => (float) $qty];
    }
}