<?php

namespace App\Modules\Sales\Controllers;

use App\Http\Controllers\Controller;
use App\Modules\Sales\Models\SalesImportBatch;
use App\Modules\Sales\Imports\SalesImport;
use App\Modules\Inventory\Services\InventoryService; // Assuming this exists or we need to use ProductService
use Illuminate\Http\Request;
use Inertia\Inertia;
use Maatwebsite\Excel\Facades\Excel;
use Illuminate\Support\Facades\DB;

class SalesImportController extends Controller
{
    public function index(Request $request)
    {
        $perPage = $request->input('per_page', 10);

        $batches = SalesImportBatch::with('importer')
            ->orderByDesc('created_at')
            ->paginate($perPage)
            ->withQueryString();

        return Inertia::render('Sales/Import/Index', [
            'batches' => $batches,
            'filters' => [
                'per_page' => $perPage,
            ],
        ]);
    }

    public function create()
    {
        return Inertia::render('Sales/Import/Create');
    }

    public function store(Request $request)
    {
        $request->validate([
            'file' => 'required|file|mimes:xlsx,xls,csv,zip',
        ]);

        DB::transaction(function () use ($request) {
            $batch = SalesImportBatch::create([
                'import_date' => now(),
                'imported_by' => auth()->id(),
                'status' => 'pending',
                'tenant_id' => tenant('id'), // If tenant context requires it, but usually automatic
            ]);

            Excel::import(new SalesImport($batch), $request->file('file'));
        });

        return redirect()->route('sales-imports.index')->with('success', '匯入成功，請確認內容。');
    }

    public function show(Request $request, SalesImportBatch $import)
    {
        $import->load(['items', 'importer']);
        
        $perPage = $request->input('per_page', 10);
        
        return Inertia::render('Sales/Import/Show', [
            'import' => $import,
            'items' => $import->items()->with(['product', 'warehouse'])->paginate($perPage)->withQueryString(),
            'filters' => [
                'per_page' => $perPage,
            ],
        ]);
    }

    public function confirm(SalesImportBatch $import, InventoryService $inventoryService)
    {
        if ($import->status !== 'pending') {
            return back()->with('error', '此批次無法確認。');
        }

        DB::transaction(function () use ($import, $inventoryService) {
            // 1. Prepare Aggregation
            $aggregatedDeductions = []; // Key: "warehouse_id:product_id:slot"
            
            // Pre-load necessary warehouses for matching
            $machineIds = $import->items->pluck('machine_id')->filter()->unique();
            $warehouses = \App\Modules\Inventory\Models\Warehouse::whereIn('code', $machineIds)->get()->keyBy('code');

            foreach ($import->items as $item) {
                // Only process shipped items with a valid product
                if ($item->product_id && $item->original_status === '已出貨') {
                    // Resolve Warehouse from Machine ID
                    $warehouse = $warehouses->get($item->machine_id);
                    
                    // Skip if machine_id is empty or warehouse not found
                    if (!$warehouse) {
                        continue;
                    }

                    // Aggregation Key includes Slot (貨道)
                    $slot = $item->slot ?: '';
                    $key = "{$warehouse->id}:{$item->product_id}:{$slot}";
                    
                    if (!isset($aggregatedDeductions[$key])) {
                        $aggregatedDeductions[$key] = [
                            'warehouse_id' => $warehouse->id,
                            'product_id' => $item->product_id,
                            'slot' => $slot,
                            'quantity' => 0,
                            'details' => []
                        ];
                    }
                    
                    $aggregatedDeductions[$key]['quantity'] += $item->quantity;
                    $aggregatedDeductions[$key]['details'][] = $item->transaction_serial;
                }
            }

            // 2. Execute Aggregated Deductions
            foreach ($aggregatedDeductions as $deduction) {
                // Construct a descriptive reason
                $serialCount = count($deduction['details']);
                $reason = "銷售出貨彙總 (批號: {$import->id}, 貨道: {$deduction['slot']}, 共 {$serialCount} 筆交易)";
                
                $inventoryService->decreaseStock(
                    $deduction['product_id'],
                    $deduction['warehouse_id'],
                    $deduction['quantity'],
                    $reason,
                    true, // Force deduction
                    $deduction['slot'] // Location/Slot
                );
            }

            // 3. Update Batch Status
            $import->update([
                'status' => 'confirmed',
                'confirmed_at' => now(),
            ]);
        });

        return redirect()->route('sales-imports.index')->with('success', '已彙總（含貨道）並扣除庫存。');
    }

    public function destroy(SalesImportBatch $import)
    {
        if ($import->status !== 'pending') {
            return back()->with('error', '只能刪除待確認的批次。');
        }

        $import->delete();
        return redirect()->route('sales-imports.index')->with('success', '已刪除匯入批次。');
    }
}