PagesController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Product;
use App\Http\Requests;
use App\Http\Controllers\Controller;

class PagesController extends Controller
{
    public function index() {
    	return view('home');
    }

    public function pasted(Request $request) {

    	if ($request->mode === 'replace') {
    		Product::truncate();
    	}

    	$lines = explode("\n", $request->sku_quantity);

    	foreach ($lines as $line) {
    		$line = trim($line);

    		$parts = explode(',', $line);

    		$sku = trim($parts[0]);
    		$quantity = trim($parts[1]);

    		if ($request->mode === 'add' && $new = Product::where('sku', $sku)->first()) {
    			$currentQuantity = $new->quantity;
    			Product::where('sku', $sku)->update(['quantity' => $quantity + $currentQuantity]);
    		}

    		if ($quantity > 0 && ! isset($new)) {
    			Product::firstOrCreate(['sku' => $sku, 'quantity' => $quantity]);
    		}
    	}
    	return view('success');
    }
}