index.php

<?php

require 'classes/Product.php';
require 'classes/ProductList.php';


class Application
{
    private $control;

    public function __construct(ProductList $control)
    {
        $this->control = $control;
    }


    function run()
    {
        echo 'Welcome!' . PHP_EOL;

        while (true) {

            $this->control->loadProducts();

            echo 'Press 1 to add product' . PHP_EOL;
            echo 'Press 2 to remove product' . PHP_EOL;
            echo 'Press 3 to show all products' . PHP_EOL;
            echo 'Press 0 to exit' . PHP_EOL;

            $input = readline('Your choice!') . PHP_EOL;
            switch ($input) {
                case 1 :
                    system('clear');
                    $name = readline('Enter name of the product: ');
                    $exist = $this->control->checkExistance($name);
                    if ($exist == false) {
                        $amount = readline('Enter amount of the product: ');
                        $type = readline('Enter type of amount (kg or pieces): ');
                        $this->control->addProduct($name, $amount, $type);
                    } else {
                        system('clear');
                        $amount = readline('This product already exists! Enter the amount in ' . $exist . ' : ');
                        $this->control->editProduct($name, $amount);
                    }
                    break;
                case 2:
                    $name = readline('Enter name of the product: ');
                    $this->control->removeProduct($name);
                    break;
                case 3:
                    system('clear');
                    echo implode('', $this->control->showProducts()) . PHP_EOL;
                    readline();
                    break;
                case 0:
                    echo 'Bye!' . PHP_EOL;
                    die;
            }
        }
    }
}

$app = new Application(new ProductList());
$app->run();