cart.inc.php

<?php
	include_once('includes/functions.inc.php');
  	session_start();
?>

<?php
	if (isset($_POST['add'])) {

		$menu = $_GET['menu'];

		// Cart has at least one product
		if (isset($_SESSION['cart'])) {

			try {
				$checkUnit = new check();
				$pid = $_GET['id'];
				$sql = "SELECT Quantity FROM product WHERE Product_ID = '$pid';";
        		$result = mysqli_query($conn, $sql);
        		$rowQuantity = mysqli_fetch_assoc($result);
				$checkUnit->checkProductQuantity($_POST['amount'], $rowQuantity['Quantity']);

				$item_array_id = array_column($_SESSION['cart'], "product_id");

				// New product is added
				if (!in_array($_GET['id'], $item_array_id)) {

					$count = count($_SESSION['cart']);

					$item_array = array(
						'product_id' => $_GET['id'],
						'item_name' => $_POST['hidden_name'],
						'item_price' => $_POST['hidden_price'],
						'item_amount' => $_POST['amount']
					);

					$_SESSION['cart'][$count] = $item_array;
					//echo '<script>window.location="index.php"</script>';
					$checkSou = new check();
					$checkSou->checkSource($menu);
				}
				// Not allow duplicate product
				else {
					echo '<script>alert("Product is added")</script>';
					//echo '<script>window.location="index.php"</script>';
					$checkSou = new check();
					$checkSou->checkSource($menu);
					
				}
			}
			catch(Exception $e) {
				$checkSou = new check();
				$checkSou->checkSource($menu);
				echo $e->getMessage();
			}

		}
		// First product is added into cart
		else {
			$item_array = array(
				'product_id' => $_GET['id'],
				'item_name' => $_POST['hidden_name'],
				'item_price' => $_POST['hidden_price'],
				'item_amount' => $_POST['amount']
			);

			$_SESSION['cart'][0] = $item_array;
			//echo '<script>window.location="index.php"</script>';
			$checkSou = new check();
			$checkSou->checkSource($menu);
		}
	}

	// Delete product in cart
	if (isset($_GET['action'])) {
		if ($_GET['action'] == "delete") {
			foreach ($_SESSION['cart'] as $key => $value) {
				if ($value['product_id'] == $_GET['id']) {
					unset($_SESSION['cart'][$key]);
					echo '<script>alert("Product is removed")</script>';
					echo '<script>window.location="cart.php"</script>';
				}
			}
		}
	}