<?php

// define the database
define("DB_SERVER","localhost");
define("DB_USERNAME","username");
define("DB_PASSWORD","password");
define("DB_NAME","name");

// settle the connection for MySQLi
$connection = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME) or die ("Cannot connect to database");

// read input from user
$product_code = isset($_POST["product-code"]);
$product_name = isset($_POST["product-name"]);
$product_stock = isset($_POST["product-stock"]);

// reading input from user
if(isset($_POST["add_product"])) {
    if (empty($_POST["product_code"]) || empty($_POST["product_name"]) || empty($_POST["product_stock"])) {
        echo "Kolom kode produk, nama produk, dan persediaan produk harus diisi";
    } else {

        // test input function for validating
        function test_input($data) {
            $data = trim($data);
            $data = stripslashes($data);
            $data = htmlspecialchars($data);
            return $data;
        }

        // validate the data that the user input by test_input function
        if ($_SERVER["REQUEST_METHOD"] == "POST") {
            $product_code = test_input($_POST["product_code"]);
            $product_name = test_input($_POST["product_name"]);
            $product_stock = test_input($_POST["product_stock"]);
        }

        // protect SQL Injecetion
        $product_code = mysqli_real_escape_string($connection, $product_code);
        $product_name = mysqli_real_escape_string($connection, $product_name);
        $product_stock = mysqli_real_escape_string($connection, $product_stock);

        // check and insert into database
        $query = "insert into inventory (no_product, nama_product, stock_product) VALUES ('$product_code', '$product_name', '$product_stock')";
        $kueri = "select * from inventory where no_product = '$product_code' and nama_product = '$product_name' and stock_product = '$product_stock'";
        $result = mysqli_query($connection, $kueri) or die (mysql_error());
        $row = mysqli_fetch_array($result, MYSQLI_ASSOC);
        if (mysqli_num_rows($result) == 1) {
            if ($row["no_product"] == $product_code) {
                echo "Data sudah ada<br />";
            }
        } else {
            $execute = mysqli_query($connection, $query) or die (mysql_error());
            echo "Data sudah ditambahkan";
        }

        // close connection access
        $connection -> close();
    }
}

?>