<?php
// Separate the logic from the HTML, in general you shouldn't have code which modifes the database in the same
// file as an HTML page
// Your database connection info - this will probably be defined somewhere else in you app, not in this file
const DB_HOST = 'localhost';
const DB_NAME = '*';
const DB_USER = '*';
const DB_PASS = '*';
// if you don't know what this does, you probably want utf8mb4. For a very old version of MySQL, you want utf8
const DB_CHARSET = 'utf8mb4';
// While developing, turn error reporting up to max and make PHP display the error messages
ini_set('display_errors', '1');
error_reporting(-1);
// First validate the request before doing anything else
// only allow POST requests
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    header('HTTP/1.1 405 Method Not Allowed');
    exit;
}
// Check that all the required form fields are defined
+if (!isset($_POST['user_id'], $_POST['winst'], $_POST['verlies'])) {
    header('HTTP/1.1 400 Bad Request');
    exit;
}
try {
    // connect to the database - again this will probably be done somewhere else in your app
    $dsn = sprintf('mysql:host=%s;dbname=%s;charset=%s', DB_HOST, DB_NAME, DB_CHARSET);
    $db = new PDO($dsn, DB_USER, DB_PASS);
    $db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); // turn off emulated prepares
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); // have PDO throw exceptions when something goes wrong
    // Prepare the query
    $stmt = $db->prepare("
      UPDATE info
      SET resultaten = resultaten + (:winst - :verlies)
      WHERE id = :user_id
    ");
    // all of these values are expected to be integers, so cast them. Anything
    // that's not a valid integer will probably end up being zero.
    $stmt->execute([
        'user_id' => (int)$_POST['user_id'],
        'winst' => (int)$_POST['winst'],
        'verlies' => (int)$_POST['verlies'],
    ]);
} catch (PDOException $e) {
    // When something goes wrong, log the error and tell the client
    error_log((string)$e);
    header('HTTP/1.1 500 Internal Server Error');
    exit;
}
// If we get here everything worked, so redirect to the results page
header('HTTP/1.1 303 See Other');
header('Location: http://fluffyme.xyz/code/workspace/CoinInfo/info.php');
?>